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

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

/// Create/edit device form. Pass an existing [device] to edit it in place;
/// omit it to create a new one. Pops with `true` on success.
class DeviceFormScreen extends StatefulWidget {
  const DeviceFormScreen({super.key, this.device});

  final Device? device;

  bool get isEditing => device != null;

  @override
  State<DeviceFormScreen> createState() => _DeviceFormScreenState();
}

class _DeviceFormScreenState extends State<DeviceFormScreen> {
  final _formKey = GlobalKey<FormState>();
  late final _nameController = TextEditingController(text: widget.device?.name);
  late final _externalIdController = TextEditingController(text: widget.device?.externalId);
  late final _protocolController = TextEditingController(text: widget.device?.protocol ?? 'mqtt');

  late Future<(List<Zone>, List<DeviceType>)> _optionsFuture;
  int? _zoneId;
  int? _deviceTypeId;

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

  @override
  void initState() {
    super.initState();
    _zoneId = widget.device?.zone?.id;
    _deviceTypeId = widget.device?.deviceType?.id;
    final apiService = context.read<ApiService>();
    _optionsFuture = (apiService.zones(), apiService.deviceTypes()).wait;
  }

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

  Future<void> _submit() async {
    if (!_formKey.currentState!.validate()) return;
    if (_zoneId == null || _deviceTypeId == null) {
      setState(() => _fieldErrors = {
            if (_zoneId == null) 'zone_id': ['Выберите зону'],
            if (_deviceTypeId == null) 'device_type_id': ['Выберите тип устройства'],
          });
      return;
    }

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

    final apiService = context.read<ApiService>();
    final name = _nameController.text.trim();
    final externalId = _externalIdController.text.trim();
    final protocol = _protocolController.text.trim().isEmpty ? 'mqtt' : _protocolController.text.trim();

    try {
      if (widget.isEditing) {
        await apiService.updateDevice(
          widget.device!.id,
          zoneId: _zoneId!,
          deviceTypeId: _deviceTypeId!,
          name: name,
          externalId: externalId,
          protocol: protocol,
        );
      } else {
        await apiService.createDevice(
          zoneId: _zoneId!,
          deviceTypeId: _deviceTypeId!,
          name: name,
          externalId: externalId,
          protocol: protocol,
        );
      }
      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 устройство' : 'Новое устройство')),
      body: FutureBuilder<(List<Zone>, List<DeviceType>)>(
        future: _optionsFuture,
        builder: (context, snapshot) {
          if (snapshot.connectionState != ConnectionState.done) {
            return const Center(child: CircularProgressIndicator());
          }
          if (snapshot.hasError) {
            return Center(child: Text('${snapshot.error}'));
          }

          final (zones, deviceTypes) = snapshot.data!;

          return Form(
            key: _formKey,
            child: ListView(
              padding: const EdgeInsets.all(16),
              children: [
                DropdownButtonFormField<int>(
                  initialValue: _zoneId,
                  decoration: InputDecoration(labelText: 'Зона', errorText: _fieldErrors['zone_id']?.first),
                  items: zones.map((z) => DropdownMenuItem(value: z.id, child: Text(z.name))).toList(),
                  onChanged: (value) => setState(() => _zoneId = value),
                ),
                const SizedBox(height: 16),
                DropdownButtonFormField<int>(
                  initialValue: _deviceTypeId,
                  decoration:
                      InputDecoration(labelText: 'Тип устройства', errorText: _fieldErrors['device_type_id']?.first),
                  items: deviceTypes
                      .map((t) => DropdownMenuItem(value: t.id, child: Text('${t.code} (${t.category})')))
                      .toList(),
                  onChanged: (value) => setState(() => _deviceTypeId = value),
                ),
                const SizedBox(height: 16),
                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: _externalIdController,
                  decoration: InputDecoration(
                    labelText: 'External ID',
                    helperText: 'Идентификатор физического устройства (ESP32 chip id и т.п.)',
                    errorText: _fieldErrors['external_id']?.first,
                  ),
                  validator: (value) => (value == null || value.trim().isEmpty) ? 'Введите external_id' : null,
                ),
                const SizedBox(height: 16),
                TextFormField(
                  controller: _protocolController,
                  decoration: InputDecoration(labelText: 'Протокол', errorText: _fieldErrors['protocol']?.first),
                ),
                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'),
                ),
              ],
            ),
          );
        },
      ),
    );
  }
}