import 'dart:io';

import 'package:flutter/material.dart';
import 'package:image_picker/image_picker.dart';
import 'package:intl/intl.dart';
import 'package:provider/provider.dart';

import '../models/fuel_entry.dart';
import '../services/app_state.dart';
import '../services/ocr_service.dart';
import '../services/receipt_parser.dart';
import '../widgets/image_source_sheet.dart';
import 'add_edit_vehicle_screen.dart';
import 'confirm_fuel_entry_screen.dart';
import 'receipt_image_screen.dart';

/// Long edge and JPEG quality a receipt photo is downscaled to unless
/// "keep max quality" is on — a receipt is a photo of small printed text,
/// not something that benefits from a multi-megapixel original, and this
/// keeps typical files in the low hundreds of KB instead of several MB.
const receiptImageMaxDimension = 1600.0;
const receiptImageQuality = 70;

class VehicleDetailScreen extends StatelessWidget {
  final String vehicleId;

  const VehicleDetailScreen({super.key, required this.vehicleId});

  Future<void> _captureReceipt(BuildContext context) async {
    final source = await chooseImageSource(context);
    if (source == null || !context.mounted) return;

    final keepMaxQuality = context.read<AppState>().keepMaxQualityReceiptPhotos;
    final picker = ImagePicker();
    XFile? photo;
    try {
      photo = await picker.pickImage(
        source: source,
        imageQuality: keepMaxQuality ? null : receiptImageQuality,
        maxWidth: keepMaxQuality ? null : receiptImageMaxDimension,
        maxHeight: keepMaxQuality ? null : receiptImageMaxDimension,
      );
    } catch (e) {
      if (context.mounted) {
        final sourceLabel = source == ImageSource.camera ? 'camera' : 'photo library';
        ScaffoldMessenger.of(context).showSnackBar(
          SnackBar(content: Text('Could not open $sourceLabel: $e')),
        );
      }
      return;
    }
    if (photo == null) return;

    final imageFile = File(photo.path);

    if (!context.mounted) return;
    showDialog(
      context: context,
      barrierDismissible: false,
      builder: (_) => const Center(child: CircularProgressIndicator()),
    );

    final ocrService = OcrService();
    String recognizedText = '';
    try {
      recognizedText = await ocrService.recognizeText(imageFile);
    } catch (_) {
      recognizedText = '';
    } finally {
      ocrService.dispose();
    }

    final parsed = ReceiptParser.parse(recognizedText);

    if (!context.mounted) return;
    Navigator.of(context).pop(); // close the OCR loading spinner

    final state = parsed.state;
    if (state != null && state != 'MO') {
      final proceed = await _confirmNonMissouriPurchase(context, state);
      if (!proceed || !context.mounted) return;
    }

    if (context.mounted) {
      Navigator.of(context).push(
        MaterialPageRoute(
          builder: (_) => ConfirmFuelEntryScreen(
            vehicleId: vehicleId,
            imageFile: imageFile,
            parsed: parsed,
          ),
        ),
      );
    }
  }

  /// Missouri's fuel tax refund only applies to fuel bought in Missouri —
  /// warn if the receipt's address is somewhere else, and let the user
  /// decide whether to log it anyway (e.g. it might still be worth
  /// tracking for other reasons even if it won't qualify for a refund).
  Future<bool> _confirmNonMissouriPurchase(BuildContext context, String stateCode) async {
    final stateName = usStateNames[stateCode] ?? stateCode;
    final proceed = await showDialog<bool>(
      context: context,
      builder: (context) => AlertDialog(
        title: const Text('Non-Missouri Purchase'),
        content: Text(
          'This receipt looks like it\'s from a gas station in $stateName. '
          'The Missouri fuel tax refund only applies to fuel purchased in '
          'Missouri.\n\nDo you still want to add this entry?',
        ),
        actions: [
          TextButton(onPressed: () => Navigator.of(context).pop(false), child: const Text('No')),
          FilledButton(onPressed: () => Navigator.of(context).pop(true), child: const Text('Yes')),
        ],
      ),
    );
    return proceed ?? false;
  }

  Future<void> _deleteEntry(BuildContext context, FuelEntry entry) async {
    final confirmed = await showDialog<bool>(
      context: context,
      builder: (context) => AlertDialog(
        title: const Text('Delete fuel entry?'),
        content: const Text('This will remove the entry and its receipt photo.'),
        actions: [
          TextButton(onPressed: () => Navigator.of(context).pop(false), child: const Text('Cancel')),
          TextButton(
            onPressed: () => Navigator.of(context).pop(true),
            child: const Text('Delete', style: TextStyle(color: Colors.red)),
          ),
        ],
      ),
    );
    if (confirmed == true && context.mounted) {
      await context.read<AppState>().deleteFuelEntry(entry.id);
    }
  }

  Widget _buildReceiptLeading(BuildContext context, FuelEntry entry) {
    if (entry.receiptImagePath != null) {
      return GestureDetector(
        onTap: () => Navigator.of(context).push(
          MaterialPageRoute(
            builder: (_) => ReceiptImageScreen(localImagePath: entry.receiptImagePath),
          ),
        ),
        child: ClipRRect(
          borderRadius: BorderRadius.circular(6),
          child: Image.file(
            File(entry.receiptImagePath!),
            width: 48,
            height: 48,
            fit: BoxFit.cover,
          ),
        ),
      );
    }
    if (entry.isReceiptUploadedToDrive) {
      return GestureDetector(
        onTap: () => Navigator.of(context).push(
          MaterialPageRoute(
            builder: (_) => ReceiptImageScreen(driveFileId: entry.receiptDriveFileId),
          ),
        ),
        child: const CircleAvatar(child: Icon(Icons.cloud_outlined)),
      );
    }
    return const CircleAvatar(child: Icon(Icons.receipt_long));
  }

  @override
  Widget build(BuildContext context) {
    final appState = context.watch<AppState>();
    final vehicle = appState.vehicleById(vehicleId);

    if (vehicle == null) {
      return const Scaffold(body: Center(child: Text('Vehicle not found')));
    }

    final entries = appState.entriesForVehicle(vehicleId);
    final totalGallons = appState.totalGallonsForVehicle(vehicleId);
    final dateFormat = DateFormat.yMMMd().add_jm();
    final currencyFormat = NumberFormat.simpleCurrency();

    return Scaffold(
      appBar: AppBar(
        title: Text(vehicle.displayLabel),
        actions: [
          IconButton(
            icon: const Icon(Icons.edit_outlined),
            tooltip: 'Edit vehicle',
            onPressed: () => Navigator.of(context).push(
              MaterialPageRoute(builder: (_) => AddEditVehicleScreen(vehicle: vehicle)),
            ),
          ),
        ],
      ),
      body: Column(
        children: [
          Container(
            width: double.infinity,
            padding: const EdgeInsets.all(16),
            color: Theme.of(context).colorScheme.surfaceContainerHighest,
            child: Column(
              crossAxisAlignment: CrossAxisAlignment.start,
              children: [
                Text('Total gallons logged', style: Theme.of(context).textTheme.labelLarge),
                Text(
                  '${totalGallons.toStringAsFixed(3)} gal',
                  style: Theme.of(context).textTheme.headlineMedium,
                ),
              ],
            ),
          ),
          Expanded(
            child: entries.isEmpty
                ? const Center(child: Text('No fuel entries yet. Tap the camera button to log a receipt.'))
                : ListView.separated(
                    padding: const EdgeInsets.all(12),
                    itemCount: entries.length,
                    separatorBuilder: (_, _) => const SizedBox(height: 8),
                    itemBuilder: (context, index) {
                      final entry = entries[index];
                      return Card(
                        clipBehavior: Clip.antiAlias,
                        child: ListTile(
                          leading: _buildReceiptLeading(context, entry),
                          title: Text('${entry.gallons.toStringAsFixed(3)} gal • ${currencyFormat.format(entry.totalCost)}'),
                          subtitle: Text(
                            '${currencyFormat.format(entry.pricePerGallon)}/gal\n${dateFormat.format(entry.date)}',
                          ),
                          isThreeLine: true,
                          trailing: IconButton(
                            icon: const Icon(Icons.delete_outline),
                            onPressed: () => _deleteEntry(context, entry),
                          ),
                        ),
                      );
                    },
                  ),
          ),
        ],
      ),
      floatingActionButton: FloatingActionButton.extended(
        onPressed: () => _captureReceipt(context),
        icon: const Icon(Icons.camera_alt_outlined),
        label: const Text('Log Fuel Receipt'),
      ),
    );
  }
}