/*
    Copyright (C) 2014-2019 de4dot@gmail.com

    This file is part of dnSpy

    dnSpy 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.

    dnSpy 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 dnSpy.  If not, see <http://www.gnu.org/licenses/>.
*/

using System;
using System.ComponentModel.Composition;
using System.Diagnostics;
using System.Reflection;
using System.Windows.Threading;
using dnSpy.Contracts.App;

namespace dnSpy.Debugger.DotNet.UI {
	[Export(typeof(UIDispatcher))]
	sealed class UIDispatcher {
		static readonly FieldInfo? _disableProcessingCountFieldInfo;
		static UIDispatcher() {
			_disableProcessingCountFieldInfo = typeof(Dispatcher).GetField("_disableProcessingCount", BindingFlags.NonPublic | BindingFlags.Instance);
			Debug2.Assert(_disableProcessingCountFieldInfo is not null && _disableProcessingCountFieldInfo.FieldType == typeof(int));
		}

		Dispatcher Dispatcher { get; }

		[ImportingConstructor]
		UIDispatcher(IAppWindow appWindow) => Dispatcher = appWindow.MainWindow.Dispatcher;

		public void VerifyAccess() => Dispatcher.VerifyAccess();
		public bool CheckAccess() => Dispatcher.CheckAccess();

		public bool IsProcessingDisabled() {
			if (_disableProcessingCountFieldInfo is null || _disableProcessingCountFieldInfo.FieldType != typeof(int))
				return false;
			return (int)_disableProcessingCountFieldInfo.GetValue(Dispatcher)! > 0;
		}

		public void Invoke(Action callback) {
			System.Diagnostics.Debugger.NotifyOfCrossThreadDependency();
			Dispatcher.Invoke(DispatcherPriority.Background, callback);
		}

		public void UIBackground(Action callback) =>
			Dispatcher.BeginInvoke(DispatcherPriority.Background, callback);

		public void UI(Action callback) =>
			// Use Send so the windows are updated as fast as possible when adding new items
			Dispatcher.BeginInvoke(DispatcherPriority.Send, callback);
	}
}