pragma solidity ^0.4.11;

/*
    Copyright 2017, Klaus Hott
    Copyright 2016, Jordi Baylina

    This program is free software: you can redistribute it and/or modify
    it under the terms of the GNU General Public License as published by
    the Free Software Foundation, either version 3 of the License, or
    (at your option) any later version.

    This program is distributed in the hope that it will be useful,
    but WITHOUT ANY WARRANTY; without even the implied warranty of
    MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
    GNU General Public License for more details.

    You should have received a copy of the GNU General Public License
    along with this program.  If not, see <http://www.gnu.org/licenses/>.
 */

/// @title MiniMeToken Contract
/// @author Jordi Baylina
/// @dev This token contract's goal is to make it easy for anyone to clone this
///  token using the token distribution at a given block, this will allow DAO's
///  and DApps to upgrade their features in a decentralized manner without
///  affecting the original token
/// @dev It is ERC20 compliant, but still needs to under go further testing.

contract ERC20 {
  /// @notice Send `_amount` tokens to `_to` from `msg.sender`
  /// @param _to The address of the recipient
  /// @param _amount The amount of tokens to be transferred
  /// @return Whether the transfer was successful or not
  function transfer(address _to, uint256 _amount) returns (bool success);

  /// @notice Send `_amount` tokens to `_to` from `_from` on the condition it
  ///  is approved by `_from`
  /// @param _from The address holding the tokens being transferred
  /// @param _to The address of the recipient
  /// @param _amount The amount of tokens to be transferred
  /// @return True if the transfer was successful
  function transferFrom(address _from, address _to, uint256 _amount
  ) returns (bool success);

  /// @param _owner The address that's balance is being requested
  /// @return The balance of `_owner` at the current block
  function balanceOf(address _owner) constant returns (uint256 balance);

  /// @notice `msg.sender` approves `_spender` to spend `_amount` tokens on
  ///  its behalf. This is a modified version of the ERC20 approve function
  ///  to be a little bit safer
  /// @param _spender The address of the account able to transfer the tokens
  /// @param _amount The amount of tokens to be approved for transfer
  /// @return True if the approval was successful
  function approve(address _spender, uint256 _amount) returns (bool success);

  /// @dev This function makes it easy to read the `allowed[]` map
  /// @param _owner The address of the account that owns the token
  /// @param _spender The address of the account able to transfer the tokens
  /// @return Amount of remaining tokens of _owner that _spender is allowed
  ///  to spend
  function allowance(address _owner, address _spender
  ) constant returns (uint256 remaining);

  /// @notice `msg.sender` approves `_spender` to send `_amount` tokens on
  ///  its behalf, and then a function is triggered in the contract that is
  ///  being approved, `_spender`. This allows users to use their tokens to
  ///  interact with contracts in one function call instead of two
  /// @param _spender The address of the contract able to transfer the tokens
  /// @param _amount The amount of tokens to be approved for transfer
  /// @return True if the function call was successful
  function approveAndCall(address _spender, uint256 _amount, bytes _extraData
  ) returns (bool success);

  /// @dev This function makes it easy to get the total number of tokens
  /// @return The total number of tokens
  function totalSupply() constant returns (uint);
}


/// @dev The token controller contract must implement these functions
contract TokenController {
    /// @notice Called when `_owner` sends ether to the MiniMe Token contract
    /// @param _owner The address that sent the ether to create tokens
    /// @return True if the ether is accepted, false if it throws
    function proxyPayment(address _owner) payable returns(bool);

    /// @notice Notifies the controller about a token transfer allowing the
    ///  controller to react if desired
    /// @param _from The origin of the transfer
    /// @param _to The destination of the transfer
    /// @param _amount The amount of the transfer
    /// @return False if the controller does not authorize the transfer
    function onTransfer(address _from, address _to, uint _amount) returns(bool);

    /// @notice Notifies the controller about an approval allowing the
    ///  controller to react if desired
    /// @param _owner The address that calls `approve()`
    /// @param _spender The spender in the `approve()` call
    /// @param _amount The amount in the `approve()` call
    /// @return False if the controller does not authorize the approval
    function onApprove(address _owner, address _spender, uint _amount)
        returns(bool);
}

contract Controlled {
    /// @notice The address of the controller is the only address that can call
    ///  a function with this modifier
    modifier onlyController { if (msg.sender != controller) throw; _; }

    address public controller;

    function Controlled() { controller = msg.sender;}

    /// @notice Changes the controller of the contract
    /// @param _newController The new controller of the contract
    function changeController(address _newController) onlyController {
        controller = _newController;
    }
}

contract ApproveAndCallFallBack {
    function receiveApproval(address from, uint256 _amount, address _token, bytes _data);
}

/// @dev The actual token contract, the default controller is the msg.sender
///  that deploys the contract, so usually this token will be deployed by a
///  token controller contract, which Giveth will call a "Campaign"
contract MiniMeToken is Controlled {

    string public name;                //The Token's name: e.g. DigixDAO Tokens
    uint8 public decimals;             //Number of decimals of the smallest unit
    string public symbol;              //An identifier: e.g. REP
    string public version = 'MMT_0.1'; //An arbitrary versioning scheme


    /// @dev `Checkpoint` is the structure that attaches a block number to a
    ///  given value, the block number attached is the one that last changed the
    ///  value
    struct  Checkpoint {

        // `fromBlock` is the block number that the value was generated from
        uint128 fromBlock;

        // `value` is the amount of tokens at a specific block number
        uint128 value;
    }

    // `parentToken` is the Token address that was cloned to produce this token;
    //  it will be 0x0 for a token that was not cloned
    MiniMeToken public parentToken;

    // `parentSnapShotBlock` is the block number from the Parent Token that was
    //  used to determine the initial distribution of the Clone Token
    uint public parentSnapShotBlock;

    // `creationBlock` is the block number that the Clone Token was created
    uint public creationBlock;

    // `balances` is the map that tracks the balance of each address, in this
    //  contract when the balance changes the block number that the change
    //  occurred is also included in the map
    mapping (address => Checkpoint[]) balances;

    // `allowed` tracks any extra transfer rights as in all ERC20 tokens
    mapping (address => mapping (address => uint256)) allowed;

    // Tracks the history of the `totalSupply` of the token
    Checkpoint[] totalSupplyHistory;

    // Flag that determines if the token is transferable or not.
    bool public transfersEnabled;

    // The factory used to create new clone tokens
    MiniMeTokenFactory public tokenFactory;

////////////////
// Constructor
////////////////

    /// @notice Constructor to create a MiniMeToken
    /// @param _tokenFactory The address of the MiniMeTokenFactory contract that
    ///  will create the Clone token contracts, the token factory needs to be
    ///  deployed first
    /// @param _parentToken Address of the parent token, set to 0x0 if it is a
    ///  new token
    /// @param _parentSnapShotBlock Block of the parent token that will
    ///  determine the initial distribution of the clone token, set to 0 if it
    ///  is a new token
    /// @param _tokenName Name of the new token
    /// @param _decimalUnits Number of decimals of the new token
    /// @param _tokenSymbol Token Symbol for the new token
    /// @param _transfersEnabled If true, tokens will be able to be transferred
    function MiniMeToken(
        address _tokenFactory,
        address _parentToken,
        uint _parentSnapShotBlock,
        string _tokenName,
        uint8 _decimalUnits,
        string _tokenSymbol,
        bool _transfersEnabled
    ) {
        tokenFactory = MiniMeTokenFactory(_tokenFactory);
        name = _tokenName;                                 // Set the name
        decimals = _decimalUnits;                          // Set the decimals
        symbol = _tokenSymbol;                             // Set the symbol
        parentToken = MiniMeToken(_parentToken);
        parentSnapShotBlock = _parentSnapShotBlock;
        transfersEnabled = _transfersEnabled;
        creationBlock = block.number;
    }


///////////////////
// ERC20 Methods
///////////////////

    /// @notice Send `_amount` tokens to `_to` from `msg.sender`
    /// @param _to The address of the recipient
    /// @param _amount The amount of tokens to be transferred
    /// @return Whether the transfer was successful or not
    function transfer(address _to, uint256 _amount) returns (bool success) {
        if (!transfersEnabled) throw;
        return doTransfer(msg.sender, _to, _amount);
    }

    /// @notice Send `_amount` tokens to `_to` from `_from` on the condition it
    ///  is approved by `_from`
    /// @param _from The address holding the tokens being transferred
    /// @param _to The address of the recipient
    /// @param _amount The amount of tokens to be transferred
    /// @return True if the transfer was successful
    function transferFrom(address _from, address _to, uint256 _amount
    ) returns (bool success) {

        // The controller of this contract can move tokens around at will,
        //  this is important to recognize! Confirm that you trust the
        //  controller of this contract, which in most situations should be
        //  another open source smart contract or 0x0
        if (msg.sender != controller) {
            if (!transfersEnabled) throw;

            // The standard ERC 20 transferFrom functionality
            if (allowed[_from][msg.sender] < _amount) return false;
            allowed[_from][msg.sender] -= _amount;
        }
        return doTransfer(_from, _to, _amount);
    }

    /// @dev This is the actual transfer function in the token contract, it can
    ///  only be called by other functions in this contract.
    /// @param _from The address holding the tokens being transferred
    /// @param _to The address of the recipient
    /// @param _amount The amount of tokens to be transferred
    /// @return True if the transfer was successful
    function doTransfer(address _from, address _to, uint _amount
    ) internal returns(bool) {

           if (_amount == 0) {
               return true;
           }

           if (parentSnapShotBlock >= block.number) throw;

           // Do not allow transfer to 0x0 or the token contract itself
           if ((_to == 0) || (_to == address(this))) throw;

           // If the amount being transfered is more than the balance of the
           //  account the transfer returns false
           var previousBalanceFrom = balanceOfAt(_from, block.number);
           if (previousBalanceFrom < _amount) {
               return false;
           }

           // Alerts the token controller of the transfer
           if (isContract(controller)) {
               if (!TokenController(controller).onTransfer(_from, _to, _amount))
               throw;
           }

           // First update the balance array with the new value for the address
           //  sending the tokens
           updateValueAtNow(balances[_from], previousBalanceFrom - _amount);

           // Then update the balance array with the new value for the address
           //  receiving the tokens
           var previousBalanceTo = balanceOfAt(_to, block.number);
           if (previousBalanceTo + _amount < previousBalanceTo) throw; // Check for overflow
           updateValueAtNow(balances[_to], previousBalanceTo + _amount);

           // An event to make the transfer easy to find on the blockchain
           Transfer(_from, _to, _amount);

           return true;
    }

    /// @param _owner The address that's balance is being requested
    /// @return The balance of `_owner` at the current block
    function balanceOf(address _owner) constant returns (uint256 balance) {
        return balanceOfAt(_owner, block.number);
    }

    /// @notice `msg.sender` approves `_spender` to spend `_amount` tokens on
    ///  its behalf. This is a modified version of the ERC20 approve function
    ///  to be a little bit safer
    /// @param _spender The address of the account able to transfer the tokens
    /// @param _amount The amount of tokens to be approved for transfer
    /// @return True if the approval was successful
    function approve(address _spender, uint256 _amount) returns (bool success) {
        if (!transfersEnabled) throw;

        // To change the approve amount you first have to reduce the addresses`
        //  allowance to zero by calling `approve(_spender,0)` if it is not
        //  already 0 to mitigate the race condition described here:
        //  https://github.com/ethereum/EIPs/issues/20#issuecomment-263524729
        if ((_amount!=0) && (allowed[msg.sender][_spender] !=0)) throw;

        // Alerts the token controller of the approve function call
        if (isContract(controller)) {
            if (!TokenController(controller).onApprove(msg.sender, _spender, _amount))
                throw;
        }

        allowed[msg.sender][_spender] = _amount;
        Approval(msg.sender, _spender, _amount);
        return true;
    }

    /// @dev This function makes it easy to read the `allowed[]` map
    /// @param _owner The address of the account that owns the token
    /// @param _spender The address of the account able to transfer the tokens
    /// @return Amount of remaining tokens of _owner that _spender is allowed
    ///  to spend
    function allowance(address _owner, address _spender
    ) constant returns (uint256 remaining) {
        return allowed[_owner][_spender];
    }

    /// @notice `msg.sender` approves `_spender` to send `_amount` tokens on
    ///  its behalf, and then a function is triggered in the contract that is
    ///  being approved, `_spender`. This allows users to use their tokens to
    ///  interact with contracts in one function call instead of two
    /// @param _spender The address of the contract able to transfer the tokens
    /// @param _amount The amount of tokens to be approved for transfer
    /// @return True if the function call was successful
    function approveAndCall(address _spender, uint256 _amount, bytes _extraData
    ) returns (bool success) {
        if (!approve(_spender, _amount)) throw;

        ApproveAndCallFallBack(_spender).receiveApproval(
            msg.sender,
            _amount,
            this,
            _extraData
        );

        return true;
    }

    /// @dev This function makes it easy to get the total number of tokens
    /// @return The total number of tokens
    function totalSupply() constant returns (uint) {
        return totalSupplyAt(block.number);
    }


////////////////
// Query balance and totalSupply in History
////////////////

    /// @dev Queries the balance of `_owner` at a specific `_blockNumber`
    /// @param _owner The address from which the balance will be retrieved
    /// @param _blockNumber The block number when the balance is queried
    /// @return The balance at `_blockNumber`
    function balanceOfAt(address _owner, uint _blockNumber) constant
        returns (uint) {

        // These next few lines are used when the balance of the token is
        //  requested before a check point was ever created for this token, it
        //  requires that the `parentToken.balanceOfAt` be queried at the
        //  genesis block for that token as this contains initial balance of
        //  this token
        if ((balances[_owner].length == 0)
            || (balances[_owner][0].fromBlock > _blockNumber)) {
            if (address(parentToken) != 0) {
                return parentToken.balanceOfAt(_owner, min(_blockNumber, parentSnapShotBlock));
            } else {
                // Has no parent
                return 0;
            }

        // This will return the expected balance during normal situations
        } else {
            return getValueAt(balances[_owner], _blockNumber);
        }
    }

    /// @notice Total amount of tokens at a specific `_blockNumber`.
    /// @param _blockNumber The block number when the totalSupply is queried
    /// @return The total amount of tokens at `_blockNumber`
    function totalSupplyAt(uint _blockNumber) constant returns(uint) {

        // These next few lines are used when the totalSupply of the token is
        //  requested before a check point was ever created for this token, it
        //  requires that the `parentToken.totalSupplyAt` be queried at the
        //  genesis block for this token as that contains totalSupply of this
        //  token at this block number.
        if ((totalSupplyHistory.length == 0)
            || (totalSupplyHistory[0].fromBlock > _blockNumber)) {
            if (address(parentToken) != 0) {
                return parentToken.totalSupplyAt(min(_blockNumber, parentSnapShotBlock));
            } else {
                return 0;
            }

        // This will return the expected totalSupply during normal situations
        } else {
            return getValueAt(totalSupplyHistory, _blockNumber);
        }
    }

////////////////
// Clone Token Method
////////////////

    /// @notice Creates a new clone token with the initial distribution being
    ///  this token at `_snapshotBlock`
    /// @param _cloneTokenName Name of the clone token
    /// @param _cloneDecimalUnits Number of decimals of the smallest unit
    /// @param _cloneTokenSymbol Symbol of the clone token
    /// @param _snapshotBlock Block when the distribution of the parent token is
    ///  copied to set the initial distribution of the new clone token;
    ///  if the block is zero than the actual block, the current block is used
    /// @param _transfersEnabled True if transfers are allowed in the clone
    /// @return The address of the new MiniMeToken Contract
    function createCloneToken(
        string _cloneTokenName,
        uint8 _cloneDecimalUnits,
        string _cloneTokenSymbol,
        uint _snapshotBlock,
        bool _transfersEnabled
        ) returns(address) {
        if (_snapshotBlock == 0) _snapshotBlock = block.number;
        MiniMeToken cloneToken = tokenFactory.createCloneToken(
            this,
            _snapshotBlock,
            _cloneTokenName,
            _cloneDecimalUnits,
            _cloneTokenSymbol,
            _transfersEnabled
            );

        cloneToken.changeController(msg.sender);

        // An event to make the token easy to find on the blockchain
        NewCloneToken(address(cloneToken), _snapshotBlock);
        return address(cloneToken);
    }

////////////////
// Generate and destroy tokens
////////////////

    /// @notice Generates `_amount` tokens that are assigned to `_owner`
    /// @param _owner The address that will be assigned the new tokens
    /// @param _amount The quantity of tokens generated
    /// @return True if the tokens are generated correctly
    function generateTokens(address _owner, uint _amount
    ) onlyController returns (bool) {
        uint curTotalSupply = getValueAt(totalSupplyHistory, block.number);
        if (curTotalSupply + _amount < curTotalSupply) throw; // Check for overflow
        updateValueAtNow(totalSupplyHistory, curTotalSupply + _amount);
        var previousBalanceTo = balanceOf(_owner);
        if (previousBalanceTo + _amount < previousBalanceTo) throw; // Check for overflow
        updateValueAtNow(balances[_owner], previousBalanceTo + _amount);
        Transfer(0, _owner, _amount);
        return true;
    }


    /// @notice Burns `_amount` tokens from `_owner`
    /// @param _owner The address that will lose the tokens
    /// @param _amount The quantity of tokens to burn
    /// @return True if the tokens are burned correctly
    function destroyTokens(address _owner, uint _amount
    ) onlyController returns (bool) {
        uint curTotalSupply = getValueAt(totalSupplyHistory, block.number);
        if (curTotalSupply < _amount) throw;
        updateValueAtNow(totalSupplyHistory, curTotalSupply - _amount);
        var previousBalanceFrom = balanceOf(_owner);
        if (previousBalanceFrom < _amount) throw;
        updateValueAtNow(balances[_owner], previousBalanceFrom - _amount);
        Transfer(_owner, 0, _amount);
        return true;
    }

////////////////
// Enable tokens transfers
////////////////


    /// @notice Enables token holders to transfer their tokens freely if true
    /// @param _transfersEnabled True if transfers are allowed in the clone
    function enableTransfers(bool _transfersEnabled) onlyController {
        transfersEnabled = _transfersEnabled;
    }

////////////////
// Internal helper functions to query and set a value in a snapshot array
////////////////

    /// @dev `getValueAt` retrieves the number of tokens at a given block number
    /// @param checkpoints The history of values being queried
    /// @param _block The block number to retrieve the value at
    /// @return The number of tokens being queried
    function getValueAt(Checkpoint[] storage checkpoints, uint _block
    ) constant internal returns (uint) {
        if (checkpoints.length == 0) return 0;

        // Shortcut for the actual value
        if (_block >= checkpoints[checkpoints.length-1].fromBlock)
            return checkpoints[checkpoints.length-1].value;
        if (_block < checkpoints[0].fromBlock) return 0;

        // Binary search of the value in the array
        uint min = 0;
        uint max = checkpoints.length-1;
        while (max > min) {
            uint mid = (max + min + 1)/ 2;
            if (checkpoints[mid].fromBlock<=_block) {
                min = mid;
            } else {
                max = mid-1;
            }
        }
        return checkpoints[min].value;
    }

    /// @dev `updateValueAtNow` used to update the `balances` map and the
    ///  `totalSupplyHistory`
    /// @param checkpoints The history of data being updated
    /// @param _value The new number of tokens
    function updateValueAtNow(Checkpoint[] storage checkpoints, uint _value
    ) internal  {
        if ((checkpoints.length == 0)
        || (checkpoints[checkpoints.length -1].fromBlock < block.number)) {
               Checkpoint newCheckPoint = checkpoints[ checkpoints.length++ ];
               newCheckPoint.fromBlock =  uint128(block.number);
               newCheckPoint.value = uint128(_value);
           } else {
               Checkpoint oldCheckPoint = checkpoints[checkpoints.length-1];
               oldCheckPoint.value = uint128(_value);
           }
    }

    /// @dev Internal function to determine if an address is a contract
    /// @param _addr The address being queried
    /// @return True if `_addr` is a contract
    function isContract(address _addr) constant internal returns(bool) {
        uint size;
        if (_addr == 0) return false;
        assembly {
            size := extcodesize(_addr)
        }
        return size>0;
    }

    /// @dev Helper function to return a min betwen the two uints
    function min(uint a, uint b) internal returns (uint) {
        return a < b ? a : b;
    }

    /// @notice The fallback function: If the contract's controller has not been
    ///  set to 0, then the `proxyPayment` method is called which relays the
    ///  ether and creates tokens as described in the token controller contract
    function ()  payable {
        if (isContract(controller)) {
            if (! TokenController(controller).proxyPayment.value(msg.value)(msg.sender))
                throw;
        } else {
            throw;
        }
    }

//////////
// Safety Methods
//////////

    /// @notice This method can be used by the controller to extract mistakenly
    ///  sent tokens to this contract.
    /// @param _token The address of the token contract that you want to recover
    ///  set to 0 in case you want to extract ether.
    function claimTokens(address _token) public onlyController {
      if (_token == 0x0) {
        controller.transfer(this.balance);
        return;
      }

      ERC20 token = ERC20(_token);
      uint256 balance = token.balanceOf(this);
      token.transfer(controller, balance);
      ClaimedTokens(_token, controller, balance);
    }

////////////////
// Events
////////////////
    event ClaimedTokens(address indexed _token, address indexed _controller, uint256 _amount);
    event Transfer(address indexed _from, address indexed _to, uint256 _amount);
    event NewCloneToken(address indexed _cloneToken, uint _snapshotBlock);
    event Approval(
        address indexed _owner,
        address indexed _spender,
        uint256 _amount
        );

}


////////////////
// MiniMeTokenFactory
////////////////

/// @dev This contract is used to generate clone contracts from a contract.
///  In solidity this is the way to create a contract from a contract of the
///  same class
contract MiniMeTokenFactory {

    /// @notice Update the DApp by creating a new token with new functionalities
    ///  the msg.sender becomes the controller of this clone token
    /// @param _parentToken Address of the token being cloned
    /// @param _snapshotBlock Block of the parent token that will
    ///  determine the initial distribution of the clone token
    /// @param _tokenName Name of the new token
    /// @param _decimalUnits Number of decimals of the new token
    /// @param _tokenSymbol Token Symbol for the new token
    /// @param _transfersEnabled If true, tokens will be able to be transferred
    /// @return The address of the new token contract
    function createCloneToken(
        address _parentToken,
        uint _snapshotBlock,
        string _tokenName,
        uint8 _decimalUnits,
        string _tokenSymbol,
        bool _transfersEnabled
    ) returns (MiniMeToken) {
        MiniMeToken newToken = new MiniMeToken(
            this,
            _parentToken,
            _snapshotBlock,
            _tokenName,
            _decimalUnits,
            _tokenSymbol,
            _transfersEnabled
            );

        newToken.changeController(msg.sender);
        return newToken;
    }
}

/**
 * @title SafeMath
 * @dev Math operations with safety checks that throw on error
 */
library SafeMath {
  function mul(uint256 a, uint256 b) internal returns (uint256) {
    uint256 c = a * b;
    assert(a == 0 || c / a == b);
    return c;
  }

  function div(uint256 a, uint256 b) internal returns (uint256) {
    // assert(b > 0); // Solidity automatically throws when dividing by 0
    uint256 c = a / b;
    // assert(a == b * c + a % b); // There is no case in which this doesn't hold
    return c;
  }

  function sub(uint256 a, uint256 b) internal returns (uint256) {
    assert(b <= a);
    return a - b;
  }

  function add(uint256 a, uint256 b) internal returns (uint256) {
    uint256 c = a + b;
    assert(c >= a);
    return c;
  }
}

contract PreSale is Controlled, TokenController {
  using SafeMath for uint256;

  uint256 constant public exchangeRate = 1; // ETH-WCT exchange rate
  uint256 constant public investor_bonus = 25;

  MiniMeToken public wct;
  address public preSaleWallet;

  uint256 public totalSupplyCap;            // Total WCT supply to be generated
  uint256 public totalSold;                 // How much tokens have been sold

  uint256 public minimum_investment;

  uint256 public startBlock;
  uint256 public endBlock;

  uint256 public initializedBlock;
  uint256 public finalizedBlock;

  bool public paused;
  bool public transferable;

  modifier initialized() {
    assert(initializedBlock != 0);
    _;
  }

  modifier contributionOpen() {
    assert(getBlockNumber() >= startBlock &&
           getBlockNumber() <= endBlock &&
           finalizedBlock == 0);
    _;
  }

  modifier notPaused() {
    require(!paused);
    _;
  }

  function PreSale(address _wct) {
    require(_wct != 0x0);
    wct = MiniMeToken(_wct);
  }

  function initialize(
      address _preSaleWallet,
      uint256 _totalSupplyCap,
      uint256 _minimum_investment,
      uint256 _startBlock,
      uint256 _endBlock
  ) public onlyController {
    // Initialize only once
    require(initializedBlock == 0);

    assert(wct.totalSupply() == 0);
    assert(wct.controller() == address(this));
    assert(wct.decimals() == 18);  // Same amount of decimals as ETH

    require(_preSaleWallet != 0x0);
    preSaleWallet = _preSaleWallet;

    assert(_startBlock >= getBlockNumber());
    require(_startBlock < _endBlock);
    startBlock = _startBlock;
    endBlock = _endBlock;

    require(_totalSupplyCap > 0);
    totalSupplyCap = _totalSupplyCap;

    minimum_investment = _minimum_investment;

    initializedBlock = getBlockNumber();
    Initialized(initializedBlock);
  }

  /// @notice If anybody sends Ether directly to this contract, consider he is
  /// getting WCTs.
  function () public payable notPaused {
    proxyPayment(msg.sender);
  }

  //////////
  // TokenController functions
  //////////

  /// @notice This method will generally be called by the WCT token contract to
  ///  acquire WCTs. Or directly from third parties that want to acquire WCTs in
  ///  behalf of a token holder.
  /// @param _th WCT holder where the WCTs will be minted.
  function proxyPayment(address _th) public payable notPaused initialized contributionOpen returns (bool) {
    require(_th != 0x0);
    doBuy(_th);
    return true;
  }

  function onTransfer(address, address, uint256) public returns (bool) {
    return transferable;
  }

  function onApprove(address, address, uint256) public returns (bool) {
    return transferable;
  }

  function doBuy(address _th) internal {
    require(msg.value >= minimum_investment);

    // Antispam mechanism
    address caller;
    if (msg.sender == address(wct)) {
      caller = _th;
    } else {
      caller = msg.sender;
    }
    assert(!isContract(caller));

    uint256 toFund = msg.value;
    uint256 leftForSale = tokensForSale();
    if (toFund > 0) {
      if (leftForSale > 0) {
        uint256 tokensGenerated = toFund.mul(exchangeRate);

        // Check total supply cap reached, sell the all remaining tokens
        if (tokensGenerated > leftForSale) {
          tokensGenerated = leftForSale;
          toFund = leftForSale.div(exchangeRate);
        }

        assert(wct.generateTokens(_th, tokensGenerated));
        totalSold = totalSold.add(tokensGenerated);

        preSaleWallet.transfer(toFund);
        NewSale(_th, toFund, tokensGenerated);
      } else {
        toFund = 0;
      }
    }

    uint256 toReturn = msg.value.sub(toFund);
    if (toReturn > 0) {
      caller.transfer(toReturn);
    }
  }

  /// @dev Internal function to determine if an address is a contract
  /// @param _addr The address being queried
  /// @return True if `_addr` is a contract
  function isContract(address _addr) constant internal returns (bool) {
    if (_addr == 0) return false;
    uint256 size;
    assembly {
      size := extcodesize(_addr)
    }
    return (size > 0);
  }

  /// @notice This method will can be called by the controller before the contribution period
  ///  end or by anybody after the `endBlock`. This method finalizes the contribution period
  ///  by creating the remaining tokens and transferring the controller to the configured
  ///  controller.
  function finalize() public initialized {
    require(finalizedBlock == 0);
    assert(getBlockNumber() >= startBlock);
    assert(msg.sender == controller || getBlockNumber() > endBlock || tokensForSale() == 0);

    wct.changeController(0x0);
    finalizedBlock = getBlockNumber();

    Finalized(finalizedBlock);
  }

  //////////
  // Constant functions
  //////////

  /// @return Total tokens availale for the sale in weis.
  function tokensForSale() public constant returns(uint256) {
    return totalSupplyCap > totalSold ? totalSupplyCap - totalSold : 0;
  }

  //////////
  // Testing specific methods
  //////////

  /// @notice This function is overridden by the test Mocks.
  function getBlockNumber() internal constant returns (uint256) {
    return block.number;
  }


  //////////
  // Safety Methods
  //////////

  /// @notice This method can be used by the controller to extract mistakenly
  ///  sent tokens to this contract.
  /// @param _token The address of the token contract that you want to recover
  ///  set to 0 in case you want to extract ether.
  function claimTokens(address _token) public onlyController {
    if (wct.controller() == address(this)) {
      wct.claimTokens(_token);
    }

    if (_token == 0x0) {
      controller.transfer(this.balance);
      return;
    }

    ERC20 token = ERC20(_token);
    uint256 balance = token.balanceOf(this);
    token.transfer(controller, balance);
    ClaimedTokens(_token, controller, balance);
  }

  /// @notice Pauses the contribution if there is any issue
  function pauseContribution(bool _paused) onlyController {
    paused = _paused;
  }

  function allowTransfers(bool _transferable) onlyController {
    transferable = _transferable;
  }

  event ClaimedTokens(address indexed _token, address indexed _controller, uint256 _amount);
  event NewSale(address indexed _th, uint256 _amount, uint256 _tokens);
  event Initialized(uint _now);
  event Finalized(uint _now);
}