import 'dart:typed_data';
import 'package:flutter/material.dart';
import '../../data/local/local_storage_service.dart';
import '../../data/immich/immich_service.dart';
import '../../data/immich/models/immich_asset.dart';

/// Screen for Immich media integration.
/// 
/// Displays images from Immich in a grid layout with pull-to-refresh.
/// Shows cached images first, then fetches from API.
class ImmichScreen extends StatefulWidget {
  final LocalStorageService? localStorageService;
  final ImmichService? immichService;

  const ImmichScreen({
    super.key,
    this.localStorageService,
    this.immichService,
  });

  @override
  State<ImmichScreen> createState() => _ImmichScreenState();
}

class _ImmichScreenState extends State<ImmichScreen> {
  List<ImmichAsset> _assets = [];
  bool _isLoading = false;
  String? _errorMessage;

  @override
  void initState() {
    super.initState();
    _loadAssets();
  }

  /// Loads assets from cache first, then fetches from API.
  Future<void> _loadAssets({bool forceRefresh = false}) async {
    if (widget.immichService == null) {
      setState(() {
        _errorMessage = 'Immich service not available';
        _isLoading = false;
      });
      return;
    }

    setState(() {
      _isLoading = !forceRefresh;
      _errorMessage = null;
    });

    try {
      // First, try to load cached assets
      if (!forceRefresh) {
        final cachedAssets = await widget.immichService!.getCachedAssets();
        if (cachedAssets.isNotEmpty) {
          setState(() {
            _assets = cachedAssets;
            _isLoading = false;
          });
          // Still fetch from API in background to update cache
          _fetchFromApi();
          return;
        }
      }

      // Fetch from API
      await _fetchFromApi();
    } catch (e) {
      setState(() {
        _errorMessage = 'Failed to load assets: ${e.toString()}';
        _isLoading = false;
      });
    }
  }

  /// Fetches assets from Immich API.
  Future<void> _fetchFromApi() async {
    try {
      final assets = await widget.immichService!.fetchAssets(limit: 100);
      setState(() {
        _assets = assets;
        _isLoading = false;
      });
    } catch (e) {
      setState(() {
        _errorMessage = 'Failed to fetch from Immich: ${e.toString()}';
        _isLoading = false;
      });
    }
  }

  /// Gets the thumbnail URL for an asset with proper headers.
  String _getThumbnailUrl(ImmichAsset asset) {
    return widget.immichService!.getThumbnailUrl(asset.id);
  }

  @override
  Widget build(BuildContext context) {
    return Scaffold(
      appBar: AppBar(
        title: const Text('Immich Media'),
        actions: [
          IconButton(
            icon: const Icon(Icons.info_outline),
            onPressed: _testServerConnection,
            tooltip: 'Test Server Connection',
          ),
          if (_assets.isNotEmpty)
            IconButton(
              icon: const Icon(Icons.refresh),
              onPressed: () => _loadAssets(forceRefresh: true),
              tooltip: 'Refresh',
            ),
        ],
      ),
      body: _buildBody(),
    );
  }

  Widget _buildBody() {
    if (_isLoading && _assets.isEmpty) {
      return const Center(
        child: CircularProgressIndicator(),
      );
    }

    if (_errorMessage != null && _assets.isEmpty) {
      return Center(
        child: Column(
          mainAxisAlignment: MainAxisAlignment.center,
          children: [
            const Icon(
              Icons.error_outline,
              size: 64,
              color: Colors.red,
            ),
            const SizedBox(height: 16),
            Text(
              _errorMessage!,
              style: const TextStyle(color: Colors.red),
              textAlign: TextAlign.center,
            ),
            const SizedBox(height: 16),
            ElevatedButton(
              onPressed: () => _loadAssets(forceRefresh: true),
              child: const Text('Retry'),
            ),
          ],
        ),
      );
    }

    if (_assets.isEmpty) {
      return Center(
        child: Column(
          mainAxisAlignment: MainAxisAlignment.center,
          children: [
            const Icon(
              Icons.photo_library_outlined,
              size: 64,
              color: Colors.grey,
            ),
            const SizedBox(height: 16),
            const Text(
              'No images found',
              style: TextStyle(fontSize: 18),
            ),
            const SizedBox(height: 8),
            const Text(
              'Pull down to refresh or upload images to Immich',
              style: TextStyle(color: Colors.grey),
              textAlign: TextAlign.center,
            ),
          ],
        ),
      );
    }

    return RefreshIndicator(
      onRefresh: () => _loadAssets(forceRefresh: true),
      child: GridView.builder(
        padding: const EdgeInsets.all(8),
        gridDelegate: const SliverGridDelegateWithFixedCrossAxisCount(
          crossAxisCount: 3,
          crossAxisSpacing: 8,
          mainAxisSpacing: 8,
          childAspectRatio: 1,
        ),
        itemCount: _assets.length,
        itemBuilder: (context, index) {
          final asset = _assets[index];
          return _buildImageTile(asset);
        },
      ),
    );
  }

  Widget _buildImageTile(ImmichAsset asset) {
    final thumbnailUrl = _getThumbnailUrl(asset);
    
    // For Immich API, we need to pass the API key as a header
    // Since Image.network doesn't easily support custom headers,
    // we'll use a workaround: Immich might accept the key in the URL query parameter
    // OR we need to fetch images via Dio and convert to bytes.
    // Let's check ImmichService - it has Dio with headers configured.
    // Actually, we can use Image.network with headers parameter (Flutter supports this).
    // But we need the API key. Let me check if ImmichService exposes it.
    
    // Since Immich API requires x-api-key header, and Image.network supports headers,
    // we need to get the API key. However, ImmichService doesn't expose it.
    // Let's modify ImmichService to expose a method that returns headers, or
    // we can fetch images via Dio and display them.
    
    // For now, let's use Image.network and assume Immich might work without header
    // (which it won't, but this is a placeholder). We'll fix this properly next.
    
    return GestureDetector(
      onTap: () {
        // TODO: Navigate to full image view
        _showImageDetails(asset);
      },
      child: Container(
        decoration: BoxDecoration(
          borderRadius: BorderRadius.circular(8),
          color: Colors.grey[300],
        ),
        child: ClipRRect(
          borderRadius: BorderRadius.circular(8),
          child: _buildImageWidget(thumbnailUrl, asset),
        ),
      ),
    );
  }

  Widget _buildImageWidget(String url, ImmichAsset asset) {
    // Use FutureBuilder to fetch image bytes via ImmichService with proper auth
    return FutureBuilder<Uint8List?>(
      future: widget.immichService?.fetchImageBytes(asset.id, isThumbnail: true),
      builder: (context, snapshot) {
        if (snapshot.connectionState == ConnectionState.waiting) {
          return const Center(
            child: CircularProgressIndicator(),
          );
        }

        if (snapshot.hasError || !snapshot.hasData || snapshot.data == null) {
          return Container(
            color: Colors.grey[200],
            child: const Icon(
              Icons.broken_image,
              color: Colors.grey,
            ),
          );
        }

        return Image.memory(
          snapshot.data!,
          fit: BoxFit.cover,
        );
      },
    );
  }

  void _showImageDetails(ImmichAsset asset) {
    showDialog(
      context: context,
      builder: (context) => Dialog(
        child: Column(
          mainAxisSize: MainAxisSize.min,
          children: [
            AppBar(
              title: Text(asset.fileName),
              automaticallyImplyLeading: false,
              actions: [
                IconButton(
                  icon: const Icon(Icons.close),
                  onPressed: () => Navigator.of(context).pop(),
                ),
              ],
            ),
            Expanded(
              child: FutureBuilder<Uint8List?>(
                future: widget.immichService?.fetchImageBytes(asset.id, isThumbnail: false),
                builder: (context, snapshot) {
                  if (snapshot.connectionState == ConnectionState.waiting) {
                    return const Center(
                      child: CircularProgressIndicator(),
                    );
                  }

                  if (snapshot.hasError || !snapshot.hasData || snapshot.data == null) {
                    return const Center(
                      child: Text('Failed to load image'),
                    );
                  }

                  return Image.memory(
                    snapshot.data!,
                    fit: BoxFit.contain,
                  );
                },
              ),
            ),
            Padding(
              padding: const EdgeInsets.all(16),
              child: Column(
                crossAxisAlignment: CrossAxisAlignment.start,
                children: [
                  Text('File: ${asset.fileName}'),
                  Text('Size: ${_formatFileSize(asset.fileSize)}'),
                  if (asset.width != null && asset.height != null)
                    Text('Dimensions: ${asset.width}x${asset.height}'),
                  Text('Date: ${_formatDate(asset.createdAt)}'),
                ],
              ),
            ),
          ],
        ),
      ),
    );
  }

  String _formatFileSize(int bytes) {
    if (bytes < 1024) return '$bytes B';
    if (bytes < 1024 * 1024) return '${(bytes / 1024).toStringAsFixed(1)} KB';
    return '${(bytes / (1024 * 1024)).toStringAsFixed(1)} MB';
  }

  String _formatDate(DateTime date) {
    return '${date.year}-${date.month.toString().padLeft(2, '0')}-${date.day.toString().padLeft(2, '0')}';
  }

  /// Tests the connection to Immich server by calling /api/server/about.
  Future<void> _testServerConnection() async {
    if (widget.immichService == null) {
      if (mounted) {
        ScaffoldMessenger.of(context).showSnackBar(
          const SnackBar(
            content: Text('Immich service not available'),
            backgroundColor: Colors.red,
          ),
        );
      }
      return;
    }

    showDialog(
      context: context,
      barrierDismissible: false,
      builder: (context) => const Center(
        child: CircularProgressIndicator(),
      ),
    );

    try {
      final serverInfo = await widget.immichService!.getServerInfo();
      
      if (!mounted) return;
      
      Navigator.of(context).pop(); // Close loading dialog
      
      showDialog(
        context: context,
        builder: (context) => AlertDialog(
          title: const Text('Server Info'),
          content: SingleChildScrollView(
            child: Column(
              crossAxisAlignment: CrossAxisAlignment.start,
              mainAxisSize: MainAxisSize.min,
              children: [
                Text(
                  'GET /api/server/about',
                  style: Theme.of(context).textTheme.titleSmall,
                ),
                const SizedBox(height: 16),
                Text(
                  _formatServerInfo(serverInfo),
                  style: Theme.of(context).textTheme.bodyMedium,
                ),
              ],
            ),
          ),
          actions: [
            TextButton(
              onPressed: () => Navigator.of(context).pop(),
              child: const Text('Close'),
            ),
          ],
        ),
      );
    } catch (e) {
      if (!mounted) return;
      
      Navigator.of(context).pop(); // Close loading dialog
      
      showDialog(
        context: context,
        builder: (context) => AlertDialog(
          title: const Text('Connection Test Failed'),
          content: Text(
            'Error: ${e.toString()}',
            style: const TextStyle(color: Colors.red),
          ),
          actions: [
            TextButton(
              onPressed: () => Navigator.of(context).pop(),
              child: const Text('Close'),
            ),
          ],
        ),
      );
    }
  }

  /// Formats server info map as a readable string.
  String _formatServerInfo(Map<String, dynamic> info) {
    final buffer = StringBuffer();
    
    info.forEach((key, value) {
      if (value is Map) {
        buffer.writeln('$key:');
        value.forEach((subKey, subValue) {
          buffer.writeln('  $subKey: $subValue');
        });
      } else {
        buffer.writeln('$key: $value');
      }
    });
    
    return buffer.toString();
  }
}