using Microsoft.Extensions.DependencyInjection;
using StellaOps.Plugin.Abstractions;
using StellaOps.Plugin.Abstractions.Capabilities;
using StellaOps.Router.Common.Plugins;

namespace StellaOps.Router.Plugin.Unified;


/// <summary>
/// Factory for creating unified transport plugin adapters from existing router transport plugins.
/// </summary>
public sealed class TransportPluginAdapterFactory
{
    private readonly IEnumerable<IRouterTransportPlugin> _plugins;
    private readonly Dictionary<string, TransportPluginAdapter> _adapters = new(StringComparer.OrdinalIgnoreCase);
    private readonly object _lock = new();

    /// <summary>
    /// Known transport protocols for each transport type.
    /// </summary>
    private static readonly Dictionary<string, TransportProtocol> KnownProtocols = new(StringComparer.OrdinalIgnoreCase)
    {
        ["tcp"] = TransportProtocol.Tcp,
        ["tls"] = TransportProtocol.Tls,
        ["udp"] = TransportProtocol.Udp,
        ["rabbitmq"] = TransportProtocol.Amqp,
        ["valkey"] = TransportProtocol.Redis,
        ["redis"] = TransportProtocol.Redis,
        ["inmemory"] = TransportProtocol.InMemory
    };

    /// <summary>
    /// Known features for each transport type.
    /// </summary>
    private static readonly Dictionary<string, TransportFeatures> KnownFeatures = new(StringComparer.OrdinalIgnoreCase)
    {
        ["tcp"] = TransportFeatures.RequestReply | TransportFeatures.Streaming | TransportFeatures.ConnectionPooling,
        ["tls"] = TransportFeatures.RequestReply | TransportFeatures.Streaming | TransportFeatures.TlsSupport | TransportFeatures.ConnectionPooling,
        ["udp"] = TransportFeatures.None, // UDP is connectionless, fire-and-forget
        ["rabbitmq"] = TransportFeatures.RequestReply | TransportFeatures.PubSub | TransportFeatures.Queuing | TransportFeatures.Acknowledgment | TransportFeatures.AutoReconnect,
        ["valkey"] = TransportFeatures.PubSub | TransportFeatures.Queuing | TransportFeatures.AutoReconnect,
        ["redis"] = TransportFeatures.PubSub | TransportFeatures.Queuing | TransportFeatures.AutoReconnect,
        ["inmemory"] = TransportFeatures.RequestReply | TransportFeatures.Streaming
    };

    /// <summary>
    /// Creates a new factory instance.
    /// </summary>
    /// <param name="plugins">The available router transport plugins.</param>
    public TransportPluginAdapterFactory(IEnumerable<IRouterTransportPlugin> plugins)
    {
        _plugins = plugins ?? throw new ArgumentNullException(nameof(plugins));
    }

    /// <summary>
    /// Gets all available unified transport plugins.
    /// </summary>
    /// <param name="serviceProvider">Service provider for availability checking.</param>
    /// <returns>List of unified transport plugins.</returns>
    public IReadOnlyList<IPlugin> GetAllPlugins(IServiceProvider serviceProvider)
    {
        var result = new List<IPlugin>();

        foreach (var plugin in _plugins)
        {
            if (plugin.IsAvailable(serviceProvider))
            {
                var adapter = GetOrCreateAdapter(plugin);
                if (adapter != null)
                {
                    result.Add(adapter);
                }
            }
        }

        return result;
    }

    /// <summary>
    /// Gets a unified transport plugin by transport name.
    /// </summary>
    /// <param name="transportName">Transport name (e.g., "tcp", "tls", "rabbitmq").</param>
    /// <returns>Unified transport plugin, or null if not found.</returns>
    public IPlugin? GetPlugin(string transportName)
    {
        var plugin = _plugins.FirstOrDefault(p =>
            p.TransportName.Equals(transportName, StringComparison.OrdinalIgnoreCase));

        if (plugin == null)
        {
            return null;
        }

        return GetOrCreateAdapter(plugin);
    }

    /// <summary>
    /// Gets the transport capability for a transport.
    /// </summary>
    /// <param name="transportName">Transport name.</param>
    /// <returns>Transport capability, or null if not found.</returns>
    public ITransportCapability? GetCapability(string transportName)
    {
        return GetPlugin(transportName) as ITransportCapability;
    }

    /// <summary>
    /// Gets all available transport names.
    /// </summary>
    /// <returns>List of transport names.</returns>
    public IReadOnlyList<string> GetAvailableTransports()
    {
        return _plugins.Select(p => p.TransportName).ToList();
    }

    private TransportPluginAdapter? GetOrCreateAdapter(IRouterTransportPlugin plugin)
    {
        lock (_lock)
        {
            if (_adapters.TryGetValue(plugin.TransportName, out var existing))
            {
                return existing;
            }

            var protocol = KnownProtocols.TryGetValue(plugin.TransportName, out var p)
                ? p
                : TransportProtocol.Tcp; // Default to TCP

            var features = KnownFeatures.TryGetValue(plugin.TransportName, out var f)
                ? f
                : TransportFeatures.RequestReply; // Default to request/reply

            var adapter = new TransportPluginAdapter(plugin, protocol, features);
            _adapters[plugin.TransportName] = adapter;

            return adapter;
        }
    }
}

/// <summary>
/// Extension methods for registering unified transport plugin services.
/// </summary>
public static class TransportPluginAdapterExtensions
{
    /// <summary>
    /// Adds unified transport plugin adapter services to the service collection.
    /// </summary>
    /// <param name="services">Service collection.</param>
    /// <returns>Service collection for chaining.</returns>
    public static IServiceCollection AddUnifiedTransportPlugins(this IServiceCollection services)
    {
        services.AddSingleton<TransportPluginAdapterFactory>();

        return services;
    }
}