BuyToken.sol

pragma solidity ^0.4.11;

contract Token {
    function transfer(address _to, uint256 _value);
    function balanceOf(address _owner) constant returns (uint256 balance);
}

contract BuyToken {

    // Ether holder, the Party that has Ether and will receive Tokens
    address buyer;
    
    // Token holder, the Party that has tokens and will receive Ether
    address seller;
    
    bool succeeded; // Swap executed
    
    // Prices for the contract
    uint256 tokens;
    uint256 eth;
    
    // Token to be swapped
    Token token;
    
    function BuyTokenEscrow (
        address _buyer,
        address _seller,
        uint256 _tokens,
        uint256 _ether,
        address _token
    ) {
        buyer = _buyer;
        seller = _seller;
        tokens = _tokens;
        eth = _ether;
        token = _token;
    }
    
    modifier onlyBuyer () { if (msg.sender != buyer) revert(); _; }
    
    modifier onlySeller () { if (msg.sender != seller) revert(); _; }
    
    modifier beforeSwap () { if (succeeded) revert(); _; }
    
    modifier afterSwap () { if (!succeeded) revert(); _; }

    function () payable {}

    function refundEth () onlyBuyer beforeSwap {
        buyer.transfer(this.balance);
    }

    function refundTokens () onlySeller beforeSwap {
        token.transfer(seller, token.balanceOf(this));
    }

    function makeSwap () {
        if (this.balance != eth) revert();
        if (token.balanceOf(this) != tokens) revert();
        succeeded = true;
    }

    function withdraw() onlySeller afterSwap {
        msg.sender.transfer(this.balance);
    }

    function withdrawTokens() onlyBuyer afterSwap {
        token.transfer(msg.sender, token.balanceOf(this));
    }
}