using System;
using System.Collections.Concurrent;
using System.Linq;
using System.Threading;
using System.Threading.Tasks;
using Jellyfin.Data.Enums;
using Jellyfin.Plugin.JellyLMS.Models;
using MediaBrowser.Controller.Library;
using MediaBrowser.Controller.Session;
using MediaBrowser.Model.Session;
using Microsoft.Extensions.DependencyInjection;
using Microsoft.Extensions.Hosting;
using Microsoft.Extensions.Logging;

namespace Jellyfin.Plugin.JellyLMS.Services;

/// <summary>
/// Background service that discovers LMS players and registers them as Jellyfin sessions.
/// This enables LMS players to appear in Jellyfin's "Cast to" device picker.
/// </summary>
public class LmsDeviceDiscoveryService : IHostedService, IDisposable
{
    private const string AppName = "JellyLMS";
    private const string AppVersion = "1.0.0";

    private readonly ILogger<LmsDeviceDiscoveryService> _logger;
    private readonly IServiceProvider _serviceProvider;
    private readonly ILmsApiClient _lmsClient;
    private readonly LmsPlayerManager _playerManager;
    private readonly ConcurrentDictionary<string, string> _registeredDeviceIds = new();
    private ISessionManager? _sessionManager;
    private Timer? _discoveryTimer;
    private bool _disposed;

    /// <summary>
    /// Initializes a new instance of the <see cref="LmsDeviceDiscoveryService"/> class.
    /// </summary>
    /// <param name="logger">The logger instance.</param>
    /// <param name="serviceProvider">The service provider for lazy resolution.</param>
    /// <param name="lmsClient">The LMS API client.</param>
    /// <param name="playerManager">The LMS player manager.</param>
    public LmsDeviceDiscoveryService(
        ILogger<LmsDeviceDiscoveryService> logger,
        IServiceProvider serviceProvider,
        ILmsApiClient lmsClient,
        LmsPlayerManager playerManager)
    {
        _logger = logger;
        _serviceProvider = serviceProvider;
        _lmsClient = lmsClient;
        _playerManager = playerManager;
        _logger.LogInformation("LMS Device Discovery Service constructed");
    }

    /// <inheritdoc />
    public Task StartAsync(CancellationToken cancellationToken)
    {
        _logger.LogInformation("LMS Device Discovery Service starting");

        // Run initial discovery after a delay, then every 15 seconds
        _discoveryTimer = new Timer(
            async _ => await DiscoverAndRegisterPlayersAsync().ConfigureAwait(false),
            null,
            TimeSpan.FromSeconds(10),
            TimeSpan.FromSeconds(15));

        return Task.CompletedTask;
    }

    /// <inheritdoc />
    public Task StopAsync(CancellationToken cancellationToken)
    {
        _logger.LogInformation("LMS Device Discovery Service stopping");

        _discoveryTimer?.Change(Timeout.Infinite, 0);
        _registeredDeviceIds.Clear();

        return Task.CompletedTask;
    }

    private ISessionManager? GetSessionManager()
    {
        if (_sessionManager != null)
        {
            return _sessionManager;
        }

        try
        {
            _sessionManager = _serviceProvider.GetService<ISessionManager>();
            if (_sessionManager == null)
            {
                _logger.LogWarning("ISessionManager not available yet");
            }
        }
        catch (Exception ex)
        {
            _logger.LogError(ex, "Failed to resolve ISessionManager");
        }

        return _sessionManager;
    }

    private async Task DiscoverAndRegisterPlayersAsync()
    {
        try
        {
            var sessionManager = GetSessionManager();
            if (sessionManager == null)
            {
                _logger.LogDebug("Session manager not available, skipping discovery");
                return;
            }

            // First test connection
            var status = await _lmsClient.TestConnectionAsync().ConfigureAwait(false);
            if (!status.IsConnected)
            {
                _logger.LogDebug("LMS server not connected, skipping player discovery");
                return;
            }

            // Get all players from LMS
            var players = await _playerManager.GetPlayersAsync(forceRefresh: true).ConfigureAwait(false);

            _logger.LogDebug("Discovered {Count} LMS players", players.Count);

            foreach (var player in players)
            {
                try
                {
                    await RegisterOrRefreshPlayerSessionAsync(sessionManager, player).ConfigureAwait(false);
                }
                catch (Exception ex)
                {
                    _logger.LogError(ex, "Failed to register player {Name} ({Mac})", player.Name, player.MacAddress);
                }
            }

            // Clean up tracked device IDs for players that no longer exist
            foreach (var mac in _registeredDeviceIds.Keys)
            {
                if (!players.Exists(p => p.MacAddress == mac))
                {
                    _registeredDeviceIds.TryRemove(mac, out _);
                    _logger.LogDebug("Removed tracking for disconnected player {Mac}", mac);
                }
            }
        }
        catch (Exception ex)
        {
            _logger.LogError(ex, "Error during LMS player discovery");
        }
    }

    private async Task RegisterOrRefreshPlayerSessionAsync(ISessionManager sessionManager, LmsPlayer player)
    {
        // Create a unique device ID for this player
        var deviceId = $"lms-{player.MacAddress}";

        // Always call LogSessionActivity to keep the session alive
        // This creates a new session if one doesn't exist, or refreshes the existing one
        var session = await sessionManager.LogSessionActivity(
            appName: AppName,
            appVersion: AppVersion,
            deviceId: deviceId,
            deviceName: player.Name,
            remoteEndPoint: player.IpAddress,
            user: null).ConfigureAwait(false);

        if (session == null)
        {
            _logger.LogWarning("Failed to create/refresh session for player {Name}", player.Name);
            return;
        }

        // Check if this is a new registration
        var isNew = !_registeredDeviceIds.ContainsKey(player.MacAddress);

        // Add our controller to the session using EnsureController pattern
        var libraryManager = _serviceProvider.GetRequiredService<ILibraryManager>();
        var (controller, created) = session.EnsureController<LmsSessionController>(
            s => new LmsSessionController(
                _logger,
                _lmsClient,
                player,
                s,
                sessionManager,
                libraryManager));

        if (created)
        {
            _logger.LogInformation("Created LmsSessionController for player {Name}", player.Name);
        }

        // Always report capabilities to ensure they're set
        // This is critical for the device to appear in "Play On" menu
        var capabilities = new ClientCapabilities
        {
            PlayableMediaTypes = [MediaType.Audio],
            SupportedCommands =
            [
                GeneralCommandType.VolumeUp,
                GeneralCommandType.VolumeDown,
                GeneralCommandType.Mute,
                GeneralCommandType.Unmute,
                GeneralCommandType.SetVolume,
                GeneralCommandType.ToggleMute
            ],
            SupportsMediaControl = true,
            SupportsPersistentIdentifier = true
        };

        sessionManager.ReportCapabilities(session.Id, capabilities);

        // Track this device
        _registeredDeviceIds[player.MacAddress] = deviceId;

        if (isNew)
        {
            _logger.LogInformation(
                "Registered LMS player {Name} ({Mac}) as session {SessionId}",
                player.Name,
                player.MacAddress,
                session.Id);
        }
    }

    /// <inheritdoc />
    public void Dispose()
    {
        Dispose(true);
        GC.SuppressFinalize(this);
    }

    /// <summary>
    /// Disposes managed resources.
    /// </summary>
    /// <param name="disposing">Whether to dispose managed resources.</param>
    protected virtual void Dispose(bool disposing)
    {
        if (_disposed)
        {
            return;
        }

        if (disposing)
        {
            _discoveryTimer?.Dispose();
        }

        _disposed = true;
    }
}