orderbook.sol

pragma solidity ^0.4.0;

contract OrderBookLUXBTC {
    
    enum OrderType { BUY, SELL }

    event OrderPlaced(uint64 id,OrderType t, uint64 price, uint64 quantity);
    event OrderMatched(uint64 id);
    
    mapping(address => uint) deposits;
    
    /// Deposit = 10 lux
    function place(uint64 id, OrderType t, uint64 price, uint64 quantity) payable {
        if (msg.value < 10 ether || price == 0 || quantity == 0) { throw; }
        OrderPlaced(id, t, price, quantity);
        deposits[msg.sender] += msg.value;
    }
    
    function take(uint64 id) returns (bool) {
        uint amount = deposits[msg.sender];
        
        if (amount < 10 ether) { throw; }
        
        // It is important to substract now this because the recipient
        // can call this function again as part of the receiving call
        // before `send` returns.
        deposits[msg.sender] -= 10 ether;

        if (!msg.sender.send(amount)) {
            // No need to call throw here, just reset the amount owing
            deposits[msg.sender] = amount;
            return false;
        }
        OrderMatched(id);  
        return true;
    }
}