using System;
using System.Collections.Concurrent;
using Svrnty.CQRS.Events.Abstractions.Sagas;

namespace Svrnty.CQRS.Events.Sagas;

/// <summary>
/// In-memory registry for saga definitions.
/// </summary>
public sealed class SagaRegistry : ISagaRegistry
{
    private readonly ConcurrentDictionary<Type, SagaDefinition> _definitionsByType = new();
    private readonly ConcurrentDictionary<string, SagaDefinition> _definitionsByName = new();
    private readonly ConcurrentDictionary<string, Type> _typesByName = new();

    /// <inheritdoc />
    public void Register<TSaga>(SagaDefinition definition) where TSaga : ISaga
    {
        if (definition == null)
            throw new ArgumentNullException(nameof(definition));

        var sagaType = typeof(TSaga);

        _definitionsByType[sagaType] = definition;
        _definitionsByName[definition.SagaName] = definition;
        _typesByName[definition.SagaName] = sagaType;
    }

    /// <inheritdoc />
    public SagaDefinition? GetDefinition<TSaga>() where TSaga : ISaga
    {
        _definitionsByType.TryGetValue(typeof(TSaga), out var definition);
        return definition;
    }

    /// <inheritdoc />
    public SagaDefinition? GetDefinitionByName(string sagaName)
    {
        if (string.IsNullOrWhiteSpace(sagaName))
            return null;

        _definitionsByName.TryGetValue(sagaName, out var definition);
        return definition;
    }

    /// <inheritdoc />
    public Type? GetSagaType(string sagaName)
    {
        if (string.IsNullOrWhiteSpace(sagaName))
            return null;

        _typesByName.TryGetValue(sagaName, out var type);
        return type;
    }
}