using System.Collections.ObjectModel;

namespace Sand.Core;

public sealed class ParticleLibrary : IParticleLibrary
{
    private readonly IReadOnlyList<ParticleDef> _definitions;
    private readonly Dictionary<string, ushort> _typeIds;

    public ParticleLibrary(IReadOnlyList<ParticleDef> definitions)
    {
        if (definitions.Count == 0)
        {
            throw new ArgumentException("At least one particle definition is required.", nameof(definitions));
        }

        _definitions = new ReadOnlyCollection<ParticleDef>(definitions.ToArray());
        _typeIds = new Dictionary<string, ushort>(StringComparer.OrdinalIgnoreCase);

        for (var index = 0; index < definitions.Count; index++)
        {
            _typeIds[definitions[index].Id] = checked((ushort)(index + 1));
        }
    }

    public IReadOnlyList<ParticleDef> Definitions => _definitions;

    public ushort GetTypeId(string id)
    {
        if (_typeIds.TryGetValue(id, out var typeId))
        {
            return typeId;
        }

        throw new KeyNotFoundException($"Unknown particle id '{id}'.");
    }

    public bool TryGetTypeId(string id, out ushort typeId) => _typeIds.TryGetValue(id, out typeId);

    public ParticleDef GetDefinition(ushort typeId)
    {
        if (typeId == 0 || typeId > _definitions.Count)
        {
            throw new ArgumentOutOfRangeException(nameof(typeId), $"Unknown type id '{typeId}'.");
        }

        return _definitions[typeId - 1];
    }
}