using System;
using System.Reflection;
using HarmonyLib;

using RobocraftX.Services;
using UnityEngine;
using RobocraftX.Common;
using TechbloxModdingAPI.Utility;

namespace TechbloxModdingAPI.App
{
    /// <summary>
    /// The Techblox application that is running this code right now.
    /// </summary>
    public class Client
    {
        // extensible engine
		protected static AppEngine appEngine = new AppEngine();

		protected static Func<object> ErrorHandlerInstanceGetter;

		protected static Action<object, Error> EnqueueError;

		protected static Action<object> HandleErrorClosed;

        /// <summary>
        /// An event that fires whenever the main menu is loaded.
        /// </summary>
		public static event EventHandler<MenuEventArgs> EnterMenu
        {
	        add => appEngine.EnterMenu += value;
			remove => appEngine.EnterMenu -= value;
		}

        /// <summary>
        /// An event that fire whenever the main menu is exited.
        /// </summary>
		public static event EventHandler<MenuEventArgs> ExitMenu
        {
	        add => appEngine.ExitMenu += value;
            remove => appEngine.ExitMenu -= value;
        }
        
        /// <summary>
        /// Techblox build version string.
		/// Usually this is in the form YYYY.mm.DD.HH.MM.SS
        /// </summary>
        /// <value>The version.</value>
		public string Version
		{
			get => Application.version;
		}

        /// <summary>
        /// Unity version string.
        /// </summary>
        /// <value>The unity version.</value>
        public string UnityVersion
		{
			get => Application.unityVersion;
		}

        /// <summary>
        /// Game saves currently visible in the menu.
		/// These take a second to completely populate after the EnterMenu event fires.
        /// </summary>
        /// <value>My games.</value>
		public Game[] MyGames
		{
			get 
			{
				if (!appEngine.IsInMenu) return new Game[0];
				return appEngine.GetMyGames();
			}
		}

        /// <summary>
        /// Whether Techblox is in the Main Menu
        /// </summary>
        /// <value><c>true</c> if in menu; <c>false</c> when loading or in a game.</value>
        public bool InMenu
		{
			get => appEngine.IsInMenu;
		}

        /// <summary>
        /// Open a popup which prompts the user to click a button.
        /// This reuses Techblox's error dialog popup
        /// </summary>
        /// <param name="popup">The popup to display. Use an instance of SingleChoicePrompt or DualChoicePrompt.</param>
        public void PromptUser(Error popup)
        {
	        // if the stuff wasn't mostly set to internal, this would be written as:
	        // RobocraftX.Services.ErrorHandler.Instance.EqueueError(error);
	        object errorHandlerInstance = ErrorHandlerInstanceGetter();
	        EnqueueError(errorHandlerInstance, popup);
        }

        // TODO
        /*public void CloseCurrentPrompt()
        {
	        // RobocraftX.Services.ErrorHandler.Instance.HandlePopupClosed(); 
	        // FIXME: this is a call that is also called when closing, not the actual closing action itself (so it doesn't work)
	        object errorHandlerInstance = ErrorHandlerInstanceGetter();
	        HandleErrorClosed(errorHandlerInstance);
        }*/

        internal static void Init()
		{
			// this would have been so much simpler if this didn't involve a bunch of internal fields & classes
			Type errorHandler = AccessTools.TypeByName("RobocraftX.Services.ErrorHandler");
			Type errorHandle = AccessTools.TypeByName("RobocraftX.Services.ErrorHandle");
			ErrorHandlerInstanceGetter = (Func<object>) AccessTools.Method("TechbloxModdingAPI.App.Client:GenInstanceGetter")
				.MakeGenericMethod(errorHandler)
				.Invoke(null, new object[0]);
			EnqueueError = (Action<object, Error>) AccessTools.Method("TechbloxModdingAPI.App.Client:GenEnqueueError")
				.MakeGenericMethod(errorHandler, errorHandle)
				.Invoke(null, new object[0]);
			/*HandleErrorClosed = (Action<object>) AccessTools.Method("TechbloxModdingAPI.App.Client:GenHandlePopupClosed")
				.MakeGenericMethod(errorHandler)
				.Invoke(null, new object[0]);*/
			// register engines
			MenuEngineManager.AddMenuEngine(appEngine);
		}

        // Creating delegates once is faster than reflection every time
        // Admittedly, this way is more difficult to code and less readable
        private static Func<object> GenInstanceGetter<T>()
        {
	        Type errorHandler = AccessTools.TypeByName("RobocraftX.Services.ErrorHandler");
	        MethodInfo instance = AccessTools.PropertyGetter(errorHandler, "Instance");
	        Func<T> getterSimple = (Func<T>) Delegate.CreateDelegate(typeof(Func<T>), null, instance);
	        Func<object> getterCasted = () => (object) getterSimple();
	        return getterCasted;
        }

        private static Action<object, Error> GenEnqueueError<T, TRes>()
        {
	        Type errorHandler = AccessTools.TypeByName("RobocraftX.Services.ErrorHandler");
	        MethodInfo enqueueError = AccessTools.Method(errorHandler, "EnqueueError");
	        Func<T, Error, TRes> enqueueSimple =
		        (Func<T, Error, TRes>) Delegate.CreateDelegate(typeof(Func<T, Error, TRes>), enqueueError);
	        Action<object, Error> enqueueCasted =
		        (object instance, Error error) => { enqueueSimple((T) instance, error); };
	        return enqueueCasted;
        }

        private static Action<object> GenHandlePopupClosed<T>()
        {
	        Type errorHandler = AccessTools.TypeByName("RobocraftX.Services.ErrorHandler");
	        MethodInfo handlePopupClosed = AccessTools.Method(errorHandler, "HandlePopupClosed");
	        Action<T> handleSimple =
		        (Action<T>) Delegate.CreateDelegate(typeof(Action<T>), handlePopupClosed);
	        Action<object> handleCasted = (object instance) => handleSimple((T) instance);
	        return handleCasted;
        }
    }
}