commit.sol

pragma solidity >=0.8.0 <0.9.0;
/**
 * @notice Function for players to commit their choice
 * @dev players can commit multiple times to change their choice until the other player commits
 * @param choice - "rock", "paper" or "scissors"
 * @param salt - a player chosen secret string used to "salt" the commit hash
 */
function commit(string memory choice, string memory salt)
    public
    validGameState(activeGame[msg.sender], GameState.CommitPhase)
{
    // Get the game hash from active game mapping
    address gameHash = activeGame[msg.sender];

    bytes32 unsaltedChoiceHash = keccak256(abi.encodePacked(choice));

    // Check choice is valid i.e. "rock", "paper", "scissors"
    require(
        unsaltedChoiceHash == rockHash ||
            unsaltedChoiceHash == paperHash ||
            unsaltedChoiceHash == scissorsHash,
        "Invalid choice. Please select 'rock', 'paper' or 'scissors'"
    );

    // Generate commit hash with choice + user chosen salt
    bytes32 commitHash = keccak256(abi.encodePacked(choice, salt));

    bool isPlayer1 = games[gameHash].player1 == msg.sender;
    if (isPlayer1) {
        games[gameHash].commit1 = commitHash;
    } else {
        games[gameHash].commit2 = commitHash;
    }

    // If both player have committed, set game state to reveal phase
    if (games[gameHash].commit1 != 0 && games[gameHash].commit2 != 0) {
        games[gameHash].gameState = GameState.RevealPhase;
    }
}