using Game.TicTacToe;
using OECS;
using System.Text;

namespace Game.TicTacToe.Tests;

internal static class TestHelpers
{
    /// <summary>
    /// Creates a fresh TicTacToe world with 9 empty cells, GameState singleton, and WinCheckSystem.
    /// </summary>
    public static (World World, SystemGroup Group) SetupGame()
    {
        var world = new World();
        var group = new SystemGroup(world);
        group.Add(new WinCheckSystem());

        for (int r = 0; r < 3; r++)
            for (int c = 0; c < 3; c++)
                world.AddComponent(world.CreateEntity(), new Cell { Row = r, Col = c });

        world.SetSingleton(new GameState
        {
            CurrentPlayer = Player.X,
            Status = GameStatus.Playing,
            MoveCount = 0
        });
        world.PostChanges();

        return (world, group);
    }

    /// <summary>
    /// Enqueues and runs a sequence of moves.
    /// </summary>
    public static void PlayMoves(World world, SystemGroup group, params (int Row, int Col)[] moves)
    {
        foreach (var (row, col) in moves)
        {
            world.Commands.Enqueue(new PlaceMarkCommand { Row = row, Col = col });
            group.RunLogical();
        }
    }

    /// <summary>
    /// Returns a human-readable textual snapshot of the world state.
    /// </summary>
    public static string SnapshotWorld(World world)
    {
        var sb = new StringBuilder();
        var state = world.ReadSingleton<GameState>();
        var statusText = state.Status switch
        {
            GameStatus.Playing => $"{(state.CurrentPlayer == Player.X ? 'X' : 'O')}'s turn, {state.MoveCount} moves",
            GameStatus.XWon => "XWon",
            GameStatus.OWon => "OWon",
            GameStatus.Draw => "Draw",
            _ => "Unknown"
        };
        sb.AppendLine($"GameState: {statusText}");

        var grid = new char?[3, 3];
        foreach (var it in world.Select<Cell, Mark>())
            grid[it.Val1.Row, it.Val1.Col] =
                it.Val2.Player == Player.X ? 'X' : 'O';

        int totalCells = 0;
        int markedCells = 0;
        for (int r = 0; r < 3; r++)
        {
            for (int c = 0; c < 3; c++)
            {
                totalCells++;
                var mark = grid[r, c];
                if (mark.HasValue)
                {
                    markedCells++;
                    sb.AppendLine($"  ({r},{c}): {mark.Value}");
                }
                else
                {
                    sb.AppendLine($"  ({r},{c}): .");
                }
            }
        }

        sb.AppendLine($"Cells: {totalCells} total, {markedCells} marked");

        return sb.ToString().TrimEnd();
    }

    /// <summary>
    /// Returns the (Row, Col) of all empty cells.
    /// </summary>
    public static List<(int Row, int Col)> GetEmptyCells(World world)
    {
        var empty = new List<(int, int)>();
        foreach (var it in world.Select(new Query<Cell>().Without<Mark>()))
            empty.Add((it.Val1.Row, it.Val1.Col));
        return empty;
    }

    /// <summary>
    /// Checks whether placing a mark at (row, col) for the given player would win the game.
    /// </summary>
    public static bool WouldWin(World world, int row, int col, Player player)
    {
        var grid = new Player[3, 3];
        foreach (var it in world.Select<Cell, Mark>())
            grid[it.Val1.Row, it.Val1.Col] = it.Val2.Player;
        grid[row, col] = player;

        for (int r = 0; r < 3; r++)
            if (grid[r, 0] == player && grid[r, 1] == player && grid[r, 2] == player)
                return true;
        for (int c = 0; c < 3; c++)
            if (grid[0, c] == player && grid[1, c] == player && grid[2, c] == player)
                return true;
        if (grid[0, 0] == player && grid[1, 1] == player && grid[2, 2] == player)
            return true;
        if (grid[0, 2] == player && grid[1, 1] == player && grid[2, 0] == player)
            return true;

        return false;
    }
}