proto_go_dart_demo/frontend/lib/screens/notes_screen.dart

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

import '../gen/notes/v1/notes.pb.dart';
import '../services/grpc_client.dart';

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

  @override
  State<NotesScreen> createState() => _NotesScreenState();
}

class _NotesScreenState extends State<NotesScreen> {
  final _client = GrpcClient.instance.noteService;
  List<Note> _notes = [];
  bool _loading = true;
  String? _error;

  @override
  void initState() {
    super.initState();
    _loadNotes();
  }

  Future<void> _loadNotes() async {
    setState(() {
      _loading = true;
      _error = null;
    });

    try {
      // Типизированный вызов — ListNotesRequest и ListNotesResponse
      // сгенерированы из proto. Если на Go стороне изменится
      // сигнатура, после перегенерации этот код не скомпилируется.
      final response = await _client.listNotes(
        ListNotesRequest(page: 1, pageSize: 50),
      );
      setState(() {
        _notes = response.notes;
        _loading = false;
      });
    } on GrpcError catch (e) {
      setState(() {
        _error = 'gRPC error: ${e.message}';
        _loading = false;
      });
    } catch (e) {
      setState(() {
        _error = 'Connection error: $e';
        _loading = false;
      });
    }
  }

  Future<void> _createNote() async {
    final titleController = TextEditingController();
    final contentController = TextEditingController();

    final confirmed = await showDialog<bool>(
      context: context,
      builder: (ctx) => AlertDialog(
        title: const Text('New Note'),
        content: Column(
          mainAxisSize: MainAxisSize.min,
          children: [
            TextField(
              controller: titleController,
              decoration: const InputDecoration(labelText: 'Title'),
              autofocus: true,
            ),
            const SizedBox(height: 8),
            TextField(
              controller: contentController,
              decoration: const InputDecoration(labelText: 'Content'),
              maxLines: 3,
            ),
          ],
        ),
        actions: [
          TextButton(
            onPressed: () => Navigator.pop(ctx, false),
            child: const Text('Cancel'),
          ),
          FilledButton(
            onPressed: () => Navigator.pop(ctx, true),
            child: const Text('Create'),
          ),
        ],
      ),
    );

    if (confirmed != true) return;

    try {
      // Типизированный вызов CreateNote.
      // CreateNoteRequest точно соответствует proto определению.
      await _client.createNote(
        CreateNoteRequest(
          title: titleController.text,
          content: contentController.text,
        ),
      );
      _loadNotes();
    } on GrpcError catch (e) {
      if (mounted) {
        ScaffoldMessenger.of(context).showSnackBar(
          SnackBar(content: Text('Error: ${e.message}')),
        );
      }
    }
  }

  Future<void> _deleteNote(Note note) async {
    try {
      await _client.deleteNote(DeleteNoteRequest(id: note.id));
      _loadNotes();
    } on GrpcError catch (e) {
      if (mounted) {
        ScaffoldMessenger.of(context).showSnackBar(
          SnackBar(content: Text('Error: ${e.message}')),
        );
      }
    }
  }

  @override
  Widget build(BuildContext context) {
    return Scaffold(
      appBar: AppBar(
        title: const Text('Notes (Flutter + Go gRPC)'),
        actions: [
          IconButton(
            icon: const Icon(Icons.refresh),
            onPressed: _loadNotes,
          ),
        ],
      ),
      floatingActionButton: FloatingActionButton(
        onPressed: _createNote,
        child: const Icon(Icons.add),
      ),
      body: _buildBody(),
    );
  }

  Widget _buildBody() {
    if (_loading) {
      return const Center(child: CircularProgressIndicator());
    }

    if (_error != null) {
      return Center(
        child: Column(
          mainAxisSize: MainAxisSize.min,
          children: [
            Text(_error!, style: const TextStyle(color: Colors.red)),
            const SizedBox(height: 16),
            const Text(
              'Make sure Go backend is running:\n'
              'cd backend && go run main.go',
              textAlign: TextAlign.center,
            ),
            const SizedBox(height: 16),
            FilledButton(
              onPressed: _loadNotes,
              child: const Text('Retry'),
            ),
          ],
        ),
      );
    }

    if (_notes.isEmpty) {
      return const Center(
        child: Text('No notes yet. Tap + to create one.'),
      );
    }

    return ListView.builder(
      itemCount: _notes.length,
      itemBuilder: (context, index) {
        final note = _notes[index];
        return Card(
          margin: const EdgeInsets.symmetric(horizontal: 16, vertical: 4),
          child: ListTile(
            title: Text(note.title),
            subtitle: Text(
              note.content,
              maxLines: 2,
              overflow: TextOverflow.ellipsis,
            ),
            trailing: IconButton(
              icon: const Icon(Icons.delete_outline),
              onPressed: () => _deleteNote(note),
            ),
          ),
        );
      },
    );
  }
}