using System.Drawing;
using System.Text;
using Pastel;

namespace Yuanshen.Common.Console;

public static class ConsolePrompt
{
    private const string ClearLine = "\u001b[2K";
    private const int PromptWidth = 60;

    private static readonly object SyncRoot = new();
    private static readonly StringBuilder Buffer = new();

    private static string _label = ">";
    private static bool _active;
    private static Func<string, ValueTask>? _handler;

    public static void Start(string label, Func<string, ValueTask> handler)
    {
        ConsoleTheme.Enable();
        _label = label;
        _handler = handler;
        _active = true;

        lock (SyncRoot)
            Draw();

        Thread thread = new(ReadLoop) { IsBackground = true, Name = "console-prompt" };
        thread.Start();
    }

    public static void Write(string line)
    {
        lock (SyncRoot)
        {
            if (_active)
                System.Console.Write("\r" + ClearLine);

            foreach (string part in line.Split('\n'))
                System.Console.WriteLine(ConsoleTheme.Center(part.TrimEnd('\r')));

            if (_active)
                Draw();
        }
    }

    public static void Reply(string line) => Write(line.Pastel(ConsoleTheme.Text));

    public static void Warn(string line) => Write(line.Pastel(Color.FromArgb(0xFF, 0xB3, 0x4D)));

    private static void Draw()
    {
        int pad = Math.Max((ConsoleTheme.Width - PromptWidth) / 2, 0);

        System.Console.Write("\r" + ClearLine);
        System.Console.Write(new string(' ', pad));
        System.Console.Write(_label.Pastel(ConsoleTheme.Accent));
        System.Console.Write(' ');
        System.Console.Write(Buffer.ToString().Pastel(ConsoleTheme.Text));
    }

    private static void ReadLoop()
    {
        while (_active)
        {
            ConsoleKeyInfo key;

            try
            {
                key = System.Console.ReadKey(intercept: true);
            }
            catch (InvalidOperationException)
            {
                _active = false;
                return;
            }

            if (key.Key == ConsoleKey.Enter)
            {
                string command;

                lock (SyncRoot)
                {
                    command = Buffer.ToString().Trim();
                    Buffer.Clear();
                    System.Console.Write("\r" + ClearLine);

                    if (command.Length != 0)
                        System.Console.WriteLine(ConsoleTheme.Center($"{_label} {command}".Pastel(ConsoleTheme.Muted)));

                    Draw();
                }

                if (command.Length != 0 && _handler is not null)
                    Dispatch(command);

                continue;
            }

            lock (SyncRoot)
            {
                if (key.Key == ConsoleKey.Backspace)
                {
                    if (Buffer.Length != 0)
                        Buffer.Length--;
                }
                else if (!char.IsControl(key.KeyChar))
                {
                    Buffer.Append(key.KeyChar);
                }

                Draw();
            }
        }
    }

    private static void Dispatch(string command)
    {
        _ = Task.Run(async () =>
        {
            try
            {
                await _handler!(command);
            }
            catch (Exception exception)
            {
                Write($"  console command failed: {exception.Message}".Pastel(Color.IndianRed));
            }
        });
    }
}