namespace FoodFactory.Core;

using System.Collections.Generic;

public class Registry<TEntry> where TEntry : notnull
{
  private readonly Dictionary<TEntry, int> _data = [];
  private readonly List<TEntry> _list = [];
  private readonly object _lock = new();
  public IReadOnlyList<TEntry> Entries => _list;
  public void Clear()
  {
    lock (_lock)
    {
      _data.Clear();
      _list.Clear();
    }
  }
  public int GetOrCreate(TEntry name)
  {
    lock (_lock)
    {
      if (_data.TryGetValue(name, out var tag))
      {
        return tag;
      }
      return CreateNewKey(name);
    }
  }
  public TEntry GetEntry(int index)
  {
    lock (_lock)
    {
      if ((uint)index >= (uint)_list.Count)
      {
        throw new KeyNotFoundException($"The index {index} you are trying to access does not exist in the registry. The registry only has {_list.Count} of type {typeof(TEntry).Name}s");
      }
      return _list[index];
    }
  }

  private int CreateNewKey(TEntry name)
  {
    int index = _list.Count;
    _list.Add(name);
    _data[name] = index;
    return index;
  }
}