oecs-sharp/examples/TicTacToe/Systems/RenderSystem.cs

using OECS;

namespace TicTacToe;

/// <summary>
/// Prints the board to the console.
/// </summary>
public class RenderSystem : ISystem
{
    public QueryDescriptor Query { get; }

    public RenderSystem(World world)
    {
        Query = world.Query().With<Cell>().Build();
    }

    public void Run(World world)
    {
        var state = world.ReadSingleton<GameState>();

        // Build a 3×3 grid.
        var grid = new char[3, 3];
        for (int r = 0; r < 3; r++)
            for (int c = 0; c < 3; c++)
                grid[r, c] = '.';

        // Fill in placed marks using the iterator API.
        var markQuery = world.Query().With<Cell>().With<Mark>().Build();
        using var markIter = world.Select<Cell, Mark>(markQuery);
        while (markIter.MoveNext())
        {
            grid[markIter.Current1.Row, markIter.Current1.Col] =
                markIter.Current2.Player == Player.X ? 'X' : 'O';
        }

        Console.WriteLine();
        Console.WriteLine("  Tic-Tac-Toe");
        Console.WriteLine("  ═══════════");
        Console.WriteLine();
        Console.WriteLine("    0   1   2");
        Console.WriteLine("  ┌───┬───┬───┐");
        for (int r = 0; r < 3; r++)
        {
            Console.Write($"{r} │");
            for (int c = 0; c < 3; c++)
            {
                Console.Write($" {grid[r, c]} ");
                if (c < 2) Console.Write("│");
            }
            Console.WriteLine("│");
            if (r < 2) Console.WriteLine("  ├───┼───┼───┤");
        }
        Console.WriteLine("  └───┴───┴───┘");
        Console.WriteLine();

        // Status line.
        var statusText = state.Status switch
        {
            GameStatus.Playing => $"{(state.CurrentPlayer == Player.X ? 'X' : 'O')}'s turn (move {state.MoveCount + 1})",
            GameStatus.XWon => "X wins!",
            GameStatus.OWon => "O wins!",
            GameStatus.Draw => "It's a draw!",
            _ => ""
        };
        Console.WriteLine($"  {statusText}");
        Console.WriteLine();
        Console.Write("  Enter row col (e.g. \"1 2\"): ");
    }
}