import 'dart:io';

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

import '../screens/confirm_fuel_entry_screen.dart';
import '../services/app_state.dart';
import '../services/ocr_service.dart';
import '../services/receipt_parser.dart';
import 'image_source_sheet.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;

/// Shared by [VehicleDetailScreen]'s "Log Fuel Receipt" button and the
/// Receipts tab's "+" action: pick a photo, OCR it, and — unless the
/// receipt looks like it's from outside Missouri, in which case the user
/// gets a chance to back out first — hand off to [ConfirmFuelEntryScreen]
/// for [vehicleId].
Future<void> captureReceiptForVehicle(BuildContext context, String vehicleId) async {
  final source = await chooseImageSource(context, heading: 'Receipt From');
  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;
}