using System;
using System.Collections.Concurrent;
using System.Collections.Generic;
using System.Linq;
using System.Threading;
using System.Threading.Tasks;
using Jellyfin.Plugin.JellyLMS.Configuration;
using Jellyfin.Plugin.JellyLMS.Models;
using MediaBrowser.Controller.Library;
using Microsoft.Extensions.Hosting;
using Microsoft.Extensions.Logging;

namespace Jellyfin.Plugin.JellyLMS.Services;

/// <summary>
/// Manages active playback sessions between Jellyfin and LMS.
/// </summary>
public class LmsSessionManager : IHostedService
{
    private readonly ILogger<LmsSessionManager> _logger;
    private readonly ILmsApiClient _lmsClient;
    private readonly LmsPlayerManager _playerManager;
    private readonly ILibraryManager _libraryManager;
    private readonly ConcurrentDictionary<string, LmsPlaybackSession> _sessions = new();

    /// <summary>
    /// Initializes a new instance of the <see cref="LmsSessionManager"/> class.
    /// </summary>
    /// <param name="logger">The logger instance.</param>
    /// <param name="lmsClient">The LMS API client.</param>
    /// <param name="playerManager">The player manager.</param>
    /// <param name="libraryManager">The Jellyfin library manager.</param>
    public LmsSessionManager(
        ILogger<LmsSessionManager> logger,
        ILmsApiClient lmsClient,
        LmsPlayerManager playerManager,
        ILibraryManager libraryManager)
    {
        _logger = logger;
        _lmsClient = lmsClient;
        _playerManager = playerManager;
        _libraryManager = libraryManager;
    }

    private PluginConfiguration Config => Plugin.Instance?.Configuration ?? new PluginConfiguration();

    /// <summary>
    /// Gets all active sessions.
    /// </summary>
    /// <returns>List of active sessions.</returns>
    public List<LmsPlaybackSession> GetActiveSessions()
    {
        return _sessions.Values.Where(s => s.State != PlaybackState.Stopped).ToList();
    }

    /// <summary>
    /// Gets a session by ID.
    /// </summary>
    /// <param name="sessionId">The session ID.</param>
    /// <returns>The session, or null if not found.</returns>
    public LmsPlaybackSession? GetSession(string sessionId)
    {
        return _sessions.GetValueOrDefault(sessionId);
    }

    /// <summary>
    /// Starts playback of a Jellyfin item on LMS players.
    /// </summary>
    /// <param name="itemId">The Jellyfin item ID.</param>
    /// <param name="playerMacs">The LMS player MAC addresses.</param>
    /// <param name="userId">Optional user ID.</param>
    /// <returns>The created session.</returns>
    public async Task<LmsPlaybackSession?> StartPlaybackAsync(
        Guid itemId,
        IEnumerable<string> playerMacs,
        Guid? userId = null)
    {
        var macList = playerMacs.ToList();
        if (macList.Count == 0)
        {
            _logger.LogWarning("No players specified for playback");
            return null;
        }

        var item = _libraryManager.GetItemById(itemId);
        if (item == null)
        {
            _logger.LogWarning("Item {ItemId} not found", itemId);
            return null;
        }

        // Build the audio stream URL
        var streamUrl = BuildStreamUrl(itemId);

        var session = new LmsPlaybackSession
        {
            ItemId = itemId,
            ItemName = item.Name,
            PlayerMacs = macList,
            State = PlaybackState.Playing,
            StreamUrl = streamUrl,
            UserId = userId,
            RuntimeTicks = item.RunTimeTicks ?? 0
        };

        // If multiple players, sync them first
        if (macList.Count > 1)
        {
            var masterMac = macList[0];
            var slaveMacs = macList.Skip(1);
            await _playerManager.CreateSyncGroupAsync(masterMac, slaveMacs).ConfigureAwait(false);
        }

        // Start playback on the first player (others will sync)
        var targetMac = macList[0];
        var success = await _lmsClient.PlayUrlAsync(targetMac, streamUrl, item.Name).ConfigureAwait(false);

        if (!success)
        {
            _logger.LogError("Failed to start playback on player {Mac}", targetMac);
            return null;
        }

        _sessions[session.SessionId] = session;
        _logger.LogInformation(
            "Started playback session {SessionId} for {Item} on {Count} players",
            session.SessionId,
            item.Name,
            macList.Count);

        return session;
    }

    /// <summary>
    /// Pauses a playback session.
    /// </summary>
    /// <param name="sessionId">The session ID.</param>
    /// <returns>True if successful.</returns>
    public async Task<bool> PauseSessionAsync(string sessionId)
    {
        if (!_sessions.TryGetValue(sessionId, out var session))
        {
            return false;
        }

        // Pause the master player (synced players will follow)
        var success = await _lmsClient.PauseAsync(session.PlayerMacs[0]).ConfigureAwait(false);

        if (success)
        {
            session.State = PlaybackState.Paused;
        }

        return success;
    }

    /// <summary>
    /// Resumes a paused playback session.
    /// </summary>
    /// <param name="sessionId">The session ID.</param>
    /// <returns>True if successful.</returns>
    public async Task<bool> ResumeSessionAsync(string sessionId)
    {
        if (!_sessions.TryGetValue(sessionId, out var session))
        {
            return false;
        }

        var success = await _lmsClient.PlayAsync(session.PlayerMacs[0]).ConfigureAwait(false);

        if (success)
        {
            session.State = PlaybackState.Playing;
        }

        return success;
    }

    /// <summary>
    /// Stops a playback session.
    /// </summary>
    /// <param name="sessionId">The session ID.</param>
    /// <returns>True if successful.</returns>
    public async Task<bool> StopSessionAsync(string sessionId)
    {
        if (!_sessions.TryGetValue(sessionId, out var session))
        {
            return false;
        }

        var success = await _lmsClient.StopAsync(session.PlayerMacs[0]).ConfigureAwait(false);

        if (success)
        {
            session.State = PlaybackState.Stopped;

            // Unsync players if there were multiple
            if (session.PlayerMacs.Count > 1)
            {
                await _playerManager.DissolveSyncGroupAsync(session.PlayerMacs[0]).ConfigureAwait(false);
            }
        }

        // Remove the session
        _sessions.TryRemove(sessionId, out _);

        return success;
    }

    /// <summary>
    /// Seeks to a position in the playback session.
    /// </summary>
    /// <param name="sessionId">The session ID.</param>
    /// <param name="positionTicks">The position in ticks.</param>
    /// <returns>True if successful.</returns>
    public async Task<bool> SeekAsync(string sessionId, long positionTicks)
    {
        if (!_sessions.TryGetValue(sessionId, out var session))
        {
            return false;
        }

        var positionSeconds = positionTicks / TimeSpan.TicksPerSecond;
        var success = await _lmsClient.SeekAsync(session.PlayerMacs[0], positionSeconds).ConfigureAwait(false);

        if (success)
        {
            session.PositionTicks = positionTicks;
        }

        return success;
    }

    /// <summary>
    /// Sets the volume for all players in a session.
    /// </summary>
    /// <param name="sessionId">The session ID.</param>
    /// <param name="volume">The volume level (0-100).</param>
    /// <returns>True if successful.</returns>
    public async Task<bool> SetVolumeAsync(string sessionId, int volume)
    {
        if (!_sessions.TryGetValue(sessionId, out var session))
        {
            return false;
        }

        var success = true;
        foreach (var mac in session.PlayerMacs)
        {
            if (!await _lmsClient.SetVolumeAsync(mac, volume).ConfigureAwait(false))
            {
                success = false;
            }
        }

        return success;
    }

    /// <summary>
    /// Updates the session state from LMS.
    /// </summary>
    /// <param name="sessionId">The session ID.</param>
    /// <returns>A task representing the operation.</returns>
    public async Task RefreshSessionStateAsync(string sessionId)
    {
        if (!_sessions.TryGetValue(sessionId, out var session))
        {
            return;
        }

        var status = await _lmsClient.GetPlayerStatusAsync(session.PlayerMacs[0]).ConfigureAwait(false);
        if (status == null)
        {
            return;
        }

        session.PositionTicks = (long)(status.Time * TimeSpan.TicksPerSecond);
        session.State = status.Mode switch
        {
            "play" => PlaybackState.Playing,
            "pause" => PlaybackState.Paused,
            _ => PlaybackState.Stopped
        };
    }

    private string BuildStreamUrl(Guid itemId)
    {
        var baseUrl = Config.JellyfinServerUrl.TrimEnd('/');
        // Direct stream URL - LMS will pull audio from Jellyfin
        return $"{baseUrl}/Audio/{itemId}/stream.mp3";
    }

    /// <inheritdoc />
    public Task StartAsync(CancellationToken cancellationToken)
    {
        _logger.LogInformation("LMS Session Manager started");
        return Task.CompletedTask;
    }

    /// <inheritdoc />
    public Task StopAsync(CancellationToken cancellationToken)
    {
        _logger.LogInformation("LMS Session Manager stopping");

        // Stop all active sessions
        foreach (var sessionId in _sessions.Keys.ToList())
        {
            _ = StopSessionAsync(sessionId);
        }

        return Task.CompletedTask;
    }
}