import 'dart:async';
import 'package:flutter/material.dart';
import 'package:flutter_riverpod/flutter_riverpod.dart';
import 'package:go_router/go_router.dart';
import 'package:image_picker/image_picker.dart';
import 'package:geolocator/geolocator.dart';
import '../../core/location/location_service.dart';
import '../../core/utils/exif_helper.dart';
import '../../config/app_config.dart';
import 'image_preview_screen.dart';
import 'scan_mode_provider.dart';
import 'camera_drawer.dart';

class CameraScreen extends ConsumerStatefulWidget {
  const CameraScreen({super.key});

  @override
  ConsumerState<CameraScreen> createState() => CameraScreenState();
}

class CameraScreenState extends ConsumerState<CameraScreen> {
  bool _isCapturing = false;
  Position? _currentPosition;
  StreamSubscription<Position>? _locationSubscription;

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

  @override
  void dispose() {
    _locationSubscription?.cancel();
    super.dispose();
  }

  Future<void> _preFetchLocation() async {
    try {
      final pos = await LocationService.determinePosition();
      if (mounted) {
        setState(() {
          _currentPosition = pos;
        });
      }

      // Live location updates
      _locationSubscription = LocationService.getPositionStream().listen(
        (Position freshPos) {
          if (mounted) {
            setState(() {
              _currentPosition = freshPos;
            });
          }
        },
      );
    } catch (_) {}
  }

  Future<void> _takePicture() async {
    if (_isCapturing) return;

    final ImagePicker picker = ImagePicker();
    try {
      final XFile? image = await picker.pickImage(
        source: ImageSource.camera,
        maxWidth: 2048,
        maxHeight: 2048,
        imageQuality: 85,
      );

      if (image != null) {
        setState(() {
          _isCapturing = true;
        });

        // Use pre-fetched location if available, otherwise fetch quick position
        Position? position = _currentPosition;
        if (position == null) {
          try {
            position = await LocationService.determinePosition().timeout(const Duration(seconds: 2));
          } catch (_) {}
        }

        setState(() {
          _isCapturing = false;
        });

        navigateToPreview(image.path, latitude: position?.latitude, longitude: position?.longitude);
      }
    } catch (e) {
      debugPrint('Error taking picture: $e');
    }
  }

  Future<void> _pickFromGallery() async {
    if (_isCapturing) return;

    final ImagePicker picker = ImagePicker();
    try {
      final XFile? image = await picker.pickImage(
        source: ImageSource.gallery,
        maxWidth: 2048,
        maxHeight: 2048,
        imageQuality: 85,
      );

      if (image != null) {
        setState(() {
          _isCapturing = true;
        });

        Position? position = _currentPosition;
        try {
          // Attempt to extract GPS from EXIF tags
          final exifGps = await ExifHelper.extractGps(image.path);
          if (exifGps != null) {
            position = Position(
              latitude: exifGps['latitude']!,
              longitude: exifGps['longitude']!,
              timestamp: DateTime.now(),
              accuracy: 0.0,
              altitude: 0.0,
              heading: 0.0,
              speed: 0.0,
              speedAccuracy: 0.0,
              altitudeAccuracy: 0.0,
              headingAccuracy: 0.0,
            );
          } else if (position == null) {
            position = await LocationService.determinePosition().timeout(const Duration(seconds: 2));
          }
        } catch (_) {}

        setState(() {
          _isCapturing = false;
        });

        navigateToPreview(image.path, latitude: position?.latitude, longitude: position?.longitude);
      }
    } catch (e) {
      debugPrint('Error picking image from gallery: $e');
    }
  }

  void navigateToPreview(String imagePath, {double? latitude, double? longitude}) {
    Navigator.push(
      context,
      MaterialPageRoute(
        builder: (context) => ImagePreviewScreen(
          imagePath: imagePath,
          latitude: latitude,
          longitude: longitude,
        ),
      ),
    );
  }

  @override
  Widget build(BuildContext context) {
    final activeMode = ref.watch(scanModeProvider);

    return Scaffold(
      backgroundColor: AppConfig.backgroundColor,
      appBar: AppBar(
        title: Text(activeMode == 'DO' ? 'Pemindai Dokumen OCR' : 'Pemindai Produk PFM'),
      ),
      drawer: const CameraDrawer(),
      body: SafeArea(
        child: Padding(
          padding: AppConfig.screenPadding,
          child: Column(
            crossAxisAlignment: CrossAxisAlignment.stretch,
            children: [
              // Upper Illustration Card
              Expanded(
                child: Container(
                  decoration: BoxDecoration(
                    color: Colors.white,
                    borderRadius: BorderRadius.circular(AppConfig.borderRadiusXL),
                    boxShadow: [
                      BoxShadow(
                        color: Colors.black.withOpacity(0.05),
                        blurRadius: 10,
                        offset: const Offset(0, 4),
                      )
                    ],
                  ),
                  child: Padding(
                    padding: AppConfig.paddingXL,
                    child: SingleChildScrollView(
                      child: activeMode == 'DO'
                          ? Column(
                              mainAxisAlignment: MainAxisAlignment.center,
                              children: [
                                Container(
                                  width: 100,
                                  height: 100,
                                  decoration: BoxDecoration(
                                    color: AppConfig.primaryColor.withOpacity(0.1),
                                    shape: BoxShape.circle,
                                  ),
                                  child: const Icon(
                                    Icons.document_scanner,
                                    size: 48,
                                    color: AppConfig.primaryColor,
                                  ),
                                ),
                                const SizedBox(height: AppConfig.spaceXL),
                                Text(
                                  'Pemindai DO',
                                  style: AppConfig.h3,
                                ),
                                const SizedBox(height: AppConfig.spaceMedium),
                                Text(
                                  'Ambil foto lembar Delivery Order (DO) Prima Fresh Mart untuk mengekstrak data PO, SO, DO, dan item barang secara otomatis.',
                                  style: AppConfig.bodyMedium.copyWith(color: AppConfig.textSecondary),
                                  textAlign: TextAlign.center,
                                ),
                                const SizedBox(height: AppConfig.spaceXL),
                                _buildGuidelineRow(Icons.lightbulb_outline, 'Pastikan pencahayaan cukup dan terang.'),
                                const SizedBox(height: AppConfig.spaceSmall),
                                _buildGuidelineRow(Icons.crop_free, 'Posisikan seluruh halaman dokumen di dalam foto.'),
                                const SizedBox(height: AppConfig.spaceSmall),
                                _buildGuidelineRow(Icons.camera_enhance_outlined, 'Pegang HP dengan stabil agar tidak buram.'),
                              ],
                            )
                          : Column(
                              mainAxisAlignment: MainAxisAlignment.center,
                              children: [
                                Container(
                                  width: 100,
                                  height: 100,
                                  decoration: BoxDecoration(
                                    color: AppConfig.primaryColor.withOpacity(0.1),
                                    shape: BoxShape.circle,
                                  ),
                                  child: const Icon(
                                    Icons.inventory_2_outlined,
                                    size: 48,
                                    color: AppConfig.primaryColor,
                                  ),
                                ),
                                const SizedBox(height: AppConfig.spaceXL),
                                Text(
                                  'Pemindai Produk',
                                  style: AppConfig.h3,
                                ),
                                const SizedBox(height: AppConfig.spaceMedium),
                                Text(
                                  'Ambil foto kemasan produk Prima Fresh Mart untuk mengidentifikasi SKU, nama item, dan mendeteksi tanggal kadaluwarsa secara otomatis.',
                                  style: AppConfig.bodyMedium.copyWith(color: AppConfig.textSecondary),
                                  textAlign: TextAlign.center,
                                ),
                                const SizedBox(height: AppConfig.spaceXL),
                                _buildGuidelineRow(Icons.lightbulb_outline, 'Pastikan kode SKU atau teks kadaluwarsa terlihat jelas.'),
                                const SizedBox(height: AppConfig.spaceSmall),
                                _buildGuidelineRow(Icons.center_focus_strong, 'Posisikan produk di tengah kamera.'),
                                const SizedBox(height: AppConfig.spaceSmall),
                                _buildGuidelineRow(Icons.flash_on, 'Gunakan pencahayaan yang cukup agar tidak buram.'),
                              ],
                            ),
                    ),
                  ),
                ),
              ),
              const SizedBox(height: AppConfig.spaceXL),

              // Action Buttons
              ElevatedButton.icon(
                onPressed: _isCapturing ? null : _takePicture,
                icon: const Icon(Icons.camera_alt),
                label: const Text('Ambil Foto Kamera'),
                style: ElevatedButton.styleFrom(
                  padding: const EdgeInsets.symmetric(vertical: 18),
                  textStyle: AppConfig.bodyLarge.copyWith(fontWeight: FontWeight.bold),
                ),
              ),
              const SizedBox(height: AppConfig.spaceMedium),
              OutlinedButton.icon(
                onPressed: _isCapturing ? null : _pickFromGallery,
                icon: const Icon(Icons.photo_library),
                label: const Text('Pilih Dari Galeri'),
                style: OutlinedButton.styleFrom(
                  padding: const EdgeInsets.symmetric(vertical: 18),
                  side: const BorderSide(color: AppConfig.primaryColor),
                  foregroundColor: AppConfig.primaryColor,
                  shape: RoundedRectangleBorder(
                    borderRadius: BorderRadius.circular(AppConfig.borderRadiusMedium),
                  ),
                  textStyle: AppConfig.bodyLarge.copyWith(fontWeight: FontWeight.bold),
                ),
              ),
              const SizedBox(height: AppConfig.spaceMedium),
              TextButton.icon(
                onPressed: _isCapturing ? null : () => context.push('/documents'),
                icon: const Icon(Icons.history_edu),
                label: const Text('Riwayat Dokumen'),
                style: TextButton.styleFrom(
                  foregroundColor: AppConfig.textSecondary,
                ),
              ),
            ],
          ),
        ),
      ),
    );
  }

  Widget _buildGuidelineRow(IconData icon, String text) {
    return Row(
      children: [
        Icon(icon, size: 18, color: AppConfig.secondaryColor),
        const SizedBox(width: AppConfig.spaceSmall),
        Expanded(
          child: Text(
            text,
            style: AppConfig.bodySmall.copyWith(color: AppConfig.textSecondary),
          ),
        ),
      ],
    );
  }
}