contract SHCToken is StandardToken {
    string public constant NAME = "商会币";
    string public constant SYMBOL = "SHC";
    uint public constant DECIMALS = 18;

    /// During token sale, we use one consistent price: 1000 SHC/ETH.
    /// We split the entire token sale period into 3 phases, each
    /// phase has a different bonus setting as specified in `bonusPercentages`.
    /// The real price for phase i is `(1 + bonusPercentages[i]/100.0) * BASE_RATE`.
    /// The first phase or early-bird phase has a much higher bonus.
    uint8[10] public bonusPercentages = [
        20,
        10,
        0
    ];

    uint public constant NUM_OF_PHASE = 3;
  
    /// Each phase contains exactly 29000 Ethereum blocks, which is roughly 7 days,
    /// which makes this 3-phase sale period roughly 21 days.
    /// See https://www.ethereum.org/crowdsale#scheduling-a-call
    uint16 public constant BLOCKS_PER_PHASE = 29000;

    /// This is where we hold ETH during this token sale. We will not transfer any Ether
    /// out of this address before we invocate the `close` function to finalize the sale. 
    /// This promise is not guanranteed by smart contract by can be verified with public
    /// Ethereum transactions data available on several blockchain browsers.
    /// This is the only address from which `start` and `close` can be invocated.
    ///
    /// Note: this will be initialized during the contract deployment.
    address public target;

    /// `firstblock` specifies from which block our token sale starts.
    /// This can only be modified once by the owner of `target` address.
    uint public firstblock = 0;

    /// Indicates whether unsold token have been issued. This part of SHC token
    /// is managed by the project team and is issued directly to `target`.
    bool public unsoldTokenIssued = false;

    /// Minimum amount of funds to be raised for the sale to succeed. 
    uint256 public constant GOAL = 3000 ether;

    /// Maximum amount of fund to be raised, the sale ends on reaching this amount.
    uint256 public constant HARD_CAP = 4500 ether;

    /// Base exchange rate is set to 1 ETH = 1050 SHC.
    uint256 public constant BASE_RATE = 1050;

    /// A simple stat for emitting events.
    uint public totalEthReceived = 0;

    /// Issue event index starting from 0.
    uint public issueIndex = 0;

    /* 
     * EVENTS
     */

    /// Emitted only once after token sale starts.
    event SaleStarted();

    /// Emitted only once after token sale ended (all token issued).
    event SaleEnded();

    /// Emitted when a function is invocated by unauthorized addresses.
    event InvalidCaller(address caller);

    /// Emitted when a function is invocated without the specified preconditions.
    /// This event will not come alone with an exception.
    event InvalidState(bytes msg);

    /// Emitted for each sucuessful token purchase.
    event Issue(uint issueIndex, address addr, uint ethAmount, uint tokenAmount);

    /// Emitted if the token sale succeeded.
    event SaleSucceeded();

    /// Emitted if the token sale failed.
    /// When token sale failed, all Ether will be return to the original purchasing
    /// address with a minor deduction of transaction fee锛坓as)
    event SaleFailed();

    /*
     * MODIFIERS
     */

    modifier onlyOwner {
        if (target == msg.sender) {
            _;
        } else {
            InvalidCaller(msg.sender);
            throw;
        }
    }

    modifier beforeStart {
        if (!saleStarted()) {
            _;
        } else {
            InvalidState("Sale has not started yet");
            throw;
        }
    }

    modifier inProgress {
        if (saleStarted() && !saleEnded()) {
            _;
        } else {
            InvalidState("Sale is not in progress");
            throw;
        }
    }

    modifier afterEnd {
        if (saleEnded()) {
            _;
        } else {
            InvalidState("Sale is not ended yet");
            throw;
        }
    }

    /**
     * CONSTRUCTOR 
     * 
     * @dev Initialize the SHC Token
     * @param _target The escrow account address, all ethers will
     * be sent to this address.
     * This address will be : 0xe597c5ab87e9d20ad445976d9b016c37f864da2b
     */
    function SHCToken(address _target) {
        target = _target;
        totalSupply = 10 ** 26;
        balances[target] = totalSupply;
    }

    /*
     * PUBLIC FUNCTIONS
     */

    /// @dev Start the token sale.
    /// @param _firstblock The block from which the sale will start.
    function start(uint _firstblock) public onlyOwner beforeStart {
        if (_firstblock <= block.number) {
            // Must specify a block in the future.
            throw;
        }

        firstblock = _firstblock;
        SaleStarted();
    }

    /// @dev Triggers unsold tokens to be issued to `target` address.
    function close() public onlyOwner afterEnd {
        if (totalEthReceived < GOAL) {
            SaleFailed();
        } else {
            SaleSucceeded();
        }
    }

    /// @dev Returns the current price.
    function price() public constant returns (uint tokens) {
        return computeTokenAmount(1 ether);
    }

    /// @dev This default function allows token to be purchased by directly
    /// sending ether to this smart contract.
    function () payable {
        issueToken(msg.sender);
    }

    /// @dev Issue token based on Ether received.
    /// @param recipient Address that newly issued token will be sent to.
    function issueToken(address recipient) payable inProgress {
        // We only accept minimum purchase of 0.01 ETH.
        assert(msg.value >= 0.01 ether);

        // We only accept maximum purchase of 35 ETH.
        assert(msg.value <= 35 ether);

        // We only accept totalEthReceived < HARD_CAP
        uint ethReceived = totalEthReceived + msg.value;
        assert(ethReceived <= HARD_CAP);

        uint tokens = computeTokenAmount(msg.value);
        totalEthReceived = totalEthReceived.add(msg.value);
        
        balances[msg.sender] = balances[msg.sender].add(tokens);
        balances[target] = balances[target].sub(tokens);

        Issue(
            issueIndex++,
            recipient,
            msg.value,
            tokens
        );

        if (!target.send(msg.value)) {
            throw;
        }
    }

    /*
     * INTERNAL FUNCTIONS
     */
  
    /// @dev Compute the amount of SHC token that can be purchased.
    /// @param ethAmount Amount of Ether to purchase SHC.
    /// @return Amount of SHC token to purchase
    function computeTokenAmount(uint ethAmount) internal constant returns (uint tokens) {
        uint phase = (block.number - firstblock).div(BLOCKS_PER_PHASE);

        // A safe check
        if (phase >= bonusPercentages.length) {
            phase = bonusPercentages.length - 1;
        }

        uint tokenBase = ethAmount.mul(BASE_RATE);
        uint tokenBonus = tokenBase.mul(bonusPercentages[phase]).div(100);

        tokens = tokenBase.add(tokenBonus);
    }

    /// @return true if sale has started, false otherwise.
    function saleStarted() constant returns (bool) {
        return (firstblock > 0 && block.number >= firstblock);
    }

    /// @return true if sale has ended, false otherwise.
    function saleEnded() constant returns (bool) {
        return firstblock > 0 && (saleDue() || hardCapReached());
    }

    /// @return true if sale is due when the last phase is finished.
    function saleDue() constant returns (bool) {
        return block.number >= firstblock + BLOCKS_PER_PHASE * NUM_OF_PHASE;
    }

    /// @return true if the hard cap is reached.
    function hardCapReached() constant returns (bool) {
        return totalEthReceived >= HARD_CAP;
    }
}
/// @title SHC Protocol Token.
/// For more information about this token sale, please visit https://gxn.io
/// @author Arnold - <arnold@gxn.io>, Bob - <bob@gxn.io>.
function hardCapReached() constant returns (bool) {
    return totalEthReceived >= HARD_CAP;
}

/// @return true if the hard cap is reached.