pragma solidity ^0.4.13;


import "./owned.sol";
import "./FixedSupplyToken.sol";


contract Exchange is owned {

    ///////////////////////
    // GENERAL STRUCTURE //
    ///////////////////////
    struct Offer{
        uint amount;
        address who;
    }

    struct OrderBook{
        uint higherPrice;
        uint lowerPrice;

        mapping (uint => Offer) offers;
        uint offers_keys;
        uint offers_length;
    }

    struct Token {
        address tokenContract;
        string symbolName;

        mapping(uint => OrderBook) buyBook;
        uint curBuyPrice;
        uint lowestBuyPrice;
        uint amountBuyPrices;

        mapping (uint => OrderBook) sellBook;
        uint curSellPrice;
        uint highestSellPrice;
        uint amountSellPrices;


    }

    mapping (uint => Token) tokens;
    uint8 symbolNameIndex;

    //////////////
    // BALANCES //
    //////////////
    mapping(address => mapping(uint8 => uint)) tokenBalanceForAddress;

    mapping(address => uint) balanceEthForAddress;


    ////////////
    // EVENTS //
    ////////////

    //EVENTS for Deposit/withdrawal
    event DepositForTokenReceived(address indexed _from, uint indexed _symbolIndex, uint _amount, uint _timestamp);

    event WithdrawalToken(address indexed _to, uint indexed _symbolIndex, uint _amount, uint _timestamp);

    event DepositForEthReceived(address indexed _from, uint _amount, uint _timestamp);

    event WithdrawalEth(address indexed _to, uint _amount, uint _timestamp);

    //events for orders
    event LimitSellOrderCreated(uint indexed _symbolIndex, address indexed _who, uint _amountTokens, uint _priceInWei, uint _orderKey);

    event SellOrderFulfilled(uint indexed _symbolIndex, uint _amount, uint _priceInWei, uint _orderKey);

    event SellOrderCanceled(uint indexed _symbolIndex, uint _priceInWei, uint _orderKey);

    event LimitBuyOrderCreated(uint indexed _symbolIndex, address indexed _who, uint _amountTokens, uint _priceInWei, uint _orderKey);

    event BuyOrderFulfilled(uint indexed _symbolIndex, uint _amount, uint _priceInWei, uint _orderKey);

    event BuyOrderCanceled(uint indexed _symbolIndex, uint _priceInWei, uint _orderKey);

    //events for management
    event TokenAddedToSystem(uint _symbolIndex, string _token, uint _timestamp);



    //////////////////////////////////
    // DEPOSIT AND WITHDRAWAL ETHER //
    //////////////////////////////////
   function depositEther() payable {
       require(balanceEthForAddress[msg.sender] + msg.value >= balanceEthForAddress[msg.sender]);
       balanceEthForAddress[msg.sender] += msg.value;
   }

   function withdrawEther(uint amountInWei){
       require(balanceEthForAddress[msg.sender] - amountInWei >= 0);
       require(balanceEthForAddress[msg.sender] - amountInWei <= balanceEthForAddress[msg.sender]);
       balanceEthForAddress[msg.sender] -= amountInWei;
       msg.sender.transfer(amountInWei);
   }

    function getEthBalanceInWei() constant returns (uint){
        return balanceEthForAddress[msg.sender];
    }
    //////////////////////
    // TOKEN MANAGEMENT //
    //////////////////////
    function addToken(string symbolName, address erc20TokenAddress) onlyOwner {
        require(!hasToken(symbolName));
        symbolNameIndex++;
        tokens[symbolNameIndex].symbolName = symbolName;
        tokens[symbolNameIndex].tokenContract = erc20TokenAddress;
    }

    function hasToken(string symbolName) constant returns(bool){
        uint8 index = getSymbolIndex(symbolName);
        if(index == 0) {
            return false;
        }
        return true;
    }

    function getSymbolIndex(string symbolName) internal returns(uint8) {
        for(uint8 i = 1; i <= symbolNameIndex; i++){
            if(stringsEqual(tokens[i].symbolName, symbolName)){
                return i;
            }
        }
        return 0;
    }


    function getSymbolIndexOrThrow(string symbolName) returns (uint8) {
        uint8 index = getSymbolIndex(symbolName);
        require(index > 0);
        return index;
    }


    //////////////////////////////////
    // DEPOSIT AND WITHDRAWAL TOKEN //
    //////////////////////////////////
    function depositToken(string symbolName, uint amount) {
        uint8 symbolNameIndex = getSymbolIndexOrThrow(symbolName);
        require(tokens[symbolName].tokenContract != address(0));

        ERC20Interface token = ERC20Interface(tokens[symbolNameIndex].tokenContract);

        require(token.transferFrom(msg.sender, address(this), amount) == true);
        require(tokenBalanceForAddress[msg.sender][symbolNameIndex] + amount >= balanceEthForAddress);

        tokenBalanceForAddress[msg.sender][symbolNameIndex] += amount;
    }

    function withdrawToken(string symbolName, uint amount) {
        uint8 symbolNameIndex = getSymbolIndexOrThrow(symbolName);
        require(tokens[symbolNameIndex].tokenContract != address(0));

        ERC20Interface token = ERC20Interface(tokens[symbolNameIndex].tokenContract);

        require(tokenBalanceForAddress[msg.sender][symbolName] - amount >= 0);
        require(tokenBalanceForAddress[msg.sender][symbolName] - amount <= tokenBalanceForAddress );

        tokenBalanceForAddress[msg.sender][symbolNameIndex] -= amount;
        require(token.transfer(msg.sender, amount) == true);
    }

    function getBalance(string symbolName) constant returns (uint) {
        uint8 symbolNameIndex = getSymbolIndexOrThrow(symbolName);
        return tokenBalanceForAddress[msg.sender][symbolNameIndex];
    }

    /////////////////////////////
    // ORDER BOOK - BID ORDERS //
    /////////////////////////////
    function getBuyOrderBook(string symbolName) constant returns (uint[], uint[]) {
        uint8 tokenNameIndex = getSymbolIndexOrThrow(symbolName);
        uint[] memory arrPricesBuy = new uint[](tokens[tokenNameIndex].amountBuyPrices);
        uint[] memory arrVolumesBuy = new uint[](tokens[tokenNameIndex].amountBuyPrices);

        uint whilePrice = tokens[tokenNameIndex].lowestBuyPrice;
        uint counter = 0;

        if(tokens[tokenNameIndex].curBuyPrice > 0 ){
            while (whilePrice <= tokens[tokenNameIndex].curBuyPrice){
                arrPricesBuy[counter] = whilePrice;
                uint volumeAtPrice = 0;
                uint offers_keys = 0;

                offers_keys = tokens[tokenNameIndex].buyBook[whilePrice].offers_keys;
                while(offers_keys <= tokens[tokenNameIndex].buyBook[whilePrice].offers_length) {
                    volumeAtPrice += tokens[tokenNameIndex].buyBook[whilePrice].offers[offers_keys].amount;
                    offers_keys++;
                }

                arrVolumesBuy[counter] = volumeAtPrice;

                // next whilePrice
                if(whilePrice == tokens[tokenNameIndex].buyBook[whilePrice].higherPrice){
                    break;
                } else {
                    whilePrice = tokens[tokenNameIndex].buyBook[whilePrice].higherPrice;
                }
                counter++;
            }
        }
        return (arrPricesBuy, arrVolumesBuy);
    }


    /////////////////////////////
    // ORDER BOOK - ASK ORDERS //
    /////////////////////////////
    function getSellOrderbook(string symbolName) constant returns(uint[], uint[]) {
        uint8 tokenNameIndex = getSymbolIndexOrThrow(symbolName);
        uint[] memory arrPricesSell = new uint[](tokens[tokenNameIndex].amountSellPrices);
        uint[] memory arrVolumesSell = new uint[](tokens[tokenNameIndex].amountSellPrices);
        uint sellWhilePrice = tokens[tokenNameIndex].curSellPrice;
        uint sellCounter = 0;
        if(tokens[tokenNameIndex].curSellPrice > 0){
            while (sellWhilePrice <= tokens[tokenNameIndex].highestSellPrice){
                arrPricesSell[sellCounter] = sellWhilePrice;
                uint sellVolumeAtPrice = 0;
                uint sell_offers_key = 0;

                sell_offers_key = tokens[tokenNameIndex].sellBook[sellWhilePrice].offers_keys;
                while(sell_offers_key <= tokens[tokenNameIndex].sellBook[sellWhilePrice].offers_length){
                    sellVolumeAtPrice += tokens[tokenNameIndex].sellBook[sellWhilePrice].offers[sell_offers_key].amount;
                    sell_offers_key++;
                }

                arrVolumesSell[sellCounter] = sellVolumeAtPrice;

                //next whilePrice
                if(tokens[tokenNameIndex].sellBook[sellWhilePrice].higherPrice == 0) {
                    break;
                } else {
                    sellWhilePrice = tokens[tokenNameIndex].sellBook[sellWhilePrice].higherPrice;
                }
                sellCounter++;
            }
        }
        // sell part
        return (arrPricesSell, arrVolumesSell);
    }



    ////////////////////////////
    // NEW ORDER - BID ORDER //
    ///////////////////////////
    function buyToken(string symbolName, uint priceInWei, uint amount){
        uint tokenNameIndex = getSymbolIndexOrThrow(symbolName);
        uint total_amount_ether_necessary = 0;
        uint total_amount_ether_available = 0;

        // if have enouhh ether, we ca, buy that:
        total_amount_ether_necessary = amount * priceInWei;

        // overflow check
        require(total_amount_ether_necessary >= amount);
        require(total_amount_ether_necessary >= priceInWei);
        require(balanceEthForAddress[msg.sender] >= total_amount_ether_necessary);
        require(balanceEthForAddress[msg.sender] - total_amount_ether_necessary >= 0);

        // first deduct the amount of ether from our balance
        balanceEthForAddress[msg.sender] -= total_amount_ether_necessary;

        if(tokens[tokenNameIndex].amountSellPrices == 0 || tokens[tokenNameIndex].curSellPrice > priceInWei){
            // limit order: we don't enouth amount to fulfill the amount

            addBuyOffer(tokenNameIndex, priceInWei, amount, msg.sender);

            LimitBuyOrderCreated(tokenNameIndex, msg.sender, amount, priceInWei, tokens[tokenNameIndex].buyBook[priceInWei].offers_length);
        } else {
            revert();
        }

    }



    ///////////////////////////
    // BID LIMIT ORDER LOGIC //
    ///////////////////////////
    function addBuyOffer(uint8 tokenIndex, uint priceInWei, uint amount, address who)  internal {
        tokens[tokenIndex].buyBook[priceInWei].offers_length++;
        tokens[tokenIndex].buyBook[priceInWei].offers[tokens[tokenIndex].buyBook[priceInWei].offers_length] = Offer(amount, who);

        if(tokens[tokenIndex].buyBook[priceInWei].offers_length == 1){
            tokens[tokenIndex].buyBook[priceInWei].offers_keys = 1;

            tokens[tokenIndex].amountBuyPrices++;

            uint curBuyPrice = tokens[tokenIndex].lowestBuyPrice;
            if(lowestBuyPrice == 0 || lowestBuyPrice > priceInWei) {
                if(curBuyPrice == 0) {
                    tokens[tokenIndex].curBuyPrice = priceInWei;
                    tokens[tokenIndex].buyBook[priceInWei].higherPrice = priceInWei;
                    tokens[tokenIndex].buyBook[priceInWei].lowerPrice = 0;
                } else {
                    tokens[tokenIndex].buyBook[lowestBuyPrice].lowerPrice = priceInWei;
                    tokens[tokenIndex].buyBook[priceInWei].higherPrice = lowerPrice;
                    tokens[tokenIndex].buyBook[priceInWei].lowerPrice = 0;
                }
                tokens[tokenIndex].lowestBuyPrice = priceInWei;
            } else if(curBuyPrice < priceInWei) {
                tokens[tokenIndex].buyBook[curBuyPrice].higherPrice = priceInWei;
                tokens[tokenIndex].buyBook[priceInWei].higherPrice = priceInWei;
                tokens[tokenIndex].buyBook[priceInWei].lowerPrice = curBuyPrice;
                tokens[tokenIndex].curBuyPrice = priceInWei;
            } else {
                uint buyPrice = tokens[tokenIndex].curBuyPrice;
                bool weFoundIt = false;
                while(buyPrice > 0 && !weFoundIt){
                    if( buyPrice < priceInWei &&
                        tokens[tokenIndex].buyBook[buyPrice].higherPrice > priceInWei) {
                            tokens[tokenIndex].buyBook[priceInWei].lowerPrice = buyPrice;
                            tokens[tokenIndex].buyBook[priceInWei].higherPrice = tokens[tokenIndex].buyBook[buyPrice].higherPrice;

                            // set the higherPrice'd order-book entries lowerPrice to the current priceInWei
                            tokens[tokenIndex].buyBook[tokens[tokenIndex].buyBook[buyPrice].higherPrice].lowerPrice = priceInWei;

                            tokens[tokenIndex].buyBook[buyPrice].higherPrice = priceInWei;

                            weFoundIt = true;
                        }
                    buyPrice = tokens[tokenIndex].buyBook[buyPrice].lowerPrice;
                }
            }
        }
    }


    ////////////////////////////
    // NEW ORDER - ASK ORDER //
    ///////////////////////////

    function sellToken(string symbolName, uint priceInWei, uint amount) {
        uint8 tokenNameIndex = getSymbolIndexOrThrow(symbolName);
        uint total_amount_ether_necessary = 0;
        uint total_amount_ether_available = 0;

        if(tokens[tokenNameIndex].amountBuyPrices == 0 || tokens[tokenNameIndex].curBuyPrice < priceInWei){
            total_amount_ether_necessary = amount * priceInWei;

            //overflow check
            require(total_amount_ether_necessary >= amount);
            require(total_amount_ether_necessary >= priceInWei);
            require(tokenBalanceForAddress[msg.sender][tokenNameIndex] >= amount);
            require(tokenBalanceForAddress[msg.sender][tokenNameIndex] - amount >= 0);
            require(balanceEthForAddress[msg.sender] + total_amount_ether_necessary >= balanceEthForAddress[msg.sender]);

            // actually substract  the amount of tokens it then
            tokenBalanceForAddress[msg.sender][tokenNameIndex] -= amount;

            // limit order: we don't have enough offers to fullfil the amount

        }
    }



    ///////////////////////////
    // ASK LIMIT ORDER LOGIC //
    ///////////////////////////


    //////////////////////////////
    // CANCEL LIMIT ORDER LOGIC //
    //////////////////////////////





 ////////////////////////////////
    // STRING COMPARISON FUNCTION //
    ////////////////////////////////
    function stringsEqual(string storage _a, string memory _b) internal returns (bool) {
        bytes storage a = bytes(_a);
        bytes memory b = bytes(_b);
        if (a.length != b.length) {
            return false;
        }
        // @todo unroll this loop
        for (uint i = 0; i < a.length; i ++) {
            if (a[i] != b[i]) {
                return false;
            }
        }
        return true;
    }



}