using System;

namespace GameCore.TinyECS
{
    public readonly struct Entity<TEnum> : IEquatable<Entity<TEnum>> where TEnum : unmanaged
    {
        public readonly TEnum type;
        public readonly int index;
        public readonly int generation;

        public Entity(TEnum type, int index, int generation)
        {
            this.type = type;
            this.index = index;
            this.generation = generation;
        }

        public override string ToString()
        {
            return $"Entity<{type}>({index},{generation})";
        }

        public bool Equals(Entity<TEnum> other)
        {
            return type.Equals(other.type) && index == other.index && generation == other.generation;
        }

        public override bool Equals(object obj)
        {
            return obj is Entity<TEnum> other && Equals(other);
        }

        public override int GetHashCode()
        {
            return HashCode.Combine(type, index, generation);
        }

        public static bool operator ==(Entity<TEnum> lhs, Entity<TEnum> rhs)
        {
            return lhs.Equals(rhs);
        }

        public static bool operator !=(Entity<TEnum> lhs, Entity<TEnum> rhs)
        {
            return !(lhs == rhs);
        }
    }
}