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

import '../viewmodels/note_view_model.dart';
import 'note_editor_screen.dart';
import 'settings_screen.dart';

class NoteListScreen extends StatelessWidget {
  const NoteListScreen({super.key});

  @override
  Widget build(BuildContext context) {
    final vm = context.watch<NoteViewModel>();

    return Scaffold(
      appBar: AppBar(
        title: const Text('Notes'),
        actions: [
          IconButton(
            icon: const Icon(Icons.more_vert),
            onPressed: () => _showMenu(context, vm),
          ),
        ],
      ),
      body: _buildBody(context, vm),
      floatingActionButton: FloatingActionButton(
        onPressed: () => _createNote(context, vm),
        child: const Icon(Icons.add),
      ),
    );
  }

  Widget _buildBody(BuildContext context, NoteViewModel vm) {
    if (vm.isLoading) {
      return const Center(child: CircularProgressIndicator());
    }

    if (vm.error != null) {
      return Center(
        child: Column(
          mainAxisSize: MainAxisSize.min,
          children: [
            Text(vm.error!, style: const TextStyle(color: Colors.red)),
            const SizedBox(height: 12),
            ElevatedButton(
              onPressed: vm.loadNotes,
              child: const Text('Retry'),
            ),
          ],
        ),
      );
    }

    if (vm.notes.isEmpty) {
      return const Center(
        child: Text(
          'No notes yet.\nTap + to create one.',
          textAlign: TextAlign.center,
          style: TextStyle(color: Colors.grey),
        ),
      );
    }

    return ListView.separated(
      padding: const EdgeInsets.symmetric(vertical: 8),
      itemCount: vm.notes.length,
      separatorBuilder: (_, __) => const Divider(height: 1),
      itemBuilder: (context, index) {
        final note = vm.notes[index];
        return ListTile(
          title: Text(
            note.title.isEmpty ? 'Untitled' : note.title,
            maxLines: 1,
            overflow: TextOverflow.ellipsis,
          ),
          subtitle: Text(
            note.content.isEmpty ? 'No content' : note.content,
            maxLines: 2,
            overflow: TextOverflow.ellipsis,
          ),
          trailing: Text(
            _formatDate(note.updatedAt),
            style: const TextStyle(fontSize: 12, color: Colors.grey),
          ),
          onTap: () => _openNote(context, note.id),
          onLongPress: () => _confirmDelete(context, vm, note.id),
        );
      },
    );
  }

  Future<void> _createNote(BuildContext context, NoteViewModel vm) async {
    final note = await vm.createNote();
    if (context.mounted) {
      Navigator.push(
        context,
        MaterialPageRoute(builder: (_) => NoteEditorScreen(noteId: note.id)),
      );
    }
  }

  void _openNote(BuildContext context, String noteId) {
    Navigator.push(
      context,
      MaterialPageRoute(builder: (_) => NoteEditorScreen(noteId: noteId)),
    );
  }

  void _showMenu(BuildContext context, NoteViewModel vm) {
    showModalBottomSheet(
      context: context,
      builder: (_) => SafeArea(
        child: Column(
          mainAxisSize: MainAxisSize.min,
          children: [
            ListTile(
              leading: const Icon(Icons.settings_outlined),
              title: const Text('Backup settings'),
              onTap: () async {
                Navigator.pop(context);
                await _openSettings(context);
              },
            ),
            ListTile(
              leading: const Icon(Icons.cloud_upload_outlined),
              title: const Text('Backup to server'),
              onTap: () {
                Navigator.pop(context);
                _runBackup(context, vm);
              },
            ),
            ListTile(
              leading: const Icon(Icons.cloud_download_outlined),
              title: const Text('Restore from server'),
              onTap: () {
                Navigator.pop(context);
                _runRestore(context, vm);
              },
            ),
          ],
        ),
      ),
    );
  }

  Future<void> _openSettings(BuildContext context) async {
    await Navigator.push(
      context,
      MaterialPageRoute(builder: (_) => const SettingsScreen()),
    );
    // Settings saved — user needs to restart the app for sync to activate.
    // We'll improve this later when we add a proper service locator.
    if (context.mounted) {
      ScaffoldMessenger.of(context).showSnackBar(
        const SnackBar(
          content: Text('Restart the app to apply backup settings.'),
        ),
      );
    }
  }

  Future<void> _runBackup(BuildContext context, NoteViewModel vm) async {
    await vm.backup();
    if (context.mounted) {
      ScaffoldMessenger.of(context).showSnackBar(
        SnackBar(
          content: Text(
            vm.backupStatus == BackupStatus.success
                ? 'Backup successful'
                : 'Backup failed: ${vm.error}',
          ),
        ),
      );
    }
  }

  Future<void> _runRestore(BuildContext context, NoteViewModel vm) async {
    await vm.restore();
    if (context.mounted) {
      ScaffoldMessenger.of(context).showSnackBar(
        SnackBar(
          content: Text(
            vm.backupStatus == BackupStatus.success
                ? 'Restore successful'
                : 'Restore failed: ${vm.error}',
          ),
        ),
      );
    }
  }

  Future<void> _confirmDelete(
      BuildContext context, NoteViewModel vm, String id) async {
    final confirmed = await showDialog<bool>(
      context: context,
      builder: (_) => AlertDialog(
        title: const Text('Delete note?'),
        content: const Text('This cannot be undone.'),
        actions: [
          TextButton(
            onPressed: () => Navigator.pop(context, false),
            child: const Text('Cancel'),
          ),
          TextButton(
            onPressed: () => Navigator.pop(context, true),
            child: const Text('Delete', style: TextStyle(color: Colors.red)),
          ),
        ],
      ),
    );
    if (confirmed == true) await vm.deleteNote(id);
  }

  String _formatDate(DateTime dt) {
    final now = DateTime.now();
    if (dt.year == now.year && dt.month == now.month && dt.day == now.day) {
      return '${dt.hour.toString().padLeft(2, '0')}:${dt.minute.toString().padLeft(2, '0')}';
    }
    return '${dt.day}/${dt.month}/${dt.year}';
  }
}