import 'package:flutter/foundation.dart';
import 'package:flutter/material.dart';
import 'package:flutter/services.dart';
import 'package:flutter_fullscreen/flutter_fullscreen.dart';
import 'package:logging/logging.dart';
import 'package:pdfrx/pdfrx.dart';
import 'package:sheetless/core/models/config.dart';
import 'package:sheetless/core/models/sheet.dart';
import 'package:sheetless/core/services/api_client.dart';
import 'package:sheetless/core/services/storage_service.dart';

import '../../shared/input/pedal_shortcuts.dart';
import 'widgets/paint_mode_layer.dart';
import 'widgets/pdf_page_display.dart';
import 'widgets/touch_navigation_layer.dart';

/// Page for viewing and annotating PDF sheet music.
class SheetViewerPage extends StatefulWidget {
  final Sheet sheet;
  final ApiClient apiClient;
  final Config config;

  const SheetViewerPage({
    super.key,
    required this.sheet,
    required this.apiClient,
    required this.config,
  });

  @override
  State<SheetViewerPage> createState() => _SheetViewerPageState();
}

class _SheetViewerPageState extends State<SheetViewerPage>
    with FullScreenListener {
  final _log = Logger('SheetViewerPage');
  final _storageService = StorageService();

  PdfDocument? _document;
  late Future<bool> _documentLoaded;
  int _currentPage = 1;
  int _totalPages = 1;
  bool _isPaintMode = false;

  @override
  void initState() {
    super.initState();
    FullScreen.addListener(this);
    FullScreen.setFullScreen(widget.config.fullscreen);
    _documentLoaded = _loadPdf();
  }

  @override
  void dispose() {
    FullScreen.removeListener(this);
    _document?.dispose();
    super.dispose();
  }

  // ---------------------------------------------------------------------------
  // PDF Loading
  // ---------------------------------------------------------------------------

  Future<bool> _loadPdf() async {
    if (kIsWeb) {
      // Web: load directly into memory
      final data = await widget.apiClient.fetchPdfData(widget.sheet.uuid);
      _document = await PdfDocument.openData(data);
    } else {
      // Native: use file cache
      final file = await widget.apiClient.getPdfFileCached(widget.sheet.uuid);
      _document = await PdfDocument.openFile(file.path);
    }

    setState(() {
      _totalPages = _document!.pages.length;
    });

    return true;
  }

  // ---------------------------------------------------------------------------
  // Fullscreen
  // ---------------------------------------------------------------------------

  @override
  void onFullScreenChanged(bool enabled, SystemUiMode? systemUiMode) {
    setState(() {
      widget.config.fullscreen = enabled;
      _storageService.writeConfig(widget.config);
    });
  }

  void _toggleFullscreen() {
    FullScreen.setFullScreen(!widget.config.fullscreen);
  }

  // ---------------------------------------------------------------------------
  // Navigation
  // ---------------------------------------------------------------------------

  void _turnPage(int delta) {
    setState(() {
      _currentPage = (_currentPage + delta).clamp(1, _totalPages);
    });
  }

  // ---------------------------------------------------------------------------
  // Mode Switching
  // ---------------------------------------------------------------------------

  void _togglePaintMode() {
    if (widget.config.twoPageMode) {
      // Paint mode only works in single page mode
      ScaffoldMessenger.of(context).showSnackBar(
        const SnackBar(
          content: Text('Paint mode is only available in single page mode'),
          duration: Duration(seconds: 2),
        ),
      );
      return;
    }

    setState(() => _isPaintMode = !_isPaintMode);
  }

  void _toggleTwoPageMode() {
    setState(() {
      widget.config.twoPageMode = !widget.config.twoPageMode;
      _storageService.writeConfig(widget.config);

      if (widget.config.twoPageMode && _isPaintMode) {
        _isPaintMode = false;
        ScaffoldMessenger.of(context).showSnackBar(
          const SnackBar(
            content: Text('Paint mode disabled in two-page mode'),
            duration: Duration(seconds: 2),
          ),
        );
      }
    });
  }

  // ---------------------------------------------------------------------------
  // UI
  // ---------------------------------------------------------------------------

  @override
  Widget build(BuildContext context) {
    return PedalShortcuts(
      onPageForward: () => _turnPage(1),
      onPageBackward: () => _turnPage(-1),
      child: Scaffold(appBar: _buildAppBar(), body: _buildBody()),
    );
  }

  PreferredSizeWidget? _buildAppBar() {
    // Hide app bar in fullscreen when document is loaded
    if (widget.config.fullscreen && _document != null) {
      return null;
    }

    return AppBar(
      title: Text(widget.sheet.name),
      actions: [
        IconButton(
          icon: Icon(
            widget.config.fullscreen ? Icons.fullscreen_exit : Icons.fullscreen,
          ),
          tooltip: widget.config.fullscreen
              ? 'Exit Fullscreen'
              : 'Enter Fullscreen',
          onPressed: _toggleFullscreen,
        ),
        IconButton(
          icon: Icon(_isPaintMode ? Icons.brush : Icons.brush_outlined),
          tooltip: 'Toggle Paint Mode',
          onPressed: _togglePaintMode,
        ),
        IconButton(
          icon: Icon(
            widget.config.twoPageMode ? Icons.filter_1 : Icons.filter_2,
          ),
          tooltip: widget.config.twoPageMode
              ? 'Single Page Mode'
              : 'Two Page Mode',
          onPressed: _toggleTwoPageMode,
        ),
      ],
    );
  }

  Widget _buildBody() {
    return FutureBuilder<bool>(
      future: _documentLoaded,
      builder: (context, snapshot) {
        if (snapshot.hasError) {
          _log.warning('Error loading PDF', snapshot.error);
          return _buildError(snapshot.error.toString());
        }

        if (snapshot.hasData && _document != null) {
          return _buildPdfViewer();
        }

        return const Center(child: CircularProgressIndicator());
      },
    );
  }

  Widget _buildPdfViewer() {
    final pageDisplay = PdfPageDisplay(
      document: _document!,
      numPages: _totalPages,
      currentPageNumber: _currentPage,
      config: widget.config,
    );

    return Stack(
      children: [
        // Show touch navigation when not in paint mode
        Visibility(
          visible: !_isPaintMode,
          child: TouchNavigationLayer(
            pageDisplay: pageDisplay,
            config: widget.config,
            onToggleFullscreen: _toggleFullscreen,
            onExit: () => Navigator.pop(context),
            onPageTurn: _turnPage,
          ),
        ),
        // Show paint mode layer when active
        Visibility(
          visible: _isPaintMode,
          child: PaintModeLayer(pageDisplay: pageDisplay),
        ),
      ],
    );
  }

  Widget _buildError(String message) {
    return Center(
      child: Padding(
        padding: const EdgeInsets.all(16.0),
        child: Text(
          message,
          style: Theme.of(
            context,
          ).textTheme.titleMedium?.copyWith(color: Colors.red),
          textAlign: TextAlign.center,
        ),
      ),
    );
  }
}