using System;
using System.Diagnostics;
using System.Reflection;
using System.Runtime;
using Barotrauma;
using Microsoft.Xna.Framework;
using HarmonyLib;

namespace FastLoadMod
{
	public class MemoryManager : IAssemblyPlugin
	{
		private static Harmony harmony;
		private static GCLatencyMode originalLatencyMode;
		private static bool isManagingMemory = false;
		
		private static Stopwatch pacemakerTimer = new Stopwatch();
		private const double PACEMAKER_INTERVAL_MS = 50.0;
		public void Initialize()
		{
			harmony = new Harmony("com.fastload.memorymanager");
			try
			{
				var updateMethod = typeof(GameMain).GetMethod("Update", BindingFlags.Instance | BindingFlags.Public | BindingFlags.NonPublic);
				if (updateMethod != null)
				{
					harmony.Patch(updateMethod, postfix: new HarmonyMethod(AccessTools.Method(typeof(MemoryManager), "PacemakerUpdate")));
				}
				var generateMethod = typeof(Level).GetMethod("Generate", BindingFlags.Public | BindingFlags.Static | BindingFlags.Instance);
				if (generateMethod != null)
				{
					harmony.Patch(generateMethod,
						prefix: new HarmonyMethod(AccessTools.Method(typeof(MemoryManager), "StartControlledBurn")),
						postfix: new HarmonyMethod(AccessTools.Method(typeof(MemoryManager), "EndControlledBurn")));
				}
				DebugConsole.NewMessage("[EnLo] MemManager working.", Color.Lime);
			}
			catch (Exception ex)
			{
				DebugConsole.NewMessage($"[EnLo] Memory Manager Error: {ex.Message}", Color.Red);
			}
		}
		
		public void Dispose()
		{
			if (isManagingMemory) EndControlledBurn();
			if (harmony != null)
			{
				harmony.UnpatchSelf();
				harmony = null;
			}
		}
		
		public void OnLoadCompleted() { }
		public void PreInitPatching() { }
		public static void StartControlledBurn()
		{
			if (!isManagingMemory)
			{
				originalLatencyMode = GCSettings.LatencyMode;
				GCSettings.LatencyMode = GCLatencyMode.SustainedLowLatency;
				isManagingMemory = true;
				pacemakerTimer.Restart();
			}
		}
		
		public static void PacemakerUpdate()
		{
			if (!isManagingMemory) return;
			if (pacemakerTimer.Elapsed.TotalMilliseconds >= PACEMAKER_INTERVAL_MS)
			{
				GC.Collect(0, GCCollectionMode.Optimized, false, false);
				pacemakerTimer.Restart();
			}
		}
		public static void EndControlledBurn()
		{
			if (isManagingMemory)
			{
				pacemakerTimer.Stop();
				GCSettings.LatencyMode = originalLatencyMode;
				isManagingMemory = false;
				GC.Collect(2, GCCollectionMode.Forced, true, true);
			}
		}
	}
}