TechbloxModdingAPI/TechbloxModdingAPI/App/Client.cs

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
    {
	    public static Client Instance { get; } = new Client();
	    
	    protected static Func<object> ErrorHandlerInstanceGetter;

		protected static Action<object, Error> EnqueueError;

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

        /// <summary>
        /// An event that fire whenever the main menu is exited.
        /// </summary>
		public static event EventHandler<MenuEventArgs> ExitMenu
        {
	        add => Game.menuEngine.ExitMenu += value;
            remove => Game.menuEngine.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 (!Game.menuEngine.IsInMenu) return Array.Empty<Game>();
				return Game.menuEngine.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 => Game.menuEngine.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);
        }

        public void CloseCurrentPrompt()
        {
	        object errorHandlerInstance = ErrorHandlerInstanceGetter();
	        var popup = GetPopupCloseMethods(errorHandlerInstance);
	        popup.Close();
        }

        public void SelectFirstPromptButton()
        {
	        object errorHandlerInstance = ErrorHandlerInstanceGetter();
	        var popup = GetPopupCloseMethods(errorHandlerInstance);
	        popup.FirstButton();
        }

        public void SelectSecondPromptButton()
        {
	        object errorHandlerInstance = ErrorHandlerInstanceGetter();
	        var popup = GetPopupCloseMethods(errorHandlerInstance);
	        popup.SecondButton();
        }

        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]);
		}

        // 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 Close, Action FirstButton, Action SecondButton) _errorPopup;

        private static (Action Close, Action FirstButton, Action SecondButton) GetPopupCloseMethods(object handler)
        {
	        if (_errorPopup.Close != null)
		        return _errorPopup;
	        Type errorHandler = handler.GetType();
	        FieldInfo field = AccessTools.Field(errorHandler, "errorPopup");
	        var errorPopup = (ErrorPopup)field.GetValue(handler);
	        MethodInfo info = AccessTools.Method(errorPopup.GetType(), "ClosePopup");
	        var close = (Action)Delegate.CreateDelegate(typeof(Action), errorPopup, info);
	        info = AccessTools.Method(errorPopup.GetType(), "HandleFirstOption");
	        var first = (Action)Delegate.CreateDelegate(typeof(Action), errorPopup, info);
	        info = AccessTools.Method(errorPopup.GetType(), "HandleSecondOption");
	        var second = (Action)Delegate.CreateDelegate(typeof(Action), errorPopup, info);
	        _errorPopup = (close, first, second);
	        return _errorPopup;
        }
    }
}