pragma solidity ^0.5.6;

contract RPS {
    address payable p1;
    address payable p2;
    uint stake;
    bytes32 p1Commitment;
    bytes32 p2Commitment;
    uint timeSinceP1;
    uint timeSinceP2;


    // 1. function RPS() public payable
    // Constructor that sets creator as player 1.
    constructor() public payable {
        p1 = msg.sender;
    }
    modifier onlyP1() {
        require(msg.sender == p1);
        _;
    }
    modifier onlyP2() {
        require(msg.sender == p2);
        _;
    }
    modifier notP1() {
        require(msg.sender != p1);
        _;
    }
    modifier notTwoPlayers() {
        require(!(p1 != address(0) && p2 != address(0)));
        _;
    }
    function p1_commit(bytes32 _commitment) public onlyP1 payable {
        // _commitment is the output of a keccak256 hash of "Rock", "Paper", or "Scissors" and a salt value
        // only callable by player 1
        // the amount of ethereum sent by player 1 defines the stake of the game
        // amount must be strictly greater than 0
        require(msg.value > 0 ether);
        stake = msg.value;
        p1Commitment = _commitment;
        timeSinceP1 = block.timestamp;
    }
    function p2_join(string calldata _play) external notP1 notTwoPlayers payable {
        // if two players: do nothing
        // else _play is either rock paper scissors
        if ((keccak256(abi.encodePacked(_play)) == keccak256(abi.encodePacked("Rock")) ||
            keccak256(abi.encodePacked(_play)) == keccak256(abi.encodePacked("Paper")) ||
            keccak256(abi.encodePacked(_play)) == keccak256(abi.encodePacked("Scissors"))) &&
            msg.value >= stake) {
            p2 = msg.sender;
            p2Commitment = keccak256(abi.encodePacked(_play));
            timeSinceP2 = block.timestamp;
        }
        // must be at least enough ethereum as the stake of the game
        // whoever sends the message is player 2 if all these are True

    }
    function p1_reveal(string calldata _play, string calldata _salt) onlyP1 external {
        // _play must be "Rock" "Paper" or "Scissors"
        if (keccak256(abi.encodePacked(_play)) == keccak256(abi.encodePacked("Rock")) ||
            keccak256(abi.encodePacked(_play)) == keccak256(abi.encodePacked("Paper")) ||
            keccak256(abi.encodePacked(_play)) == keccak256(abi.encodePacked("Scissors"))) {
            // keccak256(_play, _salt) should be equal to the commitment provident when the contract was created
            // called by player 1 only
            require(p1Commitment == keccak256(abi.encodePacked(_play, _salt)));
            // if no other player has joined, cancel the contract, refunding the stored ether to player 1
            if (p2 == address(0)) {
                selfdestruct(p1);
            }
            // if the game is a tie, erase both players' moves (but not player identities!)
            if (keccak256(abi.encodePacked(_play)) == keccak256(abi.encodePacked(p2Commitment))) {
                p1Commitment = bytes32(0);
                p2Commitment = bytes32(0);
            }
            else {
                // if not a tie, kill the contract and give the balance to player that won
                if (keccak256(abi.encodePacked(_play)) == keccak256(abi.encodePacked("Paper")) && p2Commitment == keccak256(abi.encodePacked("Rock")) ||
                    keccak256(abi.encodePacked(_play)) == keccak256(abi.encodePacked("Rock")) && p2Commitment == keccak256(abi.encodePacked("Scissors")) ||
                    keccak256(abi.encodePacked(_play)) == keccak256(abi.encodePacked("Scissors")) && p2Commitment == keccak256(abi.encodePacked("Paper"))) {
                    selfdestruct(p1);
                }
                else {
                    selfdestruct(p2);
                }
            }
            // if player 2 has not made a move in 30 seconds, cancel the contract,
            //  giving all stored ether to player 1
            if (block.timestamp - timeSinceP1 >= 30) {
                selfdestruct(p2);
            }
        }
    }
    function p2_payout() external {
        // if it's been at least 30 seconds since player 1 has made a move, kill the contract,
        // and send the balance to player 2
        if (block.timestamp - timeSinceP1 >= 30) {
            selfdestruct(p2);
        }
    }
    function p1_replay(bytes32 _commitment) onlyP1 external {
        // player 1 only
        // only if player 1 has no valid play stored (because a tie was declared)
        // sets player 1's commitment to _commitment
        if (p1Commitment == bytes32(0)) {
            p1Commitment = _commitment;
        }
    }
    function p2_replay(string calldata _play) onlyP2 external {
        // player 2 only
        // only if player 2 has no valid play stored (because a tie was declared)
        // stores play as player 2's play (should be "Rock", "Paper", or "Scissors")
        if (p2Commitment == bytes32(0)) {
            p2Commitment = keccak256(abi.encodePacked(_play));
        }
    }
}