Building a Coin Flip Game on Ethereum (Part 2) - Deploying the Contract

// SPDX-License-Identifier: MIT
pragma solidity ^0.8.20;

import "@openzeppelin/contracts/utils/Strings.sol";

contract CoinFlip {
    uint256 public totalMatches;
    uint256 public lifetimeValue;
    uint256 public minimumAmount = 0.001 ether;

    // Make all public matches accessible based on a match ID
    mapping(uint256 => Match) public matches;

    struct Match {
        address player1;
        address player2;
        uint256 bet1;
        uint256 bet2;
        bool complete;
        uint256 result;
    }

    function createMatch() public payable returns (uint256) {
        // Require that the player has sent some ether
        require(msg.value > minimumAmount, "You must send some ether to create a match");
        // Set match details for player1
        matches[totalMatches].player1 = msg.sender;
        matches[totalMatches].bet1 = msg.value;

        // Increment counters
        totalMatches++;
        lifetimeValue += msg.value;
        // Return the match ID
        return totalMatches - 1;
    }

    function joinMatch(uint matchId) public payable returns (string memory) {
        // Require that the match ID is valid
        require(matchId < totalMatches, "Invalid match ID");
        // Require that the match is not already complete
        require(matches[matchId].complete == false, "This match is already complete");
        // Require that the player has sent an amount of ether equal to the bet1 value
        require(msg.value == matches[matchId].bet1, "You must send the same amount of ether as the bet1 value");

        // Set match details for player2
        matches[matchId].player2 = msg.sender;
        matches[matchId].bet2 = msg.value;

        // Increment lifetimeValue counter
        lifetimeValue += msg.value;
        // Flip the coin and determine the winner
        return flipCoin(matchId);
    }

    function flipCoin(uint matchId) private returns (string memory) {
        // Require that the match ID is valid
        require(matchId < totalMatches, "Invalid match ID");

        // Generate a random number between 0 and 1
        uint randomNumber = uint(block.timestamp) % 2;

        // Determine the winner based on the random number
        if (randomNumber == 0) {
            // Player1 wins
            // Transfer the ether to player1
            payable(matches[matchId].player1).transfer(matches[matchId].bet1 + matches[matchId].bet2);
            matches[matchId].complete = true;
            matches[matchId].result = 1;
            return "The coin came up heads. Player 1 wins";
        } else {
            // Player2 wins
            // Transfer the ether to player2
            payable(matches
[matchId].player2).transfer(matches[matchId].bet1 + matches[matchId].bet2);
            matches[matchId].complete = true;
            matches[matchId].result = 2;
            return "The coin came up tails. Player 2 wins";
        }
    }
}