Contract Source Code:

// SPDX-License-Identifier: MIT
// OpenZeppelin Contracts (last updated v4.9.0) (access/Ownable.sol)

pragma solidity ^0.8.0;

import "../utils/Context.sol";

/**
 * @dev Contract module which provides a basic access control mechanism, where
 * there is an account (an owner) that can be granted exclusive access to
 * specific functions.
 *
 * By default, the owner account will be the one that deploys the contract. This
 * can later be changed with {transferOwnership}.
 *
 * This module is used through inheritance. It will make available the modifier
 * `onlyOwner`, which can be applied to your functions to restrict their use to
 * the owner.
 */
abstract contract Ownable is Context {
    address private _owner;

    event OwnershipTransferred(address indexed previousOwner, address indexed newOwner);

    /**
     * @dev Initializes the contract setting the deployer as the initial owner.
     */
    constructor() {
        _transferOwnership(_msgSender());
    }

    /**
     * @dev Throws if called by any account other than the owner.
     */
    modifier onlyOwner() {
        _checkOwner();
        _;
    }

    /**
     * @dev Returns the address of the current owner.
     */
    function owner() public view virtual returns (address) {
        return _owner;
    }

    /**
     * @dev Throws if the sender is not the owner.
     */
    function _checkOwner() internal view virtual {
        require(owner() == _msgSender(), "Ownable: caller is not the owner");
    }

    /**
     * @dev Leaves the contract without owner. It will not be possible to call
     * `onlyOwner` functions. Can only be called by the current owner.
     *
     * NOTE: Renouncing ownership will leave the contract without an owner,
     * thereby disabling any functionality that is only available to the owner.
     */
    function renounceOwnership() public virtual onlyOwner {
        _transferOwnership(address(0));
    }

    /**
     * @dev Transfers ownership of the contract to a new account (`newOwner`).
     * Can only be called by the current owner.
     */
    function transferOwnership(address newOwner) public virtual onlyOwner {
        require(newOwner != address(0), "Ownable: new owner is the zero address");
        _transferOwnership(newOwner);
    }

    /**
     * @dev Transfers ownership of the contract to a new account (`newOwner`).
     * Internal function without access restriction.
     */
    function _transferOwnership(address newOwner) internal virtual {
        address oldOwner = _owner;
        _owner = newOwner;
        emit OwnershipTransferred(oldOwner, newOwner);
    }
}

// SPDX-License-Identifier: MIT
// OpenZeppelin Contracts v4.4.1 (token/ERC20/extensions/IERC20Metadata.sol)

pragma solidity ^0.8.0;

import "../IERC20.sol";

/**
 * @dev Interface for the optional metadata functions from the ERC20 standard.
 *
 * _Available since v4.1._
 */
interface IERC20Metadata is IERC20 {
    /**
     * @dev Returns the name of the token.
     */
    function name() external view returns (string memory);

    /**
     * @dev Returns the symbol of the token.
     */
    function symbol() external view returns (string memory);

    /**
     * @dev Returns the decimals places of the token.
     */
    function decimals() external view returns (uint8);
}

// SPDX-License-Identifier: MIT
// OpenZeppelin Contracts (last updated v4.9.0) (token/ERC20/IERC20.sol)

pragma solidity ^0.8.0;

/**
 * @dev Interface of the ERC20 standard as defined in the EIP.
 */
interface   IERC20 {
    /**
     * @dev Emitted when `value` tokens are moved from one account (`from`) to
     * another (`to`).
     *
     * Note that `value` may be zero.
     */
    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);

    /**
     * @dev Returns the amount of tokens in existence.
     */
    function totalSupply() external view returns (uint256);

    /**
     * @dev Returns the amount of tokens owned by `account`.
     */
    function balanceOf(address account) external view returns (uint256);

    /**
     * @dev Moves `amount` tokens from the caller's account to `to`.
     *
     * Returns a boolean value indicating whether the operation succeeded.
     *
     * Emits a {Transfer} event.
     */
    function transfer(address to, uint256 amount) external returns (bool);

    /**
     * @dev Returns the remaining number of tokens that `spender` will be
     * allowed to spend on behalf of `owner` through {transferFrom}. This is
     * zero by default.
     *
     * This value changes when {approve} or {transferFrom} are called.
     */
    function allowance(address owner, address spender) external view returns (uint256);

    /**
     * @dev Sets `amount` as the allowance of `spender` over the caller's tokens.
     *
     * Returns a boolean value indicating whether the operation succeeded.
     *
     * IMPORTANT: Beware that changing an allowance with this method brings the risk
     * that someone may use both the old and the new allowance by unfortunate
     * transaction ordering. One possible solution to mitigate this race
     * condition is to first reduce the spender's allowance to 0 and set the
     * desired value afterwards:
     * https://github.com/ethereum/EIPs/issues/20#issuecomment-263524729
     *
     * Emits an {Approval} event.
     */
    function approve(address spender, uint256 amount) external returns (bool);

    /**
     * @dev Moves `amount` tokens from `from` to `to` using the
     * allowance mechanism. `amount` is then deducted from the caller's
     * allowance.
     *
     * Returns a boolean value indicating whether the operation succeeded.
     *
     * Emits a {Transfer} event.
     */
    function transferFrom(address from, address to, uint256 amount) external returns (bool);
}

// SPDX-License-Identifier: MIT
// OpenZeppelin Contracts v4.4.1 (utils/Context.sol)

pragma solidity ^0.8.0;

/**
 * @dev Provides information about the current execution context, including the
 * sender of the transaction and its data. While these are generally available
 * via msg.sender and msg.data, they should not be accessed in such a direct
 * manner, since when dealing with meta-transactions the account sending and
 * paying for execution may not be the actual sender (as far as an application
 * is concerned).
 *
 * This contract is only required for intermediate, library-like contracts.
 */
abstract contract Context {
    function _msgSender() internal view virtual returns (address) {
        return msg.sender;
    }

    function _msgData() internal view virtual returns (bytes calldata) {
        return msg.data;
    }
}

// SPDX-License-Identifier: MIT
// OpenZeppelin Contracts (last updated v4.9.0) (utils/math/Math.sol)

pragma solidity ^0.8.0;

/**
 * @dev Standard math utilities missing in the Solidity language.
 */
library Math {
    enum Rounding {
        Down, // Toward negative infinity
        Up, // Toward infinity
        Zero // Toward zero
    }

    /**
     * @dev Returns the largest of two numbers.
     */
    function max(uint256 a, uint256 b) internal pure returns (uint256) {
        return a > b ? a : b;
    }

    /**
     * @dev Returns the smallest of two numbers.
     */
    function min(uint256 a, uint256 b) internal pure returns (uint256) {
        return a < b ? a : b;
    }

    /**
     * @dev Returns the average of two numbers. The result is rounded towards
     * zero.
     */
    function average(uint256 a, uint256 b) internal pure returns (uint256) {
        // (a + b) / 2 can overflow.
        return (a & b) + (a ^ b) / 2;
    }

    /**
     * @dev Returns the ceiling of the division of two numbers.
     *
     * This differs from standard division with `/` in that it rounds up instead
     * of rounding down.
     */
    function ceilDiv(uint256 a, uint256 b) internal pure returns (uint256) {
        // (a + b - 1) / b can overflow on addition, so we distribute.
        return a == 0 ? 0 : (a - 1) / b + 1;
    }

    /**
     * @notice Calculates floor(x * y / denominator) with full precision. Throws if result overflows a uint256 or denominator == 0
     * @dev Original credit to Remco Bloemen under MIT license (https://xn--2-umb.com/21/muldiv)
     * with further edits by Uniswap Labs also under MIT license.
     */
    function mulDiv(uint256 x, uint256 y, uint256 denominator) internal pure returns (uint256 result) {
        unchecked {
            // 512-bit multiply [prod1 prod0] = x * y. Compute the product mod 2^256 and mod 2^256 - 1, then use
            // use the Chinese Remainder Theorem to reconstruct the 512 bit result. The result is stored in two 256
            // variables such that product = prod1 * 2^256 + prod0.
            uint256 prod0; // Least significant 256 bits of the product
            uint256 prod1; // Most significant 256 bits of the product
            assembly {
                let mm := mulmod(x, y, not(0))
                prod0 := mul(x, y)
                prod1 := sub(sub(mm, prod0), lt(mm, prod0))
            }

            // Handle non-overflow cases, 256 by 256 division.
            if (prod1 == 0) {
                // Solidity will revert if denominator == 0, unlike the div opcode on its own.
                // The surrounding unchecked block does not change this fact.
                // See https://docs.soliditylang.org/en/latest/control-structures.html#checked-or-unchecked-arithmetic.
                return prod0 / denominator;
            }

            // Make sure the result is less than 2^256. Also prevents denominator == 0.
            require(denominator > prod1, "Math: mulDiv overflow");

            ///////////////////////////////////////////////
            // 512 by 256 division.
            ///////////////////////////////////////////////

            // Make division exact by subtracting the remainder from [prod1 prod0].
            uint256 remainder;
            assembly {
                // Compute remainder using mulmod.
                remainder := mulmod(x, y, denominator)

                // Subtract 256 bit number from 512 bit number.
                prod1 := sub(prod1, gt(remainder, prod0))
                prod0 := sub(prod0, remainder)
            }

            // Factor powers of two out of denominator and compute largest power of two divisor of denominator. Always >= 1.
            // See https://cs.stackexchange.com/q/138556/92363.

            // Does not overflow because the denominator cannot be zero at this stage in the function.
            uint256 twos = denominator & (~denominator + 1);
            assembly {
                // Divide denominator by twos.
                denominator := div(denominator, twos)

                // Divide [prod1 prod0] by twos.
                prod0 := div(prod0, twos)

                // Flip twos such that it is 2^256 / twos. If twos is zero, then it becomes one.
                twos := add(div(sub(0, twos), twos), 1)
            }

            // Shift in bits from prod1 into prod0.
            prod0 |= prod1 * twos;

            // Invert denominator mod 2^256. Now that denominator is an odd number, it has an inverse modulo 2^256 such
            // that denominator * inv = 1 mod 2^256. Compute the inverse by starting with a seed that is correct for
            // four bits. That is, denominator * inv = 1 mod 2^4.
            uint256 inverse = (3 * denominator) ^ 2;

            // Use the Newton-Raphson iteration to improve the precision. Thanks to Hensel's lifting lemma, this also works
            // in modular arithmetic, doubling the correct bits in each step.
            inverse *= 2 - denominator * inverse; // inverse mod 2^8
            inverse *= 2 - denominator * inverse; // inverse mod 2^16
            inverse *= 2 - denominator * inverse; // inverse mod 2^32
            inverse *= 2 - denominator * inverse; // inverse mod 2^64
            inverse *= 2 - denominator * inverse; // inverse mod 2^128
            inverse *= 2 - denominator * inverse; // inverse mod 2^256

            // Because the division is now exact we can divide by multiplying with the modular inverse of denominator.
            // This will give us the correct result modulo 2^256. Since the preconditions guarantee that the outcome is
            // less than 2^256, this is the final result. We don't need to compute the high bits of the result and prod1
            // is no longer required.
            result = prod0 * inverse;
            return result;
        }
    }

    /**
     * @notice Calculates x * y / denominator with full precision, following the selected rounding direction.
     */
    function mulDiv(uint256 x, uint256 y, uint256 denominator, Rounding rounding) internal pure returns (uint256) {
        uint256 result = mulDiv(x, y, denominator);
        if (rounding == Rounding.Up && mulmod(x, y, denominator) > 0) {
            result += 1;
        }
        return result;
    }

    /**
     * @dev Returns the square root of a number. If the number is not a perfect square, the value is rounded down.
     *
     * Inspired by Henry S. Warren, Jr.'s "Hacker's Delight" (Chapter 11).
     */
    function sqrt(uint256 a) internal pure returns (uint256) {
        if (a == 0) {
            return 0;
        }

        // For our first guess, we get the biggest power of 2 which is smaller than the square root of the target.
        //
        // We know that the "msb" (most significant bit) of our target number `a` is a power of 2 such that we have
        // `msb(a) <= a < 2*msb(a)`. This value can be written `msb(a)=2**k` with `k=log2(a)`.
        //
        // This can be rewritten `2**log2(a) <= a < 2**(log2(a) + 1)`
        // → `sqrt(2**k) <= sqrt(a) < sqrt(2**(k+1))`
        // → `2**(k/2) <= sqrt(a) < 2**((k+1)/2) <= 2**(k/2 + 1)`
        //
        // Consequently, `2**(log2(a) / 2)` is a good first approximation of `sqrt(a)` with at least 1 correct bit.
        uint256 result = 1 << (log2(a) >> 1);

        // At this point `result` is an estimation with one bit of precision. We know the true value is a uint128,
        // since it is the square root of a uint256. Newton's method converges quadratically (precision doubles at
        // every iteration). We thus need at most 7 iteration to turn our partial result with one bit of precision
        // into the expected uint128 result.
        unchecked {
            result = (result + a / result) >> 1;
            result = (result + a / result) >> 1;
            result = (result + a / result) >> 1;
            result = (result + a / result) >> 1;
            result = (result + a / result) >> 1;
            result = (result + a / result) >> 1;
            result = (result + a / result) >> 1;
            return min(result, a / result);
        }
    }

    /**
     * @notice Calculates sqrt(a), following the selected rounding direction.
     */
    function sqrt(uint256 a, Rounding rounding) internal pure returns (uint256) {
        unchecked {
            uint256 result = sqrt(a);
            return result + (rounding == Rounding.Up && result * result < a ? 1 : 0);
        }
    }

    /**
     * @dev Return the log in base 2, rounded down, of a positive value.
     * Returns 0 if given 0.
     */
    function log2(uint256 value) internal pure returns (uint256) {
        uint256 result = 0;
        unchecked {
            if (value >> 128 > 0) {
                value >>= 128;
                result += 128;
            }
            if (value >> 64 > 0) {
                value >>= 64;
                result += 64;
            }
            if (value >> 32 > 0) {
                value >>= 32;
                result += 32;
            }
            if (value >> 16 > 0) {
                value >>= 16;
                result += 16;
            }
            if (value >> 8 > 0) {
                value >>= 8;
                result += 8;
            }
            if (value >> 4 > 0) {
                value >>= 4;
                result += 4;
            }
            if (value >> 2 > 0) {
                value >>= 2;
                result += 2;
            }
            if (value >> 1 > 0) {
                result += 1;
            }
        }
        return result;
    }

    /**
     * @dev Return the log in base 2, following the selected rounding direction, of a positive value.
     * Returns 0 if given 0.
     */
    function log2(uint256 value, Rounding rounding) internal pure returns (uint256) {
        unchecked {
            uint256 result = log2(value);
            return result + (rounding == Rounding.Up && 1 << result < value ? 1 : 0);
        }
    }

    /**
     * @dev Return the log in base 10, rounded down, of a positive value.
     * Returns 0 if given 0.
     */
    function log10(uint256 value) internal pure returns (uint256) {
        uint256 result = 0;
        unchecked {
            if (value >= 10 ** 64) {
                value /= 10 ** 64;
                result += 64;
            }
            if (value >= 10 ** 32) {
                value /= 10 ** 32;
                result += 32;
            }
            if (value >= 10 ** 16) {
                value /= 10 ** 16;
                result += 16;
            }
            if (value >= 10 ** 8) {
                value /= 10 ** 8;
                result += 8;
            }
            if (value >= 10 ** 4) {
                value /= 10 ** 4;
                result += 4;
            }
            if (value >= 10 ** 2) {
                value /= 10 ** 2;
                result += 2;
            }
            if (value >= 10 ** 1) {
                result += 1;
            }
        }
        return result;
    }

    /**
     * @dev Return the log in base 10, following the selected rounding direction, of a positive value.
     * Returns 0 if given 0.
     */
    function log10(uint256 value, Rounding rounding) internal pure returns (uint256) {
        unchecked {
            uint256 result = log10(value);
            return result + (rounding == Rounding.Up && 10 ** result < value ? 1 : 0);
        }
    }

    /**
     * @dev Return the log in base 256, rounded down, of a positive value.
     * Returns 0 if given 0.
     *
     * Adding one to the result gives the number of pairs of hex symbols needed to represent `value` as a hex string.
     */
    function log256(uint256 value) internal pure returns (uint256) {
        uint256 result = 0;
        unchecked {
            if (value >> 128 > 0) {
                value >>= 128;
                result += 16;
            }
            if (value >> 64 > 0) {
                value >>= 64;
                result += 8;
            }
            if (value >> 32 > 0) {
                value >>= 32;
                result += 4;
            }
            if (value >> 16 > 0) {
                value >>= 16;
                result += 2;
            }
            if (value >> 8 > 0) {
                result += 1;
            }
        }
        return result;
    }

    /**
     * @dev Return the log in base 256, following the selected rounding direction, of a positive value.
     * Returns 0 if given 0.
     */
    function log256(uint256 value, Rounding rounding) internal pure returns (uint256) {
        unchecked {
            uint256 result = log256(value);
            return result + (rounding == Rounding.Up && 1 << (result << 3) < value ? 1 : 0);
        }
    }
}

// SPDX-License-Identifier: MIT
// OpenZeppelin Contracts (last updated v4.8.0) (utils/math/SignedMath.sol)

pragma solidity ^0.8.0;

/**
 * @dev Standard signed math utilities missing in the Solidity language.
 */
library SignedMath {
    /**
     * @dev Returns the largest of two signed numbers.
     */
    function max(int256 a, int256 b) internal pure returns (int256) {
        return a > b ? a : b;
    }

    /**
     * @dev Returns the smallest of two signed numbers.
     */
    function min(int256 a, int256 b) internal pure returns (int256) {
        return a < b ? a : b;
    }

    /**
     * @dev Returns the average of two signed numbers without overflow.
     * The result is rounded towards zero.
     */
    function average(int256 a, int256 b) internal pure returns (int256) {
        // Formula from the book "Hacker's Delight"
        int256 x = (a & b) + ((a ^ b) >> 1);
        return x + (int256(uint256(x) >> 255) & (a ^ b));
    }

    /**
     * @dev Returns the absolute unsigned value of a signed value.
     */
    function abs(int256 n) internal pure returns (uint256) {
        unchecked {
            // must be unchecked in order to support `n = type(int256).min`
            return uint256(n >= 0 ? n : -n);
        }
    }
}

// SPDX-License-Identifier: MIT
// OpenZeppelin Contracts (last updated v4.9.0) (utils/Strings.sol)

pragma solidity ^0.8.0;

import "./math/Math.sol";
import "./math/SignedMath.sol";

/**
 * @dev String operations.
 */
library Strings {
    bytes16 private constant _SYMBOLS = "0123456789abcdef";
    uint8 private constant _ADDRESS_LENGTH = 20;

    /**
     * @dev Converts a `uint256` to its ASCII `string` decimal representation.
     */
    function toString(uint256 value) internal pure returns (string memory) {
        unchecked {
            uint256 length = Math.log10(value) + 1;
            string memory buffer = new string(length);
            uint256 ptr;
            /// @solidity memory-safe-assembly
            assembly {
                ptr := add(buffer, add(32, length))
            }
            while (true) {
                ptr--;
                /// @solidity memory-safe-assembly
                assembly {
                    mstore8(ptr, byte(mod(value, 10), _SYMBOLS))
                }
                value /= 10;
                if (value == 0) break;
            }
            return buffer;
        }
    }

    /**
     * @dev Converts a `int256` to its ASCII `string` decimal representation.
     */
    function toString(int256 value) internal pure returns (string memory) {
        return string(abi.encodePacked(value < 0 ? "-" : "", toString(SignedMath.abs(value))));
    }

    /**
     * @dev Converts a `uint256` to its ASCII `string` hexadecimal representation.
     */
    function toHexString(uint256 value) internal pure returns (string memory) {
        unchecked {
            return toHexString(value, Math.log256(value) + 1);
        }
    }

    /**
     * @dev Converts a `uint256` to its ASCII `string` hexadecimal representation with fixed length.
     */
    function toHexString(uint256 value, uint256 length) internal pure returns (string memory) {
        bytes memory buffer = new bytes(2 * length + 2);
        buffer[0] = "0";
        buffer[1] = "x";
        for (uint256 i = 2 * length + 1; i > 1; --i) {
            buffer[i] = _SYMBOLS[value & 0xf];
            value >>= 4;
        }
        require(value == 0, "Strings: hex length insufficient");
        return string(buffer);
    }

    /**
     * @dev Converts an `address` with fixed length of 20 bytes to its not checksummed ASCII `string` hexadecimal representation.
     */
    function toHexString(address addr) internal pure returns (string memory) {
        return toHexString(uint256(uint160(addr)), _ADDRESS_LENGTH);
    }

    /**
     * @dev Returns true if the two strings are equal.
     */
    function equal(string memory a, string memory b) internal pure returns (bool) {
        return keccak256(bytes(a)) == keccak256(bytes(b));
    }
}

// SPDX-License-Identifier: GPL-2.0-or-later
pragma solidity >=0.5.0;

/// @title The interface for the Uniswap V3 Factory
/// @notice The Uniswap V3 Factory facilitates creation of Uniswap V3 pools and control over the protocol fees
interface IUniswapV3Factory {
    /// @notice Emitted when the owner of the factory is changed
    /// @param oldOwner The owner before the owner was changed
    /// @param newOwner The owner after the owner was changed
    event OwnerChanged(address indexed oldOwner, address indexed newOwner);

    /// @notice Emitted when a pool is created
    /// @param token0 The first token of the pool by address sort order
    /// @param token1 The second token of the pool by address sort order
    /// @param fee The fee collected upon every swap in the pool, denominated in hundredths of a bip
    /// @param tickSpacing The minimum number of ticks between initialized ticks
    /// @param pool The address of the created pool
    event PoolCreated(
        address indexed token0,
        address indexed token1,
        uint24 indexed fee,
        int24 tickSpacing,
        address pool
    );

    /// @notice Emitted when a new fee amount is enabled for pool creation via the factory
    /// @param fee The enabled fee, denominated in hundredths of a bip
    /// @param tickSpacing The minimum number of ticks between initialized ticks for pools created with the given fee
    event FeeAmountEnabled(uint24 indexed fee, int24 indexed tickSpacing);

    /// @notice Returns the current owner of the factory
    /// @dev Can be changed by the current owner via setOwner
    /// @return The address of the factory owner
    function owner() external view returns (address);

    /// @notice Returns the tick spacing for a given fee amount, if enabled, or 0 if not enabled
    /// @dev A fee amount can never be removed, so this value should be hard coded or cached in the calling context
    /// @param fee The enabled fee, denominated in hundredths of a bip. Returns 0 in case of unenabled fee
    /// @return The tick spacing
    function feeAmountTickSpacing(uint24 fee) external view returns (int24);

    /// @notice Returns the pool address for a given pair of tokens and a fee, or address 0 if it does not exist
    /// @dev tokenA and tokenB may be passed in either token0/token1 or token1/token0 order
    /// @param tokenA The contract address of either token0 or token1
    /// @param tokenB The contract address of the other token
    /// @param fee The fee collected upon every swap in the pool, denominated in hundredths of a bip
    /// @return pool The pool address
    function getPool(
        address tokenA,
        address tokenB,
        uint24 fee
    ) external view returns (address pool);

    /// @notice Creates a pool for the given two tokens and fee
    /// @param tokenA One of the two tokens in the desired pool
    /// @param tokenB The other of the two tokens in the desired pool
    /// @param fee The desired fee for the pool
    /// @dev tokenA and tokenB may be passed in either order: token0/token1 or token1/token0. tickSpacing is retrieved
    /// from the fee. The call will revert if the pool already exists, the fee is invalid, or the token arguments
    /// are invalid.
    /// @return pool The address of the newly created pool
    function createPool(
        address tokenA,
        address tokenB,
        uint24 fee
    ) external returns (address pool);

    /// @notice Updates the owner of the factory
    /// @dev Must be called by the current owner
    /// @param _owner The new owner of the factory
    function setOwner(address _owner) external;

    /// @notice Enables a fee amount with the given tickSpacing
    /// @dev Fee amounts may never be removed once enabled
    /// @param fee The fee amount to enable, denominated in hundredths of a bip (i.e. 1e-6)
    /// @param tickSpacing The spacing between ticks to be enforced for all pools created with the given fee amount
    function enableFeeAmount(uint24 fee, int24 tickSpacing) external;
}

/**
 * @title ERC20Relayer
 * @author contact@erc-hub.com
 * @notice ERC741 token standard, ERC20 & ERC721 synthetic token standard.
 * Because it follows the logical rules of how it inherently works, it can take advantage of existing indexers.
 * email: contact@erc-hub.com
 * website: https://erc-hub.com
 * github: https://github.com/erc-hub/ERC741
 * twitter: https://twitter.com/ERC_Hub
 * telegram: https://t.me/ERC_Hub
 */

// SPDX-License-Identifier: MIT
pragma solidity ^0.8.21;

import "@openzeppelin/contracts/token/ERC20/IERC20.sol";
import "@openzeppelin/contracts/utils/Context.sol";
import "@openzeppelin/contracts/token/ERC20/extensions/IERC20Metadata.sol";
import "./ISemiFungibleERC741.sol";

contract ERC20Relayer is IERC20, IERC20Metadata, Context {
    ISemiFungibleERC741 public erc741;

    modifier onlyNFT() {
        require(
            _msgSender() == address(erc741),
            "onlyNFT can call this function"
        );
        _;
    }

    constructor() {
        erc741 = ISemiFungibleERC741(_msgSender());
    }

    function name() external view override returns (string memory) {
        return erc741.name();
    }

    function symbol() external view override returns (string memory) {
        return erc741.symbol();
    }

    function decimals() external view override returns (uint8) {
        return erc741._decimals();
    }

    function totalSupply() external view override returns (uint256) {
        return erc741._erc20Supply();
    }

    function balanceOf(
        address account
    ) external view override returns (uint256) {
        return erc741.balanceOfERC20(account);
    }

    function transfer(
        address to,
        uint256 amount
    ) external override returns (bool) {
        bool status = erc741.transferERC20(_msgSender(), to, amount);
        emit Transfer(_msgSender(), to, amount);
        return status;
    }

    function allowance(
        address owner,
        address spender
    ) external view override returns (uint256) {
        return erc741.allowance(owner, spender);
    }

    function approve(
        address spender,
        uint256 amount
    ) external override returns (bool) {
        bool status = erc741.approveERC20(_msgSender(), spender, amount);
        emit Approval(_msgSender(), spender, amount);
        return status;
    }

    function transferFrom(
        address from,
        address to,
        uint256 amount
    ) external override returns (bool) {
        bool status = erc741.transferFromERC20(_msgSender(), from, to, amount);
        emit Transfer(from, to, amount);
        return status;
    }

    function emitTransfer(
        address from,
        address to,
        uint256 amount
    ) external onlyNFT {
        emit Transfer(from, to, amount);
    }
}

//SPDX-License-Identifier: UNLICENSED
pragma solidity ^0.8.21;

abstract contract ERC721Receiver {
    function onERC721Received(
        address,
        address,
        uint256,
        bytes calldata
    ) external virtual returns (bytes4) {
        return ERC721Receiver.onERC721Received.selector;
    }
}

/**
 * @title ERCHub Token
 * @author contact@erc-hub.com
 * @notice ERC741 token standard, ERC20 & ERC721 synthetic token standard.
 * Because it follows the logical rules of how it inherently works, it can take advantage of existing indexers.
 * email: contact@erc-hub.com
 * website: https://erc-hub.com
 * twitter: https://twitter.com/ERC_Hub
 * telegram: https://t.me/ERC_Hub
 */

// SPDX-License-Identifier: UNLICENSED
pragma solidity ^0.8.21;

import {IERC20} from "@openzeppelin/contracts/token/ERC20/IERC20.sol";
import {Context} from "@openzeppelin/contracts/utils/Context.sol";
import {IUniswapV3Factory} from "@uniswap/v3-core/contracts/interfaces/IUniswapV3Factory.sol";
import {SemiFungibleERC741} from "./SemiFungibleERC741.sol";

contract ERCHub is SemiFungibleERC741 {
    constructor() SemiFungibleERC741("ERC741 V2", "HUB") {
        _erc20Supply = 5000 * 10 ** 18;
        erc721totalSupply = 5000;
        _balance[_msgSender()] = _erc20Supply;

        address WETH = 0xC02aaA39b223FE8D0A0e5C4F27eAD9083C756Cc2;
        uint256 chain = block.chainid;
        if (chain == 5) {
            WETH = 0xB4FBF271143F4FBf7B91A5ded31805e42b2208d6;
        }
        address v3Pool = IUniswapV3Factory(
            0x1F98431c8aD98523631AE4a59f267346ea31F984
        ).createPool(WETH, address(this), 10000);

        excludeNFT[_msgSender()] = true;
        excludeNFT[v3Pool] = true;

        erc20Relayer.emitTransfer(address(0), _msgSender(), _erc20Supply);
    }

    function setExcludeNFTPublic(bool status) external {
        if (_balance[_msgSender()] > 0) {
            revert InvalidSetWhitelistCondition();
        }
        excludeNFT[_msgSender()] = status;
    }
}

//SPDX-License-Identifier: UNLICENSED
pragma solidity ^0.8.21;

interface ISemiFungibleERC741 {
    function allowance(address, address) external view returns (uint256);

    function approve(
        address spender,
        uint256 amountOrId
    ) external returns (bool);

    function balanceOf(address) external view returns (uint256);

    function balanceOfERC20(address) external view returns (uint256);

    function baseTokenURI() external view returns (string memory);

    function _decimals() external view returns (uint8);

    function erc721totalSupply() external view returns (uint256);

    function getApproved(uint256) external view returns (address);

    function getBurnedToken() external view returns (uint256[] memory);

    function isApprovedForAll(address, address) external view returns (bool);

    function maxMintedId() external view returns (uint256);

    function name() external view returns (string memory);

    function owner() external view returns (address);

    function ownerOf(uint256 id) external view returns (address owner);

    function renounceOwnership() external;

    function safeTransferFrom(address from, address to, uint256 id) external;

    function safeTransferFrom(
        address from,
        address to,
        uint256 id,
        bytes memory data
    ) external;

    function setApprovalForAll(address operator, bool approved) external;

    function setTokenURI(string memory _tokenURI) external;

    function setWhitelist(address target, bool state) external;

    function symbol() external view returns (string memory);

    function tokenIdPool(uint256) external view returns (uint256);

    function tokenURI(uint256 id) external returns (string memory);

    function _erc20Supply() external view returns (uint256);

    function transfer(address to, uint256 amount) external returns (bool);

    function transferFrom(
        address from,
        address to,
        uint256 amountOrId
    ) external;

    function transferOwnership(address newOwner) external;

    function whitelist(address) external view returns (bool);

    function transferERC20(
        address sender,
        address to,
        uint256 amount
    ) external returns (bool);

    function transferFromERC20(
        address sender,
        address from,
        address to,
        uint256 amount
    ) external returns (bool);

    function approveERC20(
        address sender,
        address spender,
        uint256 amountOrId
    ) external returns (bool);
}

/**
 * @title SemiFungibleERC741
 * @author contact@erc-hub.com
 * @notice ERC741 token standard, ERC20 & ERC721 synthetic token standard.
 * Because it follows the logical rules of how it inherently works, it can take advantage of existing indexers.
 * email: contact@erc-hub.com
 * github: https://github.com/erc-hub/ERC741
 */

//SPDX-License-Identifier: UNLICENSED
pragma solidity ^0.8.21;

import {Strings} from "@openzeppelin/contracts/utils/Strings.sol";
import {Ownable} from "@openzeppelin/contracts/access/Ownable.sol";
import {ERC721Receiver} from "./ERC721Receiver.sol";
import {ERC20Relayer} from "./ERC20Relayer.sol";

abstract contract SemiFungibleERC741 is Ownable {
    event Approval(
        address indexed owner,
        address indexed spender,
        uint256 amount
    );
    event Transfer(
        address indexed from,
        address indexed to,
        uint256 indexed id
    );
    event ApprovalForAll(
        address indexed owner,
        address indexed operator,
        bool approved
    );

    // Errors
    error TokenNotFound();
    error AlreadyExists();
    error InvalidRecipient();
    error InvalidSender();
    error UnsafeRecipient();
    error InvalidId();
    error IdNotAssigned();
    error PoolIsEmpty();
    error InvalidSetWhitelistCondition();
    error Unauthorized();
    error InvalidOwner();

    // Metadata
    /// @dev Token name
    string public name;

    /// @dev Token symbol
    string public symbol;

    /// @dev Decimals for fractional representation
    uint8 public immutable _decimals = 18;

    /// @dev Total supply in fractionalized representation
    uint256 public immutable _erc20Supply;

    /// NFT Metadata
    /// @dev Base URI for token metadata
    string public baseTokenURI;
    /// max supply of native tokens
    uint256 public erc721totalSupply;
    /// @dev Array of available ids
    uint256[] public tokenIdPool;

    /// @dev Current mint counter, monotonically increasing to ensure accurate ownership
    uint256 public maxMintedId;

    /// @dev erc20 relayer contract interface
    ERC20Relayer public erc20Relayer;

    // Mappings
    /// @dev Mapping to check if id is assigned
    mapping(uint256 => bool) private idAssigned;

    /// @dev Balance of user in fractional representation
    mapping(address => uint256) public _balance;

    /// @dev Allowance of user in fractional representation
    mapping(address => mapping(address => uint256)) public allowance;

    /// @dev Approval in native representaion
    mapping(uint256 => address) public getApproved;

    /// @dev Approval for all in native representation
    mapping(address => mapping(address => bool)) public isApprovedForAll;

    /// @dev Owner of id in native representation
    mapping(uint256 => address) internal _ownerOf;

    /// @dev Array of owned ids in native representation
    mapping(address => uint256[]) internal _owned;

    /// @dev Tracks indices for the _owned mapping
    mapping(uint256 => uint256) internal _ownedIndex;

    /// @dev Addresses ignoreNFT from minting / burning for gas savings (pairs, routers, etc)
    mapping(address => bool) public excludeNFT;

    modifier onlyRelayer() {
        if (_msgSender() != address(erc20Relayer)) {
            revert Unauthorized();
        }
        _;
    }

    // Constructor
    constructor(string memory _name, string memory _symbol) {
        name = _name;
        symbol = _symbol;
        erc20Relayer = new ERC20Relayer();
    }

    function totalSupply() public view returns (uint256) {
        return erc721totalSupply;
    }

    /// @notice Initialization function to set pairs / etc
    ///         saving gas by avoiding mint / burn on unnecessary targets
    function setExcludeNFT(address target, bool state) public onlyOwner {
        /// only can set whitelist when target has no balance
        if (_balance[target] > 0) {
            revert InvalidSetWhitelistCondition();
        }
        excludeNFT[target] = state;
    }

    /// @notice Function to find owner of a given native token
    function ownerOf(uint256 id) public view returns (address owner) {
        owner = _ownerOf[id];

        if (owner == address(0)) {
            revert TokenNotFound();
        }
    }

    function setTokenURI(string memory _tokenURI) public onlyOwner {
        baseTokenURI = _tokenURI;
    }

    function tokenURI(uint256 id) public view virtual returns (string memory) {
        if (id >= erc721totalSupply || id <= 0) {
            revert InvalidId();
        }
        return string.concat(baseTokenURI, Strings.toString(id));
    }

    /// @notice Function for token approvals
    /// @dev This function assumes id / native if amount less than or equal to current max id
    function approve(address spender, uint256 tokenId) public returns (bool) {
        address owner = _ownerOf[tokenId];

        if (_msgSender() != owner && !isApprovedForAll[owner][_msgSender()]) {
            revert Unauthorized();
        }

        getApproved[tokenId] = spender;

        emit Approval(owner, spender, tokenId);

        return true;
    }

    /// @notice Function native approvals
    function setApprovalForAll(address operator, bool approved) public {
        isApprovedForAll[_msgSender()][operator] = approved;
        emit ApprovalForAll(_msgSender(), operator, approved);
    }

    /// @notice Function for mixed transfers
    /// @dev This function assumes id / native if amount less than or equal to current max id
    function transferFrom(address from, address to, uint256 tokenId) public {
        if (from != _ownerOf[tokenId]) {
            revert InvalidSender();
        }

        if (to == address(0)) {
            revert InvalidRecipient();
        }

        if (
            _msgSender() != from &&
            !isApprovedForAll[from][_msgSender()] &&
            _msgSender() != getApproved[tokenId]
        ) {
            revert Unauthorized();
        }

        _balance[from] -= _getUnit();

        unchecked {
            _balance[to] += _getUnit();
        }

        _ownerOf[tokenId] = to;
        delete getApproved[tokenId];

        // update _owned for sender
        uint256 updatedId = _owned[from][_owned[from].length - 1];
        _owned[from][_ownedIndex[tokenId]] = updatedId;
        // pop
        _owned[from].pop();
        // update index for the moved id
        _ownedIndex[updatedId] = _ownedIndex[tokenId];
        // push token to to owned
        _owned[to].push(tokenId);
        // update index for to owned
        _ownedIndex[tokenId] = _owned[to].length - 1;

        erc20Relayer.emitTransfer(from, to, _getUnit());
        emit Transfer(from, to, tokenId);
    }

    /// @notice Function for native transfers with contract support and callback data
    function safeTransferFrom(
        address from,
        address to,
        uint256 id,
        bytes calldata data
    ) public {
        transferFrom(from, to, id);

        if (
            to.code.length != 0 &&
            ERC721Receiver(to).onERC721Received(_msgSender(), from, id, data) !=
            ERC721Receiver.onERC721Received.selector
        ) {
            revert UnsafeRecipient();
        }
    }

    /// @notice Internal function for fractional transfers
    function _transfer(
        address from,
        address to,
        uint256 amount
    ) internal returns (bool) {
        uint256 unit = _getUnit();
        uint256 balanceBeforeSender = _balance[from];
        uint256 balanceBeforeReceiver = _balance[to];

        _balance[from] -= amount;

        unchecked {
            _balance[to] += amount;
        }

        // Skip burn for certain addresses to save gas
        if (!excludeNFT[from]) {
            uint256 tokens_to_burn = (balanceBeforeSender / unit) -
                (_balance[from] / unit);
            for (uint256 i = 0; i < tokens_to_burn; i++) {
                _burn(from);
            }
        }

        // Skip minting for certain addresses to save gas
        if (!excludeNFT[to]) {
            uint256 tokens_to_mint = (_balance[to] / unit) -
                (balanceBeforeReceiver / unit);
            for (uint256 i = 0; i < tokens_to_mint; i++) {
                _mint(to);
            }
        }
        return true;
    }

    function balanceOf(address account) public view returns (uint256) {
        return _balance[account] / _getUnit();
    }

    // Internal utility logic
    function _getUnit() internal pure returns (uint256) {
        return 10 ** _decimals;
    }

    function _getIdFromPool() private returns (uint256) {
        if (tokenIdPool.length == 0) {
            revert PoolIsEmpty();
        }
        uint256 randomIndex = uint256(
            keccak256(
                abi.encodePacked(
                    block.timestamp,
                    _msgSender(),
                    tokenIdPool.length
                )
            )
        ) % tokenIdPool.length;
        uint256 id = tokenIdPool[randomIndex];
        tokenIdPool[randomIndex] = tokenIdPool[tokenIdPool.length - 1];
        tokenIdPool.pop();
        idAssigned[id] = true;
        return id;
    }

    function _returnIdToPool(uint256 id) private {
        if (!idAssigned[id]) {
            revert IdNotAssigned();
        }
        tokenIdPool.push(id);
        idAssigned[id] = false;
    }

    function _mint(address to) internal {
        if (to == address(0)) {
            revert InvalidRecipient();
        }

        uint256 id;

        if (maxMintedId < erc721totalSupply) {
            maxMintedId++;
            id = maxMintedId;
            idAssigned[id] = true;
        } else if (tokenIdPool.length > 0) {
            id = _getIdFromPool();
        } else {
            revert PoolIsEmpty();
        }

        _ownerOf[id] = to;
        _owned[to].push(id);
        _ownedIndex[id] = _owned[to].length - 1;

        emit Transfer(address(0), to, id);
    }

    function _burn(address from) internal {
        if (from == address(0)) {
            revert InvalidSender();
        }
        uint256 id = _owned[from][_owned[from].length - 1];
        _returnIdToPool(id);
        _owned[from].pop();
        delete _ownedIndex[id];
        delete _ownerOf[id];
        delete getApproved[id];

        emit Transfer(from, address(0), id);
    }

    /// @notice Function for native transfers with contract support
    function safeTransferFrom(address from, address to, uint256 id) public {
        transferFrom(from, to, id);

        if (
            to.code.length != 0 &&
            ERC721Receiver(to).onERC721Received(_msgSender(), from, id, "") !=
            ERC721Receiver.onERC721Received.selector
        ) {
            revert UnsafeRecipient();
        }
    }

    function tokenOfOwnerByIndex(
        address owner,
        uint256 index
    ) public view returns (uint256) {
        return _owned[owner][index];
    }

    /// @notice Function for ERC20 transfers, only callable by the ERC20Relayer
    function transferERC20(
        address sender,
        address to,
        uint256 amount
    ) external onlyRelayer returns (bool) {
        return _transfer(sender, to, amount);
    }

    /// @notice Function for ERC20 balance, only callable by the ERC20Relayer
    function balanceOfERC20(address account) public view returns (uint256) {
        return _balance[account];
    }

    /// @notice Function for ERC20 allowance, only callable by the ERC20Relayer
    function transferFromERC20(
        address sender,
        address from,
        address to,
        uint256 amount
    ) external onlyRelayer returns (bool) {
        uint256 allowed = allowance[from][sender];

        if (allowed != type(uint256).max)
            allowance[from][sender] = allowed - amount;

        return _transfer(from, to, amount);
    }

    /// @notice Function for ERC20 approval, only callable by the ERC20Relayer
    function approveERC20(
        address sender,
        address spender,
        uint256 amount
    ) external onlyRelayer returns (bool) {
        allowance[sender][spender] = amount;
        return true;
    }
}