pragma solidity ^0.5.1;

interface IERC20 {
  function totalSupply() external view returns (uint256);
  function balanceOf(address who) external view returns (uint256);
  function allowance(address owner, address spender) external view returns (uint256);
  function transfer(address to, uint256 value) external returns (bool);
  function approve(address spender, uint256 value) external returns (bool);
  function transferFrom(address from, address to, uint256 value) external returns (bool);

  event Transfer(address indexed from, address indexed to, uint256 value);
  event Approval(address indexed owner, address indexed spender, uint256 value);
}

// File: openzeppelin-solidity/contracts/math/SafeMath.sol
 
 /**
 * @title SafeMath
 * @dev Unsigned math operations with safety checks that revert on error
 */
library SafeMath {
    /**
    * @dev Multiplies two unsigned integers, reverts on overflow.
    */
    function mul(uint256 a, uint256 b) internal pure returns (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-solidity/pull/522
        if (a == 0) {
            return 0;
        }

        uint256 c = a * b;
        require(c / a == b);

        return c;
    }

    /**
    * @dev Integer division of two unsigned integers truncating the quotient, reverts on division by zero.
    */
    function div(uint256 a, uint256 b) internal pure returns (uint256) {
        // Solidity only automatically asserts when dividing by 0
        require(b > 0);
        uint256 c = a / b;
        // assert(a == b * c + a % b); // There is no case in which this doesn't hold

        return c;
    }

    /**
    * @dev Subtracts two unsigned integers, reverts on overflow (i.e. if subtrahend is greater than minuend).
    */
    function sub(uint256 a, uint256 b) internal pure returns (uint256) {
        require(b <= a);
        uint256 c = a - b;

        return c;
    }

    /**
    * @dev Adds two unsigned integers, reverts on overflow.
    */
    function add(uint256 a, uint256 b) internal pure returns (uint256) {
        uint256 c = a + b;
        require(c >= a);

        return c;
    }

    /**
    * @dev Divides two unsigned integers and returns the remainder (unsigned integer modulo),
    * reverts when dividing by zero.
    */
    function mod(uint256 a, uint256 b) internal pure returns (uint256) {
        require(b != 0);
        return a % b;
    }

    /**
    * @dev Round number upwards to its nearest integer,
	*/
  function ceil(uint256 a, uint256 m) internal pure returns (uint256) {
    uint256 c = add(a,m);
    uint256 d = sub(c,1);
    return mul(div(d,m),m);
  }
}

contract ERC20 is IERC20 {

  string private _name;
  string private _symbol;
  uint8 private _decimals;

  constructor(string memory name, string memory symbol, uint8 decimals) public {
    _name = name;
    _symbol = symbol;
    _decimals = decimals;
  }

  function name() public view returns(string memory) {
    return _name;
  }

  function symbol() public view returns(string memory) {
    return _symbol;
  }

  function decimals() public view returns(uint8) {
    return _decimals;
  }
}

// File: openzeppelin-solidity/contracts/token/ERC20/ERC20.sol

/**
 * @title Standard ERC20 token
 *
 * @dev Implementation of the basic standard token.
 * https://github.com/ethereum/EIPs/blob/master/EIPS/eip-20.md
 * Originally based on code by FirstBlood:
 * https://github.com/Firstbloodio/token/blob/master/smart_contract/FirstBloodToken.sol
 *
 * This implementation emits additional Approval events, allowing applications to reconstruct the allowance status for
 * all accounts just by listening to said events. Note that this isn't required by the specification, and other
 * compliant implementations may not do it.
 */
contract Hydro is ERC20 {

  using SafeMath for uint256;
  mapping (address => uint256) private _balances;
  mapping (address => mapping (address => uint256)) private _allowed;

  string constant tokenName = "Hydro Token";
  string constant tokenSymbol = "XHT";
  uint8  constant tokenDecimals = 8;
  uint256 _totalSupply = 111111100000000;
  uint256 public basePercent = 100;

  constructor() public payable ERC20(tokenName, tokenSymbol, tokenDecimals) {
    _mint(msg.sender, _totalSupply);
  }

  function totalSupply() public view returns (uint256) {
    return _totalSupply;
  }

  function balanceOf(address owner) public view returns (uint256) {
    return _balances[owner];
  }

  function allowance(address owner, address spender) public view returns (uint256) {
    return _allowed[owner][spender];
  }

  function findOnePercent(uint256 value) public view returns (uint256)  {
    uint256 roundValue = value.ceil(basePercent);
    uint256 onePercent = roundValue.mul(basePercent).div(10000);
    return onePercent;
  }

  function transfer(address to, uint256 value) public returns (bool) {
    require(value <= _balances[msg.sender]);
    require(to != address(0));

    uint256 tokensToBurn = findOnePercent(value);
    uint256 tokensToTransfer = value.sub(tokensToBurn);

    _balances[msg.sender] = _balances[msg.sender].sub(value);
    _balances[to] = _balances[to].add(tokensToTransfer);

    _totalSupply = _totalSupply.sub(tokensToBurn);

    emit Transfer(msg.sender, to, tokensToTransfer);
    emit Transfer(msg.sender, address(0), tokensToBurn);
    return true;
  }

  function multiTransfer(address[] memory receivers, uint256[] memory amounts) public {
    for (uint256 i = 0; i < receivers.length; i++) {
      transfer(receivers[i], amounts[i]);
    }
  }

  function approve(address spender, uint256 value) public returns (bool) {
    require(spender != address(0));
    _allowed[msg.sender][spender] = value;
    emit Approval(msg.sender, spender, value);
    return true;
  }

  function transferFrom(address from, address to, uint256 value) public returns (bool) {
    require(value <= _balances[from]);
    require(value <= _allowed[from][msg.sender]);
    require(to != address(0));

    _balances[from] = _balances[from].sub(value);

    uint256 tokensToBurn = findOnePercent(value);
    uint256 tokensToTransfer = value.sub(tokensToBurn);

    _balances[to] = _balances[to].add(tokensToTransfer);
    _totalSupply = _totalSupply.sub(tokensToBurn);

    _allowed[from][msg.sender] = _allowed[from][msg.sender].sub(value);

    emit Transfer(from, to, tokensToTransfer);
    emit Transfer(from, address(0), tokensToBurn);

    return true;
  }

  function increaseAllowance(address spender, uint256 addedValue) public returns (bool) {
    require(spender != address(0));
    _allowed[msg.sender][spender] = (_allowed[msg.sender][spender].add(addedValue));
    emit Approval(msg.sender, spender, _allowed[msg.sender][spender]);
    return true;
  }

  function decreaseAllowance(address spender, uint256 subtractedValue) public returns (bool) {
    require(spender != address(0));
    _allowed[msg.sender][spender] = (_allowed[msg.sender][spender].sub(subtractedValue));
    emit Approval(msg.sender, spender, _allowed[msg.sender][spender]);
    return true;
  }

  function _mint(address account, uint256 amount) internal {
    require(amount != 0);
    _balances[account] = _balances[account].add(amount);
    emit Transfer(address(0), account, amount);
  }

  function burn(uint256 amount) external {
    _burn(msg.sender, amount);
  }

  function _burn(address account, uint256 amount) internal {
    require(amount != 0);
    require(amount <= _balances[account]);
    _totalSupply = _totalSupply.sub(amount);
    _balances[account] = _balances[account].sub(amount);
    emit Transfer(account, address(0), amount);
  }

  function burnFrom(address account, uint256 amount) external {
    require(amount <= _allowed[account][msg.sender]);
    _allowed[account][msg.sender] = _allowed[account][msg.sender].sub(amount);
    _burn(account, amount);
  }
}