pragma solidity ^0.5.6;

library SafeMath {
  function mul(uint256 a, uint256 b) internal pure returns (uint256) {
    if (a == 0) {
      return 0;
    }
    uint256 c = a * b;
    require(c / a == b);
    return c;
  }
  function div(uint256 a, uint256 b) internal pure returns (uint256) {
    require(b > 0);
    uint256 c = a / b;
    return c;
  }
  function sub(uint256 a, uint256 b) internal pure returns (uint256) {
    require(b <= a);
    uint256 c = a - b;
    return c;
  }
  function add(uint256 a, uint256 b) internal pure returns (uint256) {
    uint256 c = a + b;
    require(c >= a && c >= b);
    return c;
  }
  function mod(uint256 a, uint256 b) internal pure returns (uint256) {
    require(b != 0);
    return a % b;
  }
  function max256(uint256 a, uint256 b) internal pure returns (uint256) {
    return a >= b ? a : b;
  }
  function min256(uint256 a, uint256 b) internal pure returns (uint256) {
    return a < b ? a : b;
  }

}

contract owned {
  address public owner;

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

  modifier onlyOwner {
    require(msg.sender == owner);
    _;
  }

  function transferOwnership(address newOwner) onlyOwner public {
    owner = newOwner;
  }
}

interface tokenRecipient {
  function receiveApproval(address _from, uint256 _value, address _token, bytes calldata _extraData) external; 
}


contract TokenERC20 {
  using SafeMath for uint256;
  string public name;
  string public symbol;
  uint8 public decimals;
  uint256 public totalSupply;

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

  event Transfer(address indexed from, address indexed to, uint256 value);

  event Approval(address indexed _owner, address indexed _spender, uint256 _value);

  event Burn(address indexed from, uint256 value);


  constructor(string memory tokenName, string memory tokenSymbol, uint8 dec) public {
    decimals = dec;
    name = tokenName;                                   // Set the name for display purposes
    symbol = tokenSymbol;   
  }

  function _transfer(address _from, address _to, uint _value) internal {
    require(_to != address(0x0));
    balanceOf[_from] = balanceOf[_from].sub(_value);
    balanceOf[_to] = balanceOf[_to].add(_value);
    emit Transfer(_from, _to, _value);
  }

  function transfer(address _to, uint256 _value) public returns (bool success) {
    _transfer(msg.sender, _to, _value);
    return true;
  }


  function transferFrom(address _from, address _to, uint256 _value) public returns (bool success) {
    allowance[_from][msg.sender] = allowance[_from][msg.sender].sub(_value);
		_transfer(_from, _to, _value);
		return true;
  }


  function approve(address _spender, uint256 _value) public returns (bool success) {
    allowance[msg.sender][_spender] = _value;
    emit Approval(msg.sender, _spender, _value);
    return true;
  }


  function approveAndCall(address _spender, uint256 _value, bytes memory _extraData) public returns (bool success) {
    tokenRecipient spender = tokenRecipient(_spender);
    if (approve(_spender, _value)) {
      spender.receiveApproval(msg.sender, _value, address(this), _extraData);
      return true;
    }
  }

}


/******************************************/
/*       ADVANCED TOKEN STARTS HERE       */
/******************************************/

contract Blockburn is owned, TokenERC20  {

  string _tokenName = "Blockburn";  
  string _tokenSymbol = "BURN";
  uint8 _decimals = 18;

  address[] public frozenAddresses;

  struct frozenWallet {
    bool isFrozen; //true or false
    uint256 rewardedAmount; //amount
    uint256 frozenAmount; //amount
    uint256 frozenTime; // in days
  }

  mapping (address => frozenWallet) public frozenWallets;

  constructor() TokenERC20(_tokenName, _tokenSymbol, _decimals) public {

    /*Locked Tokens */
    frozenAddresses.push(address(0xCC0d10070F973F03b6CF463F64CF4BB5e253C7F6));
    frozenWallets[frozenAddresses[0]] = frozenWallet({
      isFrozen: true,
      rewardedAmount: 200000000 * 10 ** uint256(decimals),
      frozenAmount: 200000000 * 10 ** uint256(decimals),
      frozenTime: now + 360 * 1 days
    });
    
    /*Available Tokens */
    frozenAddresses.push(address(0x615faD1CC018e100b0994FfbdB6B7A00Cd83F4f9));
    frozenWallets[frozenAddresses[1]] = frozenWallet({
      isFrozen: true,
      rewardedAmount: 1800000000 * 10 ** uint256(decimals),
      frozenAmount: 0 * 10 ** uint256(decimals),
      frozenTime: now + 1 * 1 seconds //seconds, minutes, hours, days
    });

    for (uint256 i = 0; i < frozenAddresses.length; i++) {
      balanceOf[frozenAddresses[i]] = frozenWallets[frozenAddresses[i]].rewardedAmount;
      totalSupply = totalSupply.add(frozenWallets[frozenAddresses[i]].rewardedAmount);
    }
  }

  function _transfer(address _from, address _to, uint _value) internal {
    require(_to != address(0x0));
    require(checkFrozenWallet(_from, _value));
    balanceOf[_from] = balanceOf[_from].sub(_value);      
    balanceOf[_to] = balanceOf[_to].add(_value);     
    emit Transfer(_from, _to, _value);
  }

  function checkFrozenWallet(address _from, uint _value) public view returns (bool) {
    return(
      _from==owner || 
      (
        // !tokenFrozen && 
      (!frozenWallets[_from].isFrozen || 
       now>=frozenWallets[_from].frozenTime || 
       balanceOf[_from].sub(_value)>=frozenWallets[_from].frozenAmount))
    );
  }

  function burn(uint256 _value) onlyOwner public returns (bool success) {
    balanceOf[msg.sender] = balanceOf[msg.sender].sub(_value);   // Subtract from the sender
    totalSupply = totalSupply.sub(_value);                      // Updates totalSupply
    emit Burn(msg.sender, _value);
    return true;
  }

  function burnFrom(address _from, uint256 _value) public returns (bool success) {
    balanceOf[_from] = balanceOf[_from].sub(_value);                          // Subtract from the targeted balance
    allowance[_from][msg.sender] = allowance[_from][msg.sender].sub(_value);   // Subtract from the sender's allowance
    totalSupply = totalSupply.sub(_value);                              // Update totalSupply
    emit Burn(_from, _value);
    return true;
  }
}