openzeppelin-contracts/contracts/payment/RefundEscrow.sol

pragma solidity ^0.4.24;

import "./ConditionalEscrow.sol";
import "../ownership/Ownable.sol";


/**
 * @title RefundEscrow
 * @dev Escrow that holds funds for a beneficiary, deposited from multiple parties.
 * The contract owner may close the deposit period, and allow for either withdrawal
 * by the beneficiary, or refunds to the depositors.
 */
contract RefundEscrow is Ownable, ConditionalEscrow {
  enum State { Active, Refunding, Closed }

  event Closed();
  event RefundsEnabled();

  State private state_;
  address private beneficiary_;

  /**
   * @dev Constructor.
   * @param _beneficiary The beneficiary of the deposits.
   */
  constructor(address _beneficiary) public {
    require(_beneficiary != address(0));
    beneficiary_ = _beneficiary;
    state_ = State.Active;
  }

  /**
   * @return the current state of the escrow.
   */
  function state() public view returns(State) {
    return state_;
  }

  /**
   * @return the beneficiary of the escrow.
   */
  function beneficiary() public view returns(address) {
    return beneficiary_;
  }

  /**
   * @dev Stores funds that may later be refunded.
   * @param _refundee The address funds will be sent to if a refund occurs.
   */
  function deposit(address _refundee) public payable {
    require(state_ == State.Active);
    super.deposit(_refundee);
  }

  /**
   * @dev Allows for the beneficiary to withdraw their funds, rejecting
   * further deposits.
   */
  function close() public onlyOwner {
    require(state_ == State.Active);
    state_ = State.Closed;
    emit Closed();
  }

  /**
   * @dev Allows for refunds to take place, rejecting further deposits.
   */
  function enableRefunds() public onlyOwner {
    require(state_ == State.Active);
    state_ = State.Refunding;
    emit RefundsEnabled();
  }

  /**
   * @dev Withdraws the beneficiary's funds.
   */
  function beneficiaryWithdraw() public {
    require(state_ == State.Closed);
    beneficiary_.transfer(address(this).balance);
  }

  /**
   * @dev Returns whether refundees can withdraw their deposits (be refunded).
   */
  function withdrawalAllowed(address _payee) public view returns (bool) {
    return state_ == State.Refunding;
  }
}