// File: contracts\libraries\SafeMath.sol

pragma solidity =0.5.16;

// From https://github.com/OpenZeppelin/openzeppelin-contracts/blob/master/contracts/math/Math.sol
// Subject to the MIT license.

/**
 * @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, 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 addition of two unsigned integers, reverting with custom message on overflow.
     *
     * Counterpart to Solidity's `+` operator.
     *
     * Requirements:
     * - Addition cannot overflow.
     */
    function add(uint256 a, uint256 b, string memory errorMessage) internal pure returns (uint256) {
        uint256 c = a + b;
        require(c >= a, errorMessage);

        return c;
    }

    /**
     * @dev Returns the subtraction of two unsigned integers, reverting on underflow (when the result is negative).
     *
     * Counterpart to Solidity's `-` operator.
     *
     * Requirements:
     * - Subtraction cannot underflow.
     */
    function sub(uint256 a, uint256 b) internal pure returns (uint256) {
        return sub(a, b, "SafeMath: subtraction underflow");
    }

    /**
     * @dev Returns the subtraction of two unsigned integers, reverting with custom message on underflow (when the result is negative).
     *
     * Counterpart to Solidity's `-` operator.
     *
     * Requirements:
     * - Subtraction cannot underflow.
     */
    function sub(uint256 a, uint256 b, string memory errorMessage) internal pure returns (uint256) {
        require(b <= a, errorMessage);
        uint256 c = a - b;

        return c;
    }

    /**
     * @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) {
        // 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 0;
        }

        uint256 c = a * b;
        require(c / a == b, "SafeMath: multiplication overflow");

        return c;
    }

    /**
     * @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, string memory errorMessage) 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-contracts/pull/522
        if (a == 0) {
            return 0;
        }

        uint256 c = a * b;
        require(c / a == b, errorMessage);

        return c;
    }

    /**
     * @dev Returns the integer division of two unsigned integers.
     * Reverts 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) {
        return div(a, b, "SafeMath: division by zero");
    }

    /**
     * @dev Returns the integer division of two unsigned integers.
     * Reverts with custom message 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, string memory errorMessage) internal pure returns (uint256) {
        // Solidity only automatically asserts when dividing by 0
        require(b > 0, errorMessage);
        uint256 c = a / b;
        // assert(a == b * c + a % b); // There is no case in which this doesn't hold

        return c;
    }

    /**
     * @dev Returns the remainder of dividing two unsigned integers. (unsigned integer modulo),
     * Reverts 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) {
        return mod(a, b, "SafeMath: modulo by zero");
    }

    /**
     * @dev Returns the remainder of dividing two unsigned integers. (unsigned integer modulo),
     * Reverts with custom message 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, string memory errorMessage) internal pure returns (uint256) {
        require(b != 0, errorMessage);
        return a % b;
    }
}

// File: contracts\ImpermaxERC20.sol

pragma solidity =0.5.16;


// This contract is basically UniswapV2ERC20 with small modifications
// src: https://github.com/Uniswap/uniswap-v2-core/blob/master/contracts/UniswapV2ERC20.sol

contract ImpermaxERC20 {
	using SafeMath for uint;
	
	string public name;
	string public symbol;
	uint8 public decimals = 18;
	uint public totalSupply;
	mapping(address => uint) public balanceOf;
	mapping(address => mapping(address => uint)) public allowance;
	
	bytes32 public DOMAIN_SEPARATOR;
	mapping(address => uint) public nonces;
	
	event Transfer(address indexed from, address indexed to, uint value);
	event Approval(address indexed owner, address indexed spender, uint value);

	constructor() public {}	
	
	function _setName(string memory _name, string memory _symbol) internal {
		name = _name;
		symbol = _symbol;
		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) internal {
		balanceOf[from] = balanceOf[from].sub(value, "Impermax: TRANSFER_TOO_HIGH");
		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, "Impermax: TRANSFER_NOT_ALLOWED");
		}
		_transfer(from, to, value);
		return true;
	}
	
	function _checkSignature(address owner, address spender, uint value, uint deadline, uint8 v, bytes32 r, bytes32 s, bytes32 typehash) internal {
		require(deadline >= block.timestamp, "Impermax: EXPIRED");
		bytes32 digest = keccak256(
			abi.encodePacked(
				'\x19\x01',
				DOMAIN_SEPARATOR,
				keccak256(abi.encode(typehash, owner, spender, value, nonces[owner]++, deadline))
			)
		);
		address recoveredAddress = ecrecover(digest, v, r, s);
		require(recoveredAddress != address(0) && recoveredAddress == owner, "Impermax: INVALID_SIGNATURE");	
	}

	// keccak256("Permit(address owner,address spender,uint256 value,uint256 nonce,uint256 deadline)");
	bytes32 public constant PERMIT_TYPEHASH = 0x6e71edae12b1b97f4d1f60370fef10105fa2faae0126114a169c64845d6126c9;
	function permit(address owner, address spender, uint value, uint deadline, uint8 v, bytes32 r, bytes32 s) external {
		_checkSignature(owner, spender, value, deadline, v, r, s, PERMIT_TYPEHASH);
		_approve(owner, spender, value);
	}
}

// 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\IPoolToken.sol

pragma solidity >=0.5.0;

interface IPoolToken {

	/*** Impermax ERC20 ***/
	
	event Transfer(address indexed from, address indexed to, uint value);
	event Approval(address indexed owner, address indexed spender, 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;
	
	/*** Pool Token ***/
	
	event Mint(address indexed sender, address indexed minter, uint mintAmount, uint mintTokens);
	event Redeem(address indexed sender, address indexed redeemer, uint redeemAmount, uint redeemTokens);
	event Sync(uint totalBalance);
	
	function underlying() external view returns (address);
	function factory() external view returns (address);
	function totalBalance() external view returns (uint);
	function MINIMUM_LIQUIDITY() external pure returns (uint);

	function exchangeRate() external returns (uint);
	function mint(address minter) external returns (uint mintTokens);
	function redeem(address redeemer) external returns (uint redeemAmount);
	function skim(address to) external;
	function sync() external;
	
	function _setFactory() external;
}

// File: contracts\PoolToken.sol

pragma solidity =0.5.16;





contract PoolToken is IPoolToken, ImpermaxERC20 {
   	uint internal constant initialExchangeRate = 1e18;
	address public underlying;
	address public factory;
	uint public totalBalance;
	uint public constant MINIMUM_LIQUIDITY = 1000;
	
	event Mint(address indexed sender, address indexed minter, uint mintAmount, uint mintTokens);
	event Redeem(address indexed sender, address indexed redeemer, uint redeemAmount, uint redeemTokens);
	event Sync(uint totalBalance);
	
	/*** Initialize ***/
	
	// called once by the factory
	function _setFactory() external {
		require(factory == address(0), "Impermax: FACTORY_ALREADY_SET");
		factory = msg.sender;
	}
	
	/*** PoolToken ***/
	
	function _update() internal {
		totalBalance = IERC20(underlying).balanceOf(address(this));
		emit Sync(totalBalance);
	}

	function exchangeRate() public returns (uint) 
	{
		uint _totalSupply = totalSupply; // gas savings
		uint _totalBalance = totalBalance; // gas savings
		if (_totalSupply == 0 || _totalBalance == 0) return initialExchangeRate;
		return _totalBalance.mul(1e18).div(_totalSupply);
	}
	
	// this low-level function should be called from another contract
	function mint(address minter) external nonReentrant update returns (uint mintTokens) {
		uint balance = IERC20(underlying).balanceOf(address(this));
		uint mintAmount = balance.sub(totalBalance);
		mintTokens = mintAmount.mul(1e18).div(exchangeRate());

		if(totalSupply == 0) {
			// permanently lock the first MINIMUM_LIQUIDITY tokens
			mintTokens = mintTokens.sub(MINIMUM_LIQUIDITY);
			_mint(address(0), MINIMUM_LIQUIDITY);
		}
		require(mintTokens > 0, "Impermax: MINT_AMOUNT_ZERO");
		_mint(minter, mintTokens);
		emit Mint(msg.sender, minter, mintAmount, mintTokens);
	}

	// this low-level function should be called from another contract
	function redeem(address redeemer) external nonReentrant update returns (uint redeemAmount) {
		uint redeemTokens = balanceOf[address(this)];
		redeemAmount = redeemTokens.mul(exchangeRate()).div(1e18);

		require(redeemAmount > 0, "Impermax: REDEEM_AMOUNT_ZERO");
		require(redeemAmount <= totalBalance, "Impermax: INSUFFICIENT_CASH");
		_burn(address(this), redeemTokens);
		_safeTransfer(redeemer, redeemAmount);
		emit Redeem(msg.sender, redeemer, redeemAmount, redeemTokens);		
	}

	// force real balance to match totalBalance
	function skim(address to) external nonReentrant {
		_safeTransfer(to, IERC20(underlying).balanceOf(address(this)).sub(totalBalance));
	}

	// force totalBalance to match real balance
	function sync() external nonReentrant update {}
	
	/*** Utilities ***/
	
	// same safe transfer function used by UniSwapV2 (with fixed underlying)
	bytes4 private constant SELECTOR = bytes4(keccak256(bytes("transfer(address,uint256)")));
	function _safeTransfer(address to, uint amount) internal {
		(bool success, bytes memory data) = underlying.call(abi.encodeWithSelector(SELECTOR, to, amount));
		require(success && (data.length == 0 || abi.decode(data, (bool))), "Impermax: TRANSFER_FAILED");
	}
	
	// prevents a contract from calling itself, directly or indirectly.
	bool internal _notEntered = true;
	modifier nonReentrant() {
		require(_notEntered, "Impermax: REENTERED");
		_notEntered = false;
		_;
		_notEntered = true;
	}
	
	// update totalBalance with current balance
	modifier update() {
		_;
		_update();
	}
}

// File: contracts\xIMX.sol

pragma solidity =0.5.16;


contract xIMX is PoolToken {

	constructor(address _underlying) public {
		factory = msg.sender;
		_setName("xIMX", "Staked IMX");
		underlying = _underlying;
	}
	
}