// 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/.

#if disabledForNow
using System.Threading.Tasks;
using Verse.AI;

namespace PerformanceFish.JobSystem;

public sealed class GenClosestPatches : ClassWithFishPatches
{
	public sealed class ClosestThing_Global_Patch : FishPatch
	{
		public override string Description { get; } = "Threading for job scanning. Disabled and unstable.";
		public override bool DefaultState => false;
		public static bool ThreadingEnabled { get; set; }

		public override Expression<Action> TargetMethod { get; }
			= static () => GenClosest.ClosestThing_Global(default, null, default, null, null);

		public static CodeInstructions Transpiler(CodeInstructions CodeInstructions)
			=> Reflection.MakeReplacementCall(ClosestThing_Global_Replacement);

		private struct Variables
		{
			public IntVec3 center;
			public float maxDistanceSquared;
			public Func<Thing, float>? priorityGetter;
			public float closestDistSquared;
			public Predicate<Thing>? validator;
		}

		public static Thing? ClosestThing_Global_Replacement(IntVec3 center, IEnumerable? searchSet,
			float maxDistance = 99999f, Predicate<Thing>? validator = null, Func<Thing, float>? priorityGetter = null)
		{
			if (searchSet == null)
				return null;

			var closestDistSquared = 2.14748365E+09f;
			Thing? chosen = null;
			var bestPrio = float.MinValue;
			//float maxDistanceSquared = maxDistance * maxDistance;
			Variables variables = new()
			{
				center = center,
				maxDistanceSquared = maxDistance * maxDistance,
				validator = validator,
				priorityGetter = priorityGetter,
				closestDistSquared = closestDistSquared
			};

			var predicate = GenClosest_Predicate.GetValidator(validator?.Target)?.Target ?? validator?.Target;
			if (ThreadingEnabled
				&& validator != null
				&& JobGiver_Work_Predicate.GetScanner(predicate) is WorkGiver_DoBill
				/*or WorkGiver_ConstructDeliverResources or WorkGiver_ConstructFinishFrames*/
			)
			{
				if (searchSet is IList<Thing> thingList)
				{
					Log.Message($"Running threading code for {validator.Target.GetType()}");
					Exception? exception = null;
					try
					{
						Parallel.For<(IList<Thing> list, Variables vars)>(0, thingList.Count,
							() => (thingList, variables),
							(i, loop, listAndVars) => (listAndVars.list,
								ProcessThreaded(listAndVars.list[i], listAndVars.vars)), static _ => { });
					}
					catch (Exception ex)
					{
						exception = ex;
						Log.Error($"Caught error while threading:\n{ex}");
					}

					if (exception is null)
						Log.Message("Finished threading code without errors");

					return chosen;
				}
			}

			switch (searchSet)
			{
				case IList<Thing> thingList:
				{
					for (var i = 0; i < thingList.Count; i++)
						Process(thingList[i], variables);
					break;
				}
				case IList<Pawn> pawnList:
				{
					for (var j = 0; j < pawnList.Count; j++)
						Process(pawnList[j], variables);
					break;
				}
				case IList<Building> buildingList:
				{
					for (var k = 0; k < buildingList.Count; k++)
						Process(buildingList[k], variables);
					break;
				}
				case IList<IAttackTarget> attackTargetList:
				{
					for (var l = 0; l < attackTargetList.Count; l++)
						Process((Thing)attackTargetList[l], variables);
					break;
				}
				default:
				{
					foreach (Thing item in searchSet)
						Process(item, variables);
					break;
				}
			}

			return chosen;

			void Process<T>(T t, Variables variables) where T : Thing
			{
				if (!t.Spawned)
					return;

				float num = (variables.center - t.Position).LengthHorizontalSquared;
				if (!(num > variables.maxDistanceSquared)
					&& (variables.priorityGetter != null || num < closestDistSquared)
					&& (variables.validator == null || variables.validator(t)))
				{
					var num2 = 0f;
					if (variables.priorityGetter != null)
					{
						num2 = variables.priorityGetter(t);
						if (num2 < bestPrio || (Math.Abs(num2 - bestPrio) < 0.001f && num >= closestDistSquared))
							return;
					}

					chosen = t;
					closestDistSquared = variables.closestDistSquared = num;
					bestPrio = num2;
				}
			}

			Variables ProcessThreaded<T>(T t, Variables variables) where T : Thing
			{
				if (!t.Spawned)
					return variables;

				float num = (variables.center - t.Position).LengthHorizontalSquared;
				if (num > variables.maxDistanceSquared
					|| (variables.priorityGetter == null
						&& (!(num < variables.closestDistSquared)
							|| !(num < (variables.closestDistSquared = closestDistSquared))))
					|| (variables.validator != null && !variables.validator(t)))
				{
					return variables;
				}

				lock (Lock)
				{
					var num2 = 0f;
					if (variables.priorityGetter != null)
					{
						num2 = variables.priorityGetter(t);
						if (num2 < bestPrio || (Math.Abs(num2 - bestPrio) < 0.001f && num >= closestDistSquared))
							return variables;
					}
					else
					{
						if (num >= closestDistSquared)
							return variables;
					}

					chosen = t;
					closestDistSquared = variables.closestDistSquared = num;
					bestPrio = num2;
				}

				return variables;
			}
		}

		private static object Lock { get; } = new();

		private static Type JobGiverWorkPredicateType { get; } = AccessTools.FirstInner(typeof(JobGiver_Work),
			t => AccessTools.Field(t, "scanner") != null
				&& AccessTools.FirstMethod(t, m => m.Name.Contains("TryIssueJobPackage")) != null);

		private static JobGiver_Work_PredicateAccess JobGiver_Work_Predicate { get; }
			= (JobGiver_Work_PredicateAccess)Activator.CreateInstance(
				typeof(JobGiver_Work_PredicateAccessImplementation<>).MakeGenericType(JobGiverWorkPredicateType));

		private static Type GenClosestPredicateType { get; } = AccessTools.FirstInner(typeof(GenClosest),
			t => AccessTools.Field(t, "validator") != null
				&& AccessTools.FirstMethod(t, m => m.Name.Contains("ClosestThingReachable")) != null);

		private static GenClosest_PredicateAccess GenClosest_Predicate { get; }
			= (GenClosest_PredicateAccess)Activator.CreateInstance(
				typeof(GenClosest_PredicateAccessImplementation<>).MakeGenericType(GenClosestPredicateType));

		private abstract class JobGiver_Work_PredicateAccess
		{
			public abstract WorkGiver_Scanner? GetScanner(object? obj);
		}

		private class JobGiver_Work_PredicateAccessImplementation<T> : JobGiver_Work_PredicateAccess
		{
			public override WorkGiver_Scanner? GetScanner(object? obj) => obj is T t ? Scanner(t) : null;

			public static AccessTools.FieldRef<T, WorkGiver_Scanner> Scanner { get; }
				= AccessTools.FieldRefAccess<T, WorkGiver_Scanner>("scanner");
		}

		private abstract class GenClosest_PredicateAccess
		{
			public abstract Predicate<Thing>? GetValidator(object? obj);
		}

		private class GenClosest_PredicateAccessImplementation<T> : GenClosest_PredicateAccess
		{
			public override Predicate<Thing>? GetValidator(object? obj) => obj is T t ? Validator(t) : null;

			public static AccessTools.FieldRef<T, Predicate<Thing>> Validator { get; }
				= AccessTools.FieldRefAccess<T, Predicate<Thing>>("validator");
		}
	}
#endif
//}