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

import '../core/api_service.dart';
import '../core/auth_service.dart';
import '../models/device.dart';
import '../widgets/status_badge.dart';
import 'device_detail_screen.dart';
import 'device_form_screen.dart';

class DevicesTab extends StatefulWidget {
  const DevicesTab({super.key});

  @override
  State<DevicesTab> createState() => _DevicesTabState();
}

class _DevicesTabState extends State<DevicesTab> {
  late Future<List<Device>> _future;

  @override
  void initState() {
    super.initState();
    _future = _load();
  }

  Future<List<Device>> _load() => context.read<ApiService>().devices();

  Future<void> _refresh() async {
    final future = _load();
    setState(() => _future = future);
    await future;
  }

  Future<void> _openForm({Device? device}) async {
    final saved = await Navigator.of(context).push<bool>(
      MaterialPageRoute(builder: (_) => DeviceFormScreen(device: device)),
    );
    if (saved == true) _refresh();
  }

  Future<void> _delete(Device device) async {
    final confirmed = await showDialog<bool>(
      context: context,
      builder: (context) => AlertDialog(
        title: const Text('Удалить устройство?'),
        content: Text('«${device.name}» будет удалено без возможности восстановления.'),
        actions: [
          TextButton(onPressed: () => Navigator.pop(context, false), child: const Text('Отмена')),
          TextButton(onPressed: () => Navigator.pop(context, true), child: const Text('Удалить')),
        ],
      ),
    );
    if (confirmed != true || !mounted) return;

    try {
      await context.read<ApiService>().deleteDevice(device.id);
      _refresh();
    } catch (e) {
      if (mounted) ScaffoldMessenger.of(context).showSnackBar(SnackBar(content: Text('$e')));
    }
  }

  @override
  Widget build(BuildContext context) {
    final isOwner = context.watch<AuthService>().user?.isOwner ?? false;

    return Scaffold(
      body: RefreshIndicator(
        onRefresh: _refresh,
        child: FutureBuilder<List<Device>>(
          future: _future,
          builder: (context, snapshot) {
            if (snapshot.connectionState != ConnectionState.done) {
              return const Center(child: CircularProgressIndicator());
            }
            if (snapshot.hasError) {
              return _ErrorList(message: '${snapshot.error}', onRetry: _refresh);
            }

            final devices = snapshot.data!;
            if (devices.isEmpty) {
              return _ErrorList(message: 'Устройств пока нет.', onRetry: _refresh);
            }

            return ListView.separated(
              physics: const AlwaysScrollableScrollPhysics(),
              itemCount: devices.length,
              separatorBuilder: (context, index) => const Divider(height: 1),
              itemBuilder: (context, index) {
                final device = devices[index];
                return ListTile(
                  title: Text(device.name),
                  subtitle: Text('${device.zone?.name ?? '—'} · ${device.deviceType?.code ?? device.protocol}'),
                  trailing: Row(
                    mainAxisSize: MainAxisSize.min,
                    children: [
                      StatusBadge(status: device.status),
                      if (isOwner)
                        PopupMenuButton<String>(
                          onSelected: (value) {
                            if (value == 'edit') _openForm(device: device);
                            if (value == 'delete') _delete(device);
                          },
                          itemBuilder: (context) => const [
                            PopupMenuItem(value: 'edit', child: Text('Редактировать')),
                            PopupMenuItem(value: 'delete', child: Text('Удалить')),
                          ],
                        ),
                    ],
                  ),
                  onTap: () => Navigator.of(context).push(
                    MaterialPageRoute(builder: (_) => DeviceDetailScreen(deviceId: device.id)),
                  ),
                );
              },
            );
          },
        ),
      ),
      floatingActionButton: isOwner
          ? FloatingActionButton(onPressed: () => _openForm(), child: const Icon(Icons.add))
          : null,
    );
  }
}

class _ErrorList extends StatelessWidget {
  const _ErrorList({required this.message, required this.onRetry});

  final String message;
  final Future<void> Function() onRetry;

  @override
  Widget build(BuildContext context) {
    return ListView(
      physics: const AlwaysScrollableScrollPhysics(),
      children: [
        Padding(
          padding: const EdgeInsets.symmetric(vertical: 64, horizontal: 24),
          child: Column(
            children: [
              Text(message, textAlign: TextAlign.center),
              const SizedBox(height: 12),
              TextButton(onPressed: onRetry, child: const Text('Повторить')),
            ],
          ),
        ),
      ],
    );
  }
}