import 'package:flutter/foundation.dart' show kIsWeb;
import 'package:flutter/material.dart';
import 'package:flutter_downloader/flutter_downloader.dart';
import 'package:permission_handler/permission_handler.dart';
import 'package:youtube_player_iframe/youtube_player_iframe.dart' as yt_iframe; 
import 'package:url_launcher/url_launcher.dart';
import 'package:provider/provider.dart';
import 'package:video_player/video_player.dart';
import 'package:chewie/chewie.dart';
import 'dart:async';

import '../models/app_models.dart';
import '../services/i18n_service.dart';
import '../services/toast_service.dart';
import '../screens/pdf_viewer_screen.dart';

class LessonDetailSheet extends StatefulWidget {
  final QuickLesson lesson;
  final bool isCompleted;
  final Function(QuickLesson) onMarkComplete;

  const LessonDetailSheet({
    super.key,
    required this.lesson,
    required this.isCompleted,
    required this.onMarkComplete,
  });

  @override
  State<LessonDetailSheet> createState() => _LessonDetailSheetState();
}

class _LessonDetailSheetState extends State<LessonDetailSheet> with WidgetsBindingObserver {
  // Controllers
  yt_iframe.YoutubePlayerController? _ytIframeController; 
  VideoPlayerController? _videoPlayerController;
  ChewieController? _chewieController;
  
  StreamSubscription? _ytSubscription;

  // State flags
  bool _isLoading = true;
  bool _useExternalFallback = false;
  bool _playerInitialized = false;

  @override
  void initState() {
    super.initState();
    WidgetsBinding.instance.addObserver(this);
    _initializePlayer();
  }

  @override
  void didChangeAppLifecycleState(AppLifecycleState state) {
    if (_videoPlayerController != null) {
      try {
        if (state == AppLifecycleState.paused && _videoPlayerController!.value.isPlaying) {
          _videoPlayerController!.pause();
        }
      } catch (e) {
        print('LessonDetailSheet: erro ao pausar VideoPlayer -> $e');
      }
    }
  }

  @override
  void dispose() {
    WidgetsBinding.instance.removeObserver(this);
    
    _ytSubscription?.cancel();
    
    _chewieController?.dispose();
    _videoPlayerController?.dispose();
    
    super.dispose();
  }

  // MÉTODO FALLBACK: Adicionada verificação `mounted` antes de setState
  void _activateExternalFallback() {
    if (!mounted) return;

    _ytSubscription?.cancel();
    _ytIframeController = null;

    _chewieController?.dispose();
    _videoPlayerController?.dispose();
    _videoPlayerController = null;
    _chewieController = null;

    // ✅ CORRIGIDO: Só chama setState se o widget ainda estiver montado
    setState(() {
      _useExternalFallback = true;
      _isLoading = false;
    });
  }

  Future<void> _initializePlayer() async {
    if (_playerInitialized) return;
    _playerInitialized = true;
    if (!mounted) return;

    final rawUrl = widget.lesson.videoUrl;
    if (rawUrl == null || rawUrl.trim().isEmpty) {
      print('LessonDetailSheet: videoUrl vazio');
      _activateExternalFallback();
      return;
    }

    final videoUrl = rawUrl.trim();

    String? youtubeId;
    try {
      youtubeId = yt_iframe.YoutubePlayerController.convertUrlToId(videoUrl);
      print('LessonDetailSheet: convertUrlToId -> $youtubeId for $videoUrl');
    } catch (e) {
      youtubeId = null;
      print('LessonDetailSheet: erro convertUrlToId: $e');
    }

    if (youtubeId != null && youtubeId.isNotEmpty) {
      try {
        // ✅ CORRIGIDO: autoPlay é passado no construtor, não dentro de params.
        _ytIframeController = yt_iframe.YoutubePlayerController.fromVideoId(
          videoId: youtubeId, 
          autoPlay: kIsWeb, // Correção de erro: movemos para o local correto
          params: const yt_iframe.YoutubePlayerParams(
            showControls: true,
            showFullscreenButton: true,
            strictRelatedVideos: true,
            playsInline: true,
            mute: kIsWeb,
          ),
        );
        
        _ytSubscription?.cancel();
        _ytSubscription = _ytIframeController!.stream.listen((event) {
          
          if (event.error != null) { 
            print('LessonDetailSheet: Youtube Player Runtime Error: ${event.error}. State: ${event.playerState}. Forçando fallback.');
            // ✅ CORRIGIDO: Garante que o fallback seja chamado apenas se o widget estiver montado.
            Future.microtask(() {
                if(mounted) {
                    _activateExternalFallback();
                }
            });
          }
        });

        await Future.delayed(const Duration(milliseconds: 200));
        
        if (mounted) {
          setState(() {
            _isLoading = false;
            _useExternalFallback = false;
          });
        }
      } catch (e) {
        print('LessonDetailSheet: falha ao inicializar yt iframe controller: $e');
        _activateExternalFallback();
      }

      return;
    }

    // Tenta VideoPlayer + Chewie
    try {
      _videoPlayerController = VideoPlayerController.networkUrl(Uri.parse(videoUrl));
      await _videoPlayerController!.initialize();
      _chewieController = ChewieController(
        videoPlayerController: _videoPlayerController!,
        autoPlay: true,
        looping: false,
        allowFullScreen: true,
        aspectRatio: _videoPlayerController!.value.isInitialized
            ? _videoPlayerController!.value.aspectRatio
            : 16 / 9,
        placeholder: const Center(
          child: CircularProgressIndicator(color: Color(0xFFE94560)),
        ),
        errorBuilder: (context, errorMessage) {
          print('LessonDetailSheet: Chewie errorBuilder -> $errorMessage');
          return const Center(
            child: Padding(
              padding: EdgeInsets.all(16.0),
              child: Text(
                'Erro ao carregar o vídeo. Tente o botão abaixo.',
                style: TextStyle(color: Colors.white),
                textAlign: TextAlign.center,
              ),
            ),
          );
        },
      );

      if (mounted) {
        setState(() {
          _isLoading = false;
          _useExternalFallback = false;
        });
      }
    } catch (e) {
      print('LessonDetailSheet: falha VideoPlayer/Chewie -> $e');
      _videoPlayerController?.dispose();
      _videoPlayerController = null;
      _chewieController?.dispose();
      _chewieController = null;
      _activateExternalFallback();
    }
  }

  Widget _buildExternalPlayerFallback() {
    final url = widget.lesson.videoUrl;
    final i18n = Provider.of<I18nService>(context, listen: false);

    return Container(
      height: 250, 
      color: const Color(0xFF1A1A2E),
      child: Center(
        child: Column(
          mainAxisAlignment: MainAxisAlignment.center,
          children: [
            const Icon(Icons.videocam_off, color: Color(0xFFE94560), size: 50),
            const SizedBox(height: 16),
            const Padding(
              padding: EdgeInsets.symmetric(horizontal: 20.0),
              child: Text(
                'O player nativo falhou (pode ser devido a restrições de rede ou incompatibilidade na Web). Abra o vídeo diretamente no navegador.',
                style: TextStyle(color: Colors.white, fontSize: 16),
                textAlign: TextAlign.center,
              ),
            ),
            const SizedBox(height: 16),
            ElevatedButton.icon(
              onPressed: () async {
                if (url != null && url.isNotEmpty) {
                  final uri = Uri.parse(url);
                  await launchUrl(uri, mode: LaunchMode.externalApplication);
                } else {
                  ToastService.show(
                      message: i18n.t('URL de vídeo não disponível.'),
                      type: ToastType.error, );
                }
              },
              icon: const Icon(Icons.open_in_new),
              label: const Text('Abrir no Navegador'),
              style: ElevatedButton.styleFrom(
                backgroundColor: const Color(0xFFE94560),
                foregroundColor: Colors.white,
              ),
            ),
          ],
        ),
      ),
    );
  }

  Widget _buildVideoPlayer() {
    return Container(
      height: 250, 
      decoration: const BoxDecoration(
        gradient: LinearGradient(
          colors: [Color(0xFF553C9A), Color(0xFF282A52)],
          begin: Alignment.topCenter,
          end: Alignment.bottomCenter,
        ),
        borderRadius: BorderRadius.vertical(top: Radius.circular(30)),
      ),
      child: _isLoading
          ? const Center(child: CircularProgressIndicator(color: Color(0xFFE94560)))
          : ClipRRect(
              borderRadius: const BorderRadius.vertical(top: Radius.circular(30)),
              child: Builder(
                builder: (context) {
                  if (_ytIframeController != null) {
                    return yt_iframe.YoutubePlayer(
                      controller: _ytIframeController!,
                      aspectRatio: 16 / 9,
                    );
                  }

                  if (_chewieController != null) {
                    return Chewie(controller: _chewieController!);
                  }

                  if (_useExternalFallback) {
                    return _buildExternalPlayerFallback(); 
                  }

                  return const Center(
                    child: Text(
                      'URL de vídeo inválida ou não disponível.',
                      style: TextStyle(color: Colors.white),
                      textAlign: TextAlign.center,
                    ),
                  );
                },
              ),
            ),
    );
  }

  Future<void> _downloadFile(String url, String fileName) async {
    final i18n = Provider.of<I18nService>(context, listen: false);

    if (yt_iframe.YoutubePlayerController.convertUrlToId(url) != null) {
      ToastService.show(
        message: 'Não é possível fazer o download de vídeos do YouTube diretamente.',
        type: ToastType.error,
      );
      return;
    }

    if (url.isEmpty) {
      ToastService.show(
        message: 'A URL do recurso não está disponível.',
        type: ToastType.error,
      );
      return;
    }

    if (Theme.of(context).platform == TargetPlatform.android ||
        Theme.of(context).platform == TargetPlatform.iOS) {
      final status = await Permission.storage.request();
      if (status.isGranted) {
        await FlutterDownloader.enqueue(
          url: url,
          savedDir: '/storage/emulated/0/Download', 
          fileName: fileName,
          showNotification: true,
          openFileFromNotification: true,
        );
        ToastService.show(message: 'Download iniciado');
      } else {
        ToastService.show(
          message: 'Permissão de armazenamento negada',
          type: ToastType.error,
        );
      }
    } else {
      try {
        if (await canLaunchUrl(Uri.parse(url))) {
          await launchUrl(Uri.parse(url), mode: LaunchMode.externalApplication);
          ToastService.show(message: 'Download iniciado no navegador');
        } else {
          ToastService.show(
            message: 'Não foi possível iniciar o download. Verifique a URL.',
            type: ToastType.error,
          );
        }
      } catch (e) {
        ToastService.show(
          message: 'Ocorreu um erro ao iniciar o download: $e',
          type: ToastType.error,
        );
      }
    }
  }

  // --- Widgets de UI ---

  Widget _buildLessonHeader(I18nService i18n) {
    return ShaderMask(
      shaderCallback: (bounds) => const LinearGradient(
        colors: [Color(0xFFE94560), Color(0xFFF07E3F)],
      ).createShader(bounds),
      child: Text(
        widget.lesson.titulo ?? '',
        style: const TextStyle(
          fontSize: 28,
          fontWeight: FontWeight.bold,
          color: Colors.white,
        ),
      ),
    );
  }

  Widget _buildLessonContent() {
    return Text(
      widget.lesson.conteudo ?? '',
      style: TextStyle(
        fontSize: 16,
        color: Colors.white.withOpacity(0.8),
      ),
    );
  }

  // ✅ Mantido o uso de Expanded para garantir que a Row se ajusta
  Widget _buildVideoActions(I18nService i18n) {
    return Row(
      children: [
        // Duração: Ocupa 1/3 do espaço
        Expanded(
          flex: 1, 
          child: _buildDurationWidget(i18n),
        ),
        const SizedBox(width: 8),
        // Download: Ocupa 2/3 do espaço
        Expanded(
          flex: 2, 
          child: _buildDownloadVideoButton(i18n),
        ),
      ],
    );
  }

  Widget _buildBookSection(I18nService i18n) {
    return Column(
      crossAxisAlignment: CrossAxisAlignment.start,
      children: [
        const SizedBox(height: 24),
        Text(
          'Recursos Adicionais',
          style: TextStyle(
            fontSize: 20,
            fontWeight: FontWeight.bold,
            color: Colors.white.withOpacity(0.9),
          ),
        ),
        const SizedBox(height: 12),
        _buildReadBookOnlineButton(i18n),
        const SizedBox(height: 16),
        _buildDownloadBookButton(i18n),
      ],
    );
  }

  // ✅ CORREÇÃO FINAL DE LAYOUT: Otimizado para evitar overflow vertical e horizontal
  Widget _buildDurationWidget(I18nService i18n) {
    return Container(
      padding: const EdgeInsets.symmetric(horizontal: 8, vertical: 8), 
      decoration: BoxDecoration(
        gradient: const LinearGradient(
          colors: [Color(0xFF553C9A), Color(0xFF282A52)],
          begin: Alignment.centerLeft,
          end: Alignment.centerRight,
        ),
        borderRadius: BorderRadius.circular(20),
        boxShadow: [
          BoxShadow(
            color: Colors.black.withOpacity(0.3),
            blurRadius: 10,
            offset: const Offset(0, 5),
          ),
        ],
      ),
      child: Center(
        child: Row(
          mainAxisAlignment: MainAxisAlignment.center,
          children: [
            const Icon(Icons.access_time_rounded, size: 20, color: Colors.white),
            const SizedBox(width: 4),
            // Força o texto a quebrar ou a usar '...' se o espaço no Expanded for muito pequeno
            Flexible( 
              child: Text(
                '${i18n.t('duration')}: ${widget.lesson.duracao ?? ''}', 
                style: const TextStyle(
                  fontSize: 14,
                  color: Colors.white,
                  fontWeight: FontWeight.w600,
                ),
                overflow: TextOverflow.ellipsis,
              ),
            ),
          ],
        ),
      ),
    );
  }

  Widget _buildMarkCompleteButton(I18nService i18n) {
    return Container(
      width: double.infinity,
      decoration: BoxDecoration(
        borderRadius: BorderRadius.circular(30),
        gradient: widget.isCompleted
            ? const LinearGradient(
                colors: [Colors.green, Colors.greenAccent],
                begin: Alignment.centerLeft,
                end: Alignment.centerRight,
              )
            : const LinearGradient(
                colors: [Color(0xFFE94560), Color(0xFFF07E3F)],
                begin: Alignment.centerLeft,
                end: Alignment.centerRight,
              ),
        boxShadow: [
          BoxShadow(
            color: Colors.black.withOpacity(0.4),
            blurRadius: 10,
            offset: const Offset(0, 5),
          ),
        ],
      ),
      child: ElevatedButton.icon(
        onPressed: widget.isCompleted
            ? null
            : () {
                widget.onMarkComplete(widget.lesson);
                Navigator.pop(context);
                ToastService.show(message: i18n.t('lesson_completed'));
              },
        icon: widget.isCompleted
            ? const Icon(Icons.check_circle_rounded, color: Colors.white)
            : const Icon(Icons.check_circle_outline_rounded, color: Colors.white),
        label: Text(
          widget.isCompleted ? i18n.t('completed') : i18n.t('mark_as_complete'),
          style: const TextStyle(fontWeight: FontWeight.bold),
        ),
        style: ElevatedButton.styleFrom(
          foregroundColor: Colors.white,
          backgroundColor: Colors.transparent,
          shadowColor: Colors.transparent,
          shape: RoundedRectangleBorder(
            borderRadius: BorderRadius.circular(25),
          ),
          padding: const EdgeInsets.symmetric(horizontal: 20, vertical: 12),
          elevation: 0,
        ),
      ),
    );
  }

  Widget _buildDownloadVideoButton(I18nService i18n) {
    return InkWell(
      onTap: () {
        if (widget.lesson.videoUrl != null) {
          _downloadFile(widget.lesson.videoUrl!, widget.lesson.titulo ?? 'video');
        } else {
          ToastService.show(
              message: i18n.t('URL do vídeo não disponível.'), type: ToastType.error);
        }
      },
      child: Container(
        height: 50,
        padding: const EdgeInsets.symmetric(horizontal: 16),
        decoration: BoxDecoration(
          borderRadius: BorderRadius.circular(30),
          gradient: const LinearGradient(
            colors: [Color(0xFFE94560), Color(0xFFF07E3F)],
            begin: Alignment.centerLeft,
            end: Alignment.centerRight,
          ),
          boxShadow: [
            BoxShadow(
              color: const Color(0xFFE94560).withOpacity(0.4),
              blurRadius: 10,
              offset: const Offset(0, 5),
            ),
          ],
        ),
        child: Row(
          mainAxisAlignment: MainAxisAlignment.center,
          children: [
            const Icon(Icons.cloud_download_rounded, color: Colors.white, size: 24),
            const SizedBox(width: 8),
            Text(
              i18n.t('download_video'),
              style: const TextStyle(
                color: Colors.white,
                fontSize: 16,
                fontWeight: FontWeight.bold,
              ),
            ),
          ],
        ),
      ),
    );
  }

  Widget _buildReadBookOnlineButton(I18nService i18n) {
    return InkWell(
      onTap: () {
        if (widget.lesson.bookUrl != null && widget.lesson.bookUrl!.isNotEmpty) {
          if (kIsWeb) {
            launchUrl(Uri.parse(widget.lesson.bookUrl!), mode: LaunchMode.platformDefault);
          } else {
            Navigator.push(
              context,
              MaterialPageRoute(
                builder: (context) => PdfViewerScreen(pdfUrl: widget.lesson.bookUrl!),
              ),
            );
          }
        } else {
          ToastService.show(
            message: i18n.t('URL do livro não disponível.'),
            type: ToastType.error,
          );
        }
      },
      child: Container(
        height: 60,
        width: double.infinity,
        decoration: BoxDecoration(
          borderRadius: BorderRadius.circular(30),
          gradient: const LinearGradient(
            colors: [Color(0xFF553C9A), Color(0xFF4D2C8E)],
            begin: Alignment.centerLeft,
            end: Alignment.centerRight,
          ),
          boxShadow: [
            BoxShadow(
            color: const Color(0xFF553C9A).withOpacity(0.4),
            blurRadius: 10,
            offset: const Offset(0, 5),
            ),
          ],
        ),
        child: Center(
          child: Text(
            i18n.t('read_book_online'),
            style: const TextStyle(
              color: Colors.white,
              fontSize: 18,
              fontWeight: FontWeight.bold,
            ),
          ),
        ),
      ),
    );
  }

  Widget _buildDownloadBookButton(I18nService i18n) {
    return InkWell(
      onTap: () {
        if (widget.lesson.bookUrl != null) {
          _downloadFile(widget.lesson.bookUrl!, widget.lesson.titulo ?? 'livro');
        } else {
          ToastService.show(
              message: i18n.t('URL do livro não disponível.'), type: ToastType.error);
        }
      },
      child: Container(
        height: 60,
        width: double.infinity,
        decoration: BoxDecoration(
          borderRadius: BorderRadius.circular(30),
          gradient: const LinearGradient(
            colors: [Color(0xFF4D2C8E), Color(0xFF553C9A)],
            begin: Alignment.centerLeft,
            end: Alignment.centerRight,
          ),
          boxShadow: [
            BoxShadow(
              color: const Color(0xFF4D2C8E).withOpacity(0.4),
              blurRadius: 10,
              offset: const Offset(0, 5),
            ),
          ],
        ),
        child: Center(
          child: Text(
            i18n.t('download_book'),
            style: const TextStyle(
              color: Colors.white,
              fontSize: 18,
              fontWeight: FontWeight.bold,
            ),
          ),
        ),
      ),
    );
  }

  // Método build principal
  @override
  Widget build(BuildContext context) {
    final i18n = Provider.of<I18nService>(context);

    // O SingleChildScrollView evita que o conteúdo transborde verticalmente
    return SingleChildScrollView(
      child: Container(
        decoration: const BoxDecoration(
          color: Color(0xFF1A1A2E),
          borderRadius: BorderRadius.vertical(top: Radius.circular(30)),
        ),
        padding: const EdgeInsets.only(bottom: 20),
        child: Column(
          crossAxisAlignment: CrossAxisAlignment.start,
          mainAxisSize: MainAxisSize.min,
          children: [
            _buildVideoPlayer(),
            Padding(
              padding: const EdgeInsets.all(20.0),
              child: Column(
                crossAxisAlignment: CrossAxisAlignment.start,
                children: [
                  _buildLessonHeader(i18n),
                  const SizedBox(height: 8),
                  _buildLessonContent(),
                  const SizedBox(height: 24),
                  _buildVideoActions(i18n),
                  const SizedBox(height: 24),
                  _buildBookSection(i18n),
                  const SizedBox(height: 32),
                  _buildMarkCompleteButton(i18n),
                ],
              ),
            ),
          ],
        ),
      ),
    );
  }
}