namespace Theater_ECS;

using System;
using System.Reflection;
using System.Collections;

[AttributeUsage(.Method)]
struct SystemMethodAttribute : Attribute, IOnTypeInit
{
	private StringView _Name;
	private Span<Type> _Types;

	public this(StringView name, params Span<Type> types)
	{
		_Name = name;
		_Types = types;
	}

	[Comptime]
	public void OnTypeInit(Type type, Self* prev)
	{
		//InitializeFunction
		Compiler.EmitTypeBody(type, scope $"""
			public override bool IntializeSystem(ECS ecs)
			\{
			{InitializeSystemTypes( .. scope .())}
				return true;
			\}

			""");


		Compiler.EmitTypeBody(type, scope $"""
			[System.DisableChecks]
			public override void RunSystem(ECS ecs)
			\{
				Lock(ecs);

				Component lowest = System.int_cosize.MaxValue;
				System.int_cosize lowestAmount = System.int_cosize.MaxValue;
				for(var c in _ComponentMap)
				\{
					if(ecs.[System.Friend]_ComponentsPacked[c.value].Count < lowestAmount)
					\{
						lowest = c.value;
						lowestAmount = ecs.[System.Friend]_ComponentsPacked[c.value].Count;
					\}
				\}
					
						
				ecs.GetEntityFromComponent(lowest, _Target);

				{CacheComponentData(.. scope .())}


				for(var e in _Target)
				\{

					{_Name}(
					{GetComponentData(.. scope .())}
					);
				\}

				_Target.Clear();

				Unlock(ecs);

			\}

			private void Lock(ECS ecs)
			\{
				for(var i in _ComponentMap)
					ecs.[System.Friend]_ComponentsPacked[i.value].Use();
			\}

			private void Unlock(ECS ecs)
			\{
				for(var i in _ComponentMap)
					ecs.[System.Friend]_ComponentsPacked[i.value].StopUsing();	
			\}
			""");
	}

	private void InitializeSystemTypes(String buffer)
	{
		for(var i in _Types)
		{
			buffer.Append(scope $"""
					if(ecs.GetComponent<{i.GetName( .. scope .())}>() == -1)
						return false;
					_ComponentMap.Add(typeof({i.GetName(.. scope .())}), ecs.GetComponent<{i.GetName( .. scope .())}>());


				""");
		}
	}

	private void GetComponentData(String buffer)
	{
		for(var i in _Types)
		{
			buffer.Append(scope $"""
					ref *ecs.[System.Friend]_ComponentsPacked[_{i.GetName(.. scope .())}].Get<{i.GetName(.. scope .())}>(ecs.[System.Friend]_EntityList[_{i.GetName(.. scope .())}][e])
				""");
			if(@i.Index+1 < _Types.Length)
				buffer.Append(",\n");
		}
	}

	private void CacheComponentData(String buffer)
	{
		for(var i in _Types)
		{
			buffer.Append(scope $"Component _{i.GetName(.. scope .())} = _ComponentMap[typeof({i.GetName(.. scope .())})];\n");
		}
	}
}