pragma solidity ^0.4.11; import '../token/MintableToken.sol'; import '../math/SafeMath.sol'; /** * @title Crowdsale * @dev Crowdsale is a base contract for managing a token crowdsale. * Crowdsales have a start and end block, where investors can make * token purchases and the crowdsale will assign them tokens based * on a token per ETH rate. Funds collected are forwarded to a wallet * as they arrive. */ contract Crowdsale { using SafeMath for uint256; // The token being sold MintableToken public token; // start and end block where investments are allowed (both inclusive) uint256 public startBlock; uint256 public endBlock; // address where funds are collected address public wallet; // how many token units a buyer gets per wei uint256 public rate; // amount of raised money in wei uint256 public weiRaised; /** * event for token purchase logging * @param purchaser who paid for the tokens * @param beneficiary who got the tokens * @param value weis paid for purchase * @param amount amount of tokens purchased */ event TokenPurchase(address indexed purchaser, address indexed beneficiary, uint256 value, uint256 amount); constructor(uint256 _startBlock, uint256 _endBlock, uint256 _rate, address _wallet) { require(_startBlock >= block.number); require(_endBlock >= _startBlock); require(_rate > 0); require(_wallet != address(0x0)); token = createTokenContract(); startBlock = _startBlock; endBlock = _endBlock; rate = _rate; wallet = _wallet; } // creates the token to be sold. // override this method to have crowdsale of a specific mintable token. function createTokenContract() internal returns (MintableToken) { return new MintableToken(); } // fallback function can be used to buy tokens function () external payable { buyTokens(msg.sender); } // low level token purchase function function buyTokens(address beneficiary) payable { require(beneficiary != address(0x0)); require(validPurchase()); uint256 weiAmount = msg.value; uint256 updatedWeiRaised = weiRaised.add(weiAmount); // calculate token amount to be created uint256 tokens = weiAmount.mul(rate); // update state weiRaised = updatedWeiRaised; token.mint(beneficiary, tokens); emit TokenPurchase(msg.sender, beneficiary, weiAmount, tokens); forwardFunds(); } // send ether to the fund collection wallet // override to create custom fund forwarding mechanisms function forwardFunds() internal { wallet.transfer(msg.value); } // @return true if the transaction can buy tokens function validPurchase() internal view returns (bool) { uint256 current = block.number; bool withinPeriod = current >= startBlock && current <= endBlock; bool nonZeroPurchase = msg.value != 0; return withinPeriod && nonZeroPurchase; } // @return true if crowdsale event has ended function hasEnded() public view returns (bool) { return block.number > endBlock; } }