// Copyright © 2017 Paddy Xu
//
// This file is part of QuickLook program.
//
// This program is free software: you can redistribute it and/or modify
// it under the terms of the GNU General Public License as published by
// the Free Software Foundation, either version 3 of the License, or
// (at your option) any later version.
//
// This program is distributed in the hope that it will be useful,
// but WITHOUT ANY WARRANTY; without even the implied warranty of
// MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
// GNU General Public License for more details.
//
// You should have received a copy of the GNU General Public License
// along with this program.  If not, see <http://www.gnu.org/licenses/>.

using System;
using System.Diagnostics;
using System.IO;
using System.IO.Pipes;
using System.Security.Principal;
using System.Threading.Tasks;
using System.Windows;
using System.Windows.Threading;

namespace QuickLook;

internal static class PipeMessages
{
    public const string RunAndClose = "QuickLook.App.PipeMessages.RunAndClose";
    public const string Switch = "QuickLook.App.PipeMessages.Switch";
    public const string Invoke = "QuickLook.App.PipeMessages.Invoke";
    public const string Toggle = "QuickLook.App.PipeMessages.Toggle";
    public const string Forget = "QuickLook.App.PipeMessages.Forget";
    public const string Close = "QuickLook.App.PipeMessages.Close";
    public const string Quit = "QuickLook.App.PipeMessages.Quit";
}

internal class PipeServerManager : IDisposable
{
    private static readonly string PipeName = "QuickLook.App.Pipe." + WindowsIdentity.GetCurrent().User?.Value;
    private static PipeServerManager _instance;

    private DispatcherOperation _lastOperation;

    private NamedPipeServerStream _server;

    public PipeServerManager()
    {
        _server = new NamedPipeServerStream(PipeName, PipeDirection.In);

        new Task(() =>
        {
            using (var reader = new StreamReader(_server))
            {
                Debug.WriteLine("PipeManager: Ready");

                while (true)
                {
                    _server.WaitForConnection();
                    var msg = reader.ReadLine();

                    Debug.WriteLine($"PipeManager: {msg}");

                    // dispatch message
                    if (MessageReceived(msg))
                        return;

                    _server.Disconnect();
                }
            }
        }).Start();
    }

    public void Dispose()
    {
        GC.SuppressFinalize(this);

        if (_server != null)
            SendMessage(PipeMessages.Quit);
        _server?.Dispose();
        _server = null;
    }

    public static void SendMessage(string pipeMessage, string path = null)
    {
        if (path == null)
            path = "";

        try
        {
            using (var client = new NamedPipeClientStream(".", PipeName, PipeDirection.Out))
            {
                client.Connect();

                using (var writer = new StreamWriter(client))
                {
                    writer.WriteLine($"{pipeMessage}|{path}");
                    writer.Flush();
                }
            }
        }
        catch (Exception e)
        {
            Debug.WriteLine(e.ToString());
        }
    }

    private bool MessageReceived(string msg)
    {
        var split = msg.IndexOf('|');
        if (split == -1)
            return false;

        if (_lastOperation != null && _lastOperation.Status == DispatcherOperationStatus.Pending)
        {
            _lastOperation.Abort();
            Debug.WriteLine("Dispatcher task canceled");
        }

        var wParam = msg.Substring(0, split);
        var lParam = msg.Substring(split + 1, msg.Length - split - 1);

        switch (wParam)
        {
            case PipeMessages.RunAndClose:
                Application.Current.Dispatcher.BeginInvoke(
                    new Action(() => ViewWindowManager.GetInstance().RunAndClosePreview()),
                    DispatcherPriority.ApplicationIdle);
                return false;

            case PipeMessages.Invoke:
                _lastOperation = Application.Current.Dispatcher.BeginInvoke(
                    new Action(() => ViewWindowManager.GetInstance().InvokePreview(lParam)),
                    DispatcherPriority.ApplicationIdle);
                return false;

            case PipeMessages.Switch:
                _lastOperation = Application.Current.Dispatcher.BeginInvoke(
                    new Action(() => ViewWindowManager.GetInstance().SwitchPreview(lParam)),
                    DispatcherPriority.ApplicationIdle);
                return false;

            case PipeMessages.Toggle:
                _lastOperation = Application.Current.Dispatcher.BeginInvoke(
                    new Action(() => ViewWindowManager.GetInstance().TogglePreview(lParam)),
                    DispatcherPriority.ApplicationIdle);
                return false;

            case PipeMessages.Forget:
                Application.Current.Dispatcher.BeginInvoke(
                    new Action(() => ViewWindowManager.GetInstance().ForgetCurrentWindow()),
                    DispatcherPriority.ApplicationIdle);
                return false;

            case PipeMessages.Close:
                Application.Current.Dispatcher.BeginInvoke(
                    new Action(() => ViewWindowManager.GetInstance().ClosePreview()),
                    DispatcherPriority.ApplicationIdle);
                return false;

            case PipeMessages.Quit:
                return true;

            default:
                return false;
        }
    }

    public static PipeServerManager GetInstance()
    {
        return _instance ??= new PipeServerManager();
    }
}