import 'dart:io';
import 'dart:async';
import 'dart:convert';
import 'package:shelf/shelf.dart';
import 'package:shelf/shelf_io.dart' as shelf_io;
import 'package:shelf_static/shelf_static.dart';
import 'package:shelf_router/shelf_router.dart';
import 'package:http/http.dart' as http;
import 'package:args/args.dart';
import 'database/database.dart';
import 'api/auth_handler.dart';
import 'api/users_handler.dart';
import 'api/playlists_handler.dart';
import 'middleware/auth_middleware.dart';

void main(List<String> args) async {
  // Parse command line arguments
  final parser = ArgParser()
    ..addOption('port', abbr: 'p', defaultsTo: '8089')
    ..addOption('path', defaultsTo: '/app/web');
  
  final result = parser.parse(args);
  final port = int.parse(result['port']);
  final webPath = result['path'];

  // Initialize database
  final db = AppDatabase();
  await db.init();
  await db.seedAdmin();

  // Create API handlers
  final authHandler = AuthHandler(db);
  final playlistsHandler = PlaylistsHandler(db);
  final usersHandler = UsersHandler(db);

  // Setup router
  final apiRouter = Router()
    // Auth endpoints (no auth middleware) - full path including /api/
    ..mount('/api/auth', authHandler.router)
    // Playlists endpoints (with auth middleware)
    ..mount('/api/playlists', Pipeline()
      .addMiddleware(authMiddleware(db))
      .addHandler(playlistsHandler.router.call))
    // Users endpoints (with auth middleware)
    ..mount('/api/users', Pipeline()
      .addMiddleware(authMiddleware(db))
      .addHandler(usersHandler.router.call));

  // Create handlers
  final staticHandler = createStaticHandler(
    webPath,
    defaultDocument: 'index.html',
    listDirectories: false,
  );

  // Main handler with API proxy and FFmpeg streaming
  final handler = Cascade()
    .add(_createApiHandler(apiRouter))
    .add(_createStreamHandler())  // FFmpeg streaming endpoint
    .add(_createXtreamProxyHandler())
    // .add(_createHlsHandler())  // REMOVED: HLS obsolete with direct stream
    .add(staticHandler)
    .handler;

  // Add middleware
  final pipeline = Pipeline()
    .addMiddleware(logRequests())
    .addMiddleware(_corsMiddleware())
    .addHandler(handler);

  // Start server
  final server = await shelf_io.serve(
    pipeline,
    InternetAddress.anyIPv4,
    port,
  );

  print('Server started on port ${server.port}');
  print('Serving static files from: $webPath');
  print('REST API available at: /api/auth/* and /api/playlists/*');
  print('Xtream proxy available at: /api/xtream/*');
  print('FFmpeg streaming available at: /api/stream/*');
  
  // Clean expired sessions periodically (every hour)
  Timer.periodic(const Duration(hours: 1), (_) {
    db.cleanExpiredSessions();
    print('Cleaned expired sessions');
  });
}

/// Create API handler
Handler _createApiHandler(Router apiRouter) {
  return (Request request) async {
    final path = request.url.path;
    
    // Only handle /api/* requests (excluding /api/xtream)
    if (path.startsWith('api/') && !path.startsWith('api/xtream/')) {
      return apiRouter(request);
    }
    
    return Response.notFound('Not found');
  };
}

/// CORS middleware to allow cross-origin requests
Middleware _corsMiddleware() {
  return (Handler handler) {
    return (Request request) async {
      // Handle preflight requests
      if (request.method == 'OPTIONS') {
        return Response.ok('', headers: _corsHeaders);
      }

      // Process request and add CORS headers to response
      final response = await handler(request);
      return response.change(headers: _corsHeaders);
    };
  };
}

final _corsHeaders = {
  'Access-Control-Allow-Origin': '*',
  'Access-Control-Allow-Methods': 'GET, POST, PUT, DELETE, OPTIONS',
  'Access-Control-Allow-Headers': 'Origin, Content-Type, Accept, Authorization',
};

/// Create Xtream proxy handler with M3U8 URL rewriting support
Handler _createXtreamProxyHandler() {
  return (Request request) async {
    final path = request.url.path;

    // Only handle /api/xtream/* requests
    if (!path.startsWith('api/xtream/')) {
      return Response.notFound('Not found');
    }

    try {
      // Extract target URL from request
      // Format: /api/xtream/http://server:port/path
      // Note: URL might be URL-encoded (e.g., http%3A%2F%2F...)
      String apiPath = path.substring('api/xtream/'.length);
      
      // Decode URL if it's encoded (http%3A%2F%2F -> http://)
      if (apiPath.startsWith('http%3A') || apiPath.startsWith('https%3A')) {
        apiPath = Uri.decodeComponent(apiPath);
      }
      
      // The client will send the full URL after /api/xtream/
      if (!apiPath.startsWith('http://') && !apiPath.startsWith('https://')) {
        return Response.badRequest(
          body: 'Invalid API URL. Expected format: /api/xtream/http://...',
        );
      }

      // Reconstruct the full target URL with query parameters
      String fullUrl = apiPath;
      if (request.url.query.isNotEmpty) {
        // If the target URL already has query params, append with &
        if (fullUrl.contains('?')) {
          fullUrl = '$fullUrl&${request.url.query}';
        } else {
          fullUrl = '$fullUrl?${request.url.query}';
        }
      }
      
      final targetUrl = Uri.parse(fullUrl);
      final baseUrl = '${targetUrl.scheme}://${targetUrl.host}${targetUrl.hasPort ? ':${targetUrl.port}' : ''}';
      
      // Check if this is a video file that needs streaming
      final lowerPath = targetUrl.path.toLowerCase();
      final isVideoFile = lowerPath.endsWith('.mp4') || 
                          lowerPath.endsWith('.mkv') || 
                          lowerPath.endsWith('.avi') ||
                          lowerPath.endsWith('.ts') ||
                          lowerPath.endsWith('.m4v') ||
                          lowerPath.contains('/movie/') ||
                          lowerPath.contains('/series/');

      print('Proxying request to: $targetUrl (video streaming: $isVideoFile)');

      // For video files, use streaming with Range support for seeking
      if (isVideoFile) {
        final rangeHeader = request.headers['range'];
        return _streamVideoFile(targetUrl, rangeHeader);
      }

      // Headers to simulate a legitimate IPTV client (VLC/Kodi style)
      final proxyHeaders = {
        'User-Agent': 'VLC/3.0.18 LibVLC/3.0.18',
        'Accept': '*/*',
        'Accept-Encoding': 'identity',
        'Connection': 'keep-alive',
        'Icy-MetaData': '1',
      };

      // Use simple http.get/post for non-video content
      http.Response response;
      if (request.method == 'GET') {
        response = await http.get(targetUrl, headers: proxyHeaders).timeout(
          const Duration(seconds: 30),
          onTimeout: () => http.Response('Request timeout', 504),
        );
      } else if (request.method == 'POST') {
        final body = await request.readAsString();
        response = await http.post(targetUrl, headers: proxyHeaders, body: body).timeout(
          const Duration(seconds: 30),
          onTimeout: () => http.Response('Request timeout', 504),
        );
      } else {
        return Response(405, body: 'Method not allowed');
      }

      // Check if this is an M3U8/HLS playlist that needs URL rewriting
      final contentType = response.headers['content-type'] ?? '';
      final isM3u8 = fullUrl.endsWith('.m3u8') || 
                     contentType.contains('application/vnd.apple.mpegurl') ||
                     contentType.contains('application/x-mpegurl') ||
                     contentType.contains('audio/mpegurl');

      if (isM3u8 && response.statusCode == 200) {
        // Rewrite URLs in M3U8 playlist to go through proxy
        final rewrittenBody = _rewriteM3u8Urls(
          response.body, 
          baseUrl, 
          targetUrl.path,
          request.requestedUri.origin,
        );
        
        print('Rewrote M3U8 playlist URLs for: $targetUrl');
        
        return Response(
          response.statusCode,
          body: rewrittenBody,
          headers: {
            'content-type': 'application/vnd.apple.mpegurl',
            'access-control-allow-origin': '*',
          },
        );
      }

      return Response(
        response.statusCode,
        body: response.bodyBytes,
        headers: {
          'content-type': response.headers['content-type'] ?? 'application/json',
          'access-control-allow-origin': '*',
        },
      );
    } catch (e, stackTrace) {
      print('Proxy error: $e');
      print(stackTrace);
      return Response.internalServerError(
        body: jsonEncode({'error': 'Proxy error', 'message': e.toString()}),
        headers: {'content-type': 'application/json'},
      );
    }
  };
}

/// Stream video file using HttpClient with Range support for seeking
Future<Response> _streamVideoFile(Uri targetUrl, String? rangeHeader) async {
  try {
    final client = HttpClient();
    // Increase timeouts for large video files
    client.connectionTimeout = const Duration(seconds: 60);
    client.idleTimeout = const Duration(minutes: 5);  // Keep connection alive longer
    
    final req = await client.getUrl(targetUrl);
    req.headers.set('User-Agent', 'VLC/3.0.18 LibVLC/3.0.18');
    req.headers.set('Accept', '*/*');
    req.headers.set('Connection', 'keep-alive');
    req.headers.set('Accept-Encoding', 'identity');  // Don't compress video
    
    // Forward the Range header for seeking support
    if (rangeHeader != null && rangeHeader.isNotEmpty) {
      req.headers.set('Range', rangeHeader);
      print('Video streaming with Range: $rangeHeader');
    }
    
    final response = await req.close();
    
    // Get content type from response
    final contentType = response.headers.contentType?.mimeType ?? 'video/mp4';
    
    // Build response headers for optimal streaming/buffering
    final responseHeaders = <String, String>{
      'content-type': contentType,
      'access-control-allow-origin': '*',
      'accept-ranges': 'bytes',
      'cache-control': 'no-cache',  // Allow browser to cache but revalidate
      'connection': 'keep-alive',
    };
    
    // Add Content-Length if available (critical for seeking)
    if (response.contentLength > 0) {
      responseHeaders['content-length'] = response.contentLength.toString();
    }
    
    // Add Content-Range if this is a partial response (206)
    final contentRange = response.headers.value('content-range');
    if (contentRange != null) {
      responseHeaders['content-range'] = contentRange;
    }
    
    // Return appropriate status code (200 for full, 206 for partial)
    return Response(
      response.statusCode,
      body: response,
      headers: responseHeaders,
    );
  } catch (e) {
    print('Video streaming error: $e');
    return Response.internalServerError(
      body: jsonEncode({'error': 'Video streaming error', 'message': e.toString()}),
      headers: {'content-type': 'application/json'},
    );
  }
}

/// Rewrite URLs in M3U8 playlist to go through the proxy
/// 
/// Handles both relative and absolute URLs in HLS playlists
String _rewriteM3u8Urls(String m3u8Content, String baseUrl, String originalPath, String proxyOrigin) {
  final lines = m3u8Content.split('\n');
  final rewrittenLines = <String>[];
  
  // Get directory path for relative URL resolution
  final pathSegments = originalPath.split('/');
  pathSegments.removeLast(); // Remove filename
  final basePath = pathSegments.join('/');
  
  for (final line in lines) {
    final trimmedLine = line.trim();
    
    // Skip empty lines and comments (except URI in comments)
    if (trimmedLine.isEmpty) {
      rewrittenLines.add(line);
      continue;
    }
    
    // Handle lines that contain URLs (not starting with #, or EXT-X-KEY/EXT-X-MAP with URI)
    if (!trimmedLine.startsWith('#')) {
      // This is a segment URL
      final rewrittenUrl = _rewriteUrl(trimmedLine, baseUrl, basePath, proxyOrigin);
      rewrittenLines.add(rewrittenUrl);
    } else if (trimmedLine.contains('URI="')) {
      // Handle EXT-X-KEY, EXT-X-MAP, etc. with URI attribute
      final rewrittenLine = trimmedLine.replaceAllMapped(
        RegExp(r'URI="([^"]+)"'),
        (match) {
          final uri = match.group(1)!;
          final rewrittenUri = _rewriteUrl(uri, baseUrl, basePath, proxyOrigin);
          return 'URI="$rewrittenUri"';
        },
      );
      rewrittenLines.add(rewrittenLine);
    } else {
      rewrittenLines.add(line);
    }
  }
  
  return rewrittenLines.join('\n');
}

/// Rewrite a single URL to go through the proxy
String _rewriteUrl(String url, String baseUrl, String basePath, String proxyOrigin) {
  String fullUrl;
  
  if (url.startsWith('http://') || url.startsWith('https://')) {
    // Already absolute URL
    fullUrl = url;
  } else if (url.startsWith('/')) {
    // Absolute path, relative to server root
    fullUrl = '$baseUrl$url';
  } else {
    // Relative path, relative to current directory
    fullUrl = '$baseUrl$basePath/$url';
  }
  
  // Wrap with proxy
  return '$proxyOrigin/api/xtream/$fullUrl';
}

// ============================================
// FFmpeg Stream Transcoding Handler
// ============================================

/// Active FFmpeg processes by stream ID
final Map<String, Process> _activeStreams = {};

/// Create handler for FFmpeg streaming
/// 
/// This endpoint starts an FFmpeg process that connects to the IPTV server
/// with proper headers and transcodes the stream to local HLS files.
Handler _createStreamHandler() {
  return (Request request) async {
    final path = request.url.path;

    // Only handle /api/stream/* requests
    if (!path.startsWith('api/stream/')) {
      return Response.notFound('Not found');
    }

    try {
      // Extract stream ID
      final pathParts = path.split('/');
      if (pathParts.length < 3) {
        return Response.badRequest(body: 'Invalid stream path');
      }
      
      final streamId = pathParts[2];
      
      // Get parameters
      final iptvUrl = request.url.queryParameters['url'];
      if (iptvUrl == null || iptvUrl.isEmpty) {
        return Response.badRequest(body: 'Missing url parameter');
      }

      print('Starting Direct Stream for ID: $streamId');
      print('Source: $iptvUrl');

      // Setup FFmpeg arguments for fMP4 piping
      // Determine if it's VOD or Live
      final isVod = streamId.startsWith('vod_'); // Or use extension check
      
      final ffmpegArgs = <String>[
        '-hide_banner',
        '-loglevel', 'error', // Minimize logs, only errors
        '-user_agent', 'VLC/3.0.18 LibVLC/3.0.18',
        '-headers', 'Accept: */*\r\nConnection: keep-alive\r\n',
        
        // Input resilience flags
        '-reconnect', '1',
        '-reconnect_streamed', '1',
        '-reconnect_delay_max', '10',
        '-reconnect_on_network_error', '1',
        '-reconnect_on_http_error', '4xx,5xx',
        '-rw_timeout', '15000000', // 15s timeout
        
        // Probing settings to ensure stream detection
        '-analyzeduration', '20000000', // 20s
        '-probesize', '10000000',      // 10MB
        
        '-i', iptvUrl,
        
        // Output format: MPEG-TS for streaming (compatible with mpegts.js)
        '-f', 'mpegts',
        
        // Video: Copy is BEST for performance (0% CPU)
        // Browsers support H.264 well.
        '-c:v', 'copy',
        
        // Audio: Transcode to AAC is SAFEST for browsers
        // (Many IPTV streams typically use MP2/AC3 which browsers hate)
        '-c:a', 'aac',
        '-b:a', '128k',
        '-ar', '44100',
        '-ac', '2',
        
        // Fix for MPEG-TS timestamps
        '-fflags', '+genpts',
        
        // Output to stdout pipe
        'pipe:1'
      ];

      // Start the process
      final process = await Process.start('ffmpeg', ffmpegArgs);
      
      // Manage process lifecycle
      // We use a StreamController to pipe stdout to the response
      // AND detect when the client disconnects to kill the process.
      final controller = StreamController<List<int>>();
      
      // Pipe stdout to controller
      process.stdout.listen(
        (data) {
          if (!controller.isClosed) controller.add(data);
        },
        onError: (e) {
          print('FFmpeg stdout error: $e');
          if (!controller.isClosed) controller.addError(e);
        },
        onDone: () {
          print('FFmpeg process finished for $streamId');
          if (!controller.isClosed) controller.close();
        },
      );

      // Log stderr for debug
      process.stderr.transform(utf8.decoder).listen((data) {
        if (data.contains('Error') || data.contains('error')) {
          print('FFmpeg Error [$streamId]: $data');
        }
      });

      // CLEANUP: When the HTTP client disconnects, the stream subscription
      // will be cancelled. We MUST kill the FFmpeg process then.
      controller.onCancel = () {
        print('Client disconnected for $streamId. Killing FFmpeg...');
        process.kill();
      };

      return Response.ok(
        controller.stream,
        headers: {
          'Content-Type': 'video/MP2T',
          'Access-Control-Allow-Origin': '*',
          'Cache-Control': 'no-cache, no-store',
          'Connection': 'keep-alive',
        },
      );

    } catch (e, stackTrace) {
      print('Stream setup error: $e');
      print(stackTrace);
      return Response.internalServerError(
        body: jsonEncode({'error': 'Stream setup error', 'message': e.toString()}),
        headers: {'content-type': 'application/json'},
      );
    }
  };
}