GameMinter.sol

// SPDX-License-Identifier: MIT
pragma solidity ^0.8.10;

import 'base64/base64.sol';
import '../ConnectFour.sol';
import 'solmate/tokens/ERC721.sol';
import 'StringUtils/StringUtils.sol';

/// @title Connect 4 Game Minter
/// @author Miguel Piedrafita
/// @notice A contract that mints winning connect 4 games, and generates SVGs representing the board
contract GameMinter is ERC721('Connect 4', 'CONN4'), StringUtils {
	/// ERRORS ///

	/// @notice Thrown when the game cannot be minted, which can happen if the game doesn't exist, is still in progress, or you didn't win.
	error CannotMintGame();

	/// @notice The address of the Connect 4 contract
	ConnectFour public immutable connect4;

	/// @notice Deploys a GameMinter instance, pointing to the specified Connect 4 address
	/// @param _connect4 The address of the Connect 4 contract you want to integrate with.
	constructor(ConnectFour _connect4) {
		connect4 = _connect4;
	}

	/// @notice Mints a new Connect4 NFT, based on a game you won
	/// @param gameId The ID of the game you're trying to mint, which will also be your tokenId
	function mint(uint256 gameId) public payable {
		(address player1, address player2, , bool finished) = connect4.getGame(gameId);
		bool didPlayer1Win = connect4.didPlayerWin(gameId, 0);
		if (!finished || msg.sender != (didPlayer1Win ? player1 : player2)) revert CannotMintGame();

		_mint(msg.sender, gameId);
	}

	/// @dev Generates an SVG representing the Connect 4 board, for internal use
	/// @param id The ID of the game you're trying to represent
	function drawBoard(uint256 id) internal view returns (string memory) {
		(uint64 player1Board, uint64 player2Board) = connect4.getBoards(id);

		string[] memory rows = new string[](7);
		for (uint256 rowNum = 0; rowNum < 7; rowNum++) {
			string[] memory columns = new string[](6);
			for (uint256 colNum = 0; colNum < 6; colNum++) {
				uint256 bbPos = 7 * rowNum + colNum;

				if ((player1Board >> bbPos) % 2 == 0 && (player2Board >> bbPos) % 2 == 0) continue;

				columns[colNum] = string(
					abi.encodePacked(
						'<circle cx="50" cy="',
						toString((5 - colNum) * 100 + 50),
						'" r="45" fill="',
						(player1Board >> bbPos) % 2 == 0 ? '#22d3ee' : '#f472b6',
						'"></circle>'
					)
				);
			}

			rows[rowNum] = string(
				abi.encodePacked(
					'<svg x="',
					toString(rowNum * 100),
					'" y="0">',
					columns[0],
					columns[1],
					columns[2],
					columns[3],
					columns[4],
					columns[5],
					'<rect width="100" height="600" fill="#7c3aed" mask="url(#cell-mask)"></rect></svg>'
				)
			);
		}

		string memory encoded = string(
			abi.encodePacked(
				'<svg xmlns="http://www.w3.org/2000/svg" viewBox="0 0 700 600" stroke="none" width="350px"><defs>'
				'<pattern id="cell-pattern" patternUnits="userSpaceOnUse" width="100" height="100"><circle cx="50" cy="50" r="45" fill="black"></circle></pattern>',
				'<mask id="cell-mask"><rect width="100" height="600" fill="white"></rect><rect width="100" height="600" fill="url(#cell-pattern)"></rect></mask></defs>',
				rows[0],
				rows[1],
				rows[2]
			)
		);

		encoded = Base64.encode(abi.encodePacked(encoded, rows[3], rows[4], rows[5], rows[6], '</svg>'));

		return string(abi.encodePacked('data:image/svg+xml;base64,', encoded));
	}

	/// @notice Returns on-chain metadata for this NFT, including a generated board SVG
	/// @param id The ID of the token you're trying to look up, which should match the ID of the game you won
	function tokenURI(uint256 id) public view override returns (string memory) {
		(address player1, address player2, , ) = connect4.getGame(id);
		address winner = connect4.didPlayerWin(id, 0) ? player1 : player2;

		bytes memory json = abi.encodePacked(
			'{"name": "Connect Four #',
			toString(id),
			unicode'", "description": "This NFT represents a game of Connect4 played on the blockchain, and won by ',
			winner,
			'.", "image": "',
			drawBoard(id),
			'"}'
		);

		return string(abi.encodePacked('data:application/json;base64,', Base64.encode(json)));
	}
}