using System.Globalization;
using Minesweeper.Core;

namespace Minesweeper.Cli;

/// <summary>Turns typed text and raw keystrokes into <see cref="Command"/> instances. This is the
/// only place that translates the one-based coordinates a player sees into engine coordinates.</summary>
public static class CommandParser
{
    /// <summary>Parses a typed line. Coordinates are one-based, e.g. <c>reveal 3 4</c>.</summary>
    public static Command Parse(string input)
    {
        var text = input.Trim();
        if (text.Length == 0)
        {
            return new Command.Noop();
        }

        var parts = text.Split([' ', ',', ';', '\t'], StringSplitOptions.RemoveEmptyEntries);
        var verb = parts[0].ToLowerInvariant();

        switch (verb)
        {
            case "q" or "quit" or "exit":
                return new Command.Quit();
            case "n" or "new":
                return new Command.NewGame();
            case "h" or "help" or "?":
                return new Command.ShowHelp();
            case "d" or "difficulty":
                return ParseDifficulty(parts, text);
            case "r" or "reveal" or "open":
                return ParseCell(parts, 1, cell => new Command.Reveal(cell), text);
            case "f" or "flag" or "mark":
                return ParseCell(parts, 1, cell => new Command.Flag(cell), text);
            case "c" or "chord":
                return ParseCell(parts, 1, cell => new Command.Chord(cell), text);
            case "go" or "goto":
                return ParseCell(parts, 1, cell => new Command.SetCursor(cell), text);
        }

        // A bare "3 4" reveals that cell, since revealing is by far the most common action.
        return ParseCell(parts, 0, cell => new Command.Reveal(cell), text);
    }

    /// <summary>Maps a keystroke from keyboard-driven mode onto a command.</summary>
    public static Command FromKey(ConsoleKeyInfo key) => key.Key switch
    {
        ConsoleKey.UpArrow => new Command.MoveCursor(-1, 0),
        ConsoleKey.DownArrow => new Command.MoveCursor(1, 0),
        ConsoleKey.LeftArrow => new Command.MoveCursor(0, -1),
        ConsoleKey.RightArrow => new Command.MoveCursor(0, 1),
        ConsoleKey.Enter or ConsoleKey.Spacebar => new Command.RevealAtCursor(),
        ConsoleKey.F => new Command.FlagAtCursor(),
        ConsoleKey.C => new Command.ChordAtCursor(),
        ConsoleKey.N => new Command.NewGame(),
        ConsoleKey.H => new Command.ShowHelp(),
        ConsoleKey.D1 => new Command.ChangeDifficulty(GameDifficulty.Beginner),
        ConsoleKey.D2 => new Command.ChangeDifficulty(GameDifficulty.Intermediate),
        ConsoleKey.D3 => new Command.ChangeDifficulty(GameDifficulty.Expert),
        ConsoleKey.Escape or ConsoleKey.Q => new Command.Quit(),
        _ => new Command.Noop(),
    };

    private static Command ParseDifficulty(string[] parts, string text)
    {
        if (parts.Length < 2)
        {
            return new Command.ShowHelp();
        }

        return parts[1].ToLowerInvariant() switch
        {
            "1" or "b" or "beginner" or "easy" => new Command.ChangeDifficulty(GameDifficulty.Beginner),
            "2" or "i" or "intermediate" or "medium" => new Command.ChangeDifficulty(GameDifficulty.Intermediate),
            "3" or "e" or "expert" or "hard" => new Command.ChangeDifficulty(GameDifficulty.Expert),
            _ => new Command.Unknown(text),
        };
    }

    private static Command ParseCell(string[] parts, int offset, Func<CellLocation, Command> factory, string text)
    {
        if (parts.Length - offset < 2 ||
            !TryParseCoordinate(parts[offset], out var row) ||
            !TryParseCoordinate(parts[offset + 1], out var column))
        {
            return new Command.Unknown(text);
        }

        return factory(new CellLocation(row - 1, column - 1));
    }

    private static bool TryParseCoordinate(string token, out int value) =>
        int.TryParse(token, NumberStyles.None, CultureInfo.InvariantCulture, out value) && value > 0;
}