Escrow Smart Contract Example

Escrow.sol.js

pragma solidity 0.5.2;

contract Escrow {
    
    //state variables
    address payable buyer;
    address payable seller;
    address arbiter;
    uint public amountInWei;
    
    
    //solidity events
    event FundingReceived(uint _timestamp);
    event SellerPaid(uint _timestamp);
    event BuyerRefunded(uint _timestamp);
    
    
    //constructor function; used to set initial state of contract
    constructor(address payable _buyer, address _arbiter, uint _amountInWei) public {
        seller = msg.sender;
        buyer = _buyer;
        arbiter = _arbiter;
        amountInWei = _amountInWei;
    }
    
    //function for buyer to fund; payable keyword must be used
    function fund() public payable {
        require(msg.sender == buyer &&  //conditional checks to make sure only the buyer's address
                msg.value == amountInWei//can send the correcr amount to the contract
                );
        emit FundingReceived(now); //emit FundingReceived() event
    }
    
    //function for buyer to payout seller
    function payoutToSeller() public {
        require(msg.sender == buyer || msg.sender == arbiter); //only buyer or arbiter can execute this function
        seller.transfer(address(this).balance); //using the solidity's built in transfer function, the funds are sent to the seller
        emit SellerPaid(now); //emit SellerPaid() event
    }
    
    //function for seller to refund the buyer
    function refundBuyer() public {
        require(msg.sender == seller || msg.sender == arbiter);//only buyer or arbiter can execute this function
        buyer.transfer(address(this).balance); //using the solidity's built in transfer function, the funds are returned to the buyer
        emit BuyerRefunded(now);//emit BuyerRefunded() event
    }
}