// Copyright (c) 2023 bradson
// This Source Code Form is subject to the terms of the Mozilla Public
// License, v. 2.0. If a copy of the MPL was not distributed with this
// file, You can obtain one at https://mozilla.org/MPL/2.0/.

using System.Diagnostics;
using Mono.Cecil;
using Mono.Cecil.Cil;
using MonoMod.Utils;
using PerformanceFish.Prepatching;
using Verse.Steam;

namespace PerformanceFish;

public sealed class UtilityPrepatches : ClassWithFishPrepatches
{
	public sealed class CreateModClassesPatch : FishPrepatch
	{
		public override string? Description { get; }
			= "Hook for very early loading of patches, right after the game finishes loading up game assemblies into "
			+ "its process and before it launches any processes on them. Certain patches require this.";

		public override bool Enabled => true;

		public override bool ShowSettings => false;

		public override MethodBase TargetMethodBase { get; } = methodof(LoadedModManager.CreateModClasses);

		public override void Transpiler(ILProcessor ilProcessor, ModuleDefinition module)
			=> ilProcessor.ReplaceBodyWith(ReplacementBody);

		public static void Prefix()
		{
			try
			{
				OnAssembliesLoaded.Start();
			}
			catch (Exception e)
			{
				Log.Error($"Exception caught within OnAssembliesLoaded:\n{e}\n{new StackTrace(true)}");
			}
		}

		public static void ReplacementBody()
		{
			var runningModClasses = RunningModClasses;
			var assemblyToModContentPack = BuildAssemblyToModContentPackMap();

			foreach (var type in typeof(Mod).InstantiableDescendantsAndSelf())
			{
				if (type is null)
					continue;

				DeepProfiler.Start("Loading " + type?.ToString() + " mod class");
				try
				{
					if (!runningModClasses.ContainsKey(type))
					{
						assemblyToModContentPack.TryGetValue(type.Assembly, out var modContentPack);
						runningModClasses[type] = (Mod)Activator.CreateInstance(type, modContentPack);
					}
				}
				catch (Exception ex)
				{
					Log.Error("Error while instantiating a mod of type " + type?.ToString() + ": " + ex);
				}
				finally
				{
					DeepProfiler.End();
				}
			}
		}

		private static Dictionary<Assembly, ModContentPack> BuildAssemblyToModContentPackMap()
		{
			var runningMods = LoadedModManager.RunningModsListForReading;
			var assemblyToModContentPack = new Dictionary<Assembly, ModContentPack>();

			for (var i = 0; i < runningMods.Count; i++)
			{
				var modContentPack = runningMods[i];
				var loadedAssemblies = modContentPack.assemblies.loadedAssemblies;

				for (var j = 0; j < loadedAssemblies.Count; j++)
					assemblyToModContentPack.TryAdd(loadedAssemblies[j], modContentPack);
			}

			return assemblyToModContentPack;
		}

		private static Dictionary<Type, Mod> RunningModClasses
			=> (Dictionary<Type, Mod>)(_runningModClassesField ??=
				AccessTools.Field(typeof(LoadedModManager), "runningModClasses")).GetValue(null)!;

		private static FieldInfo? _runningModClassesField;
	}

	public sealed class NoSteamLogWarning : FishPrepatch
	{
		public override string? Description { get; }
			= "Disables the \"[Steamworks.NET] SteamAPI.Init() failed\" warning. It's duplicated with prepatcher "
			+ "anyway";

		public override MethodBase TargetMethodBase { get; }
			= AccessTools.DeclaredMethod(typeof(SteamManager), nameof(SteamManager.InitIfNeeded));

		public override void Transpiler(ILProcessor ilProcessor, ModuleDefinition module)
		{
			var codes = ilProcessor.instructions;
			
			var warningIndex = codes.FirstIndexOf(static code
				=> code.Operand is string text && text.Contains("SteamAPI.Init() failed"));

			if (warningIndex < 0)
				return;
			
			codes[warningIndex].OpCode = OpCodes.Nop;
			codes[warningIndex].Operand = null;
			
			codes[++warningIndex].OpCode = OpCodes.Nop;
			codes[warningIndex].Operand = null;
		}
	}
	
	public sealed class NoSteamFailWindow : FishPrepatch
	{
		public override string? Description { get; }
			= "Disables the window that opens when running the steam version of rimworld without steam. Off by default";

		public override bool DefaultState => false;

		public override MethodBase TargetMethodBase { get; }
			= AccessTools.DeclaredMethod(typeof(UIRoot_Entry), nameof(UIRoot_Entry.Init));

		public override void Transpiler(ILProcessor ilProcessor, ModuleDefinition module)
		{
			var codes = ilProcessor.instructions;
			
			var steamInitializedProperty
				= AccessTools.PropertyGetter(typeof(SteamManager), nameof(SteamManager.Initialized));

			var instruction = codes.FirstOrDefault(code
				=> code.Operand is MethodReference method && method.Is(steamInitializedProperty));

			if (instruction is null)
				return;
			
			instruction.OpCode = OpCodes.Ldc_I4_1;
			instruction.Operand = null;
		}
	}
}