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125 lines
3.5 KiB
125 lines
3.5 KiB
/* solium-disable security/no-block-members */
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pragma solidity ^0.4.24;
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import "../token/ERC20/SafeERC20.sol";
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import "../ownership/Ownable.sol";
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import "../math/SafeMath.sol";
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/**
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* @title TokenVesting
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* @dev A token holder contract that can release its token balance gradually like a
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* typical vesting scheme, with a cliff and vesting period. Optionally revocable by the
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* owner.
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*/
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contract TokenVesting is Ownable {
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using SafeMath for uint256;
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using SafeERC20 for IERC20;
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event Released(uint256 amount);
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event Revoked();
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// beneficiary of tokens after they are released
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address public beneficiary;
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uint256 public cliff;
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uint256 public start;
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uint256 public duration;
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bool public revocable;
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mapping (address => uint256) public released;
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mapping (address => bool) public revoked;
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/**
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* @dev Creates a vesting contract that vests its balance of any ERC20 token to the
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* _beneficiary, gradually in a linear fashion until _start + _duration. By then all
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* of the balance will have vested.
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* @param _beneficiary address of the beneficiary to whom vested tokens are transferred
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* @param _cliff duration in seconds of the cliff in which tokens will begin to vest
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* @param _start the time (as Unix time) at which point vesting starts
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* @param _duration duration in seconds of the period in which the tokens will vest
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* @param _revocable whether the vesting is revocable or not
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*/
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constructor(
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address _beneficiary,
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uint256 _start,
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uint256 _cliff,
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uint256 _duration,
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bool _revocable
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)
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public
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{
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require(_beneficiary != address(0));
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require(_cliff <= _duration);
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beneficiary = _beneficiary;
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revocable = _revocable;
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duration = _duration;
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cliff = _start.add(_cliff);
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start = _start;
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}
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/**
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* @notice Transfers vested tokens to beneficiary.
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* @param _token ERC20 token which is being vested
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*/
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function release(IERC20 _token) public {
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uint256 unreleased = releasableAmount(_token);
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require(unreleased > 0);
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released[_token] = released[_token].add(unreleased);
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_token.safeTransfer(beneficiary, unreleased);
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emit Released(unreleased);
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}
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/**
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* @notice Allows the owner to revoke the vesting. Tokens already vested
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* remain in the contract, the rest are returned to the owner.
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* @param _token ERC20 token which is being vested
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*/
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function revoke(IERC20 _token) public onlyOwner {
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require(revocable);
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require(!revoked[_token]);
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uint256 balance = _token.balanceOf(address(this));
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uint256 unreleased = releasableAmount(_token);
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uint256 refund = balance.sub(unreleased);
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revoked[_token] = true;
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_token.safeTransfer(owner, refund);
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emit Revoked();
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}
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/**
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* @dev Calculates the amount that has already vested but hasn't been released yet.
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* @param _token ERC20 token which is being vested
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*/
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function releasableAmount(IERC20 _token) public view returns (uint256) {
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return vestedAmount(_token).sub(released[_token]);
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}
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/**
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* @dev Calculates the amount that has already vested.
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* @param _token ERC20 token which is being vested
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*/
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function vestedAmount(IERC20 _token) public view returns (uint256) {
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uint256 currentBalance = _token.balanceOf(this);
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uint256 totalBalance = currentBalance.add(released[_token]);
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if (block.timestamp < cliff) {
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return 0;
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} else if (block.timestamp >= start.add(duration) || revoked[_token]) {
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return totalBalance;
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} else {
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return totalBalance.mul(block.timestamp.sub(start)).div(duration);
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}
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}
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}
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