using System;
using MoonTools.ECS.Collections;

namespace MoonTools.ECS;

internal class ArchetypeSignature : IEquatable<ArchetypeSignature>
{
	public static ArchetypeSignature Empty = new ArchetypeSignature(0);

	IndexableSet<TypeId> Ids;

	public int Count => Ids.Count;

	public TypeId this[int i] => Ids[i];

	public ArchetypeSignature()
	{
		Ids = new IndexableSet<TypeId>();
	}

	public ArchetypeSignature(int capacity)
	{
		Ids = new IndexableSet<TypeId>(capacity);
	}

	// Maintains sorted order
	public void Insert(TypeId componentId)
	{
		Ids.Add(componentId);
	}

	public void Remove(TypeId componentId)
	{
		Ids.Remove(componentId);
	}

	public bool Contains(TypeId componentId)
	{
		return Ids.Contains(componentId);
	}

	public void CopyTo(ArchetypeSignature other)
	{
		foreach (var id in Ids.AsSpan())
		{
			other.Ids.Add(id);
		}
	}

	public override bool Equals(object? obj)
	{
		return obj is ArchetypeSignature signature && Equals(signature);
	}

	public bool Equals(ArchetypeSignature? other)
	{
		if (other == null)
		{
			return false;
		}

		if (Ids.Count != other.Ids.Count)
		{
			return false;
		}

		for (int i = 0; i < Ids.Count; i += 1)
		{
			if (Ids[i] != other.Ids[i])
			{
				return false;
			}
		}

		return true;
	}

	public override int GetHashCode()
	{
		var hashcode = 1;

		foreach (var id in Ids)
		{
			hashcode = HashCode.Combine(hashcode, id);
		}

		return hashcode;
	}
}