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

import '../app/error_message.dart';
import '../app/load_state.dart';
import '../features/groups/group_form_logic.dart';
import '../models/ignis_device.dart';
import '../models/ignis_group.dart';
import '../providers/providers.dart';
import '../widgets/load_error_view.dart';

class GroupEditScreen extends ConsumerStatefulWidget {
  const GroupEditScreen({super.key});

  @override
  ConsumerState<GroupEditScreen> createState() => _GroupEditScreenState();
}

class _GroupEditScreenState extends ConsumerState<GroupEditScreen> {
  final _formKey = GlobalKey<FormState>();
  final _idCtrl = TextEditingController();
  final _nameCtrl = TextEditingController();
  final Set<String> _selectedMacs = <String>{};

  bool _saving = false;
  bool _rescanning = false;
  bool _deviceSelectionTouched = false;
  bool _idEditedManually = false;
  bool _syncingIdFromName = false;

  @override
  void initState() {
    super.initState();
    _nameCtrl.addListener(_handleNameChanged);
    _idCtrl.addListener(_handleIdChanged);
    Future<void>.microtask(() async {
      await _loadDevices();
      try {
        await ref.read(groupsProvider.notifier).refresh();
      } catch (_) {
        // Покажем текущее состояние через экран, без лишнего шума.
      }
    });
  }

  @override
  void dispose() {
    _nameCtrl.removeListener(_handleNameChanged);
    _idCtrl.removeListener(_handleIdChanged);
    _idCtrl.dispose();
    _nameCtrl.dispose();
    super.dispose();
  }

  void _handleNameChanged() {
    if (_idEditedManually) {
      return;
    }
    final slug = slugifyGroupId(_nameCtrl.text);
    _syncingIdFromName = true;
    _idCtrl.value = _idCtrl.value.copyWith(
      text: slug,
      selection: TextSelection.collapsed(offset: slug.length),
      composing: TextRange.empty,
    );
    _syncingIdFromName = false;
  }

  void _handleIdChanged() {
    if (_syncingIdFromName) {
      return;
    }
    final suggested = slugifyGroupId(_nameCtrl.text);
    final current = _idCtrl.text.trim();
    _idEditedManually = current.isNotEmpty && current != suggested;
  }

  Future<void> _loadDevices() async {
    await ref.read(devicesProvider.notifier).load();
  }

  Future<void> _rescan() async {
    setState(() => _rescanning = true);
    try {
      final response = await ref.read(apiProvider).rescanNetwork();
      await ref.read(devicesProvider.notifier).load();
      final summary = response.data is Map
          ? Map<String, dynamic>.from(response.data as Map)
          : const <String, dynamic>{};
      final message = formatRescanSummary(summary);

      if (!mounted) return;
      ScaffoldMessenger.of(context).showSnackBar(
        SnackBar(
          content: Text(message),
          duration: const Duration(seconds: 2),
        ),
      );
    } catch (e) {
      if (!mounted) return;
      ScaffoldMessenger.of(context).showSnackBar(
        SnackBar(content: Text('Ошибка сканирования: ${describeLoadError(e)}')),
      );
    } finally {
      if (mounted) {
        setState(() => _rescanning = false);
      }
    }
  }

  @override
  Widget build(BuildContext context) {
    final devicesState = ref.watch(devicesProvider);
    final devices = devicesState.data;
    final groups = ref.watch(groupsProvider);
    final conflicts = findGroupMembershipConflicts(_selectedMacs, groups);

    return Scaffold(
      appBar: AppBar(
        title: const Text('НОВАЯ ГРУППА'),
        actions: [
          IconButton(
            icon: _rescanning
                ? const SizedBox(
                    width: 20,
                    height: 20,
                    child: CircularProgressIndicator(strokeWidth: 2),
                  )
                : const Icon(Icons.refresh),
            tooltip: 'Пересканировать сеть',
            onPressed: _rescanning ? null : _rescan,
          ),
        ],
      ),
      body: Form(
        key: _formKey,
        autovalidateMode: AutovalidateMode.onUserInteraction,
        child: Padding(
          padding: const EdgeInsets.all(16),
          child: Column(
            crossAxisAlignment: CrossAxisAlignment.start,
            children: [
              TextFormField(
                controller: _nameCtrl,
                decoration: const InputDecoration(
                  labelText: 'Название группы',
                  hintText: 'Например: Спальня',
                  prefixIcon: Icon(Icons.label),
                ),
                textCapitalization: TextCapitalization.sentences,
                validator: (value) => validateGroupName(value ?? ''),
              ),
              const SizedBox(height: 12),
              TextFormField(
                controller: _idCtrl,
                decoration: InputDecoration(
                  labelText: 'ID группы',
                  hintText: 'Например: bedroom',
                  helperText: _idEditedManually
                      ? 'Используется в API и расписаниях'
                      : 'Подставляется автоматически из названия',
                  prefixIcon: const Icon(Icons.tag),
                ),
                autocorrect: false,
                enableSuggestions: false,
                validator: (value) => validateGroupId(value ?? '', groups),
              ),
              const SizedBox(height: 8),
              const Text(
                'Выберите устройства, которые будут управляться как одна группа.',
                style: TextStyle(color: Colors.white54),
              ),
              const SizedBox(height: 16),
              Row(
                mainAxisAlignment: MainAxisAlignment.spaceBetween,
                children: [
                  Text(
                    'Устройства (${_selectedMacs.length} выбрано)',
                    style: const TextStyle(
                      fontSize: 14,
                      fontWeight: FontWeight.bold,
                      color: Colors.white70,
                    ),
                  ),
                  TextButton(
                    onPressed: devices.isEmpty
                        ? null
                        : () {
                            setState(() {
                              _deviceSelectionTouched = true;
                              if (_selectedMacs.length == devices.length) {
                                _selectedMacs.clear();
                              } else {
                                _selectedMacs
                                  ..clear()
                                  ..addAll(
                                    devices.map(
                                      (device) => device.groupMemberId,
                                    ),
                                  );
                              }
                            });
                          },
                    child: Text(
                      _selectedMacs.length == devices.length
                          ? 'Снять все'
                          : 'Выбрать все',
                      style: const TextStyle(fontSize: 12),
                    ),
                  ),
                ],
              ),
              if (_deviceSelectionTouched && _selectedMacs.isEmpty)
                const Padding(
                  padding: EdgeInsets.only(top: 4, bottom: 8),
                  child: Text(
                    'Выберите хотя бы одно устройство',
                    style: TextStyle(color: Colors.redAccent, fontSize: 12),
                  ),
                )
              else
                const SizedBox(height: 8),
              if (conflicts.isNotEmpty)
                Padding(
                  padding: const EdgeInsets.only(bottom: 12),
                  child: _ConflictBanner(conflicts: conflicts),
                ),
              Expanded(child: _buildDevices(devicesState, devices)),
              Padding(
                padding: EdgeInsets.only(
                  top: 12,
                  bottom: MediaQuery.of(context).padding.bottom + 8,
                ),
                child: SizedBox(
                  width: double.infinity,
                  height: 48,
                  child: ElevatedButton(
                    style: ElevatedButton.styleFrom(
                      backgroundColor: Colors.deepOrange,
                      foregroundColor: Colors.white,
                    ),
                    onPressed: _saving ? null : _save,
                    child: _saving
                        ? const SizedBox(
                            width: 20,
                            height: 20,
                            child: CircularProgressIndicator(
                              strokeWidth: 2,
                              color: Colors.white,
                            ),
                          )
                        : const Text('СОЗДАТЬ ГРУППУ'),
                  ),
                ),
              ),
            ],
          ),
        ),
      ),
    );
  }

  Widget _buildDevices(
    LoadState<List<IgnisDevice>> devicesState,
    List<IgnisDevice> devices,
  ) {
    if ((devicesState.isIdle || devicesState.isLoading) && devices.isEmpty) {
      return const Center(
        child: CircularProgressIndicator(color: Colors.deepOrange),
      );
    }

    if (devicesState.hasError && devices.isEmpty) {
      return LoadErrorView(
        title: 'Не удалось загрузить устройства',
        message: devicesState.errorMessage,
        icon: Icons.lightbulb_outline,
        onRetry: _loadDevices,
      );
    }

    if (devices.isEmpty) {
      return const Center(
        child: Text(
          'Устройства не найдены.\nПересканируйте сеть и попробуйте снова.',
          textAlign: TextAlign.center,
          style: TextStyle(color: Colors.white38),
        ),
      );
    }

    final hasStatusHeader = devicesState.isLoading || devicesState.hasError;
    final statusHeaderCount = hasStatusHeader ? 1 : 0;

    return ListView.builder(
      itemCount: devices.length + statusHeaderCount,
      itemBuilder: (context, index) {
        if (hasStatusHeader && index == 0) {
          if (devicesState.isLoading) {
            return const Padding(
              padding: EdgeInsets.only(bottom: 12),
              child: LinearProgressIndicator(color: Colors.deepOrange),
            );
          }

          return LoadErrorBanner(
            title: 'Не удалось обновить устройства',
            message: devicesState.errorMessage,
            onRetry: _loadDevices,
          );
        }

        final device = devices[index - statusHeaderCount];
        final selected = _selectedMacs.contains(device.groupMemberId);

        return CheckboxListTile(
          value: selected,
          activeColor: Colors.deepOrange,
          title: Text(device.name),
          subtitle: device.subtitle == null
              ? null
              : Text(
                  device.subtitle!,
                  style: const TextStyle(fontSize: 11, color: Colors.white38),
                ),
          onChanged: (value) {
            setState(() {
              _deviceSelectionTouched = true;
              if (value == true) {
                _selectedMacs.add(device.groupMemberId);
              } else {
                _selectedMacs.remove(device.groupMemberId);
              }
            });
          },
        );
      },
    );
  }

  Future<void> _save() async {
    FocusScope.of(context).unfocus();
    setState(() => _deviceSelectionTouched = true);

    if (!_formKey.currentState!.validate()) {
      return;
    }
    if (_selectedMacs.isEmpty) {
      return;
    }

    final groups = ref.read(groupsProvider);
    final conflicts = findGroupMembershipConflicts(_selectedMacs, groups);
    if (conflicts.isNotEmpty) {
      final shouldContinue = await _confirmConflicts(conflicts);
      if (shouldContinue != true) {
        return;
      }
    }

    setState(() => _saving = true);
    try {
      final id = _idCtrl.text.trim().toLowerCase();
      final name = _nameCtrl.text.trim();
      await ref.read(apiProvider).createGroup(id, name, _selectedMacs.toList());
      await ref.read(groupsProvider.notifier).refresh();
      if (!mounted) return;
      ScaffoldMessenger.of(context).showSnackBar(
        const SnackBar(
          content: Text('Группа создана'),
          duration: Duration(seconds: 1),
        ),
      );
      Navigator.of(context).pop();
    } catch (e) {
      if (!mounted) return;
      ScaffoldMessenger.of(context).showSnackBar(
        SnackBar(content: Text('Ошибка создания: ${describeLoadError(e)}')),
      );
    } finally {
      if (mounted) {
        setState(() => _saving = false);
      }
    }
  }

  Future<bool?> _confirmConflicts(List<IgnisGroup> conflicts) {
    return showDialog<bool>(
      context: context,
      builder: (ctx) => AlertDialog(
        title: const Text('Устройства уже состоят в других группах'),
        content: Text(
          'Выбранные устройства уже входят в: ${conflicts.map((group) => group.name).join(', ')}.\n\nПродолжить создание новой группы?',
        ),
        actions: [
          TextButton(
            onPressed: () => Navigator.of(ctx).pop(false),
            child: const Text('Отмена'),
          ),
          ElevatedButton(
            style: ElevatedButton.styleFrom(backgroundColor: Colors.deepOrange),
            onPressed: () => Navigator.of(ctx).pop(true),
            child: const Text('Продолжить'),
          ),
        ],
      ),
    );
  }

}

int _summaryInt(Map<String, dynamic> summary, String key) {
  final value = summary[key];
  if (value is int) {
    return value;
  }
  return int.tryParse(value?.toString() ?? '') ?? 0;
}

String formatRescanSummary(Map<String, dynamic> summary) {
  final found = _summaryInt(summary, 'found');
  final added = _summaryInt(summary, 'added');
  final updated = _summaryInt(summary, 'updated');
  final removed = _summaryInt(summary, 'removed_offline');

  if (added == 0 && updated == 0 && removed == 0 && found == 0) {
    return 'Сканирование завершено: устройства не найдены';
  }

  if (added == 0 && removed == 0) {
    return 'Сканирование завершено: найдено $found, обновлено $updated';
  }

  return 'Сканирование завершено: найдено $found, новых $added, обновлено $updated, убрано $removed';
}

class _ConflictBanner extends StatelessWidget {
  final List<IgnisGroup> conflicts;

  const _ConflictBanner({required this.conflicts});

  @override
  Widget build(BuildContext context) {
    return Container(
      width: double.infinity,
      padding: const EdgeInsets.all(12),
      decoration: BoxDecoration(
        color: Colors.amber.withValues(alpha: 0.12),
        borderRadius: BorderRadius.circular(12),
        border: Border.all(color: Colors.amber.withValues(alpha: 0.3)),
      ),
      child: Text(
        'Внимание: часть выбранных устройств уже состоит в группах ${conflicts.map((group) => group.name).join(', ')}.',
        style: const TextStyle(color: Colors.amber),
      ),
    );
  }
}