namespace Theater_ECS.Internal.Managers;

using System;
using System.Collections;

class SystemsManager : IEnumerable<(String key, System value)>
{
	private ECS _owner;
	private Dictionary<String, System> _registeredSystems = new .() ~ delete _;
	private Dictionary<String, (function void(ECS), float, SystemSection)> _registeredLooseSystems = new .() ~ DeleteDictionaryAndKeys!(_);

	private bool _dirty = false;
	private List<System> _sortedSystems = new .() ~ delete _;
	private List<(function void(ECS), float, SystemSection)> _sortedLooseSystems = new .() ~ delete _;

	public this(ECS ecs)
	{
		_owner = ecs;
	}

	///Registers a system and returns false if its already contained
	public bool RegisterSystem(System sys, StringView id)
	{
		if (_registeredSystems.ContainsKeyAlt<StringView>(id) || _registeredLooseSystems.ContainsKeyAlt<StringView>(id))
			return false;
		_dirty = true;
		_registeredSystems.Add(new .(id), sys);
		sys.RegisterSystem(_owner);
		return true;
	}

	///Register a system without an actual system object
	public bool RegisterLooseSystem(StringView id, function void(ECS) func, float runtimeDelay = 0, SystemSection section = .TECS_Update)
	{
		if (_registeredSystems.ContainsKeyAlt<StringView>(id) || _registeredLooseSystems.ContainsKeyAlt<StringView>(id))
			return false;
		_dirty = true;
		_registeredLooseSystems.Add(new .(id), (func, runtimeDelay, section));
		return true;
	}

	///Deregister a single system
	public Result<System> DeregisterSystem(StringView id)
	{
		_dirty = true;
		if (!(_registeredSystems.ContainsKeyAlt<StringView>(id) || _registeredLooseSystems.ContainsKeyAlt<StringView>(id)))
			return .Err;
		if (_registeredSystems.ContainsKeyAlt<StringView>(id))
			return .Ok(_registeredSystems.GetAndRemoveAlt<StringView>(id).Value.value);
		else
		{
			_registeredLooseSystems.Remove(scope .(id));
			return .Ok(null);
		}
	}

	///Remove all systems from use and return the amount of systems cleared
	public int ClearAllSystems()
	{
		_dirty = true;
		var c = _registeredSystems.Count;
		_registeredSystems.Clear();
		return c;
	}

	///Runs all systems once
	public void RunAllSystems(ECS ecs, float delta = 0)
	{
		if (_dirty)
		{
			SortSystemPriorites();
			_dirty = false;
		}

		int counter = 0;
		int counterLoose = 0;

		for (uint8 section <= 255)
		{
			if (_sortedSystems.Count > counter)
				while (_sortedSystems[counter].Section == (.)section)
				{
					_sortedSystems[counter].RunSystem(ecs);
					counter++;
				}

			if (_sortedLooseSystems.Count > counterLoose)
				while (_sortedLooseSystems[counterLoose].2 == (.)section)
				{
					_sortedLooseSystems[counterLoose].0(ecs);
					counter++;
				}
		}
	}

	///Run all systems that fall inbetween two Sections
	public void RunSystemsBetween(ECS ecs, SystemSection sectionStart, SystemSection sectionEnd, float delta = 0)
	{
		if (_dirty)
		{
			SortSystemPriorites();
			_dirty = false;
		}

		int counter = 0;
		int counterLoose = 0;

		for (uint8 section = (.)sectionStart; section <= (uint8)sectionEnd; section++)
		{
			if (_sortedSystems.Count > counter)
				while (_sortedSystems[counter].Section == (.)section)
				{
					_sortedSystems[counter].RunSystem(ecs);
					counter++;
				}

			if (_sortedLooseSystems.Count > counterLoose)
				while (_sortedLooseSystems[counterLoose].2 == (.)section)
				{
					_sortedLooseSystems[counterLoose].0(ecs);
					counter++;
				}
		}
	}

	///Run all systems with a specific section
	public void RunSystemsBySection(ECS ecs, SystemSection section, float delta = 0)
	{
		if (_dirty)
		{
			SortSystemPriorites();
			_dirty = false;
		}

		int counter = 0;
		int counterLoose = 0;

		if (_sortedSystems.Count > counter)
			while (_sortedSystems[counter].Section == (.)section)
			{
				_sortedSystems[counter].RunSystem(ecs);
				counter++;
			}

		if (_sortedLooseSystems.Count > counterLoose)
			while (_sortedLooseSystems[counterLoose].2 == (.)section)
			{
				_sortedLooseSystems[counterLoose].0(ecs);
				counter++;
			}
	}

	///Run a single system
	public Result<void> RunSystem(StringView id, ECS ecs)
	{
		if (!_registeredSystems.ContainsKeyAlt<StringView>(id))
			return .Err;

		_registeredSystems[scope .(id)].RunSystem(ecs);

		return .Ok;
	}

	///Runs a function over all systems
	public void EnumerateSystems(delegate void(System) func)
	{
		for (var i in _registeredSystems)
			func.Invoke(i.value);
	}

	public int Count => _registeredSystems.Count;

	public Dictionary<String, System>.Enumerator GetEnumerator() => _registeredSystems.GetEnumerator();
	public Dictionary<String, (function void(ECS), float, SystemSection)>.Enumerator GetLooseEnumerator() => _registeredLooseSystems.GetEnumerator();


	private void SortSystemPriorites()
	{
		_sortedSystems.Clear();
		_sortedLooseSystems.Clear();

		for (var i in _registeredSystems)
			_sortedSystems.Add(i.value);

		_sortedSystems.Sort(scope (a, b) =>
			{
				return a.Section - b.Section;
			});

		for (var i in _registeredLooseSystems)
			_sortedLooseSystems.Add(i.value);

		_sortedLooseSystems.Sort(scope (a, b) =>
			{
				return a.2 - b.2;
			});
	}

}