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

import '../core/api_client.dart';
import '../core/api_service.dart';
import '../models/zone.dart';

/// Create/edit zone form. Pass an existing [zone] to edit it in place;
/// omit it to create a new one. Pops with `true` on success so the caller
/// knows to refresh its list.
class ZoneFormScreen extends StatefulWidget {
  const ZoneFormScreen({super.key, this.zone});

  final Zone? zone;

  bool get isEditing => zone != null;

  @override
  State<ZoneFormScreen> createState() => _ZoneFormScreenState();
}

class _ZoneFormScreenState extends State<ZoneFormScreen> {
  final _formKey = GlobalKey<FormState>();
  late final _nameController = TextEditingController(text: widget.zone?.name);
  late final _descriptionController = TextEditingController(text: widget.zone?.description);

  bool _isSubmitting = false;
  Map<String, List<String>> _fieldErrors = {};

  @override
  void dispose() {
    _nameController.dispose();
    _descriptionController.dispose();
    super.dispose();
  }

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

    setState(() {
      _isSubmitting = true;
      _fieldErrors = {};
    });

    final apiService = context.read<ApiService>();
    final name = _nameController.text.trim();
    final description = _descriptionController.text.trim();

    try {
      if (widget.isEditing) {
        await apiService.updateZone(widget.zone!.id, name: name, description: description);
      } else {
        await apiService.createZone(name: name, description: description);
      }
      if (mounted) Navigator.of(context).pop(true);
    } on ApiException catch (e) {
      setState(() => _fieldErrors = e.errors ?? {});
      if (e.errors == null && mounted) {
        ScaffoldMessenger.of(context).showSnackBar(SnackBar(content: Text(e.message)));
      }
    } finally {
      if (mounted) setState(() => _isSubmitting = false);
    }
  }

  @override
  Widget build(BuildContext context) {
    return Scaffold(
      appBar: AppBar(title: Text(widget.isEditing ? 'Редактировать зону' : 'Новая зона')),
      body: Form(
        key: _formKey,
        child: ListView(
          padding: const EdgeInsets.all(16),
          children: [
            TextFormField(
              controller: _nameController,
              decoration: InputDecoration(labelText: 'Название', errorText: _fieldErrors['name']?.first),
              validator: (value) => (value == null || value.trim().isEmpty) ? 'Введите название' : null,
            ),
            const SizedBox(height: 16),
            TextFormField(
              controller: _descriptionController,
              decoration: InputDecoration(labelText: 'Описание', errorText: _fieldErrors['description']?.first),
              maxLines: 3,
            ),
            const SizedBox(height: 24),
            FilledButton(
              onPressed: _isSubmitting ? null : _submit,
              child: _isSubmitting
                  ? const SizedBox(height: 20, width: 20, child: CircularProgressIndicator(strokeWidth: 2))
                  : Text(widget.isEditing ? 'Сохранить' : 'Создать'),
            ),
          ],
        ),
      ),
    );
  }
}