pragma solidity =0.6.6;

interface IUniswapV2Factory {
    event PairCreated(address indexed token0, address indexed token1, address pair, uint);

    function feeTo() external view returns (address);
    function feeToSetter() external view returns (address);

    function getPair(address tokenA, address tokenB) external view returns (address pair);
    function allPairs(uint) external view returns (address pair);
    function allPairsLength() external view returns (uint);

    function createPair(address tokenA, address tokenB) external returns (address pair);

    function setFeeTo(address) external;
    function setFeeToSetter(address) external;
}

interface IUniswapV2Pair {
    event Approval(address indexed owner, address indexed spender, uint value);
    event Transfer(address indexed from, address indexed to, uint value);

    function name() external pure returns (string memory);
    function symbol() external pure returns (string memory);
    function decimals() external pure returns (uint8);
    function totalSupply() external view returns (uint);
    function balanceOf(address owner) external view returns (uint);
    function allowance(address owner, address spender) external view returns (uint);

    function approve(address spender, uint value) external returns (bool);
    function transfer(address to, uint value) external returns (bool);
    function transferFrom(address from, address to, uint value) external returns (bool);

    function DOMAIN_SEPARATOR() external view returns (bytes32);
    function PERMIT_TYPEHASH() external pure returns (bytes32);
    function nonces(address owner) external view returns (uint);

    function permit(address owner, address spender, uint value, uint deadline, uint8 v, bytes32 r, bytes32 s) external;

    event Mint(address indexed sender, uint amount0, uint amount1);
    event Burn(address indexed sender, uint amount0, uint amount1, address indexed to);
    event Swap(
        address indexed sender,
        uint amount0In,
        uint amount1In,
        uint amount0Out,
        uint amount1Out,
        address indexed to
    );
    event Sync(uint112 reserve0, uint112 reserve1);

    function MINIMUM_LIQUIDITY() external pure returns (uint);
    function factory() external view returns (address);
    function token0() external view returns (address);
    function token1() external view returns (address);
    function getReserves() external view returns (uint112 reserve0, uint112 reserve1, uint32 blockTimestampLast);
    function price0CumulativeLast() external view returns (uint);
    function price1CumulativeLast() external view returns (uint);
    function kLast() external view returns (uint);

    function mint(address to) external returns (uint liquidity);
    function burn(address to) external returns (uint amount0, uint amount1);
    function swap(uint amount0Out, uint amount1Out, address to, bytes calldata data) external;
    function skim(address to) external;
    function sync() external;

    function initialize(address, address) external;
}

interface IUniswapV2Router01 {
    function factory() external pure returns (address);
    function WETH() external pure returns (address);

    function addLiquidity(
        address tokenA,
        address tokenB,
        uint amountADesired,
        uint amountBDesired,
        uint amountAMin,
        uint amountBMin,
        address to,
        uint deadline
    ) external returns (uint amountA, uint amountB, uint liquidity);
    function addLiquidityETH(
        address token,
        uint amountTokenDesired,
        uint amountTokenMin,
        uint amountETHMin,
        address to,
        uint deadline
    ) external payable returns (uint amountToken, uint amountETH, uint liquidity);
    function removeLiquidity(
        address tokenA,
        address tokenB,
        uint liquidity,
        uint amountAMin,
        uint amountBMin,
        address to,
        uint deadline
    ) external returns (uint amountA, uint amountB);
    function removeLiquidityETH(
        address token,
        uint liquidity,
        uint amountTokenMin,
        uint amountETHMin,
        address to,
        uint deadline
    ) external returns (uint amountToken, uint amountETH);
    function removeLiquidityWithPermit(
        address tokenA,
        address tokenB,
        uint liquidity,
        uint amountAMin,
        uint amountBMin,
        address to,
        uint deadline,
        bool approveMax, uint8 v, bytes32 r, bytes32 s
    ) external returns (uint amountA, uint amountB);
    function removeLiquidityETHWithPermit(
        address token,
        uint liquidity,
        uint amountTokenMin,
        uint amountETHMin,
        address to,
        uint deadline,
        bool approveMax, uint8 v, bytes32 r, bytes32 s
    ) external returns (uint amountToken, uint amountETH);
    function swapExactTokensForTokens(
        uint amountIn,
        uint amountOutMin,
        address[] calldata path,
        address to,
        uint deadline
    ) external returns (uint[] memory amounts);
    function swapTokensForExactTokens(
        uint amountOut,
        uint amountInMax,
        address[] calldata path,
        address to,
        uint deadline
    ) external returns (uint[] memory amounts);
    function swapExactETHForTokens(uint amountOutMin, address[] calldata path, address to, uint deadline)
        external
        payable
        returns (uint[] memory amounts);
    function swapTokensForExactETH(uint amountOut, uint amountInMax, address[] calldata path, address to, uint deadline)
        external
        returns (uint[] memory amounts);
    function swapExactTokensForETH(uint amountIn, uint amountOutMin, address[] calldata path, address to, uint deadline)
        external
        returns (uint[] memory amounts);
    function swapETHForExactTokens(uint amountOut, address[] calldata path, address to, uint deadline)
        external
        payable
        returns (uint[] memory amounts);

    function quote(uint amountA, uint reserveA, uint reserveB) external pure returns (uint amountB);
    function getAmountOut(uint amountIn, uint reserveIn, uint reserveOut) external pure returns (uint amountOut);
    function getAmountIn(uint amountOut, uint reserveIn, uint reserveOut) external pure returns (uint amountIn);
    function getAmountsOut(uint amountIn, address[] calldata path) external view returns (uint[] memory amounts);
    function getAmountsIn(uint amountOut, address[] calldata path) external view returns (uint[] memory amounts);
}

interface IUniswapV2Router02 is IUniswapV2Router01 {
    function removeLiquidityETHSupportingFeeOnTransferTokens(
        address token,
        uint liquidity,
        uint amountTokenMin,
        uint amountETHMin,
        address to,
        uint deadline
    ) external returns (uint amountETH);
    function removeLiquidityETHWithPermitSupportingFeeOnTransferTokens(
        address token,
        uint liquidity,
        uint amountTokenMin,
        uint amountETHMin,
        address to,
        uint deadline,
        bool approveMax, uint8 v, bytes32 r, bytes32 s
    ) external returns (uint amountETH);

    function swapExactTokensForTokensSupportingFeeOnTransferTokens(
        uint amountIn,
        uint amountOutMin,
        address[] calldata path,
        address to,
        uint deadline
    ) external;
    function swapExactETHForTokensSupportingFeeOnTransferTokens(
        uint amountOutMin,
        address[] calldata path,
        address to,
        uint deadline
    ) external payable;
    function swapExactTokensForETHSupportingFeeOnTransferTokens(
        uint amountIn,
        uint amountOutMin,
        address[] calldata path,
        address to,
        uint deadline
    ) external;
}

interface IERC20 {
    event Approval(address indexed owner, address indexed spender, uint value);
    event Transfer(address indexed from, address indexed to, uint value);

    function name() external view returns (string memory);
    function symbol() external view returns (string memory);
    function decimals() external view returns (uint8);
    function totalSupply() external view returns (uint);
    function balanceOf(address owner) external view returns (uint);
    function allowance(address owner, address spender) external view returns (uint);

    function approve(address spender, uint value) external returns (bool);
    function transfer(address to, uint value) external returns (bool);
    function transferFrom(address from, address to, uint value) external returns (bool);
}

interface IWETH {
    function deposit() external payable;
    function transfer(address to, uint value) external returns (bool);
    function withdraw(uint) external;
}

contract UniswapV2Router02 is IUniswapV2Router02 {
    using SafeMath for uint;

    address public immutable override factory;
    address public immutable override WETH;

    modifier ensure(uint deadline) {
        require(deadline >= block.timestamp, 'UniswapV2Router: EXPIRED');
        _;
    }

    constructor(address _factory, address _WETH) public {
        factory = _factory;
        WETH = _WETH;
    }

    receive() external payable {
        assert(msg.sender == WETH); // only accept ETH via fallback from the WETH contract
    }

    // **** ADD LIQUIDITY ****
    function _addLiquidity(
        address tokenA,
        address tokenB,
        uint amountADesired,
        uint amountBDesired,
        uint amountAMin,
        uint amountBMin
    ) internal virtual returns (uint amountA, uint amountB) {
        // create the pair if it doesn't exist yet
        if (IUniswapV2Factory(factory).getPair(tokenA, tokenB) == address(0)) {
            IUniswapV2Factory(factory).createPair(tokenA, tokenB);
        }
        (uint reserveA, uint reserveB) = UniswapV2Library.getReserves(factory, tokenA, tokenB);
        if (reserveA == 0 && reserveB == 0) {
            (amountA, amountB) = (amountADesired, amountBDesired);
        } else {
            uint amountBOptimal = UniswapV2Library.quote(amountADesired, reserveA, reserveB);
            if (amountBOptimal <= amountBDesired) {
                require(amountBOptimal >= amountBMin, 'UniswapV2Router: INSUFFICIENT_B_AMOUNT');
                (amountA, amountB) = (amountADesired, amountBOptimal);
            } else {
                uint amountAOptimal = UniswapV2Library.quote(amountBDesired, reserveB, reserveA);
                assert(amountAOptimal <= amountADesired);
                require(amountAOptimal >= amountAMin, 'UniswapV2Router: INSUFFICIENT_A_AMOUNT');
                (amountA, amountB) = (amountAOptimal, amountBDesired);
            }
        }
    }
    function addLiquidity(
        address tokenA,
        address tokenB,
        uint amountADesired,
        uint amountBDesired,
        uint amountAMin,
        uint amountBMin,
        address to,
        uint deadline
    ) external virtual override ensure(deadline) returns (uint amountA, uint amountB, uint liquidity) {
        (amountA, amountB) = _addLiquidity(tokenA, tokenB, amountADesired, amountBDesired, amountAMin, amountBMin);
        address pair = UniswapV2Library.pairFor(factory, tokenA, tokenB);
        TransferHelper.safeTransferFrom(tokenA, msg.sender, pair, amountA);
        TransferHelper.safeTransferFrom(tokenB, msg.sender, pair, amountB);
        liquidity = IUniswapV2Pair(pair).mint(to);
    }
    function addLiquidityETH(
        address token,
        uint amountTokenDesired,
        uint amountTokenMin,
        uint amountETHMin,
        address to,
        uint deadline
    ) external virtual override payable ensure(deadline) returns (uint amountToken, uint amountETH, uint liquidity) {
        (amountToken, amountETH) = _addLiquidity(
            token,
            WETH,
            amountTokenDesired,
            msg.value,
            amountTokenMin,
            amountETHMin
        );
        address pair = UniswapV2Library.pairFor(factory, token, WETH);
        TransferHelper.safeTransferFrom(token, msg.sender, pair, amountToken);
        IWETH(WETH).deposit{value: amountETH}();
        assert(IWETH(WETH).transfer(pair, amountETH));
        liquidity = IUniswapV2Pair(pair).mint(to);
        // refund dust eth, if any
        if (msg.value > amountETH) TransferHelper.safeTransferETH(msg.sender, msg.value - amountETH);
    }

    // **** REMOVE LIQUIDITY ****
    function removeLiquidity(
        address tokenA,
        address tokenB,
        uint liquidity,
        uint amountAMin,
        uint amountBMin,
        address to,
        uint deadline
    ) public virtual override ensure(deadline) returns (uint amountA, uint amountB) {
        address pair = UniswapV2Library.pairFor(factory, tokenA, tokenB);
        IUniswapV2Pair(pair).transferFrom(msg.sender, pair, liquidity); // send liquidity to pair
        (uint amount0, uint amount1) = IUniswapV2Pair(pair).burn(to);
        (address token0,) = UniswapV2Library.sortTokens(tokenA, tokenB);
        (amountA, amountB) = tokenA == token0 ? (amount0, amount1) : (amount1, amount0);
        require(amountA >= amountAMin, 'UniswapV2Router: INSUFFICIENT_A_AMOUNT');
        require(amountB >= amountBMin, 'UniswapV2Router: INSUFFICIENT_B_AMOUNT');
    }
    function removeLiquidityETH(
        address token,
        uint liquidity,
        uint amountTokenMin,
        uint amountETHMin,
        address to,
        uint deadline
    ) public virtual override ensure(deadline) returns (uint amountToken, uint amountETH) {
        (amountToken, amountETH) = removeLiquidity(
            token,
            WETH,
            liquidity,
            amountTokenMin,
            amountETHMin,
            address(this),
            deadline
        );
        TransferHelper.safeTransfer(token, to, amountToken);
        IWETH(WETH).withdraw(amountETH);
        TransferHelper.safeTransferETH(to, amountETH);
    }
    function removeLiquidityWithPermit(
        address tokenA,
        address tokenB,
        uint liquidity,
        uint amountAMin,
        uint amountBMin,
        address to,
        uint deadline,
        bool approveMax, uint8 v, bytes32 r, bytes32 s
    ) external virtual override returns (uint amountA, uint amountB) {
        address pair = UniswapV2Library.pairFor(factory, tokenA, tokenB);
        uint value = approveMax ? uint(-1) : liquidity;
        IUniswapV2Pair(pair).permit(msg.sender, address(this), value, deadline, v, r, s);
        (amountA, amountB) = removeLiquidity(tokenA, tokenB, liquidity, amountAMin, amountBMin, to, deadline);
    }
    function removeLiquidityETHWithPermit(
        address token,
        uint liquidity,
        uint amountTokenMin,
        uint amountETHMin,
        address to,
        uint deadline,
        bool approveMax, uint8 v, bytes32 r, bytes32 s
    ) external virtual override returns (uint amountToken, uint amountETH) {
        address pair = UniswapV2Library.pairFor(factory, token, WETH);
        uint value = approveMax ? uint(-1) : liquidity;
        IUniswapV2Pair(pair).permit(msg.sender, address(this), value, deadline, v, r, s);
        (amountToken, amountETH) = removeLiquidityETH(token, liquidity, amountTokenMin, amountETHMin, to, deadline);
    }

    // **** REMOVE LIQUIDITY (supporting fee-on-transfer tokens) ****
    function removeLiquidityETHSupportingFeeOnTransferTokens(
        address token,
        uint liquidity,
        uint amountTokenMin,
        uint amountETHMin,
        address to,
        uint deadline
    ) public virtual override ensure(deadline) returns (uint amountETH) {
        (, amountETH) = removeLiquidity(
            token,
            WETH,
            liquidity,
            amountTokenMin,
            amountETHMin,
            address(this),
            deadline
        );
        TransferHelper.safeTransfer(token, to, IERC20(token).balanceOf(address(this)));
        IWETH(WETH).withdraw(amountETH);
        TransferHelper.safeTransferETH(to, amountETH);
    }
    function removeLiquidityETHWithPermitSupportingFeeOnTransferTokens(
        address token,
        uint liquidity,
        uint amountTokenMin,
        uint amountETHMin,
        address to,
        uint deadline,
        bool approveMax, uint8 v, bytes32 r, bytes32 s
    ) external virtual override returns (uint amountETH) {
        address pair = UniswapV2Library.pairFor(factory, token, WETH);
        uint value = approveMax ? uint(-1) : liquidity;
        IUniswapV2Pair(pair).permit(msg.sender, address(this), value, deadline, v, r, s);
        amountETH = removeLiquidityETHSupportingFeeOnTransferTokens(
            token, liquidity, amountTokenMin, amountETHMin, to, deadline
        );
    }

    // **** SWAP ****
    // requires the initial amount to have already been sent to the first pair
    function _swap(uint[] memory amounts, address[] memory path, address _to) internal virtual {
        for (uint i; i < path.length - 1; i++) {
            (address input, address output) = (path[i], path[i + 1]);
            (address token0,) = UniswapV2Library.sortTokens(input, output);
            uint amountOut = amounts[i + 1];
            (uint amount0Out, uint amount1Out) = input == token0 ? (uint(0), amountOut) : (amountOut, uint(0));
            address to = i < path.length - 2 ? UniswapV2Library.pairFor(factory, output, path[i + 2]) : _to;
            IUniswapV2Pair(UniswapV2Library.pairFor(factory, input, output)).swap(
                amount0Out, amount1Out, to, new bytes(0)
            );
        }
    }
    function swapExactTokensForTokens(
        uint amountIn,
        uint amountOutMin,
        address[] calldata path,
        address to,
        uint deadline
    ) external virtual override ensure(deadline) returns (uint[] memory amounts) {
        amounts = UniswapV2Library.getAmountsOut(factory, amountIn, path);
        require(amounts[amounts.length - 1] >= amountOutMin, 'UniswapV2Router: INSUFFICIENT_OUTPUT_AMOUNT');
        TransferHelper.safeTransferFrom(
            path[0], msg.sender, UniswapV2Library.pairFor(factory, path[0], path[1]), amounts[0]
        );
        _swap(amounts, path, to);
    }
    function swapTokensForExactTokens(
        uint amountOut,
        uint amountInMax,
        address[] calldata path,
        address to,
        uint deadline
    ) external virtual override ensure(deadline) returns (uint[] memory amounts) {
        amounts = UniswapV2Library.getAmountsIn(factory, amountOut, path);
        require(amounts[0] <= amountInMax, 'UniswapV2Router: EXCESSIVE_INPUT_AMOUNT');
        TransferHelper.safeTransferFrom(
            path[0], msg.sender, UniswapV2Library.pairFor(factory, path[0], path[1]), amounts[0]
        );
        _swap(amounts, path, to);
    }
    function swapExactETHForTokens(uint amountOutMin, address[] calldata path, address to, uint deadline)
        external
        virtual
        override
        payable
        ensure(deadline)
        returns (uint[] memory amounts)
    {
        require(path[0] == WETH, 'UniswapV2Router: INVALID_PATH');
        amounts = UniswapV2Library.getAmountsOut(factory, msg.value, path);
        require(amounts[amounts.length - 1] >= amountOutMin, 'UniswapV2Router: INSUFFICIENT_OUTPUT_AMOUNT');
        IWETH(WETH).deposit{value: amounts[0]}();
        assert(IWETH(WETH).transfer(UniswapV2Library.pairFor(factory, path[0], path[1]), amounts[0]));
        _swap(amounts, path, to);
    }
    function swapTokensForExactETH(uint amountOut, uint amountInMax, address[] calldata path, address to, uint deadline)
        external
        virtual
        override
        ensure(deadline)
        returns (uint[] memory amounts)
    {
        require(path[path.length - 1] == WETH, 'UniswapV2Router: INVALID_PATH');
        amounts = UniswapV2Library.getAmountsIn(factory, amountOut, path);
        require(amounts[0] <= amountInMax, 'UniswapV2Router: EXCESSIVE_INPUT_AMOUNT');
        TransferHelper.safeTransferFrom(
            path[0], msg.sender, UniswapV2Library.pairFor(factory, path[0], path[1]), amounts[0]
        );
        _swap(amounts, path, address(this));
        IWETH(WETH).withdraw(amounts[amounts.length - 1]);
        TransferHelper.safeTransferETH(to, amounts[amounts.length - 1]);
    }
    function swapExactTokensForETH(uint amountIn, uint amountOutMin, address[] calldata path, address to, uint deadline)
        external
        virtual
        override
        ensure(deadline)
        returns (uint[] memory amounts)
    {
        require(path[path.length - 1] == WETH, 'UniswapV2Router: INVALID_PATH');
        amounts = UniswapV2Library.getAmountsOut(factory, amountIn, path);
        require(amounts[amounts.length - 1] >= amountOutMin, 'UniswapV2Router: INSUFFICIENT_OUTPUT_AMOUNT');
        TransferHelper.safeTransferFrom(
            path[0], msg.sender, UniswapV2Library.pairFor(factory, path[0], path[1]), amounts[0]
        );
        _swap(amounts, path, address(this));
        IWETH(WETH).withdraw(amounts[amounts.length - 1]);
        TransferHelper.safeTransferETH(to, amounts[amounts.length - 1]);
    }
    function swapETHForExactTokens(uint amountOut, address[] calldata path, address to, uint deadline)
        external
        virtual
        override
        payable
        ensure(deadline)
        returns (uint[] memory amounts)
    {
        require(path[0] == WETH, 'UniswapV2Router: INVALID_PATH');
        amounts = UniswapV2Library.getAmountsIn(factory, amountOut, path);
        require(amounts[0] <= msg.value, 'UniswapV2Router: EXCESSIVE_INPUT_AMOUNT');
        IWETH(WETH).deposit{value: amounts[0]}();
        assert(IWETH(WETH).transfer(UniswapV2Library.pairFor(factory, path[0], path[1]), amounts[0]));
        _swap(amounts, path, to);
        // refund dust eth, if any
        if (msg.value > amounts[0]) TransferHelper.safeTransferETH(msg.sender, msg.value - amounts[0]);
    }

    // **** SWAP (supporting fee-on-transfer tokens) ****
    // requires the initial amount to have already been sent to the first pair
    function _swapSupportingFeeOnTransferTokens(address[] memory path, address _to) internal virtual {
        for (uint i; i < path.length - 1; i++) {
            (address input, address output) = (path[i], path[i + 1]);
            (address token0,) = UniswapV2Library.sortTokens(input, output);
            IUniswapV2Pair pair = IUniswapV2Pair(UniswapV2Library.pairFor(factory, input, output));
            uint amountInput;
            uint amountOutput;
            { // scope to avoid stack too deep errors
            (uint reserve0, uint reserve1,) = pair.getReserves();
            (uint reserveInput, uint reserveOutput) = input == token0 ? (reserve0, reserve1) : (reserve1, reserve0);
            amountInput = IERC20(input).balanceOf(address(pair)).sub(reserveInput);
            amountOutput = UniswapV2Library.getAmountOut(amountInput, reserveInput, reserveOutput);
            }
            (uint amount0Out, uint amount1Out) = input == token0 ? (uint(0), amountOutput) : (amountOutput, uint(0));
            address to = i < path.length - 2 ? UniswapV2Library.pairFor(factory, output, path[i + 2]) : _to;
            pair.swap(amount0Out, amount1Out, to, new bytes(0));
        }
    }
    function swapExactTokensForTokensSupportingFeeOnTransferTokens(
        uint amountIn,
        uint amountOutMin,
        address[] calldata path,
        address to,
        uint deadline
    ) external virtual override ensure(deadline) {
        TransferHelper.safeTransferFrom(
            path[0], msg.sender, UniswapV2Library.pairFor(factory, path[0], path[1]), amountIn
        );
        uint balanceBefore = IERC20(path[path.length - 1]).balanceOf(to);
        _swapSupportingFeeOnTransferTokens(path, to);
        require(
            IERC20(path[path.length - 1]).balanceOf(to).sub(balanceBefore) >= amountOutMin,
            'UniswapV2Router: INSUFFICIENT_OUTPUT_AMOUNT'
        );
    }
    function swapExactETHForTokensSupportingFeeOnTransferTokens(
        uint amountOutMin,
        address[] calldata path,
        address to,
        uint deadline
    )
        external
        virtual
        override
        payable
        ensure(deadline)
    {
        require(path[0] == WETH, 'UniswapV2Router: INVALID_PATH');
        uint amountIn = msg.value;
        IWETH(WETH).deposit{value: amountIn}();
        assert(IWETH(WETH).transfer(UniswapV2Library.pairFor(factory, path[0], path[1]), amountIn));
        uint balanceBefore = IERC20(path[path.length - 1]).balanceOf(to);
        _swapSupportingFeeOnTransferTokens(path, to);
        require(
            IERC20(path[path.length - 1]).balanceOf(to).sub(balanceBefore) >= amountOutMin,
            'UniswapV2Router: INSUFFICIENT_OUTPUT_AMOUNT'
        );
    }
    function swapExactTokensForETHSupportingFeeOnTransferTokens(
        uint amountIn,
        uint amountOutMin,
        address[] calldata path,
        address to,
        uint deadline
    )
        external
        virtual
        override
        ensure(deadline)
    {
        require(path[path.length - 1] == WETH, 'UniswapV2Router: INVALID_PATH');
        TransferHelper.safeTransferFrom(
            path[0], msg.sender, UniswapV2Library.pairFor(factory, path[0], path[1]), amountIn
        );
        _swapSupportingFeeOnTransferTokens(path, address(this));
        uint amountOut = IERC20(WETH).balanceOf(address(this));
        require(amountOut >= amountOutMin, 'UniswapV2Router: INSUFFICIENT_OUTPUT_AMOUNT');
        IWETH(WETH).withdraw(amountOut);
        TransferHelper.safeTransferETH(to, amountOut);
    }

    // **** LIBRARY FUNCTIONS ****
    function quote(uint amountA, uint reserveA, uint reserveB) public pure virtual override returns (uint amountB) {
        return UniswapV2Library.quote(amountA, reserveA, reserveB);
    }

    function getAmountOut(uint amountIn, uint reserveIn, uint reserveOut)
        public
        pure
        virtual
        override
        returns (uint amountOut)
    {
        return UniswapV2Library.getAmountOut(amountIn, reserveIn, reserveOut);
    }

    function getAmountIn(uint amountOut, uint reserveIn, uint reserveOut)
        public
        pure
        virtual
        override
        returns (uint amountIn)
    {
        return UniswapV2Library.getAmountIn(amountOut, reserveIn, reserveOut);
    }

    function getAmountsOut(uint amountIn, address[] memory path)
        public
        view
        virtual
        override
        returns (uint[] memory amounts)
    {
        return UniswapV2Library.getAmountsOut(factory, amountIn, path);
    }

    function getAmountsIn(uint amountOut, address[] memory path)
        public
        view
        virtual
        override
        returns (uint[] memory amounts)
    {
        return UniswapV2Library.getAmountsIn(factory, amountOut, path);
    }
}

// a library for performing overflow-safe math, courtesy of DappHub (https://github.com/dapphub/ds-math)

library SafeMath {
    function add(uint x, uint y) internal pure returns (uint z) {
        require((z = x + y) >= x, 'ds-math-add-overflow');
    }

    function sub(uint x, uint y) internal pure returns (uint z) {
        require((z = x - y) <= x, 'ds-math-sub-underflow');
    }

    function mul(uint x, uint y) internal pure returns (uint z) {
        require(y == 0 || (z = x * y) / y == x, 'ds-math-mul-overflow');
    }
}

library UniswapV2Library {
    using SafeMath for uint;

    // returns sorted token addresses, used to handle return values from pairs sorted in this order
    function sortTokens(address tokenA, address tokenB) internal pure returns (address token0, address token1) {
        require(tokenA != tokenB, 'UniswapV2Library: IDENTICAL_ADDRESSES');
        (token0, token1) = tokenA < tokenB ? (tokenA, tokenB) : (tokenB, tokenA);
        require(token0 != address(0), 'UniswapV2Library: ZERO_ADDRESS');
    }

    // calculates the CREATE2 address for a pair without making any external calls
    function pairFor(address factory, address tokenA, address tokenB) internal pure returns (address pair) {
        (address token0, address token1) = sortTokens(tokenA, tokenB);
        pair = address(uint(keccak256(abi.encodePacked(
                hex'ff',
                factory,
                keccak256(abi.encodePacked(token0, token1)),
                hex'96e8ac4277198ff8b6f785478aa9a39f403cb768dd02cbee326c3e7da348845f' // init code hash
            ))));
    }

    // fetches and sorts the reserves for a pair
    function getReserves(address factory, address tokenA, address tokenB) internal view returns (uint reserveA, uint reserveB) {
        (address token0,) = sortTokens(tokenA, tokenB);
        (uint reserve0, uint reserve1,) = IUniswapV2Pair(pairFor(factory, tokenA, tokenB)).getReserves();
        (reserveA, reserveB) = tokenA == token0 ? (reserve0, reserve1) : (reserve1, reserve0);
    }

    // given some amount of an asset and pair reserves, returns an equivalent amount of the other asset
    function quote(uint amountA, uint reserveA, uint reserveB) internal pure returns (uint amountB) {
        require(amountA > 0, 'UniswapV2Library: INSUFFICIENT_AMOUNT');
        require(reserveA > 0 && reserveB > 0, 'UniswapV2Library: INSUFFICIENT_LIQUIDITY');
        amountB = amountA.mul(reserveB) / reserveA;
    }

    // given an input amount of an asset and pair reserves, returns the maximum output amount of the other asset
    function getAmountOut(uint amountIn, uint reserveIn, uint reserveOut) internal pure returns (uint amountOut) {
        require(amountIn > 0, 'UniswapV2Library: INSUFFICIENT_INPUT_AMOUNT');
        require(reserveIn > 0 && reserveOut > 0, 'UniswapV2Library: INSUFFICIENT_LIQUIDITY');
        uint amountInWithFee = amountIn.mul(997);
        uint numerator = amountInWithFee.mul(reserveOut);
        uint denominator = reserveIn.mul(1000).add(amountInWithFee);
        amountOut = numerator / denominator;
    }

    // given an output amount of an asset and pair reserves, returns a required input amount of the other asset
    function getAmountIn(uint amountOut, uint reserveIn, uint reserveOut) internal pure returns (uint amountIn) {
        require(amountOut > 0, 'UniswapV2Library: INSUFFICIENT_OUTPUT_AMOUNT');
        require(reserveIn > 0 && reserveOut > 0, 'UniswapV2Library: INSUFFICIENT_LIQUIDITY');
        uint numerator = reserveIn.mul(amountOut).mul(1000);
        uint denominator = reserveOut.sub(amountOut).mul(997);
        amountIn = (numerator / denominator).add(1);
    }

    // performs chained getAmountOut calculations on any number of pairs
    function getAmountsOut(address factory, uint amountIn, address[] memory path) internal view returns (uint[] memory amounts) {
        require(path.length >= 2, 'UniswapV2Library: INVALID_PATH');
        amounts = new uint[](path.length);
        amounts[0] = amountIn;
        for (uint i; i < path.length - 1; i++) {
            (uint reserveIn, uint reserveOut) = getReserves(factory, path[i], path[i + 1]);
            amounts[i + 1] = getAmountOut(amounts[i], reserveIn, reserveOut);
        }
    }

    // performs chained getAmountIn calculations on any number of pairs
    function getAmountsIn(address factory, uint amountOut, address[] memory path) internal view returns (uint[] memory amounts) {
        require(path.length >= 2, 'UniswapV2Library: INVALID_PATH');
        amounts = new uint[](path.length);
        amounts[amounts.length - 1] = amountOut;
        for (uint i = path.length - 1; i > 0; i--) {
            (uint reserveIn, uint reserveOut) = getReserves(factory, path[i - 1], path[i]);
            amounts[i - 1] = getAmountIn(amounts[i], reserveIn, reserveOut);
        }
    }
}

// helper methods for interacting with ERC20 tokens and sending ETH that do not consistently return true/false
library TransferHelper {
    function safeApprove(address token, address to, uint value) internal {
        // bytes4(keccak256(bytes('approve(address,uint256)')));
        (bool success, bytes memory data) = token.call(abi.encodeWithSelector(0x095ea7b3, to, value));
        require(success && (data.length == 0 || abi.decode(data, (bool))), 'TransferHelper: APPROVE_FAILED');
    }

    function safeTransfer(address token, address to, uint value) internal {
        // bytes4(keccak256(bytes('transfer(address,uint256)')));
        (bool success, bytes memory data) = token.call(abi.encodeWithSelector(0xa9059cbb, to, value));
        require(success && (data.length == 0 || abi.decode(data, (bool))), 'TransferHelper: TRANSFER_FAILED');
    }

    function safeTransferFrom(address token, address from, address to, uint value) internal {
        // bytes4(keccak256(bytes('transferFrom(address,address,uint256)')));
        (bool success, bytes memory data) = token.call(abi.encodeWithSelector(0x23b872dd, from, to, value));
        require(success && (data.length == 0 || abi.decode(data, (bool))), 'TransferHelper: TRANSFER_FROM_FAILED');
    }

    function safeTransferETH(address to, uint value) internal {
        (bool success,) = to.call{value:value}(new bytes(0));
        require(success, 'TransferHelper: ETH_TRANSFER_FAILED');
    }
}

// SPDX-License-Identifier: MIT
pragma solidity ^0.6.0;
import './UpgradeabilityProxy.sol';
/**
 * @title AdminUpgradeabilityProxy
 * @dev This contract combines an upgradeability proxy with an authorization
 * mechanism for administrative tasks.
 * All external functions in this contract must be guarded by the
 * `ifAdmin` modifier. See ethereum/solidity#3864 for a Solidity
 * feature proposal that would enable this to be done automatically.
 */
contract AdminUpgradeabilityProxy is UpgradeabilityProxy {
  /**
   * Contract constructor.
   * @param _logic address of the initial implementation.
   * @param _admin Address of the proxy administrator.
   * @param _data Data to send as msg.data to the implementation to initialize the proxied contract.
   * It should include the signature and the parameters of the function to be called, as described in
   * https://solidity.readthedocs.io/en/v0.4.24/abi-spec.html#function-selector-and-argument-encoding.
   * This parameter is optional, if no data is given the initialization call to proxied contract will be skipped.
   */
  constructor(address _logic, address _admin, bytes memory _data) UpgradeabilityProxy(_logic, _data) public payable {
    assert(ADMIN_SLOT == bytes32(uint256(keccak256('eip1967.proxy.admin')) - 1));
    _setAdmin(_admin);
  }
  /**
   * @dev Emitted when the administration has been transferred.
   * @param previousAdmin Address of the previous admin.
   * @param newAdmin Address of the new admin.
   */
  event AdminChanged(address previousAdmin, address newAdmin);
  /**
   * @dev Storage slot with the admin of the contract.
   * This is the keccak-256 hash of "eip1967.proxy.admin" subtracted by 1, and is
   * validated in the constructor.
   */
  bytes32 internal constant ADMIN_SLOT = 0xb53127684a568b3173ae13b9f8a6016e243e63b6e8ee1178d6a717850b5d6103;
  /**
   * @dev Modifier to check whether the `msg.sender` is the admin.
   * If it is, it will run the function. Otherwise, it will delegate the call
   * to the implementation.
   */
  modifier ifAdmin() {
    if (msg.sender == _admin()) {
      _;
    } else {
      _fallback();
    }
  }
  /**
   * @return The address of the proxy admin.
   */
  function admin() external ifAdmin returns (address) {
    return _admin();
  }
  /**
   * @return The address of the implementation.
   */
  function implementation() external ifAdmin returns (address) {
    return _implementation();
  }
  /**
   * @dev Changes the admin of the proxy.
   * Only the current admin can call this function.
   * @param newAdmin Address to transfer proxy administration to.
   */
  function changeAdmin(address newAdmin) external ifAdmin {
    require(newAdmin != address(0), "Cannot change the admin of a proxy to the zero address");
    emit AdminChanged(_admin(), newAdmin);
    _setAdmin(newAdmin);
  }
  /**
   * @dev Upgrade the backing implementation of the proxy.
   * Only the admin can call this function.
   * @param newImplementation Address of the new implementation.
   */
  function upgradeTo(address newImplementation) external ifAdmin {
    _upgradeTo(newImplementation);
  }
  /**
   * @dev Upgrade the backing implementation of the proxy and call a function
   * on the new implementation.
   * This is useful to initialize the proxied contract.
   * @param newImplementation Address of the new implementation.
   * @param data Data to send as msg.data in the low level call.
   * It should include the signature and the parameters of the function to be called, as described in
   * https://solidity.readthedocs.io/en/v0.4.24/abi-spec.html#function-selector-and-argument-encoding.
   */
  function upgradeToAndCall(address newImplementation, bytes calldata data) payable external ifAdmin {
    _upgradeTo(newImplementation);
    (bool success,) = newImplementation.delegatecall(data);
    require(success);
  }
  /**
   * @return adm The admin slot.
   */
  function _admin() internal view returns (address adm) {
    bytes32 slot = ADMIN_SLOT;
    assembly {
      adm := sload(slot)
    }
  }
  /**
   * @dev Sets the address of the proxy admin.
   * @param newAdmin Address of the new proxy admin.
   */
  function _setAdmin(address newAdmin) internal {
    bytes32 slot = ADMIN_SLOT;
    assembly {
      sstore(slot, newAdmin)
    }
  }
  /**
   * @dev Only fall back when the sender is not the admin.
   */
  function _willFallback() internal override virtual {
    require(msg.sender != _admin(), "Cannot call fallback function from the proxy admin");
    super._willFallback();
  }
}
// SPDX-License-Identifier: MIT
pragma solidity ^0.6.0;
import './Proxy.sol';
import '@openzeppelin/contracts/utils/Address.sol';
/**
 * @title UpgradeabilityProxy
 * @dev This contract implements a proxy that allows to change the
 * implementation address to which it will delegate.
 * Such a change is called an implementation upgrade.
 */
contract UpgradeabilityProxy is Proxy {
  /**
   * @dev Contract constructor.
   * @param _logic Address of the initial implementation.
   * @param _data Data to send as msg.data to the implementation to initialize the proxied contract.
   * It should include the signature and the parameters of the function to be called, as described in
   * https://solidity.readthedocs.io/en/v0.4.24/abi-spec.html#function-selector-and-argument-encoding.
   * This parameter is optional, if no data is given the initialization call to proxied contract will be skipped.
   */
  constructor(address _logic, bytes memory _data) public payable {
    assert(IMPLEMENTATION_SLOT == bytes32(uint256(keccak256('eip1967.proxy.implementation')) - 1));
    _setImplementation(_logic);
    if(_data.length > 0) {
      (bool success,) = _logic.delegatecall(_data);
      require(success);
    }
  }  
  /**
   * @dev Emitted when the implementation is upgraded.
   * @param implementation Address of the new implementation.
   */
  event Upgraded(address indexed implementation);
  /**
   * @dev Storage slot with the address of the current implementation.
   * This is the keccak-256 hash of "eip1967.proxy.implementation" subtracted by 1, and is
   * validated in the constructor.
   */
  bytes32 internal constant IMPLEMENTATION_SLOT = 0x360894a13ba1a3210667c828492db98dca3e2076cc3735a920a3ca505d382bbc;
  /**
   * @dev Returns the current implementation.
   * @return impl Address of the current implementation
   */
  function _implementation() internal override view returns (address impl) {
    bytes32 slot = IMPLEMENTATION_SLOT;
    assembly {
      impl := sload(slot)
    }
  }
  /**
   * @dev Upgrades the proxy to a new implementation.
   * @param newImplementation Address of the new implementation.
   */
  function _upgradeTo(address newImplementation) internal {
    _setImplementation(newImplementation);
    emit Upgraded(newImplementation);
  }
  /**
   * @dev Sets the implementation address of the proxy.
   * @param newImplementation Address of the new implementation.
   */
  function _setImplementation(address newImplementation) internal {
    require(Address.isContract(newImplementation), "Cannot set a proxy implementation to a non-contract address");
    bytes32 slot = IMPLEMENTATION_SLOT;
    assembly {
      sstore(slot, newImplementation)
    }
  }
}
// SPDX-License-Identifier: MIT
pragma solidity ^0.6.0;
/**
 * @title Proxy
 * @dev Implements delegation of calls to other contracts, with proper
 * forwarding of return values and bubbling of failures.
 * It defines a fallback function that delegates all calls to the address
 * returned by the abstract _implementation() internal function.
 */
abstract contract Proxy {
  /**
   * @dev Fallback function.
   * Implemented entirely in `_fallback`.
   */
  fallback () payable external {
    _fallback();
  }
  /**
   * @dev Receive function.
   * Implemented entirely in `_fallback`.
   */
  receive () payable external {
    _fallback();
  }
  /**
   * @return The Address of the implementation.
   */
  function _implementation() internal virtual view returns (address);
  /**
   * @dev Delegates execution to an implementation contract.
   * This is a low level function that doesn't return to its internal call site.
   * It will return to the external caller whatever the implementation returns.
   * @param implementation Address to delegate.
   */
  function _delegate(address implementation) internal {
    assembly {
      // Copy msg.data. We take full control of memory in this inline assembly
      // block because it will not return to Solidity code. We overwrite the
      // Solidity scratch pad at memory position 0.
      calldatacopy(0, 0, calldatasize())
      // Call the implementation.
      // out and outsize are 0 because we don't know the size yet.
      let result := delegatecall(gas(), implementation, 0, calldatasize(), 0, 0)
      // Copy the returned data.
      returndatacopy(0, 0, returndatasize())
      switch result
      // delegatecall returns 0 on error.
      case 0 { revert(0, returndatasize()) }
      default { return(0, returndatasize()) }
    }
  }
  /**
   * @dev Function that is run as the first thing in the fallback function.
   * Can be redefined in derived contracts to add functionality.
   * Redefinitions must call super._willFallback().
   */
  function _willFallback() internal virtual {
  }
  /**
   * @dev fallback implementation.
   * Extracted to enable manual triggering.
   */
  function _fallback() internal {
    _willFallback();
    _delegate(_implementation());
  }
}
// SPDX-License-Identifier: MIT
pragma solidity >=0.6.2 <0.8.0;
/**
 * @dev Collection of functions related to the address type
 */
library Address {
    /**
     * @dev Returns true if `account` is a contract.
     *
     * [IMPORTANT]
     * ====
     * It is unsafe to assume that an address for which this function returns
     * false is an externally-owned account (EOA) and not a contract.
     *
     * Among others, `isContract` will return false for the following
     * types of addresses:
     *
     *  - an externally-owned account
     *  - a contract in construction
     *  - an address where a contract will be created
     *  - an address where a contract lived, but was destroyed
     * ====
     */
    function isContract(address account) internal view returns (bool) {
        // This method relies on extcodesize, which returns 0 for contracts in
        // construction, since the code is only stored at the end of the
        // constructor execution.
        uint256 size;
        // solhint-disable-next-line no-inline-assembly
        assembly { size := extcodesize(account) }
        return size > 0;
    }
    /**
     * @dev Replacement for Solidity's `transfer`: sends `amount` wei to
     * `recipient`, forwarding all available gas and reverting on errors.
     *
     * https://eips.ethereum.org/EIPS/eip-1884[EIP1884] increases the gas cost
     * of certain opcodes, possibly making contracts go over the 2300 gas limit
     * imposed by `transfer`, making them unable to receive funds via
     * `transfer`. {sendValue} removes this limitation.
     *
     * https://diligence.consensys.net/posts/2019/09/stop-using-soliditys-transfer-now/[Learn more].
     *
     * IMPORTANT: because control is transferred to `recipient`, care must be
     * taken to not create reentrancy vulnerabilities. Consider using
     * {ReentrancyGuard} or the
     * https://solidity.readthedocs.io/en/v0.5.11/security-considerations.html#use-the-checks-effects-interactions-pattern[checks-effects-interactions pattern].
     */
    function sendValue(address payable recipient, uint256 amount) internal {
        require(address(this).balance >= amount, "Address: insufficient balance");
        // solhint-disable-next-line avoid-low-level-calls, avoid-call-value
        (bool success, ) = recipient.call{ value: amount }("");
        require(success, "Address: unable to send value, recipient may have reverted");
    }
    /**
     * @dev Performs a Solidity function call using a low level `call`. A
     * plain`call` is an unsafe replacement for a function call: use this
     * function instead.
     *
     * If `target` reverts with a revert reason, it is bubbled up by this
     * function (like regular Solidity function calls).
     *
     * Returns the raw returned data. To convert to the expected return value,
     * use https://solidity.readthedocs.io/en/latest/units-and-global-variables.html?highlight=abi.decode#abi-encoding-and-decoding-functions[`abi.decode`].
     *
     * Requirements:
     *
     * - `target` must be a contract.
     * - calling `target` with `data` must not revert.
     *
     * _Available since v3.1._
     */
    function functionCall(address target, bytes memory data) internal returns (bytes memory) {
      return functionCall(target, data, "Address: low-level call failed");
    }
    /**
     * @dev Same as {xref-Address-functionCall-address-bytes-}[`functionCall`], but with
     * `errorMessage` as a fallback revert reason when `target` reverts.
     *
     * _Available since v3.1._
     */
    function functionCall(address target, bytes memory data, string memory errorMessage) internal returns (bytes memory) {
        return functionCallWithValue(target, data, 0, errorMessage);
    }
    /**
     * @dev Same as {xref-Address-functionCall-address-bytes-}[`functionCall`],
     * but also transferring `value` wei to `target`.
     *
     * Requirements:
     *
     * - the calling contract must have an ETH balance of at least `value`.
     * - the called Solidity function must be `payable`.
     *
     * _Available since v3.1._
     */
    function functionCallWithValue(address target, bytes memory data, uint256 value) internal returns (bytes memory) {
        return functionCallWithValue(target, data, value, "Address: low-level call with value failed");
    }
    /**
     * @dev Same as {xref-Address-functionCallWithValue-address-bytes-uint256-}[`functionCallWithValue`], but
     * with `errorMessage` as a fallback revert reason when `target` reverts.
     *
     * _Available since v3.1._
     */
    function functionCallWithValue(address target, bytes memory data, uint256 value, string memory errorMessage) internal returns (bytes memory) {
        require(address(this).balance >= value, "Address: insufficient balance for call");
        require(isContract(target), "Address: call to non-contract");
        // solhint-disable-next-line avoid-low-level-calls
        (bool success, bytes memory returndata) = target.call{ value: value }(data);
        return _verifyCallResult(success, returndata, errorMessage);
    }
    /**
     * @dev Same as {xref-Address-functionCall-address-bytes-}[`functionCall`],
     * but performing a static call.
     *
     * _Available since v3.3._
     */
    function functionStaticCall(address target, bytes memory data) internal view returns (bytes memory) {
        return functionStaticCall(target, data, "Address: low-level static call failed");
    }
    /**
     * @dev Same as {xref-Address-functionCall-address-bytes-string-}[`functionCall`],
     * but performing a static call.
     *
     * _Available since v3.3._
     */
    function functionStaticCall(address target, bytes memory data, string memory errorMessage) internal view returns (bytes memory) {
        require(isContract(target), "Address: static call to non-contract");
        // solhint-disable-next-line avoid-low-level-calls
        (bool success, bytes memory returndata) = target.staticcall(data);
        return _verifyCallResult(success, returndata, errorMessage);
    }
    function _verifyCallResult(bool success, bytes memory returndata, string memory errorMessage) private pure returns(bytes memory) {
        if (success) {
            return returndata;
        } else {
            // Look for revert reason and bubble it up if present
            if (returndata.length > 0) {
                // The easiest way to bubble the revert reason is using memory via assembly
                // solhint-disable-next-line no-inline-assembly
                assembly {
                    let returndata_size := mload(returndata)
                    revert(add(32, returndata), returndata_size)
                }
            } else {
                revert(errorMessage);
            }
        }
    }
}

// File: contracts/interfaces/IUniswapV2Pair.sol

pragma solidity >=0.5.0;

interface IUniswapV2Pair {
    event Approval(address indexed owner, address indexed spender, uint value);
    event Transfer(address indexed from, address indexed to, uint value);

    function name() external pure returns (string memory);
    function symbol() external pure returns (string memory);
    function decimals() external pure returns (uint8);
    function totalSupply() external view returns (uint);
    function balanceOf(address owner) external view returns (uint);
    function allowance(address owner, address spender) external view returns (uint);

    function approve(address spender, uint value) external returns (bool);
    function transfer(address to, uint value) external returns (bool);
    function transferFrom(address from, address to, uint value) external returns (bool);

    function DOMAIN_SEPARATOR() external view returns (bytes32);
    function PERMIT_TYPEHASH() external pure returns (bytes32);
    function nonces(address owner) external view returns (uint);

    function permit(address owner, address spender, uint value, uint deadline, uint8 v, bytes32 r, bytes32 s) external;

    event Mint(address indexed sender, uint amount0, uint amount1);
    event Burn(address indexed sender, uint amount0, uint amount1, address indexed to);
    event Swap(
        address indexed sender,
        uint amount0In,
        uint amount1In,
        uint amount0Out,
        uint amount1Out,
        address indexed to
    );
    event Sync(uint112 reserve0, uint112 reserve1);

    function MINIMUM_LIQUIDITY() external pure returns (uint);
    function factory() external view returns (address);
    function token0() external view returns (address);
    function token1() external view returns (address);
    function getReserves() external view returns (uint112 reserve0, uint112 reserve1, uint32 blockTimestampLast);
    function price0CumulativeLast() external view returns (uint);
    function price1CumulativeLast() external view returns (uint);
    function kLast() external view returns (uint);

    function mint(address to) external returns (uint liquidity);
    function burn(address to) external returns (uint amount0, uint amount1);
    function swap(uint amount0Out, uint amount1Out, address to, bytes calldata data) external;
    function skim(address to) external;
    function sync() external;

    function initialize(address, address) external;
}

// File: contracts/interfaces/IUniswapV2ERC20.sol

pragma solidity >=0.5.0;

interface IUniswapV2ERC20 {
    event Approval(address indexed owner, address indexed spender, uint value);
    event Transfer(address indexed from, address indexed to, uint value);

    function name() external pure returns (string memory);
    function symbol() external pure returns (string memory);
    function decimals() external pure returns (uint8);
    function totalSupply() external view returns (uint);
    function balanceOf(address owner) external view returns (uint);
    function allowance(address owner, address spender) external view returns (uint);

    function approve(address spender, uint value) external returns (bool);
    function transfer(address to, uint value) external returns (bool);
    function transferFrom(address from, address to, uint value) external returns (bool);

    function DOMAIN_SEPARATOR() external view returns (bytes32);
    function PERMIT_TYPEHASH() external pure returns (bytes32);
    function nonces(address owner) external view returns (uint);

    function permit(address owner, address spender, uint value, uint deadline, uint8 v, bytes32 r, bytes32 s) external;
}

// File: contracts/libraries/SafeMath.sol

pragma solidity =0.5.16;

// a library for performing overflow-safe math, courtesy of DappHub (https://github.com/dapphub/ds-math)

library SafeMath {
    function add(uint x, uint y) internal pure returns (uint z) {
        require((z = x + y) >= x, 'ds-math-add-overflow');
    }

    function sub(uint x, uint y) internal pure returns (uint z) {
        require((z = x - y) <= x, 'ds-math-sub-underflow');
    }

    function mul(uint x, uint y) internal pure returns (uint z) {
        require(y == 0 || (z = x * y) / y == x, 'ds-math-mul-overflow');
    }
}

// File: contracts/UniswapV2ERC20.sol

pragma solidity =0.5.16;



contract UniswapV2ERC20 is IUniswapV2ERC20 {
    using SafeMath for uint;

    string public constant name = 'Uniswap V2';
    string public constant symbol = 'UNI-V2';
    uint8 public constant decimals = 18;
    uint  public totalSupply;
    mapping(address => uint) public balanceOf;
    mapping(address => mapping(address => uint)) public allowance;

    bytes32 public DOMAIN_SEPARATOR;
    // keccak256("Permit(address owner,address spender,uint256 value,uint256 nonce,uint256 deadline)");
    bytes32 public constant PERMIT_TYPEHASH = 0x6e71edae12b1b97f4d1f60370fef10105fa2faae0126114a169c64845d6126c9;
    mapping(address => uint) public nonces;

    event Approval(address indexed owner, address indexed spender, uint value);
    event Transfer(address indexed from, address indexed to, uint value);

    constructor() public {
        uint chainId;
        assembly {
            chainId := chainid
        }
        DOMAIN_SEPARATOR = keccak256(
            abi.encode(
                keccak256('EIP712Domain(string name,string version,uint256 chainId,address verifyingContract)'),
                keccak256(bytes(name)),
                keccak256(bytes('1')),
                chainId,
                address(this)
            )
        );
    }

    function _mint(address to, uint value) internal {
        totalSupply = totalSupply.add(value);
        balanceOf[to] = balanceOf[to].add(value);
        emit Transfer(address(0), to, value);
    }

    function _burn(address from, uint value) internal {
        balanceOf[from] = balanceOf[from].sub(value);
        totalSupply = totalSupply.sub(value);
        emit Transfer(from, address(0), value);
    }

    function _approve(address owner, address spender, uint value) private {
        allowance[owner][spender] = value;
        emit Approval(owner, spender, value);
    }

    function _transfer(address from, address to, uint value) private {
        balanceOf[from] = balanceOf[from].sub(value);
        balanceOf[to] = balanceOf[to].add(value);
        emit Transfer(from, to, value);
    }

    function approve(address spender, uint value) external returns (bool) {
        _approve(msg.sender, spender, value);
        return true;
    }

    function transfer(address to, uint value) external returns (bool) {
        _transfer(msg.sender, to, value);
        return true;
    }

    function transferFrom(address from, address to, uint value) external returns (bool) {
        if (allowance[from][msg.sender] != uint(-1)) {
            allowance[from][msg.sender] = allowance[from][msg.sender].sub(value);
        }
        _transfer(from, to, value);
        return true;
    }

    function permit(address owner, address spender, uint value, uint deadline, uint8 v, bytes32 r, bytes32 s) external {
        require(deadline >= block.timestamp, 'UniswapV2: EXPIRED');
        bytes32 digest = keccak256(
            abi.encodePacked(
                '\x19\x01',
                DOMAIN_SEPARATOR,
                keccak256(abi.encode(PERMIT_TYPEHASH, owner, spender, value, nonces[owner]++, deadline))
            )
        );
        address recoveredAddress = ecrecover(digest, v, r, s);
        require(recoveredAddress != address(0) && recoveredAddress == owner, 'UniswapV2: INVALID_SIGNATURE');
        _approve(owner, spender, value);
    }
}

// File: contracts/libraries/Math.sol

pragma solidity =0.5.16;

// a library for performing various math operations

library Math {
    function min(uint x, uint y) internal pure returns (uint z) {
        z = x < y ? x : y;
    }

    // babylonian method (https://en.wikipedia.org/wiki/Methods_of_computing_square_roots#Babylonian_method)
    function sqrt(uint y) internal pure returns (uint z) {
        if (y > 3) {
            z = y;
            uint x = y / 2 + 1;
            while (x < z) {
                z = x;
                x = (y / x + x) / 2;
            }
        } else if (y != 0) {
            z = 1;
        }
    }
}

// File: contracts/libraries/UQ112x112.sol

pragma solidity =0.5.16;

// a library for handling binary fixed point numbers (https://en.wikipedia.org/wiki/Q_(number_format))

// range: [0, 2**112 - 1]
// resolution: 1 / 2**112

library UQ112x112 {
    uint224 constant Q112 = 2**112;

    // encode a uint112 as a UQ112x112
    function encode(uint112 y) internal pure returns (uint224 z) {
        z = uint224(y) * Q112; // never overflows
    }

    // divide a UQ112x112 by a uint112, returning a UQ112x112
    function uqdiv(uint224 x, uint112 y) internal pure returns (uint224 z) {
        z = x / uint224(y);
    }
}

// File: contracts/interfaces/IERC20.sol

pragma solidity >=0.5.0;

interface IERC20 {
    event Approval(address indexed owner, address indexed spender, uint value);
    event Transfer(address indexed from, address indexed to, uint value);

    function name() external view returns (string memory);
    function symbol() external view returns (string memory);
    function decimals() external view returns (uint8);
    function totalSupply() external view returns (uint);
    function balanceOf(address owner) external view returns (uint);
    function allowance(address owner, address spender) external view returns (uint);

    function approve(address spender, uint value) external returns (bool);
    function transfer(address to, uint value) external returns (bool);
    function transferFrom(address from, address to, uint value) external returns (bool);
}

// File: contracts/interfaces/IUniswapV2Factory.sol

pragma solidity >=0.5.0;

interface IUniswapV2Factory {
    event PairCreated(address indexed token0, address indexed token1, address pair, uint);

    function feeTo() external view returns (address);
    function feeToSetter() external view returns (address);

    function getPair(address tokenA, address tokenB) external view returns (address pair);
    function allPairs(uint) external view returns (address pair);
    function allPairsLength() external view returns (uint);

    function createPair(address tokenA, address tokenB) external returns (address pair);

    function setFeeTo(address) external;
    function setFeeToSetter(address) external;
}

// File: contracts/interfaces/IUniswapV2Callee.sol

pragma solidity >=0.5.0;

interface IUniswapV2Callee {
    function uniswapV2Call(address sender, uint amount0, uint amount1, bytes calldata data) external;
}

// File: contracts/UniswapV2Pair.sol

pragma solidity =0.5.16;








contract UniswapV2Pair is IUniswapV2Pair, UniswapV2ERC20 {
    using SafeMath  for uint;
    using UQ112x112 for uint224;

    uint public constant MINIMUM_LIQUIDITY = 10**3;
    bytes4 private constant SELECTOR = bytes4(keccak256(bytes('transfer(address,uint256)')));

    address public factory;
    address public token0;
    address public token1;

    uint112 private reserve0;           // uses single storage slot, accessible via getReserves
    uint112 private reserve1;           // uses single storage slot, accessible via getReserves
    uint32  private blockTimestampLast; // uses single storage slot, accessible via getReserves

    uint public price0CumulativeLast;
    uint public price1CumulativeLast;
    uint public kLast; // reserve0 * reserve1, as of immediately after the most recent liquidity event

    uint private unlocked = 1;
    modifier lock() {
        require(unlocked == 1, 'UniswapV2: LOCKED');
        unlocked = 0;
        _;
        unlocked = 1;
    }

    function getReserves() public view returns (uint112 _reserve0, uint112 _reserve1, uint32 _blockTimestampLast) {
        _reserve0 = reserve0;
        _reserve1 = reserve1;
        _blockTimestampLast = blockTimestampLast;
    }

    function _safeTransfer(address token, address to, uint value) private {
        (bool success, bytes memory data) = token.call(abi.encodeWithSelector(SELECTOR, to, value));
        require(success && (data.length == 0 || abi.decode(data, (bool))), 'UniswapV2: TRANSFER_FAILED');
    }

    event Mint(address indexed sender, uint amount0, uint amount1);
    event Burn(address indexed sender, uint amount0, uint amount1, address indexed to);
    event Swap(
        address indexed sender,
        uint amount0In,
        uint amount1In,
        uint amount0Out,
        uint amount1Out,
        address indexed to
    );
    event Sync(uint112 reserve0, uint112 reserve1);

    constructor() public {
        factory = msg.sender;
    }

    // called once by the factory at time of deployment
    function initialize(address _token0, address _token1) external {
        require(msg.sender == factory, 'UniswapV2: FORBIDDEN'); // sufficient check
        token0 = _token0;
        token1 = _token1;
    }

    // update reserves and, on the first call per block, price accumulators
    function _update(uint balance0, uint balance1, uint112 _reserve0, uint112 _reserve1) private {
        require(balance0 <= uint112(-1) && balance1 <= uint112(-1), 'UniswapV2: OVERFLOW');
        uint32 blockTimestamp = uint32(block.timestamp % 2**32);
        uint32 timeElapsed = blockTimestamp - blockTimestampLast; // overflow is desired
        if (timeElapsed > 0 && _reserve0 != 0 && _reserve1 != 0) {
            // * never overflows, and + overflow is desired
            price0CumulativeLast += uint(UQ112x112.encode(_reserve1).uqdiv(_reserve0)) * timeElapsed;
            price1CumulativeLast += uint(UQ112x112.encode(_reserve0).uqdiv(_reserve1)) * timeElapsed;
        }
        reserve0 = uint112(balance0);
        reserve1 = uint112(balance1);
        blockTimestampLast = blockTimestamp;
        emit Sync(reserve0, reserve1);
    }

    // if fee is on, mint liquidity equivalent to 1/6th of the growth in sqrt(k)
    function _mintFee(uint112 _reserve0, uint112 _reserve1) private returns (bool feeOn) {
        address feeTo = IUniswapV2Factory(factory).feeTo();
        feeOn = feeTo != address(0);
        uint _kLast = kLast; // gas savings
        if (feeOn) {
            if (_kLast != 0) {
                uint rootK = Math.sqrt(uint(_reserve0).mul(_reserve1));
                uint rootKLast = Math.sqrt(_kLast);
                if (rootK > rootKLast) {
                    uint numerator = totalSupply.mul(rootK.sub(rootKLast));
                    uint denominator = rootK.mul(5).add(rootKLast);
                    uint liquidity = numerator / denominator;
                    if (liquidity > 0) _mint(feeTo, liquidity);
                }
            }
        } else if (_kLast != 0) {
            kLast = 0;
        }
    }

    // this low-level function should be called from a contract which performs important safety checks
    function mint(address to) external lock returns (uint liquidity) {
        (uint112 _reserve0, uint112 _reserve1,) = getReserves(); // gas savings
        uint balance0 = IERC20(token0).balanceOf(address(this));
        uint balance1 = IERC20(token1).balanceOf(address(this));
        uint amount0 = balance0.sub(_reserve0);
        uint amount1 = balance1.sub(_reserve1);

        bool feeOn = _mintFee(_reserve0, _reserve1);
        uint _totalSupply = totalSupply; // gas savings, must be defined here since totalSupply can update in _mintFee
        if (_totalSupply == 0) {
            liquidity = Math.sqrt(amount0.mul(amount1)).sub(MINIMUM_LIQUIDITY);
           _mint(address(0), MINIMUM_LIQUIDITY); // permanently lock the first MINIMUM_LIQUIDITY tokens
        } else {
            liquidity = Math.min(amount0.mul(_totalSupply) / _reserve0, amount1.mul(_totalSupply) / _reserve1);
        }
        require(liquidity > 0, 'UniswapV2: INSUFFICIENT_LIQUIDITY_MINTED');
        _mint(to, liquidity);

        _update(balance0, balance1, _reserve0, _reserve1);
        if (feeOn) kLast = uint(reserve0).mul(reserve1); // reserve0 and reserve1 are up-to-date
        emit Mint(msg.sender, amount0, amount1);
    }

    // this low-level function should be called from a contract which performs important safety checks
    function burn(address to) external lock returns (uint amount0, uint amount1) {
        (uint112 _reserve0, uint112 _reserve1,) = getReserves(); // gas savings
        address _token0 = token0;                                // gas savings
        address _token1 = token1;                                // gas savings
        uint balance0 = IERC20(_token0).balanceOf(address(this));
        uint balance1 = IERC20(_token1).balanceOf(address(this));
        uint liquidity = balanceOf[address(this)];

        bool feeOn = _mintFee(_reserve0, _reserve1);
        uint _totalSupply = totalSupply; // gas savings, must be defined here since totalSupply can update in _mintFee
        amount0 = liquidity.mul(balance0) / _totalSupply; // using balances ensures pro-rata distribution
        amount1 = liquidity.mul(balance1) / _totalSupply; // using balances ensures pro-rata distribution
        require(amount0 > 0 && amount1 > 0, 'UniswapV2: INSUFFICIENT_LIQUIDITY_BURNED');
        _burn(address(this), liquidity);
        _safeTransfer(_token0, to, amount0);
        _safeTransfer(_token1, to, amount1);
        balance0 = IERC20(_token0).balanceOf(address(this));
        balance1 = IERC20(_token1).balanceOf(address(this));

        _update(balance0, balance1, _reserve0, _reserve1);
        if (feeOn) kLast = uint(reserve0).mul(reserve1); // reserve0 and reserve1 are up-to-date
        emit Burn(msg.sender, amount0, amount1, to);
    }

    // this low-level function should be called from a contract which performs important safety checks
    function swap(uint amount0Out, uint amount1Out, address to, bytes calldata data) external lock {
        require(amount0Out > 0 || amount1Out > 0, 'UniswapV2: INSUFFICIENT_OUTPUT_AMOUNT');
        (uint112 _reserve0, uint112 _reserve1,) = getReserves(); // gas savings
        require(amount0Out < _reserve0 && amount1Out < _reserve1, 'UniswapV2: INSUFFICIENT_LIQUIDITY');

        uint balance0;
        uint balance1;
        { // scope for _token{0,1}, avoids stack too deep errors
        address _token0 = token0;
        address _token1 = token1;
        require(to != _token0 && to != _token1, 'UniswapV2: INVALID_TO');
        if (amount0Out > 0) _safeTransfer(_token0, to, amount0Out); // optimistically transfer tokens
        if (amount1Out > 0) _safeTransfer(_token1, to, amount1Out); // optimistically transfer tokens
        if (data.length > 0) IUniswapV2Callee(to).uniswapV2Call(msg.sender, amount0Out, amount1Out, data);
        balance0 = IERC20(_token0).balanceOf(address(this));
        balance1 = IERC20(_token1).balanceOf(address(this));
        }
        uint amount0In = balance0 > _reserve0 - amount0Out ? balance0 - (_reserve0 - amount0Out) : 0;
        uint amount1In = balance1 > _reserve1 - amount1Out ? balance1 - (_reserve1 - amount1Out) : 0;
        require(amount0In > 0 || amount1In > 0, 'UniswapV2: INSUFFICIENT_INPUT_AMOUNT');
        { // scope for reserve{0,1}Adjusted, avoids stack too deep errors
        uint balance0Adjusted = balance0.mul(1000).sub(amount0In.mul(3));
        uint balance1Adjusted = balance1.mul(1000).sub(amount1In.mul(3));
        require(balance0Adjusted.mul(balance1Adjusted) >= uint(_reserve0).mul(_reserve1).mul(1000**2), 'UniswapV2: K');
        }

        _update(balance0, balance1, _reserve0, _reserve1);
        emit Swap(msg.sender, amount0In, amount1In, amount0Out, amount1Out, to);
    }

    // force balances to match reserves
    function skim(address to) external lock {
        address _token0 = token0; // gas savings
        address _token1 = token1; // gas savings
        _safeTransfer(_token0, to, IERC20(_token0).balanceOf(address(this)).sub(reserve0));
        _safeTransfer(_token1, to, IERC20(_token1).balanceOf(address(this)).sub(reserve1));
    }

    // force reserves to match balances
    function sync() external lock {
        _update(IERC20(token0).balanceOf(address(this)), IERC20(token1).balanceOf(address(this)), reserve0, reserve1);
    }
}

// Copyright (C) 2015, 2016, 2017 Dapphub

// This program is free software: you can redistribute it and/or modify
// it under the terms of the GNU General Public License as published by
// the Free Software Foundation, either version 3 of the License, or
// (at your option) any later version.

// This program is distributed in the hope that it will be useful,
// but WITHOUT ANY WARRANTY; without even the implied warranty of
// MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
// GNU General Public License for more details.

// You should have received a copy of the GNU General Public License
// along with this program.  If not, see <http://www.gnu.org/licenses/>.

pragma solidity ^0.4.18;

contract WETH9 {
    string public name     = "Wrapped Ether";
    string public symbol   = "WETH";
    uint8  public decimals = 18;

    event  Approval(address indexed src, address indexed guy, uint wad);
    event  Transfer(address indexed src, address indexed dst, uint wad);
    event  Deposit(address indexed dst, uint wad);
    event  Withdrawal(address indexed src, uint wad);

    mapping (address => uint)                       public  balanceOf;
    mapping (address => mapping (address => uint))  public  allowance;

    function() public payable {
        deposit();
    }
    function deposit() public payable {
        balanceOf[msg.sender] += msg.value;
        Deposit(msg.sender, msg.value);
    }
    function withdraw(uint wad) public {
        require(balanceOf[msg.sender] >= wad);
        balanceOf[msg.sender] -= wad;
        msg.sender.transfer(wad);
        Withdrawal(msg.sender, wad);
    }

    function totalSupply() public view returns (uint) {
        return this.balance;
    }

    function approve(address guy, uint wad) public returns (bool) {
        allowance[msg.sender][guy] = wad;
        Approval(msg.sender, guy, wad);
        return true;
    }

    function transfer(address dst, uint wad) public returns (bool) {
        return transferFrom(msg.sender, dst, wad);
    }

    function transferFrom(address src, address dst, uint wad)
        public
        returns (bool)
    {
        require(balanceOf[src] >= wad);

        if (src != msg.sender && allowance[src][msg.sender] != uint(-1)) {
            require(allowance[src][msg.sender] >= wad);
            allowance[src][msg.sender] -= wad;
        }

        balanceOf[src] -= wad;
        balanceOf[dst] += wad;

        Transfer(src, dst, wad);

        return true;
    }
}


/*
                    GNU GENERAL PUBLIC LICENSE
                       Version 3, 29 June 2007

 Copyright (C) 2007 Free Software Foundation, Inc. <http://fsf.org/>
 Everyone is permitted to copy and distribute verbatim copies
 of this license document, but changing it is not allowed.

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  When we speak of free software, we are referring to freedom, not
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  Developers that use the GNU GPL protect your rights with two steps:
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            How to Apply These Terms to Your New Programs

  If you develop a new program, and you want it to be of the greatest
possible use to the public, the best way to achieve this is to make it
free software which everyone can redistribute and change under these terms.

  To do so, attach the following notices to the program.  It is safest
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Also add information on how to contact you by electronic and paper mail.

  If the program does terminal interaction, make it output a short
notice like this when it starts in an interactive mode:

    <program>  Copyright (C) <year>  <name of author>
    This program comes with ABSOLUTELY NO WARRANTY; for details type `show w'.
    This is free software, and you are welcome to redistribute it
    under certain conditions; type `show c' for details.

The hypothetical commands `show w' and `show c' should show the appropriate
parts of the General Public License.  Of course, your program's commands
might be different; for a GUI interface, you would use an "about box".

  You should also get your employer (if you work as a programmer) or school,
if any, to sign a "copyright disclaimer" for the program, if necessary.
For more information on this, and how to apply and follow the GNU GPL, see
<http://www.gnu.org/licenses/>.

  The GNU General Public License does not permit incorporating your program
into proprietary programs.  If your program is a subroutine library, you
may consider it more useful to permit linking proprietary applications with
the library.  If this is what you want to do, use the GNU Lesser General
Public License instead of this License.  But first, please read
<http://www.gnu.org/philosophy/why-not-lgpl.html>.

*/

// SPDX-License-Identifier: MIT
pragma solidity 0.7.3;

/**
 * This code contains elements of ERC20BurnableUpgradeable.sol https://github.com/OpenZeppelin/openzeppelin-contracts-upgradeable/blob/master/contracts/token/ERC20/ERC20BurnableUpgradeable.sol
 * Those have been inlined for the purpose of gas optimization.
 */


/**
 * @dev Collection of functions related to the address type
 */
library AddressUpgradeable {
    /**
     * @dev Returns true if `account` is a contract.
     *
     * [IMPORTANT]
     * ====
     * It is unsafe to assume that an address for which this function returns
     * false is an externally-owned account (EOA) and not a contract.
     *
     * Among others, `isContract` will return false for the following
     * types of addresses:
     *
     *  - an externally-owned account
     *  - a contract in construction
     *  - an address where a contract will be created
     *  - an address where a contract lived, but was destroyed
     * ====
     */
    function isContract(address account) internal view returns (bool) {
        // This method relies on extcodesize, which returns 0 for contracts in
        // construction, since the code is only stored at the end of the
        // constructor execution.

        uint256 size;
        // solhint-disable-next-line no-inline-assembly
        assembly { size := extcodesize(account) }
        return size > 0;
    }

    /**
     * @dev Replacement for Solidity's `transfer`: sends `amount` wei to
     * `recipient`, forwarding all available gas and reverting on errors.
     *
     * https://eips.ethereum.org/EIPS/eip-1884[EIP1884] increases the gas cost
     * of certain opcodes, possibly making contracts go over the 2300 gas limit
     * imposed by `transfer`, making them unable to receive funds via
     * `transfer`. {sendValue} removes this limitation.
     *
     * https://diligence.consensys.net/posts/2019/09/stop-using-soliditys-transfer-now/[Learn more].
     *
     * IMPORTANT: because control is transferred to `recipient`, care must be
     * taken to not create reentrancy vulnerabilities. Consider using
     * {ReentrancyGuard} or the
     * https://solidity.readthedocs.io/en/v0.5.11/security-considerations.html#use-the-checks-effects-interactions-pattern[checks-effects-interactions pattern].
     */
    function sendValue(address payable recipient, uint256 amount) internal {
        require(address(this).balance >= amount, "Address: insufficient balance");

        // solhint-disable-next-line avoid-low-level-calls, avoid-call-value
        (bool success, ) = recipient.call{ value: amount }("");
        require(success, "Address: unable to send value, recipient may have reverted");
    }

    /**
     * @dev Performs a Solidity function call using a low level `call`. A
     * plain`call` is an unsafe replacement for a function call: use this
     * function instead.
     *
     * If `target` reverts with a revert reason, it is bubbled up by this
     * function (like regular Solidity function calls).
     *
     * Returns the raw returned data. To convert to the expected return value,
     * use https://solidity.readthedocs.io/en/latest/units-and-global-variables.html?highlight=abi.decode#abi-encoding-and-decoding-functions[`abi.decode`].
     *
     * Requirements:
     *
     * - `target` must be a contract.
     * - calling `target` with `data` must not revert.
     *
     * _Available since v3.1._
     */
    function functionCall(address target, bytes memory data) internal returns (bytes memory) {
      return functionCall(target, data, "Address: low-level call failed");
    }

    /**
     * @dev Same as {xref-Address-functionCall-address-bytes-}[`functionCall`], but with
     * `errorMessage` as a fallback revert reason when `target` reverts.
     *
     * _Available since v3.1._
     */
    function functionCall(address target, bytes memory data, string memory errorMessage) internal returns (bytes memory) {
        return functionCallWithValue(target, data, 0, errorMessage);
    }

    /**
     * @dev Same as {xref-Address-functionCall-address-bytes-}[`functionCall`],
     * but also transferring `value` wei to `target`.
     *
     * Requirements:
     *
     * - the calling contract must have an ETH balance of at least `value`.
     * - the called Solidity function must be `payable`.
     *
     * _Available since v3.1._
     */
    function functionCallWithValue(address target, bytes memory data, uint256 value) internal returns (bytes memory) {
        return functionCallWithValue(target, data, value, "Address: low-level call with value failed");
    }

    /**
     * @dev Same as {xref-Address-functionCallWithValue-address-bytes-uint256-}[`functionCallWithValue`], but
     * with `errorMessage` as a fallback revert reason when `target` reverts.
     *
     * _Available since v3.1._
     */
    function functionCallWithValue(address target, bytes memory data, uint256 value, string memory errorMessage) internal returns (bytes memory) {
        require(address(this).balance >= value, "Address: insufficient balance for call");
        require(isContract(target), "Address: call to non-contract");

        // solhint-disable-next-line avoid-low-level-calls
        (bool success, bytes memory returndata) = target.call{ value: value }(data);
        return _verifyCallResult(success, returndata, errorMessage);
    }

    /**
     * @dev Same as {xref-Address-functionCall-address-bytes-}[`functionCall`],
     * but performing a static call.
     *
     * _Available since v3.3._
     */
    function functionStaticCall(address target, bytes memory data) internal view returns (bytes memory) {
        return functionStaticCall(target, data, "Address: low-level static call failed");
    }

    /**
     * @dev Same as {xref-Address-functionCall-address-bytes-string-}[`functionCall`],
     * but performing a static call.
     *
     * _Available since v3.3._
     */
    function functionStaticCall(address target, bytes memory data, string memory errorMessage) internal view returns (bytes memory) {
        require(isContract(target), "Address: static call to non-contract");

        // solhint-disable-next-line avoid-low-level-calls
        (bool success, bytes memory returndata) = target.staticcall(data);
        return _verifyCallResult(success, returndata, errorMessage);
    }

    function _verifyCallResult(bool success, bytes memory returndata, string memory errorMessage) private pure returns(bytes memory) {
        if (success) {
            return returndata;
        } else {
            // Look for revert reason and bubble it up if present
            if (returndata.length > 0) {
                // The easiest way to bubble the revert reason is using memory via assembly

                // solhint-disable-next-line no-inline-assembly
                assembly {
                    let returndata_size := mload(returndata)
                    revert(add(32, returndata), returndata_size)
                }
            } else {
                revert(errorMessage);
            }
        }
    }
}



/**
 * @dev This is a base contract to aid in writing upgradeable contracts, or any kind of contract that will be deployed
 * behind a proxy. Since a proxied contract can't have a constructor, it's common to move constructor logic to an
 * external initializer function, usually called `initialize`. It then becomes necessary to protect this initializer
 * function so it can only be called once. The {initializer} modifier provided by this contract will have this effect.
 *
 * TIP: To avoid leaving the proxy in an uninitialized state, the initializer function should be called as early as
 * possible by providing the encoded function call as the `_data` argument to {UpgradeableProxy-constructor}.
 *
 * CAUTION: When used with inheritance, manual care must be taken to not invoke a parent initializer twice, or to ensure
 * that all initializers are idempotent. This is not verified automatically as constructors are by Solidity.
 */
abstract contract Initializable {

    /**
     * @dev Indicates that the contract has been initialized.
     */
    bool private _initialized;

    /**
     * @dev Indicates that the contract is in the process of being initialized.
     */
    bool private _initializing;

    /**
     * @dev Modifier to protect an initializer function from being invoked twice.
     */
    modifier initializer() {
        require(_initializing || _isConstructor() || !_initialized, "Initializable: contract is already initialized");

        bool isTopLevelCall = !_initializing;
        if (isTopLevelCall) {
            _initializing = true;
            _initialized = true;
        }

        _;

        if (isTopLevelCall) {
            _initializing = false;
        }
    }

    /// @dev Returns true if and only if the function is running in the constructor
    function _isConstructor() private view returns (bool) {
        return !AddressUpgradeable.isContract(address(this));
    }
}



/**
 * @dev Wrappers over Solidity's arithmetic operations with added overflow
 * checks.
 *
 * Arithmetic operations in Solidity wrap on overflow. This can easily result
 * in bugs, because programmers usually assume that an overflow raises an
 * error, which is the standard behavior in high level programming languages.
 * `SafeMath` restores this intuition by reverting the transaction when an
 * operation overflows.
 *
 * Using this library instead of the unchecked operations eliminates an entire
 * class of bugs, so it's recommended to use it always.
 */
library SafeMath {
    /**
     * @dev Returns the addition of two unsigned integers, with an overflow flag.
     *
     * _Available since v3.4._
     */
    function tryAdd(uint256 a, uint256 b) internal pure returns (bool, uint256) {
        uint256 c = a + b;
        if (c < a) return (false, 0);
        return (true, c);
    }

    /**
     * @dev Returns the substraction of two unsigned integers, with an overflow flag.
     *
     * _Available since v3.4._
     */
    function trySub(uint256 a, uint256 b) internal pure returns (bool, uint256) {
        if (b > a) return (false, 0);
        return (true, a - b);
    }

    /**
     * @dev Returns the multiplication of two unsigned integers, with an overflow flag.
     *
     * _Available since v3.4._
     */
    function tryMul(uint256 a, uint256 b) internal pure returns (bool, uint256) {
        // Gas optimization: this is cheaper than requiring 'a' not being zero, but the
        // benefit is lost if 'b' is also tested.
        // See: https://github.com/OpenZeppelin/openzeppelin-contracts/pull/522
        if (a == 0) return (true, 0);
        uint256 c = a * b;
        if (c / a != b) return (false, 0);
        return (true, c);
    }

    /**
     * @dev Returns the division of two unsigned integers, with a division by zero flag.
     *
     * _Available since v3.4._
     */
    function tryDiv(uint256 a, uint256 b) internal pure returns (bool, uint256) {
        if (b == 0) return (false, 0);
        return (true, a / b);
    }

    /**
     * @dev Returns the remainder of dividing two unsigned integers, with a division by zero flag.
     *
     * _Available since v3.4._
     */
    function tryMod(uint256 a, uint256 b) internal pure returns (bool, uint256) {
        if (b == 0) return (false, 0);
        return (true, a % b);
    }

    /**
     * @dev Returns the addition of two unsigned integers, reverting on
     * overflow.
     *
     * Counterpart to Solidity's `+` operator.
     *
     * Requirements:
     *
     * - Addition cannot overflow.
     */
    function add(uint256 a, uint256 b) internal pure returns (uint256) {
        uint256 c = a + b;
        require(c >= a, "SafeMath: addition overflow");
        return c;
    }

    /**
     * @dev Returns the subtraction of two unsigned integers, reverting on
     * overflow (when the result is negative).
     *
     * Counterpart to Solidity's `-` operator.
     *
     * Requirements:
     *
     * - Subtraction cannot overflow.
     */
    function sub(uint256 a, uint256 b) internal pure returns (uint256) {
        require(b <= a, "SafeMath: subtraction overflow");
        return a - b;
    }

    /**
     * @dev Returns the multiplication of two unsigned integers, reverting on
     * overflow.
     *
     * Counterpart to Solidity's `*` operator.
     *
     * Requirements:
     *
     * - Multiplication cannot overflow.
     */
    function mul(uint256 a, uint256 b) internal pure returns (uint256) {
        if (a == 0) return 0;
        uint256 c = a * b;
        require(c / a == b, "SafeMath: multiplication overflow");
        return c;
    }

    /**
     * @dev Returns the integer division of two unsigned integers, reverting on
     * division by zero. The result is rounded towards zero.
     *
     * Counterpart to Solidity's `/` operator. Note: this function uses a
     * `revert` opcode (which leaves remaining gas untouched) while Solidity
     * uses an invalid opcode to revert (consuming all remaining gas).
     *
     * Requirements:
     *
     * - The divisor cannot be zero.
     */
    function div(uint256 a, uint256 b) internal pure returns (uint256) {
        require(b > 0, "SafeMath: division by zero");
        return a / b;
    }

    /**
     * @dev Returns the remainder of dividing two unsigned integers. (unsigned integer modulo),
     * reverting when dividing by zero.
     *
     * Counterpart to Solidity's `%` operator. This function uses a `revert`
     * opcode (which leaves remaining gas untouched) while Solidity uses an
     * invalid opcode to revert (consuming all remaining gas).
     *
     * Requirements:
     *
     * - The divisor cannot be zero.
     */
    function mod(uint256 a, uint256 b) internal pure returns (uint256) {
        require(b > 0, "SafeMath: modulo by zero");
        return a % b;
    }

    /**
     * @dev Returns the subtraction of two unsigned integers, reverting with custom message on
     * overflow (when the result is negative).
     *
     * CAUTION: This function is deprecated because it requires allocating memory for the error
     * message unnecessarily. For custom revert reasons use {trySub}.
     *
     * Counterpart to Solidity's `-` operator.
     *
     * Requirements:
     *
     * - Subtraction cannot overflow.
     */
    function sub(uint256 a, uint256 b, string memory errorMessage) internal pure returns (uint256) {
        require(b <= a, errorMessage);
        return a - b;
    }

    /**
     * @dev Returns the integer division of two unsigned integers, reverting with custom message on
     * division by zero. The result is rounded towards zero.
     *
     * CAUTION: This function is deprecated because it requires allocating memory for the error
     * message unnecessarily. For custom revert reasons use {tryDiv}.
     *
     * Counterpart to Solidity's `/` operator. Note: this function uses a
     * `revert` opcode (which leaves remaining gas untouched) while Solidity
     * uses an invalid opcode to revert (consuming all remaining gas).
     *
     * Requirements:
     *
     * - The divisor cannot be zero.
     */
    function div(uint256 a, uint256 b, string memory errorMessage) internal pure returns (uint256) {
        require(b > 0, errorMessage);
        return a / b;
    }

    /**
     * @dev Returns the remainder of dividing two unsigned integers. (unsigned integer modulo),
     * reverting with custom message when dividing by zero.
     *
     * CAUTION: This function is deprecated because it requires allocating memory for the error
     * message unnecessarily. For custom revert reasons use {tryMod}.
     *
     * Counterpart to Solidity's `%` operator. This function uses a `revert`
     * opcode (which leaves remaining gas untouched) while Solidity uses an
     * invalid opcode to revert (consuming all remaining gas).
     *
     * Requirements:
     *
     * - The divisor cannot be zero.
     */
    function mod(uint256 a, uint256 b, string memory errorMessage) internal pure returns (uint256) {
        require(b > 0, errorMessage);
        return a % b;
    }
}


/**
 * @title ProofOfHumanity Interface
 * @dev See https://github.com/Proof-Of-Humanity/Proof-Of-Humanity.
 */
interface IProofOfHumanity {
  function isRegistered(address _submissionID)
    external
    view
    returns (
      bool registered
    );
}

/**
 * @title Universal Basic Income
 * @dev UBI is an ERC20 compatible token that is connected to a Proof of Humanity registry. 
 *
 * Tokens are issued and drip over time for every verified submission on a Proof of Humanity registry.
 * The accrued tokens are updated directly on every wallet using the `balanceOf` function.
 * The tokens get effectively minted and persisted in memory when someone interacts with the contract doing a `transfer` or `burn`. 
 */
contract UBI is Initializable {

  /* Events */
  
  /**
   * @dev Emitted when `value` tokens are moved from one account (`from`) to another (`to`).
   *
   * Note that `value` may be zero.
   * Also note that due to continuous minting we cannot emit transfer events from the address 0 when tokens are created.
   * In order to keep consistency, we decided not to emit those events from the address 0 even when minting is done within a transaction.
   */
  event Transfer(address indexed from, address indexed to, uint256 value);

  /**
   * @dev Emitted when the allowance of a `spender` for an `owner` is set by
   * a call to {approve}. `value` is the new allowance.
   */
  event Approval(address indexed owner, address indexed spender, uint256 value);

  using SafeMath for uint256;

  /* Storage */
  
  mapping (address => uint256) private balance;

  mapping (address => mapping (address => uint256)) public allowance;

  /// @dev A lower bound of the total supply. Does not take into account tokens minted as UBI by an address before it moves those (transfer or burn).
  uint256 public totalSupply;
  
  /// @dev Name of the token.
  string public name;
  
  /// @dev Symbol of the token.
  string public symbol;
  
  /// @dev Number of decimals of the token.
  uint8 public decimals;

  /// @dev How many tokens per second will be minted for every valid human.
  uint256 public accruedPerSecond;

  /// @dev The contract's governor.
  address public governor;
  
  /// @dev The Proof Of Humanity registry to reference.
  IProofOfHumanity public proofOfHumanity; 

  /// @dev Timestamp since human started accruing.
  mapping(address => uint256) public accruedSince;

  /* Modifiers */

  /// @dev Verifies that the sender has ability to modify governed parameters.
  modifier onlyByGovernor() {
    require(governor == msg.sender, "The caller is not the governor.");
    _;
  }

  /* Initializer */

  /** @dev Constructor.
  *  @param _initialSupply for the UBI coin including all decimals.
  *  @param _name for UBI coin.
  *  @param _symbol for UBI coin ticker.
  *  @param _accruedPerSecond How much of the token is accrued per block.
  *  @param _proofOfHumanity The Proof Of Humanity registry to reference.
  */
  function initialize(uint256 _initialSupply, string memory _name, string memory _symbol, uint256 _accruedPerSecond, IProofOfHumanity _proofOfHumanity) public initializer {
    name = _name;
    symbol = _symbol;
    decimals = 18;

    accruedPerSecond = _accruedPerSecond;
    proofOfHumanity = _proofOfHumanity;
    governor = msg.sender;

    balance[msg.sender] = _initialSupply;
    totalSupply = _initialSupply;
  }

  /* External */

  /** @dev Starts accruing UBI for a registered submission.
  *  @param _human The submission ID.
  */
  function startAccruing(address _human) external {
    require(proofOfHumanity.isRegistered(_human), "The submission is not registered in Proof Of Humanity.");
    require(accruedSince[_human] == 0, "The submission is already accruing UBI.");
    accruedSince[_human] = block.timestamp;
  }

  /** @dev Allows anyone to report a submission that
  *  should no longer receive UBI due to removal from the
  *  Proof Of Humanity registry. The reporter receives any
  *  leftover accrued UBI.
  *  @param _human The submission ID.
  */
  function reportRemoval(address _human) external  {
    require(!proofOfHumanity.isRegistered(_human), "The submission is still registered in Proof Of Humanity.");
    require(accruedSince[_human] != 0, "The submission is not accruing UBI.");
    uint256 newSupply = accruedPerSecond.mul(block.timestamp.sub(accruedSince[_human]));

    accruedSince[_human] = 0;

    balance[msg.sender] = balance[msg.sender].add(newSupply);
    totalSupply = totalSupply.add(newSupply);
  }

  /** @dev Changes `governor` to `_governor`.
  *  @param _governor The address of the new governor.
  */
  function changeGovernor(address _governor) external onlyByGovernor {
    governor = _governor;
  }

  /** @dev Changes `proofOfHumanity` to `_proofOfHumanity`.
  *  @param _proofOfHumanity Registry that meets interface of Proof of Humanity.
  */
  function changeProofOfHumanity(IProofOfHumanity _proofOfHumanity) external onlyByGovernor {
    proofOfHumanity = _proofOfHumanity;
  }

  /** @dev Transfers `_amount` to `_recipient` and withdraws accrued tokens.
  *  @param _recipient The entity receiving the funds.
  *  @param _amount The amount to tranfer in base units.
  */
  function transfer(address _recipient, uint256 _amount) public returns (bool) {
    uint256 newSupplyFrom;
    if (accruedSince[msg.sender] != 0 && proofOfHumanity.isRegistered(msg.sender)) {
        newSupplyFrom = accruedPerSecond.mul(block.timestamp.sub(accruedSince[msg.sender]));
        totalSupply = totalSupply.add(newSupplyFrom);
        accruedSince[msg.sender] = block.timestamp;
    }
    balance[msg.sender] = balance[msg.sender].add(newSupplyFrom).sub(_amount, "ERC20: transfer amount exceeds balance");
    balance[_recipient] = balance[_recipient].add(_amount);
    emit Transfer(msg.sender, _recipient, _amount);
    return true;
  }
  
  /** @dev Transfers `_amount` from `_sender` to `_recipient` and withdraws accrued tokens.
  *  @param _sender The entity to take the funds from.
  *  @param _recipient The entity receiving the funds.
  *  @param _amount The amount to tranfer in base units.
  */
  function transferFrom(address _sender, address _recipient, uint256 _amount) public returns (bool) {
    uint256 newSupplyFrom;
    allowance[_sender][msg.sender] = allowance[_sender][msg.sender].sub(_amount, "ERC20: transfer amount exceeds allowance");
    if (accruedSince[_sender] != 0 && proofOfHumanity.isRegistered(_sender)) {
        newSupplyFrom = accruedPerSecond.mul(block.timestamp.sub(accruedSince[_sender]));
        totalSupply = totalSupply.add(newSupplyFrom);
        accruedSince[_sender] = block.timestamp;
    }
    balance[_sender] = balance[_sender].add(newSupplyFrom).sub(_amount, "ERC20: transfer amount exceeds balance");
    balance[_recipient] = balance[_recipient].add(_amount);       
    emit Transfer(_sender, _recipient, _amount);
    return true;
  }

  /** @dev Approves `_spender` to spend `_amount`.
  *  @param _spender The entity allowed to spend funds.
  *  @param _amount The amount of base units the entity will be allowed to spend.
  */
  function approve(address _spender, uint256 _amount) public returns (bool) {
    allowance[msg.sender][_spender] = _amount;
    emit Approval(msg.sender, _spender, _amount);
    return true;
  }

  /** @dev Increases the `_spender` allowance by `_addedValue`.
  *  @param _spender The entity allowed to spend funds.
  *  @param _addedValue The amount of extra base units the entity will be allowed to spend.
  */  
  function increaseAllowance(address _spender, uint256 _addedValue) public returns (bool) {
    uint256 newAllowance = allowance[msg.sender][_spender].add(_addedValue);
    allowance[msg.sender][_spender] = newAllowance;
    emit Approval(msg.sender, _spender, newAllowance);
    return true;
  }

  /** @dev Decreases the `_spender` allowance by `_subtractedValue`.
  *  @param _spender The entity whose spending allocation will be reduced.
  *  @param _subtractedValue The reduction of spending allocation in base units.
  */  
  function decreaseAllowance(address _spender, uint256 _subtractedValue) public returns (bool) {
    uint256 newAllowance = allowance[msg.sender][_spender].sub(_subtractedValue, "ERC20: decreased allowance below zero");
    allowance[msg.sender][_spender] = newAllowance;
    emit Approval(msg.sender, _spender, newAllowance);
    return true;
  }
  
  /** @dev Burns `_amount` of tokens and withdraws accrued tokens.
  *  @param _amount The quantity of tokens to burn in base units.
  */  
  function burn(uint256 _amount) public {
    uint256 newSupplyFrom;
    if(accruedSince[msg.sender] != 0 && proofOfHumanity.isRegistered(msg.sender)) {
      newSupplyFrom = accruedPerSecond.mul(block.timestamp.sub(accruedSince[msg.sender]));
      accruedSince[msg.sender] = block.timestamp;
    }
    balance[msg.sender] = balance[msg.sender].add(newSupplyFrom).sub(_amount, "ERC20: burn amount exceeds balance");
    totalSupply = totalSupply.add(newSupplyFrom).sub(_amount);
    emit Transfer(msg.sender, address(0), _amount);
  }

  /** @dev Burns `_amount` of tokens from `_account` and withdraws accrued tokens.
  *  @param _account The entity to burn tokens from.
  *  @param _amount The quantity of tokens to burn in base units.
  */  
  function burnFrom(address _account, uint256 _amount) public {
    uint256 newSupplyFrom;
    allowance[_account][msg.sender] = allowance[_account][msg.sender].sub(_amount, "ERC20: burn amount exceeds allowance");
    if (accruedSince[_account] != 0 && proofOfHumanity.isRegistered(_account)) {
        newSupplyFrom = accruedPerSecond.mul(block.timestamp.sub(accruedSince[_account]));
        accruedSince[_account] = block.timestamp;
    }
    balance[_account] = balance[_account].add(newSupplyFrom).sub(_amount, "ERC20: burn amount exceeds balance");
    totalSupply = totalSupply.add(newSupplyFrom).sub(_amount);
    emit Transfer(_account, address(0), _amount);
  }
  
  /* Getters */

  /** @dev Calculates how much UBI a submission has available for withdrawal.
  *  @param _human The submission ID.
  *  @return accrued The available UBI for withdrawal.
  */
  function getAccruedValue(address _human) public view returns (uint256 accrued) {
    // If this human have not started to accrue, or is not registered, return 0.
    if (accruedSince[_human] == 0 || !proofOfHumanity.isRegistered(_human)) return 0;

    else return accruedPerSecond.mul(block.timestamp.sub(accruedSince[_human]));
  }
  
  /**
  * @dev Calculates the current user accrued balance.
  * @param _human The submission ID.
  * @return The current balance including accrued Universal Basic Income of the user.
  **/
  function balanceOf(address _human) public view returns (uint256) {
    return getAccruedValue(_human).add(balance[_human]);
  }  
}

// File: https://github.com/kleros/ethereum-libraries/blob/39b54dec298117f9753d1a7dd2f08d596d26acdb/contracts/CappedMath.sol

/**
 *  @authors: [@mtsalenc]
 *  @reviewers: [@clesaege]
 *  @auditors: []
 *  @bounties: []
 *  @deployments: []
 */

pragma solidity ^0.5;


/**
 * @title CappedMath
 * @dev Math operations with caps for under and overflow.
 */
library CappedMath {
    uint constant private UINT_MAX = 2**256 - 1;
    uint64 constant private UINT64_MAX = 2**64 - 1;

    /**
     * @dev Adds two unsigned integers, returns 2^256 - 1 on overflow.
     */
    function addCap(uint _a, uint _b) internal pure returns (uint) {
        uint c = _a + _b;
        return c >= _a ? c : UINT_MAX;
    }

    /**
     * @dev Subtracts two integers, returns 0 on underflow.
     */
    function subCap(uint _a, uint _b) internal pure returns (uint) {
        if (_b > _a)
            return 0;
        else
            return _a - _b;
    }

    /**
     * @dev Multiplies two unsigned integers, returns 2^256 - 1 on overflow.
     */
    function mulCap(uint _a, uint _b) internal pure returns (uint) {
        // Gas optimization: this is cheaper than requiring '_a' not being zero, but the
        // benefit is lost if '_b' is also tested.
        // See: https://github.com/OpenZeppelin/openzeppelin-solidity/pull/522
        if (_a == 0)
            return 0;

        uint c = _a * _b;
        return c / _a == _b ? c : UINT_MAX;
    }

    function addCap64(uint64 _a, uint64 _b) internal pure returns (uint64) {
        uint64 c = _a + _b;
        return c >= _a ? c : UINT64_MAX;
    }


    function subCap64(uint64 _a, uint64 _b) internal pure returns (uint64) {
        if (_b > _a)
            return 0;
        else
            return _a - _b;
    }

    function mulCap64(uint64 _a, uint64 _b) internal pure returns (uint64) {
        if (_a == 0)
            return 0;

        uint64 c = _a * _b;
        return c / _a == _b ? c : UINT64_MAX;
    }
}

// File: https://github.com/kleros/erc-792/blob/c00f37dacdbf296e038bbaec9ad86c6a2f4b48d1/contracts/erc-1497/IEvidence.sol

pragma solidity ^0.5;


/** @title IEvidence
 *  ERC-1497: Evidence Standard
 */
interface IEvidence {

    /** @dev To be emitted when meta-evidence is submitted.
     *  @param _metaEvidenceID Unique identifier of meta-evidence.
     *  @param _evidence A link to the meta-evidence JSON.
     */
    event MetaEvidence(uint indexed _metaEvidenceID, string _evidence);

    /** @dev To be raised when evidence is submitted. Should point to the resource (evidences are not to be stored on chain due to gas considerations).
     *  @param _arbitrator The arbitrator of the contract.
     *  @param _evidenceGroupID Unique identifier of the evidence group the evidence belongs to.
     *  @param _party The address of the party submiting the evidence. Note that 0x0 refers to evidence not submitted by any party.
     *  @param _evidence A URI to the evidence JSON file whose name should be its keccak256 hash followed by .json.
     */
    event Evidence(IArbitrator indexed _arbitrator, uint indexed _evidenceGroupID, address indexed _party, string _evidence);

    /** @dev To be emitted when a dispute is created to link the correct meta-evidence to the disputeID.
     *  @param _arbitrator The arbitrator of the contract.
     *  @param _disputeID ID of the dispute in the Arbitrator contract.
     *  @param _metaEvidenceID Unique identifier of meta-evidence.
     *  @param _evidenceGroupID Unique identifier of the evidence group that is linked to this dispute.
     */
    event Dispute(IArbitrator indexed _arbitrator, uint indexed _disputeID, uint _metaEvidenceID, uint _evidenceGroupID);

}

// File: https://github.com/kleros/erc-792/blob/c00f37dacdbf296e038bbaec9ad86c6a2f4b48d1/contracts/IArbitrator.sol

/**
 *  @title Arbitrator
 *  @author Clément Lesaege - <clement@lesaege.com>
 */

pragma solidity ^0.5;


/** @title Arbitrator
 *  Arbitrator abstract contract.
 *  When developing arbitrator contracts we need to:
 *  -Define the functions for dispute creation (createDispute) and appeal (appeal). Don't forget to store the arbitrated contract and the disputeID (which should be unique, may nbDisputes).
 *  -Define the functions for cost display (arbitrationCost and appealCost).
 *  -Allow giving rulings. For this a function must call arbitrable.rule(disputeID, ruling).
 */
interface IArbitrator {

    enum DisputeStatus {Waiting, Appealable, Solved}


    /** @dev To be emitted when a dispute is created.
     *  @param _disputeID ID of the dispute.
     *  @param _arbitrable The contract which created the dispute.
     */
    event DisputeCreation(uint indexed _disputeID, IArbitrable indexed _arbitrable);

    /** @dev To be emitted when a dispute can be appealed.
     *  @param _disputeID ID of the dispute.
     */
    event AppealPossible(uint indexed _disputeID, IArbitrable indexed _arbitrable);

    /** @dev To be emitted when the current ruling is appealed.
     *  @param _disputeID ID of the dispute.
     *  @param _arbitrable The contract which created the dispute.
     */
    event AppealDecision(uint indexed _disputeID, IArbitrable indexed _arbitrable);

    /** @dev Create a dispute. Must be called by the arbitrable contract.
     *  Must be paid at least arbitrationCost(_extraData).
     *  @param _choices Amount of choices the arbitrator can make in this dispute.
     *  @param _extraData Can be used to give additional info on the dispute to be created.
     *  @return disputeID ID of the dispute created.
     */
    function createDispute(uint _choices, bytes calldata _extraData) external payable returns(uint disputeID);

    /** @dev Compute the cost of arbitration. It is recommended not to increase it often, as it can be highly time and gas consuming for the arbitrated contracts to cope with fee augmentation.
     *  @param _extraData Can be used to give additional info on the dispute to be created.
     *  @return cost Amount to be paid.
     */
    function arbitrationCost(bytes calldata _extraData) external view returns(uint cost);

    /** @dev Appeal a ruling. Note that it has to be called before the arbitrator contract calls rule.
     *  @param _disputeID ID of the dispute to be appealed.
     *  @param _extraData Can be used to give extra info on the appeal.
     */
    function appeal(uint _disputeID, bytes calldata _extraData) external payable;

    /** @dev Compute the cost of appeal. It is recommended not to increase it often, as it can be higly time and gas consuming for the arbitrated contracts to cope with fee augmentation.
     *  @param _disputeID ID of the dispute to be appealed.
     *  @param _extraData Can be used to give additional info on the dispute to be created.
     *  @return cost Amount to be paid.
     */
    function appealCost(uint _disputeID, bytes calldata _extraData) external view returns(uint cost);

    /** @dev Compute the start and end of the dispute's current or next appeal period, if possible. If not known or appeal is impossible: should return (0, 0).
     *  @param _disputeID ID of the dispute.
     *  @return The start and end of the period.
     */
    function appealPeriod(uint _disputeID) external view returns(uint start, uint end);

    /** @dev Return the status of a dispute.
     *  @param _disputeID ID of the dispute to rule.
     *  @return status The status of the dispute.
     */
    function disputeStatus(uint _disputeID) external view returns(DisputeStatus status);

    /** @dev Return the current ruling of a dispute. This is useful for parties to know if they should appeal.
     *  @param _disputeID ID of the dispute.
     *  @return ruling The ruling which has been given or the one which will be given if there is no appeal.
     */
    function currentRuling(uint _disputeID) external view returns(uint ruling);

}

// File: https://github.com/kleros/erc-792/blob/c00f37dacdbf296e038bbaec9ad86c6a2f4b48d1/contracts/IArbitrable.sol

/**
 *  @title IArbitrable
 *  @author Enrique Piqueras - <enrique@kleros.io>
 */

pragma solidity ^0.5;


/** @title IArbitrable
 *  Arbitrable interface.
 *  When developing arbitrable contracts, we need to:
 *  -Define the action taken when a ruling is received by the contract.
 *  -Allow dispute creation. For this a function must call arbitrator.createDispute.value(_fee)(_choices,_extraData);
 */
interface IArbitrable {

    /** @dev To be raised when a ruling is given.
     *  @param _arbitrator The arbitrator giving the ruling.
     *  @param _disputeID ID of the dispute in the Arbitrator contract.
     *  @param _ruling The ruling which was given.
     */
    event Ruling(IArbitrator indexed _arbitrator, uint indexed _disputeID, uint _ruling);

    /** @dev Give a ruling for a dispute. Must be called by the arbitrator.
     *  The purpose of this function is to ensure that the address calling it has the right to rule on the contract.
     *  @param _disputeID ID of the dispute in the Arbitrator contract.
     *  @param _ruling Ruling given by the arbitrator. Note that 0 is reserved for "Not able/wanting to make a decision".
     */
    function rule(uint _disputeID, uint _ruling) external;
}

// File: browser/github/Proof-Of-Humanity/Proof-Of-Humanity/contracts/ProofOfHumanity.sol

/**
 *  @authors: [@unknownunknown1, @nix1g]
 *  @reviewers: [@fnanni-0*, @mtsalenc*, @nix1g*, @clesaege*, @hbarcelos*, @ferittuncer]
 *  @auditors: []
 *  @bounties: []
 *  @deployments: []
 *  @tools: [MythX*]
 */

pragma solidity ^0.5.13;
pragma experimental ABIEncoderV2;

/**
 *  @title ProofOfHumanity
 *  This contract is a curated registry for people. The users are identified by their address and can be added or removed through the request-challenge protocol.
 *  In order to challenge a registration request the challenger must provide one of the four reasons.
 *  New registration requests firstly should gain sufficient amount of vouches from other registered users and only after that they can be accepted or challenged.
 *  The users who vouched for submission that lost the challenge with the reason Duplicate or DoesNotExist would be penalized with optional fine or ban period.
 *  NOTE: This contract trusts that the Arbitrator is honest and will not reenter or modify its costs during a call.
 *  The arbitrator must support appeal period.
 */
contract ProofOfHumanity is IArbitrable, IEvidence {
    using CappedMath for uint;
    using CappedMath for uint64;

    /* Constants and immutable */

    uint private constant RULING_OPTIONS = 2; // The amount of non 0 choices the arbitrator can give.
    uint private constant AUTO_PROCESSED_VOUCH = 10; // The number of vouches that will be automatically processed when executing a request.
    uint private constant FULL_REASONS_SET = 15; // Indicates that reasons' bitmap is full. 0b1111.
    uint private constant MULTIPLIER_DIVISOR = 10000; // Divisor parameter for multipliers.

    bytes32 private DOMAIN_SEPARATOR; // The EIP-712 domainSeparator specific to this deployed instance. It is used to verify the IsHumanVoucher's signature.
    bytes32 private constant IS_HUMAN_VOUCHER_TYPEHASH = 0xa9e3fa1df5c3dbef1e9cfb610fa780355a0b5e0acb0fa8249777ec973ca789dc; // The EIP-712 typeHash of IsHumanVoucher. keccak256("IsHumanVoucher(address vouchedSubmission,uint256 voucherExpirationTimestamp)").

    /* Enums */

    enum Status {
        None, // The submission doesn't have a pending status.
        Vouching, // The submission is in the state where it can be vouched for and crowdfunded.
        PendingRegistration, // The submission is in the state where it can be challenged. Or accepted to the list, if there are no challenges within the time limit.
        PendingRemoval // The submission is in the state where it can be challenged. Or removed from the list, if there are no challenges within the time limit.
    }

    enum Party {
        None, // Party per default when there is no challenger or requester. Also used for unconclusive ruling.
        Requester, // Party that made the request to change a status.
        Challenger // Party that challenged the request to change a status.
    }

    enum Reason {
        None, // No reason specified. This option should be used to challenge removal requests.
        IncorrectSubmission, // The submission does not comply with the submission rules.
        Deceased, // The submitter has existed but does not exist anymore.
        Duplicate, // The submitter is already registered. The challenger has to point to the identity already registered or to a duplicate submission.
        DoesNotExist // The submitter is not real. For example, this can be used for videos showing computer generated persons.
    }

    /* Structs */

    struct Submission {
        Status status; // The current status of the submission.
        bool registered; // Whether the submission is in the registry or not. Note that a registered submission won't have privileges (e.g. vouching) if its duration expired.
        bool hasVouched; // True if this submission used its vouch for another submission. This is set back to false once the vouch is processed.
        uint64 submissionTime; // The time when the submission was accepted to the list.
        uint64 index; // Index of a submission.
        Request[] requests; // List of status change requests made for the submission.
    }

    struct Request {
        bool disputed; // True if a dispute was raised. Note that the request can enter disputed state multiple times, once per reason.
        bool resolved; // True if the request is executed and/or all raised disputes are resolved.
        bool requesterLost; // True if the requester has already had a dispute that wasn't ruled in his favor.
        Reason currentReason; // Current reason a registration request was challenged with. Is left empty for removal requests.
        uint8 usedReasons; // Bitmap of the reasons used by challengers of this request.
        uint16 nbParallelDisputes; // Tracks the number of simultaneously raised disputes. Parallel disputes are only allowed for reason Duplicate.
        uint16 arbitratorDataID; // The index of the relevant arbitratorData struct. All the arbitrator info is stored in a separate struct to reduce gas cost.
        uint16 lastChallengeID; // The ID of the last challenge, which is equal to the total number of challenges for the request.
        uint32 lastProcessedVouch; // Stores the index of the last processed vouch in the array of vouches. It is used for partial processing of the vouches in resolved submissions.
        uint64 currentDuplicateIndex; // Stores the index of the duplicate submission provided by the challenger who is currently winning.
        uint64 challengePeriodStart; // Time when the submission can be challenged.
        address payable requester; // Address that made a request. It is left empty for the registration requests since it matches submissionID in that case.
        address payable ultimateChallenger; // Address of the challenger who won a dispute and who users that vouched for the request must pay the fines to.
        address[] vouches; // Stores the addresses of submissions that vouched for this request and whose vouches were used in this request.
        mapping(uint => Challenge) challenges; // Stores all the challenges of this request. challengeID -> Challenge.
        mapping(address => bool) challengeDuplicates; // Indicates whether a certain duplicate address has been used in a challenge or not.
    }

    // Some arrays below have 3 elements to map with the Party enums for better readability:
    // - 0: is unused, matches `Party.None`.
    // - 1: for `Party.Requester`.
    // - 2: for `Party.Challenger`.
    struct Round {
        uint[3] paidFees; // Tracks the fees paid by each side in this round.
        Party sideFunded; // Stores the side that successfully paid the appeal fees in the latest round. Note that if both sides have paid a new round is created.
        uint feeRewards; // Sum of reimbursable fees and stake rewards available to the parties that made contributions to the side that ultimately wins a dispute.
        mapping(address => uint[3]) contributions; // Maps contributors to their contributions for each side.
    }

    struct Challenge {
        uint disputeID; // The ID of the dispute related to the challenge.
        Party ruling; // Ruling given by the arbitrator of the dispute.
        uint16 lastRoundID; // The ID of the last round.
        uint64 duplicateSubmissionIndex; // Index of a submission, which is a supposed duplicate of a challenged submission. It is only used for reason Duplicate.
        address payable challenger; // Address that challenged the request.
        mapping(uint => Round) rounds; // Tracks the info of each funding round of the challenge.
    }

    // The data tied to the arbitrator that will be needed to recover the submission info for arbitrator's call.
    struct DisputeData {
        uint96 challengeID; // The ID of the challenge of the request.
        address submissionID; // The submission, which ongoing request was challenged.
    }

    struct ArbitratorData {
        IArbitrator arbitrator; // Address of the trusted arbitrator to solve disputes.
        uint96 metaEvidenceUpdates; // The meta evidence to be used in disputes.
        bytes arbitratorExtraData; // Extra data for the arbitrator.
    }

    /* Storage */

    address public governor; // The address that can make governance changes to the parameters of the contract.

    uint public submissionBaseDeposit; // The base deposit to make a new request for a submission.

    // Note that to ensure correct contract behaviour the sum of challengePeriodDuration and renewalPeriodDuration should be less than submissionDuration.
    uint64 public submissionDuration; // Time after which the registered submission will no longer be considered registered. The submitter has to reapply to the list to refresh it.
    uint64 public renewalPeriodDuration; //  The duration of the period when the registered submission can reapply.
    uint64 public challengePeriodDuration; // The time after which a request becomes executable if not challenged. Note that this value should be less than the time spent on potential dispute's resolution, to avoid complications of parallel dispute handling.

    uint64 public requiredNumberOfVouches; // The number of registered users that have to vouch for a new registration request in order for it to enter PendingRegistration state.

    uint public sharedStakeMultiplier; // Multiplier for calculating the fee stake that must be paid in the case where arbitrator refused to arbitrate.
    uint public winnerStakeMultiplier; // Multiplier for calculating the fee stake paid by the party that won the previous round.
    uint public loserStakeMultiplier; // Multiplier for calculating the fee stake paid by the party that lost the previous round.

    uint public submissionCounter; // The total count of all submissions that made a registration request at some point. Includes manually added submissions as well.

    ArbitratorData[] public arbitratorDataList; // Stores the arbitrator data of the contract. Updated each time the data is changed.

    mapping(address => Submission) private submissions; // Maps the submission ID to its data. submissions[submissionID]. It is private because of getSubmissionInfo().
    mapping(address => mapping(address => bool)) public vouches; // Indicates whether or not the voucher has vouched for a certain submission. vouches[voucherID][submissionID].
    mapping(address => mapping(uint => DisputeData)) public arbitratorDisputeIDToDisputeData; // Maps a dispute ID with its data. arbitratorDisputeIDToDisputeData[arbitrator][disputeID].

    /* Modifiers */

    modifier onlyGovernor {require(msg.sender == governor, "The caller must be the governor"); _;}

    /* Events */

    /**
     *  @dev Emitted when a vouch is added.
     *  @param _submissionID The submission that receives the vouch.
     *  @param _voucher The address that vouched.
     */
    event VouchAdded(address indexed _submissionID, address indexed _voucher);

    /**
     *  @dev Emitted when a vouch is removed.
     *  @param _submissionID The submission which vouch is removed.
     *  @param _voucher The address that removes its vouch.
     */
    event VouchRemoved(address indexed _submissionID, address indexed _voucher);

    /** @dev Emitted when the request to add a submission to the registry is made.
     *  @param _submissionID The ID of the submission.
     *  @param _requestID The ID of the newly created request.
     */
    event AddSubmission(address indexed _submissionID, uint _requestID);

    /** @dev Emitted when the reapplication request is made.
     *  @param _submissionID The ID of the submission.
     *  @param _requestID The ID of the newly created request.
     */
    event ReapplySubmission(address indexed _submissionID, uint _requestID);

    /** @dev Emitted when the removal request is made.
     *  @param _requester The address that made the request.
     *  @param _submissionID The ID of the submission.
     *  @param _requestID The ID of the newly created request.
     */
    event RemoveSubmission(address indexed _requester, address indexed _submissionID, uint _requestID);

    /** @dev Emitted when the submission is challenged.
     *  @param _submissionID The ID of the submission.
     *  @param _requestID The ID of the latest request.
     *  @param _challengeID The ID of the challenge.
     */
    event SubmissionChallenged(address indexed _submissionID, uint indexed _requestID, uint _challengeID);

    /** @dev To be emitted when someone contributes to the appeal process.
     *  @param _submissionID The ID of the submission.
     *  @param _challengeID The index of the challenge.
     *  @param _party The party which received the contribution.
     *  @param _contributor The address of the contributor.
     *  @param _amount The amount contributed.
     */
    event AppealContribution(address indexed _submissionID, uint indexed _challengeID, Party _party, address indexed _contributor, uint _amount);

    /** @dev Emitted when one of the parties successfully paid its appeal fees.
     *  @param _submissionID The ID of the submission.
     *  @param _challengeID The index of the challenge which appeal was funded.
     *  @param _side The side that is fully funded.
     */
    event HasPaidAppealFee(address indexed _submissionID, uint indexed _challengeID, Party _side);

    /** @dev Emitted when the challenge is resolved.
     *  @param _submissionID The ID of the submission.
     *  @param _requestID The ID of the latest request.
     *  @param _challengeID The ID of the challenge that was resolved.
     */
    event ChallengeResolved(address indexed _submissionID, uint indexed _requestID, uint _challengeID);

    /** @dev Emitted in the constructor using most of its parameters.
     *  This event is needed for Subgraph. ArbitratorExtraData and renewalPeriodDuration are not needed for this event.
     */
    event ArbitratorComplete(
        IArbitrator _arbitrator,
        address indexed _governor,
        uint _submissionBaseDeposit,
        uint _submissionDuration,
        uint _challengePeriodDuration,
        uint _requiredNumberOfVouches,
        uint _sharedStakeMultiplier,
        uint _winnerStakeMultiplier,
        uint _loserStakeMultiplier
    );

    /** @dev Constructor.
     *  @param _arbitrator The trusted arbitrator to resolve potential disputes.
     *  @param _arbitratorExtraData Extra data for the trusted arbitrator contract.
     *  @param _registrationMetaEvidence The URI of the meta evidence object for registration requests.
     *  @param _clearingMetaEvidence The URI of the meta evidence object for clearing requests.
     *  @param _submissionBaseDeposit The base deposit to make a request for a submission.
     *  @param _submissionDuration Time in seconds during which the registered submission won't automatically lose its status.
     *  @param _renewalPeriodDuration Value that defines the duration of submission's renewal period.
     *  @param _challengePeriodDuration The time in seconds during which the request can be challenged.
     *  @param _multipliers The array that contains fee stake multipliers to avoid 'stack too deep' error.
     *  @param _requiredNumberOfVouches The number of vouches the submission has to have to pass from Vouching to PendingRegistration state.
     */
    constructor(
        IArbitrator _arbitrator,
        bytes memory _arbitratorExtraData,
        string memory _registrationMetaEvidence,
        string memory _clearingMetaEvidence,
        uint _submissionBaseDeposit,
        uint64 _submissionDuration,
        uint64 _renewalPeriodDuration,
        uint64 _challengePeriodDuration,
        uint[3] memory _multipliers,
        uint64 _requiredNumberOfVouches
    ) public {
        emit MetaEvidence(0, _registrationMetaEvidence);
        emit MetaEvidence(1, _clearingMetaEvidence);

        governor = msg.sender;
        submissionBaseDeposit = _submissionBaseDeposit;
        submissionDuration = _submissionDuration;
        renewalPeriodDuration = _renewalPeriodDuration;
        challengePeriodDuration = _challengePeriodDuration;
        sharedStakeMultiplier = _multipliers[0];
        winnerStakeMultiplier = _multipliers[1];
        loserStakeMultiplier = _multipliers[2];
        requiredNumberOfVouches = _requiredNumberOfVouches;

        ArbitratorData storage arbitratorData = arbitratorDataList[arbitratorDataList.length++];
        arbitratorData.arbitrator = _arbitrator;
        arbitratorData.arbitratorExtraData = _arbitratorExtraData;
        emit ArbitratorComplete(_arbitrator, msg.sender, _submissionBaseDeposit, _submissionDuration, _challengePeriodDuration, _requiredNumberOfVouches, _multipliers[0], _multipliers[1], _multipliers[2]);

        // EIP-712.
        bytes32 DOMAIN_TYPEHASH = 0x8cad95687ba82c2ce50e74f7b754645e5117c3a5bec8151c0726d5857980a866; // keccak256("EIP712Domain(string name,uint256 chainId,address verifyingContract)").
        uint256 chainId;
        assembly { chainId := chainid } // block.chainid got introduced in Solidity v0.8.0.
        DOMAIN_SEPARATOR = keccak256(abi.encode(DOMAIN_TYPEHASH, keccak256("Proof of Humanity"), chainId, address(this)));
    }

    /* External and Public */

    // ************************ //
    // *      Governance      * //
    // ************************ //

    /** @dev Allows the governor to directly add new submissions to the list as a part of the seeding event.
     *  @param _submissionIDs The addresses of newly added submissions.
     *  @param _evidence The array of evidence links for each submission.
     *  @param _names The array of names of the submitters. This parameter is for Subgraph only and it won't be used in this function.
     */
    function addSubmissionManually(address[] calldata _submissionIDs, string[] calldata _evidence, string[] calldata _names) external onlyGovernor {
        uint counter = submissionCounter;
        uint arbitratorDataID = arbitratorDataList.length - 1;
        for (uint i = 0; i < _submissionIDs.length; i++) {
            Submission storage submission = submissions[_submissionIDs[i]];
            require(submission.requests.length == 0, "Submission already been created");
            submission.index = uint64(counter);
            counter++;

            Request storage request = submission.requests[submission.requests.length++];
            submission.registered = true;

            submission.submissionTime = uint64(now);
            request.arbitratorDataID = uint16(arbitratorDataID);
            request.resolved = true;

            if (bytes(_evidence[i]).length > 0)
                emit Evidence(arbitratorDataList[arbitratorDataID].arbitrator, uint(_submissionIDs[i]), msg.sender, _evidence[i]);
        }
        submissionCounter = counter;
    }

    /** @dev Allows the governor to directly remove a registered entry from the list as a part of the seeding event.
     *  @param _submissionID The address of a submission to remove.
     */
    function removeSubmissionManually(address _submissionID) external onlyGovernor {
        Submission storage submission = submissions[_submissionID];
        require(submission.registered && submission.status == Status.None, "Wrong status");
        submission.registered = false;
    }

    /** @dev Change the base amount required as a deposit to make a request for a submission.
     *  @param _submissionBaseDeposit The new base amount of wei required to make a new request.
     */
    function changeSubmissionBaseDeposit(uint _submissionBaseDeposit) external onlyGovernor {
        submissionBaseDeposit = _submissionBaseDeposit;
    }

    /** @dev Change the duration of the submission, renewal and challenge periods.
     *  @param _submissionDuration The new duration of the time the submission is considered registered.
     *  @param _renewalPeriodDuration The new value that defines the duration of submission's renewal period.
     *  @param _challengePeriodDuration The new duration of the challenge period. It should be lower than the time for a dispute.
     */
    function changeDurations(uint64 _submissionDuration, uint64 _renewalPeriodDuration, uint64 _challengePeriodDuration) external onlyGovernor {
        require(_challengePeriodDuration.addCap64(_renewalPeriodDuration) < _submissionDuration, "Incorrect inputs");
        submissionDuration = _submissionDuration;
        renewalPeriodDuration = _renewalPeriodDuration;
        challengePeriodDuration = _challengePeriodDuration;
    }

    /** @dev Change the number of vouches required for the request to pass to the pending state.
     *  @param _requiredNumberOfVouches The new required number of vouches.
     */
    function changeRequiredNumberOfVouches(uint64 _requiredNumberOfVouches) external onlyGovernor {
        requiredNumberOfVouches = _requiredNumberOfVouches;
    }

    /** @dev Change the proportion of arbitration fees that must be paid as fee stake by parties when there is no winner or loser (e.g. when the arbitrator refused to rule).
     *  @param _sharedStakeMultiplier Multiplier of arbitration fees that must be paid as fee stake. In basis points.
     */
    function changeSharedStakeMultiplier(uint _sharedStakeMultiplier) external onlyGovernor {
        sharedStakeMultiplier = _sharedStakeMultiplier;
    }

    /** @dev Change the proportion of arbitration fees that must be paid as fee stake by the winner of the previous round.
     *  @param _winnerStakeMultiplier Multiplier of arbitration fees that must be paid as fee stake. In basis points.
     */
    function changeWinnerStakeMultiplier(uint _winnerStakeMultiplier) external onlyGovernor {
        winnerStakeMultiplier = _winnerStakeMultiplier;
    }

    /** @dev Change the proportion of arbitration fees that must be paid as fee stake by the party that lost the previous round.
     *  @param _loserStakeMultiplier Multiplier of arbitration fees that must be paid as fee stake. In basis points.
     */
    function changeLoserStakeMultiplier(uint _loserStakeMultiplier) external onlyGovernor {
        loserStakeMultiplier = _loserStakeMultiplier;
    }

    /** @dev Change the governor of the contract.
     *  @param _governor The address of the new governor.
     */
    function changeGovernor(address _governor) external onlyGovernor {
        governor = _governor;
    }

    /** @dev Update the meta evidence used for disputes.
     *  @param _registrationMetaEvidence The meta evidence to be used for future registration request disputes.
     *  @param _clearingMetaEvidence The meta evidence to be used for future clearing request disputes.
     */
    function changeMetaEvidence(string calldata _registrationMetaEvidence, string calldata _clearingMetaEvidence) external onlyGovernor {
        ArbitratorData storage arbitratorData = arbitratorDataList[arbitratorDataList.length - 1];
        uint96 newMetaEvidenceUpdates = arbitratorData.metaEvidenceUpdates + 1;
        arbitratorDataList.push(ArbitratorData({
            arbitrator: arbitratorData.arbitrator,
            metaEvidenceUpdates: newMetaEvidenceUpdates,
            arbitratorExtraData: arbitratorData.arbitratorExtraData
        }));
        emit MetaEvidence(2 * newMetaEvidenceUpdates, _registrationMetaEvidence);
        emit MetaEvidence(2 * newMetaEvidenceUpdates + 1, _clearingMetaEvidence);
    }

    /** @dev Change the arbitrator to be used for disputes that may be raised in the next requests. The arbitrator is trusted to support appeal period and not reenter.
     *  @param _arbitrator The new trusted arbitrator to be used in the next requests.
     *  @param _arbitratorExtraData The extra data used by the new arbitrator.
     */
    function changeArbitrator(IArbitrator _arbitrator, bytes calldata _arbitratorExtraData) external onlyGovernor {
        ArbitratorData storage arbitratorData = arbitratorDataList[arbitratorDataList.length - 1];
        arbitratorDataList.push(ArbitratorData({
            arbitrator: _arbitrator,
            metaEvidenceUpdates: arbitratorData.metaEvidenceUpdates,
            arbitratorExtraData: _arbitratorExtraData
        }));
    }

    // ************************ //
    // *       Requests       * //
    // ************************ //

    /** @dev Make a request to add a new entry to the list. Paying the full deposit right away is not required as it can be crowdfunded later.
     *  @param _evidence A link to evidence using its URI.
     *  @param _name The name of the submitter. This parameter is for Subgraph only and it won't be used in this function.
     */
    function addSubmission(string calldata _evidence, string calldata _name) external payable {
        Submission storage submission = submissions[msg.sender];
        require(!submission.registered && submission.status == Status.None, "Wrong status");
        if (submission.requests.length == 0) {
            submission.index = uint64(submissionCounter);
            submissionCounter++;
        }
        submission.status = Status.Vouching;
        emit AddSubmission(msg.sender, submission.requests.length);
        requestRegistration(msg.sender, _evidence);
    }

    /** @dev Make a request to refresh a submissionDuration. Paying the full deposit right away is not required as it can be crowdfunded later.
     *  Note that the user can reapply even when current submissionDuration has not expired, but only after the start of renewal period.
     *  @param _evidence A link to evidence using its URI.
     *  @param _name The name of the submitter. This parameter is for Subgraph only and it won't be used in this function.
     */
    function reapplySubmission(string calldata _evidence, string calldata _name) external payable {
        Submission storage submission = submissions[msg.sender];
        require(submission.registered && submission.status == Status.None, "Wrong status");
        uint renewalAvailableAt = submission.submissionTime.addCap64(submissionDuration.subCap64(renewalPeriodDuration));
        require(now >= renewalAvailableAt, "Can't reapply yet");
        submission.status = Status.Vouching;
        emit ReapplySubmission(msg.sender, submission.requests.length);
        requestRegistration(msg.sender, _evidence);
    }

    /** @dev Make a request to remove a submission from the list. Requires full deposit. Accepts enough ETH to cover the deposit, reimburses the rest.
     *  Note that this request can't be made during the renewal period to avoid spam leading to submission's expiration.
     *  @param _submissionID The address of the submission to remove.
     *  @param _evidence A link to evidence using its URI.
     */
    function removeSubmission(address _submissionID, string calldata _evidence) external payable {
        Submission storage submission = submissions[_submissionID];
        require(submission.registered && submission.status == Status.None, "Wrong status");
        uint renewalAvailableAt = submission.submissionTime.addCap64(submissionDuration.subCap64(renewalPeriodDuration));
        require(now < renewalAvailableAt, "Can't remove after renewal");
        submission.status = Status.PendingRemoval;

        Request storage request = submission.requests[submission.requests.length++];
        request.requester = msg.sender;
        request.challengePeriodStart = uint64(now);

        uint arbitratorDataID = arbitratorDataList.length - 1;
        request.arbitratorDataID = uint16(arbitratorDataID);

        Round storage round = request.challenges[0].rounds[0];

        IArbitrator requestArbitrator = arbitratorDataList[arbitratorDataID].arbitrator;
        uint arbitrationCost = requestArbitrator.arbitrationCost(arbitratorDataList[arbitratorDataID].arbitratorExtraData);
        uint totalCost = arbitrationCost.addCap(submissionBaseDeposit);
        contribute(round, Party.Requester, msg.sender, msg.value, totalCost);

        require(round.paidFees[uint(Party.Requester)] >= totalCost, "You must fully fund your side");
        round.sideFunded = Party.Requester;

        emit RemoveSubmission(msg.sender, _submissionID, submission.requests.length - 1);

        if (bytes(_evidence).length > 0)
            emit Evidence(requestArbitrator, submission.requests.length - 1 + uint(_submissionID), msg.sender, _evidence);
    }

    /** @dev Fund the requester's deposit. Accepts enough ETH to cover the deposit, reimburses the rest.
     *  @param _submissionID The address of the submission which ongoing request to fund.
     */
    function fundSubmission(address _submissionID) external payable {
        Submission storage submission = submissions[_submissionID];
        require(submission.status == Status.Vouching, "Wrong status");
        Request storage request = submission.requests[submission.requests.length - 1];
        Challenge storage challenge = request.challenges[0];
        Round storage round = challenge.rounds[0];

        ArbitratorData storage arbitratorData = arbitratorDataList[request.arbitratorDataID];
        uint arbitrationCost = arbitratorData.arbitrator.arbitrationCost(arbitratorData.arbitratorExtraData);
        uint totalCost = arbitrationCost.addCap(submissionBaseDeposit);
        contribute(round, Party.Requester, msg.sender, msg.value, totalCost);

        if (round.paidFees[uint(Party.Requester)] >= totalCost)
            round.sideFunded = Party.Requester;
    }

    /** @dev Vouch for the submission. Note that the event spam is not an issue as it will be handled by the UI.
     *  @param _submissionID The address of the submission to vouch for.
     */
    function addVouch(address _submissionID) external {
        vouches[msg.sender][_submissionID] = true;
        emit VouchAdded(_submissionID, msg.sender);
    }

    /** @dev Remove the submission's vouch that has been added earlier. Note that the event spam is not an issue as it will be handled by the UI.
     *  @param _submissionID The address of the submission to remove vouch from.
     */
    function removeVouch(address _submissionID) external {
        vouches[msg.sender][_submissionID] = false;
        emit VouchRemoved(_submissionID, msg.sender);
    }

    /** @dev Allows to withdraw a mistakenly added submission while it's still in a vouching state.
     */
    function withdrawSubmission() external {
        Submission storage submission = submissions[msg.sender];
        require(submission.status == Status.Vouching, "Wrong status");
        Request storage request = submission.requests[submission.requests.length - 1];

        submission.status = Status.None;
        request.resolved = true;

        withdrawFeesAndRewards(msg.sender, msg.sender, submission.requests.length - 1, 0, 0); // Automatically withdraw for the requester.
    }

    /** @dev Change submission's state from Vouching to PendingRegistration if all conditions are met.
     *  @param _submissionID The address of the submission which status to change.
     *  @param _vouches Array of users whose vouches to count.
     *  @param _signatures Array of EIP-712 signatures of struct IsHumanVoucher (optional).
     *  @param _expirationTimestamps Array of expiration timestamps for each signature (optional).
     *  struct IsHumanVoucher {
     *      address vouchedSubmission;
     *      uint256 voucherExpirationTimestamp;
     *  }
     */
    function changeStateToPending(address _submissionID, address[] calldata _vouches, bytes[] calldata _signatures, uint[] calldata _expirationTimestamps) external {
        Submission storage submission = submissions[_submissionID];
        require(submission.status == Status.Vouching, "Wrong status");
        Request storage request = submission.requests[submission.requests.length - 1];
        /* solium-disable indentation */
        {
            Challenge storage challenge = request.challenges[0];
            Round storage round = challenge.rounds[0];
            require(round.sideFunded == Party.Requester, "Requester is not funded");
        }
        /* solium-enable indentation */
        uint timeOffset = now - submissionDuration; // Precompute the offset before the loop for efficiency and then compare it with the submission time to check the expiration.

        bytes2 PREFIX = "\x19\x01";
        for (uint i = 0; i < _signatures.length && request.vouches.length < requiredNumberOfVouches; i++) {
            address voucherAddress;
            /* solium-disable indentation */
            {
                // Get typed structure hash.
                bytes32 messageHash = keccak256(abi.encode(IS_HUMAN_VOUCHER_TYPEHASH, _submissionID, _expirationTimestamps[i]));
                bytes32 hash = keccak256(abi.encodePacked(PREFIX, DOMAIN_SEPARATOR, messageHash));

                // Decode the signature.
                bytes memory signature = _signatures[i];
                bytes32 r;
                bytes32 s;
                uint8 v;
                assembly {
                    r := mload(add(signature, 0x20))
                    s := mload(add(signature, 0x40))
                    v := byte(0, mload(add(signature, 0x60)))
                }
                if (v < 27) v += 27;
                require(v == 27 || v == 28, "Invalid signature");

                // Recover the signer's address.
                voucherAddress = ecrecover(hash, v, r, s);
            }
            /* solium-enable indentation */

            Submission storage voucher = submissions[voucherAddress];
            if (!voucher.hasVouched && voucher.registered && timeOffset <= voucher.submissionTime &&
            now < _expirationTimestamps[i] && _submissionID != voucherAddress) {
                request.vouches.push(voucherAddress);
                voucher.hasVouched = true;
                emit VouchAdded(_submissionID, voucherAddress);
            }
        }

        for (uint i = 0; i<_vouches.length && request.vouches.length<requiredNumberOfVouches; i++) {
            // Check that the vouch isn't currently used by another submission and the voucher has a right to vouch.
            Submission storage voucher = submissions[_vouches[i]];
            if (!voucher.hasVouched && voucher.registered && timeOffset <= voucher.submissionTime &&
            vouches[_vouches[i]][_submissionID] && _submissionID != _vouches[i]) {
                request.vouches.push(_vouches[i]);
                voucher.hasVouched = true;
            }
        }
        require(request.vouches.length >= requiredNumberOfVouches, "Not enough valid vouches");
        submission.status = Status.PendingRegistration;
        request.challengePeriodStart = uint64(now);
    }

    /** @dev Challenge the submission's request. Accepts enough ETH to cover the deposit, reimburses the rest.
     *  @param _submissionID The address of the submission which request to challenge.
     *  @param _reason The reason to challenge the request. Left empty for removal requests.
     *  @param _duplicateID The address of a supposed duplicate submission. Ignored if the reason is not Duplicate.
     *  @param _evidence A link to evidence using its URI. Ignored if not provided.
     */
    function challengeRequest(address _submissionID, Reason _reason, address _duplicateID, string calldata _evidence) external payable {
        Submission storage submission = submissions[_submissionID];
        if (submission.status == Status.PendingRegistration)
            require(_reason != Reason.None, "Reason must be specified");
        else if (submission.status == Status.PendingRemoval)
            require(_reason == Reason.None, "Reason must be left empty");
        else
            revert("Wrong status");

        Request storage request = submission.requests[submission.requests.length - 1];
        require(now - request.challengePeriodStart <= challengePeriodDuration, "Time to challenge has passed");

        Challenge storage challenge = request.challenges[request.lastChallengeID];
        /* solium-disable indentation */
        {
            Reason currentReason = request.currentReason;
            if (_reason == Reason.Duplicate) {
                require(submissions[_duplicateID].status > Status.None || submissions[_duplicateID].registered, "Wrong duplicate status");
                require(_submissionID != _duplicateID, "Can't be a duplicate of itself");
                require(currentReason == Reason.Duplicate || currentReason == Reason.None, "Another reason is active");
                require(!request.challengeDuplicates[_duplicateID], "Duplicate address already used");
                request.challengeDuplicates[_duplicateID] = true;
                challenge.duplicateSubmissionIndex = submissions[_duplicateID].index;
            } else
                require(!request.disputed, "The request is disputed");

            if (currentReason != _reason) {
                uint8 reasonBit = 1 << (uint8(_reason) - 1); // Get the bit that corresponds with reason's index.
                require((reasonBit & ~request.usedReasons) == reasonBit, "The reason has already been used");

                request.usedReasons ^= reasonBit; // Mark the bit corresponding with reason's index as 'true', to indicate that the reason was used.
                request.currentReason = _reason;
            }
        }
        /* solium-enable indentation */

        Round storage round = challenge.rounds[0];
        ArbitratorData storage arbitratorData = arbitratorDataList[request.arbitratorDataID];

        uint arbitrationCost = arbitratorData.arbitrator.arbitrationCost(arbitratorData.arbitratorExtraData);
        contribute(round, Party.Challenger, msg.sender, msg.value, arbitrationCost);
        require(round.paidFees[uint(Party.Challenger)] >= arbitrationCost, "You must fully fund your side");
        round.feeRewards = round.feeRewards.subCap(arbitrationCost);
        round.sideFunded = Party.None; // Set this back to 0, since it's no longer relevant as the new round is created.

        challenge.disputeID = arbitratorData.arbitrator.createDispute.value(arbitrationCost)(RULING_OPTIONS, arbitratorData.arbitratorExtraData);
        challenge.challenger = msg.sender;

        DisputeData storage disputeData = arbitratorDisputeIDToDisputeData[address(arbitratorData.arbitrator)][challenge.disputeID];
        disputeData.challengeID = uint96(request.lastChallengeID);
        disputeData.submissionID = _submissionID;

        request.disputed = true;
        request.nbParallelDisputes++;

        challenge.lastRoundID++;
        emit SubmissionChallenged(_submissionID, submission.requests.length - 1, disputeData.challengeID);

        request.lastChallengeID++;

        emit Dispute(
            arbitratorData.arbitrator,
            challenge.disputeID,
            submission.status == Status.PendingRegistration ? 2 * arbitratorData.metaEvidenceUpdates : 2 * arbitratorData.metaEvidenceUpdates + 1,
            submission.requests.length - 1 + uint(_submissionID)
        );

        if (bytes(_evidence).length > 0)
            emit Evidence(arbitratorData.arbitrator, submission.requests.length - 1 + uint(_submissionID), msg.sender, _evidence);
    }

    /** @dev Takes up to the total amount required to fund a side of an appeal. Reimburses the rest. Creates an appeal if both sides are fully funded.
     *  @param _submissionID The address of the submission which request to fund.
     *  @param _challengeID The index of a dispute, created for the request.
     *  @param _side The recipient of the contribution.
     */
    function fundAppeal(address _submissionID, uint _challengeID, Party _side) external payable {
        require(_side != Party.None); // You can only fund either requester or challenger.
        Submission storage submission = submissions[_submissionID];
        require(submission.status == Status.PendingRegistration || submission.status == Status.PendingRemoval, "Wrong status");
        Request storage request = submission.requests[submission.requests.length - 1];
        require(request.disputed, "No dispute to appeal");
        require(_challengeID < request.lastChallengeID, "Challenge out of bounds");

        Challenge storage challenge = request.challenges[_challengeID];
        ArbitratorData storage arbitratorData = arbitratorDataList[request.arbitratorDataID];

        (uint appealPeriodStart, uint appealPeriodEnd) = arbitratorData.arbitrator.appealPeriod(challenge.disputeID);
        require(now >= appealPeriodStart && now < appealPeriodEnd, "Appeal period is over");

        uint multiplier;
        /* solium-disable indentation */
        {
            Party winner = Party(arbitratorData.arbitrator.currentRuling(challenge.disputeID));
            if (winner == _side){
                multiplier = winnerStakeMultiplier;
            } else if (winner == Party.None){
                multiplier = sharedStakeMultiplier;
            } else {
                multiplier = loserStakeMultiplier;
                require(now-appealPeriodStart < (appealPeriodEnd-appealPeriodStart)/2, "Appeal period is over for loser");
            }
        }
        /* solium-enable indentation */

        Round storage round = challenge.rounds[challenge.lastRoundID];
        require(_side != round.sideFunded, "Side is already funded");

        uint appealCost = arbitratorData.arbitrator.appealCost(challenge.disputeID, arbitratorData.arbitratorExtraData);
        uint totalCost = appealCost.addCap((appealCost.mulCap(multiplier)) / MULTIPLIER_DIVISOR);
        uint contribution = contribute(round, _side, msg.sender, msg.value, totalCost);
        emit AppealContribution(_submissionID, _challengeID, _side, msg.sender, contribution);

        if (round.paidFees[uint(_side)] >= totalCost) {
            if (round.sideFunded == Party.None) {
                round.sideFunded = _side;
            } else {
                // Both sides are fully funded. Create an appeal.
                arbitratorData.arbitrator.appeal.value(appealCost)(challenge.disputeID, arbitratorData.arbitratorExtraData);
                challenge.lastRoundID++;
                round.feeRewards = round.feeRewards.subCap(appealCost);
                round.sideFunded = Party.None; // Set this back to default in the past round as it's no longer relevant.
            }
            emit HasPaidAppealFee(_submissionID, _challengeID, _side);
        }
    }

    /** @dev Execute a request if the challenge period passed and no one challenged the request.
     *  @param _submissionID The address of the submission with the request to execute.
     */
    function executeRequest(address _submissionID) external {
        Submission storage submission = submissions[_submissionID];
        uint requestID = submission.requests.length - 1;
        Request storage request = submission.requests[requestID];
        require(now - request.challengePeriodStart > challengePeriodDuration, "Can't execute yet");
        require(!request.disputed, "The request is disputed");
        address payable requester;
        if (submission.status == Status.PendingRegistration) {
            // It is possible for the requester to lose without a dispute if he was penalized for bad vouching while reapplying.
            if (!request.requesterLost) {
                submission.registered = true;
                submission.submissionTime = uint64(now);
            }
            requester = address(uint160(_submissionID));
        } else if (submission.status == Status.PendingRemoval) {
            submission.registered = false;
            requester = request.requester;
        } else
            revert("Incorrect status.");

        submission.status = Status.None;
        request.resolved = true;

        if (request.vouches.length != 0)
            processVouches(_submissionID, requestID, AUTO_PROCESSED_VOUCH);

        withdrawFeesAndRewards(requester, _submissionID, requestID, 0, 0); // Automatically withdraw for the requester.
    }

    /** @dev Processes vouches of the resolved request, so vouchings of users who vouched for it can be used in other submissions.
     *  Penalizes users who vouched for bad submissions.
     *  @param _submissionID The address of the submission which vouches to iterate.
     *  @param _requestID The ID of the request which vouches to iterate.
     *  @param _iterations The number of iterations to go through.
     */
    function processVouches(address _submissionID, uint _requestID, uint _iterations) public {
        Submission storage submission = submissions[_submissionID];
        Request storage request = submission.requests[_requestID];
        require(request.resolved, "Submission must be resolved");

        uint lastProcessedVouch = request.lastProcessedVouch;
        uint endIndex = _iterations.addCap(lastProcessedVouch);
        uint vouchCount = request.vouches.length;

        if (endIndex > vouchCount)
            endIndex = vouchCount;

        Reason currentReason = request.currentReason;
        // If the ultimate challenger is defined that means that the request was ruled in favor of the challenger.
        bool applyPenalty = request.ultimateChallenger != address(0x0) && (currentReason == Reason.Duplicate || currentReason == Reason.DoesNotExist);
        for (uint i = lastProcessedVouch; i < endIndex; i++) {
            Submission storage voucher = submissions[request.vouches[i]];
            voucher.hasVouched = false;
            if (applyPenalty) {
                // Check the situation when vouching address is in the middle of reapplication process.
                if (voucher.status == Status.Vouching || voucher.status == Status.PendingRegistration)
                    voucher.requests[voucher.requests.length - 1].requesterLost = true;

                voucher.registered = false;
            }
        }
        request.lastProcessedVouch = uint32(endIndex);
    }

    /** @dev Reimburses contributions if no disputes were raised. If a dispute was raised, sends the fee stake rewards and reimbursements proportionally to the contributions made to the winner of a dispute.
     *  @param _beneficiary The address that made contributions to a request.
     *  @param _submissionID The address of the submission with the request from which to withdraw.
     *  @param _requestID The request from which to withdraw.
     *  @param _challengeID The ID of the challenge from which to withdraw.
     *  @param _round The round from which to withdraw.
     */
    function withdrawFeesAndRewards(address payable _beneficiary, address _submissionID, uint _requestID, uint _challengeID, uint _round) public {
        Submission storage submission = submissions[_submissionID];
        Request storage request = submission.requests[_requestID];
        Challenge storage challenge = request.challenges[_challengeID];
        Round storage round = challenge.rounds[_round];
        require(request.resolved, "Submission must be resolved");
        require(_beneficiary != address(0x0), "Beneficiary must not be empty");

        Party ruling = challenge.ruling;
        uint reward;
        // Reimburse the payment if the last round wasn't fully funded.
        // Note that the 0 round is always considered funded if there is a challenge. If there was no challenge the requester will be reimbursed with the subsequent condition, since the ruling will be Party.None.
        if (_round != 0 && _round == challenge.lastRoundID) {
            reward = round.contributions[_beneficiary][uint(Party.Requester)] + round.contributions[_beneficiary][uint(Party.Challenger)];
        } else if (ruling == Party.None) {
            uint totalFeesInRound = round.paidFees[uint(Party.Challenger)] + round.paidFees[uint(Party.Requester)];
            uint claimableFees = round.contributions[_beneficiary][uint(Party.Challenger)] + round.contributions[_beneficiary][uint(Party.Requester)];
            reward = totalFeesInRound > 0 ? claimableFees * round.feeRewards / totalFeesInRound : 0;
        } else {
            // Challenger, who ultimately wins, will be able to get the deposit of the requester, even if he didn't participate in the initial dispute.
            if (_round == 0 && _beneficiary == request.ultimateChallenger && _challengeID == 0) {
                reward = round.feeRewards;
                round.feeRewards = 0;
            // This condition will prevent claiming a reward, intended for the ultimate challenger.
            } else if (request.ultimateChallenger==address(0x0) || _challengeID!=0 || _round!=0) {
                uint paidFees = round.paidFees[uint(ruling)];
                reward = paidFees > 0
                    ? (round.contributions[_beneficiary][uint(ruling)] * round.feeRewards) / paidFees
                    : 0;
            }
        }
        round.contributions[_beneficiary][uint(Party.Requester)] = 0;
        round.contributions[_beneficiary][uint(Party.Challenger)] = 0;
        _beneficiary.send(reward);
    }

    /** @dev Give a ruling for a dispute. Can only be called by the arbitrator. TRUSTED.
     *  Accounts for the situation where the winner loses a case due to paying less appeal fees than expected.
     *  @param _disputeID ID of the dispute in the arbitrator contract.
     *  @param _ruling Ruling given by the arbitrator. Note that 0 is reserved for "Refused to arbitrate".
     */
    function rule(uint _disputeID, uint _ruling) public {
        Party resultRuling = Party(_ruling);
        DisputeData storage disputeData = arbitratorDisputeIDToDisputeData[msg.sender][_disputeID];
        address submissionID = disputeData.submissionID;
        uint challengeID = disputeData.challengeID;
        Submission storage submission = submissions[submissionID];

        Request storage request = submission.requests[submission.requests.length - 1];
        Challenge storage challenge = request.challenges[challengeID];
        Round storage round = challenge.rounds[challenge.lastRoundID];
        ArbitratorData storage arbitratorData = arbitratorDataList[request.arbitratorDataID];

        require(address(arbitratorData.arbitrator) == msg.sender);
        require(!request.resolved);

        // The ruling is inverted if the loser paid its fees.
        if (round.sideFunded == Party.Requester) // If one side paid its fees, the ruling is in its favor. Note that if the other side had also paid, an appeal would have been created.
            resultRuling = Party.Requester;
        else if (round.sideFunded == Party.Challenger)
            resultRuling = Party.Challenger;

        emit Ruling(IArbitrator(msg.sender), _disputeID, uint(resultRuling));
        executeRuling(submissionID, challengeID, resultRuling);
    }

    /** @dev Submit a reference to evidence. EVENT.
     *  @param _submissionID The address of the submission which the evidence is related to.
     *  @param _evidence A link to an evidence using its URI.
     */
    function submitEvidence(address _submissionID, string calldata _evidence) external {
        Submission storage submission = submissions[_submissionID];
        Request storage request = submission.requests[submission.requests.length - 1];
        ArbitratorData storage arbitratorData = arbitratorDataList[request.arbitratorDataID];

        emit Evidence(arbitratorData.arbitrator, submission.requests.length - 1 + uint(_submissionID), msg.sender, _evidence);
    }

    /* Internal */

    /** @dev Make a request to register/reapply the submission. Paying the full deposit right away is not required as it can be crowdfunded later.
     *  @param _submissionID The address of the submission.
     *  @param _evidence A link to evidence using its URI.
     */
    function requestRegistration(address _submissionID, string memory _evidence) internal {
        Submission storage submission = submissions[_submissionID];
        Request storage request = submission.requests[submission.requests.length++];

        uint arbitratorDataID = arbitratorDataList.length - 1;
        request.arbitratorDataID = uint16(arbitratorDataID);

        Round storage round = request.challenges[0].rounds[0];

        IArbitrator requestArbitrator = arbitratorDataList[arbitratorDataID].arbitrator;
        uint arbitrationCost = requestArbitrator.arbitrationCost(arbitratorDataList[arbitratorDataID].arbitratorExtraData);
        uint totalCost = arbitrationCost.addCap(submissionBaseDeposit);
        contribute(round, Party.Requester, msg.sender, msg.value, totalCost);

        if (round.paidFees[uint(Party.Requester)] >= totalCost)
            round.sideFunded = Party.Requester;

        if (bytes(_evidence).length > 0)
            emit Evidence(requestArbitrator, submission.requests.length - 1 + uint(_submissionID), msg.sender, _evidence);
    }

    /** @dev Returns the contribution value and remainder from available ETH and required amount.
     *  @param _available The amount of ETH available for the contribution.
     *  @param _requiredAmount The amount of ETH required for the contribution.
     *  @return taken The amount of ETH taken.
     *  @return remainder The amount of ETH left from the contribution.
     */
    function calculateContribution(uint _available, uint _requiredAmount)
        internal
        pure
        returns(uint taken, uint remainder)
    {
        if (_requiredAmount > _available)
            return (_available, 0);

        remainder = _available - _requiredAmount;
        return (_requiredAmount, remainder);
    }

    /** @dev Make a fee contribution.
     *  @param _round The round to contribute to.
     *  @param _side The side to contribute to.
     *  @param _contributor The contributor.
     *  @param _amount The amount contributed.
     *  @param _totalRequired The total amount required for this side.
     *  @return The amount of fees contributed.
     */
    function contribute(Round storage _round, Party _side, address payable _contributor, uint _amount, uint _totalRequired) internal returns (uint) {
        uint contribution;
        uint remainingETH;
        (contribution, remainingETH) = calculateContribution(_amount, _totalRequired.subCap(_round.paidFees[uint(_side)]));
        _round.contributions[_contributor][uint(_side)] += contribution;
        _round.paidFees[uint(_side)] += contribution;
        _round.feeRewards += contribution;

        if (remainingETH != 0)
            _contributor.send(remainingETH);

        return contribution;
    }

    /** @dev Execute the ruling of a dispute.
     *  @param _submissionID ID of the submission.
     *  @param _challengeID ID of the challenge, related to the dispute.
     *  @param _winner Ruling given by the arbitrator. Note that 0 is reserved for "Refused to arbitrate".
     */
    function executeRuling(address _submissionID, uint _challengeID, Party _winner) internal {
        Submission storage submission = submissions[_submissionID];
        uint requestID = submission.requests.length - 1;
        Status status = submission.status;

        Request storage request = submission.requests[requestID];
        uint nbParallelDisputes = request.nbParallelDisputes;

        Challenge storage challenge = request.challenges[_challengeID];

        if (status == Status.PendingRemoval) {
            if (_winner == Party.Requester)
                submission.registered = false;

            submission.status = Status.None;
            request.resolved = true;
        } else if (status == Status.PendingRegistration) {
            // For a registration request there can be more than one dispute.
            if (_winner == Party.Requester) {
                if (nbParallelDisputes == 1) {
                    // Check whether or not the requester won all of his previous disputes for current reason.
                    if (!request.requesterLost) {
                        if (request.usedReasons == FULL_REASONS_SET) {
                            // All reasons being used means the request can't be challenged again, so we can update its status.
                            submission.status = Status.None;
                            submission.registered = true;
                            submission.submissionTime = uint64(now);
                            request.resolved = true;
                        } else {
                            // Refresh the state of the request so it can be challenged again.
                            request.disputed = false;
                            request.challengePeriodStart = uint64(now);
                            request.currentReason = Reason.None;
                        }
                    } else {
                        submission.status = Status.None;
                        request.resolved = true;
                    }
                }
            // Challenger won or it’s a tie.
            } else {
                request.requesterLost = true;
                // Update the status of the submission if there is no more disputes left.
                if (nbParallelDisputes == 1) {
                    submission.status = Status.None;
                    request.resolved = true;
                }
                // Store the challenger that made the requester lose. Update the challenger if there is a duplicate with lower submission time, which is indicated by submission's index.
                if (_winner==Party.Challenger && (request.ultimateChallenger==address(0x0) || challenge.duplicateSubmissionIndex<request.currentDuplicateIndex)) {
                    request.ultimateChallenger = challenge.challenger;
                    request.currentDuplicateIndex = challenge.duplicateSubmissionIndex;
                }
            }
        }
        // Decrease the number of parallel disputes each time the dispute is resolved. Store the rulings of each dispute for correct distribution of rewards.
        request.nbParallelDisputes--;
        challenge.ruling = _winner;
        emit ChallengeResolved(_submissionID, requestID, _challengeID);
    }

    // ************************ //
    // *       Getters        * //
    // ************************ //

    /** @dev Returns true if the submission is registered and not expired.
     *  @param _submissionID The address of the submission.
     *  @return Whether the submission is registered or not.
     */
    function isRegistered(address _submissionID) external view returns (bool) {
        Submission storage submission = submissions[_submissionID];
        return submission.registered && now - submission.submissionTime <= submissionDuration;
    }

    /** @dev Gets the number of times the arbitrator data was updated.
     *  @return The number of arbitrator data updates.
     */
    function getArbitratorDataListCount() external view returns (uint) {
        return arbitratorDataList.length;
    }

    /** @dev Checks whether the duplicate address has been used in challenging the request or not.
     *  @param _submissionID The address of the submission to check.
     *  @param _requestID The request to check.
     *  @param _duplicateID The duplicate to check.
     *  @return Whether the duplicate has been used.
     */
    function checkRequestDuplicates(address _submissionID, uint _requestID, address _duplicateID) external view returns (bool) {
        Request storage request = submissions[_submissionID].requests[_requestID];
        return request.challengeDuplicates[_duplicateID];
    }

    /** @dev Gets the contributions made by a party for a given round of a given challenge of a request.
     *  @param _submissionID The address of the submission.
     *  @param _requestID The request to query.
     *  @param _challengeID the challenge to query.
     *  @param _round The round to query.
     *  @param _contributor The address of the contributor.
     *  @return The contributions.
     */
    function getContributions(
        address _submissionID,
        uint _requestID,
        uint _challengeID,
        uint _round,
        address _contributor
    ) external view returns(uint[3] memory contributions) {
        Request storage request = submissions[_submissionID].requests[_requestID];
        Challenge storage challenge = request.challenges[_challengeID];
        Round storage round = challenge.rounds[_round];
        contributions = round.contributions[_contributor];
    }

    /** @dev Returns the information of the submission. Includes length of requests array.
     *  @param _submissionID The address of the queried submission.
     *  @return The information of the submission.
     */
    function getSubmissionInfo(address _submissionID)
        external
        view
        returns (
            Status status,
            uint64 submissionTime,
            uint64 index,
            bool registered,
            bool hasVouched,
            uint numberOfRequests
        )
    {
        Submission storage submission = submissions[_submissionID];
        return (
            submission.status,
            submission.submissionTime,
            submission.index,
            submission.registered,
            submission.hasVouched,
            submission.requests.length
        );
    }

    /** @dev Gets the information of a particular challenge of the request.
     *  @param _submissionID The address of the queried submission.
     *  @param _requestID The request to query.
     *  @param _challengeID The challenge to query.
     *  @return The information of the challenge.
     */
    function getChallengeInfo(address _submissionID, uint _requestID, uint _challengeID)
        external
        view
        returns (
            uint16 lastRoundID,
            address challenger,
            uint disputeID,
            Party ruling,
            uint64 duplicateSubmissionIndex
        )
    {
        Request storage request = submissions[_submissionID].requests[_requestID];
        Challenge storage challenge = request.challenges[_challengeID];
        return (
            challenge.lastRoundID,
            challenge.challenger,
            challenge.disputeID,
            challenge.ruling,
            challenge.duplicateSubmissionIndex
        );
    }

    /** @dev Gets information of a request of a submission.
     *  @param _submissionID The address of the queried submission.
     *  @param _requestID The request to be queried.
     *  @return The request information.
     */
    function getRequestInfo(address _submissionID, uint _requestID)
        external
        view
        returns (
            bool disputed,
            bool resolved,
            bool requesterLost,
            Reason currentReason,
            uint16 nbParallelDisputes,
            uint16 lastChallengeID,
            uint16 arbitratorDataID,
            address payable requester,
            address payable ultimateChallenger,
            uint8 usedReasons
        )
    {
        Request storage request = submissions[_submissionID].requests[_requestID];
        return (
            request.disputed,
            request.resolved,
            request.requesterLost,
            request.currentReason,
            request.nbParallelDisputes,
            request.lastChallengeID,
            request.arbitratorDataID,
            request.requester,
            request.ultimateChallenger,
            request.usedReasons
        );
    }

    /** @dev Gets the number of vouches of a particular request.
     *  @param _submissionID The address of the queried submission.
     *  @param _requestID The request to query.
     *  @return The current number of vouches.
     */
    function getNumberOfVouches(address _submissionID, uint _requestID) external view returns (uint) {
        Request storage request = submissions[_submissionID].requests[_requestID];
        return request.vouches.length;
    }

    /** @dev Gets the information of a round of a request.
     *  @param _submissionID The address of the queried submission.
     *  @param _requestID The request to query.
     *  @param _challengeID The challenge to query.
     *  @param _round The round to query.
     *  @return The round information.
     */
    function getRoundInfo(address _submissionID, uint _requestID, uint _challengeID, uint _round)
        external
        view
        returns (
            bool appealed,
            uint[3] memory paidFees,
            Party sideFunded,
            uint feeRewards
        )
    {
        Request storage request = submissions[_submissionID].requests[_requestID];
        Challenge storage challenge = request.challenges[_challengeID];
        Round storage round = challenge.rounds[_round];
        appealed = _round < (challenge.lastRoundID);
        return (
            appealed,
            round.paidFees,
            round.sideFunded,
            round.feeRewards
        );
    }
}