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110 lines
3.1 KiB
110 lines
3.1 KiB
pragma solidity ^0.4.18;
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import "../token/MintableToken.sol";
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import "../math/SafeMath.sol";
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/**
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* @title Crowdsale
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* @dev Crowdsale is a base contract for managing a token crowdsale.
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* Crowdsales have a start and end timestamps, where investors can make
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* token purchases and the crowdsale will assign them tokens based
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* on a token per ETH rate. Funds collected are forwarded to a wallet
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* as they arrive.
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*/
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contract Crowdsale {
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using SafeMath for uint256;
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// The token being sold
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MintableToken public token;
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// start and end timestamps where investments are allowed (both inclusive)
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uint256 public startTime;
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uint256 public endTime;
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// address where funds are collected
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address public wallet;
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// how many token units a buyer gets per wei
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uint256 public rate;
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// amount of raised money in wei
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uint256 public weiRaised;
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/**
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* event for token purchase logging
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* @param purchaser who paid for the tokens
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* @param beneficiary who got the tokens
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* @param value weis paid for purchase
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* @param amount amount of tokens purchased
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*/
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event TokenPurchase(address indexed purchaser, address indexed beneficiary, uint256 value, uint256 amount);
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function Crowdsale(uint256 _startTime, uint256 _endTime, uint256 _rate, address _wallet) public {
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require(_startTime >= now);
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require(_endTime >= _startTime);
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require(_rate > 0);
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require(_wallet != address(0));
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token = createTokenContract();
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startTime = _startTime;
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endTime = _endTime;
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rate = _rate;
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wallet = _wallet;
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}
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// fallback function can be used to buy tokens
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function () external payable {
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buyTokens(msg.sender);
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}
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// low level token purchase function
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function buyTokens(address beneficiary) public payable {
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require(beneficiary != address(0));
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require(validPurchase());
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uint256 weiAmount = msg.value;
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// calculate token amount to be created
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uint256 tokens = getTokenAmount(weiAmount);
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// update state
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weiRaised = weiRaised.add(weiAmount);
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token.mint(beneficiary, tokens);
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TokenPurchase(msg.sender, beneficiary, weiAmount, tokens);
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forwardFunds();
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}
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// @return true if crowdsale event has ended
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function hasEnded() public view returns (bool) {
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return now > endTime;
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}
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// creates the token to be sold.
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// override this method to have crowdsale of a specific mintable token.
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function createTokenContract() internal returns (MintableToken) {
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return new MintableToken();
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}
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// Override this method to have a way to add business logic to your crowdsale when buying
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function getTokenAmount(uint256 weiAmount) internal view returns(uint256) {
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return weiAmount.mul(rate);
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}
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// send ether to the fund collection wallet
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// override to create custom fund forwarding mechanisms
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function forwardFunds() internal {
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wallet.transfer(msg.value);
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}
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// @return true if the transaction can buy tokens
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function validPurchase() internal view returns (bool) {
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bool withinPeriod = now >= startTime && now <= endTime;
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bool nonZeroPurchase = msg.value != 0;
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return withinPeriod && nonZeroPurchase;
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}
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}
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