import 'dart:io';

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

import '../models/vehicle.dart';
import '../services/app_state.dart';
import '../services/ocr_service.dart';
import '../services/vin_parser.dart';
import '../widgets/image_source_sheet.dart';

/// Add/edit form for a vehicle. Pass an existing [vehicle] to edit it, or
/// omit it to create a new one.
class AddEditVehicleScreen extends StatefulWidget {
  final Vehicle? vehicle;

  const AddEditVehicleScreen({super.key, this.vehicle});

  @override
  State<AddEditVehicleScreen> createState() => _AddEditVehicleScreenState();
}

class _AddEditVehicleScreenState extends State<AddEditVehicleScreen> {
  final _formKey = GlobalKey<FormState>();
  late final TextEditingController _nicknameController;
  late final TextEditingController _vinController;

  bool _saving = false;
  bool _scanningVin = false;
  String? _error;

  bool get _isEditing => widget.vehicle != null;

  @override
  void initState() {
    super.initState();
    _nicknameController = TextEditingController(text: widget.vehicle?.nickname ?? '');
    _vinController = TextEditingController(text: widget.vehicle?.vin ?? '');
  }

  @override
  void dispose() {
    _nicknameController.dispose();
    _vinController.dispose();
    super.dispose();
  }

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

    final picker = ImagePicker();
    XFile? photo;
    try {
      photo = await picker.pickImage(source: source, imageQuality: 85);
    } catch (e) {
      if (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;

    setState(() => _scanningVin = true);

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

    if (!mounted) return;

    final vin = VinParser.parse(recognizedText);
    setState(() => _scanningVin = false);

    if (vin != null) {
      _vinController.text = vin;
    } else if (mounted) {
      ScaffoldMessenger.of(context).showSnackBar(
        const SnackBar(
          content: Text("Couldn't read a VIN from that photo. Please enter it manually."),
        ),
      );
    }
  }

  Future<void> _save() async {
    if (!_formKey.currentState!.validate()) return;

    setState(() {
      _saving = true;
      _error = null;
    });

    final nickname = _nicknameController.text.trim();
    final appState = context.read<AppState>();

    try {
      if (_isEditing) {
        await appState.updateVehicle(widget.vehicle!.copyWith(
          vin: _vinController.text.trim(),
          nickname: nickname.isEmpty ? null : nickname,
          clearNickname: nickname.isEmpty,
        ));
      } else {
        await appState.addVehicle(
          vin: _vinController.text.trim(),
          nickname: nickname.isEmpty ? null : nickname,
        );
      }

      if (mounted) Navigator.of(context).pop();
    } on DuplicateVinException catch (e) {
      setState(() => _error = e.toString());
    } finally {
      if (mounted) setState(() => _saving = false);
    }
  }

  Future<void> _confirmDelete() async {
    final confirmed = await showDialog<bool>(
      context: context,
      builder: (context) => AlertDialog(
        title: const Text('Delete vehicle?'),
        content: Text(
          'This will also delete all fuel entries and receipt photos logged for '
          '${widget.vehicle!.displayLabel}. This cannot be undone.',
        ),
        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 && mounted) {
      await context.read<AppState>().deleteVehicle(widget.vehicle!.id);
      if (mounted) {
        Navigator.of(context)
          ..pop()
          ..pop();
      }
    }
  }

  @override
  Widget build(BuildContext context) {
    return Scaffold(
      appBar: AppBar(
        title: Text(_isEditing ? 'Edit Vehicle' : 'Add Vehicle'),
        actions: [
          if (_isEditing)
            IconButton(
              icon: const Icon(Icons.delete_outline),
              tooltip: 'Delete vehicle',
              onPressed: _confirmDelete,
            ),
        ],
      ),
      body: Form(
        key: _formKey,
        child: ListView(
          padding: const EdgeInsets.all(16),
          children: [
            TextFormField(
              controller: _nicknameController,
              decoration: const InputDecoration(
                labelText: 'Nickname (optional)',
                hintText: 'e.g. Mom\'s Car, Red Ford F-150',
              ),
              textCapitalization: TextCapitalization.words,
            ),
            const SizedBox(height: 12),
            TextFormField(
              controller: _vinController,
              decoration: InputDecoration(
                labelText: 'VIN *',
                hintText: 'Vehicle Identification Number',
                helperText: 'Required — tap the camera to scan it from a photo',
                suffixIcon: _scanningVin
                    ? const Padding(
                        padding: EdgeInsets.all(12),
                        child: SizedBox(
                          height: 20,
                          width: 20,
                          child: CircularProgressIndicator(strokeWidth: 2),
                        ),
                      )
                    : IconButton(
                        icon: const Icon(Icons.camera_alt_outlined),
                        tooltip: 'Scan VIN from a photo',
                        onPressed: _scanVin,
                      ),
              ),
              textCapitalization: TextCapitalization.characters,
              validator: (v) => (v == null || v.trim().isEmpty) ? 'Required' : null,
            ),
            if (_error != null) ...[
              const SizedBox(height: 12),
              Text(_error!, style: TextStyle(color: Theme.of(context).colorScheme.error)),
            ],
            const SizedBox(height: 24),
            FilledButton(
              onPressed: _saving ? null : _save,
              child: _saving
                  ? const SizedBox(height: 20, width: 20, child: CircularProgressIndicator(strokeWidth: 2))
                  : Text(_isEditing ? 'Save Changes' : 'Add Vehicle'),
            ),
          ],
        ),
      ),
    );
  }
}