Flutter

Uses the standard http package — add it to your pubspec.yaml:

dependencies:
  http: ^1.2.0

VoltaClient

import 'dart:convert';
import 'package:http/http.dart' as http;

class VoltaClient {
  final String apiUrl;
  final String apiKey;
  final String layoutId;
  String? _token;

  VoltaClient({
    required this.apiUrl,
    required this.apiKey,
    required this.layoutId,
  });

  Map<String, String> get _keyHeaders => {
    'x-api-key': apiKey,
    'Content-Type': 'application/json',
  };

  Map<String, String> get _tokenHeaders => {
    'Authorization': 'Bearer $_token',
    'Content-Type': 'application/json',
  };

  // Step 1: Discover controls
  Future<Map<String, dynamic>> getLayoutInfo() async {
    final res = await http.get(
      Uri.parse('$apiUrl/layout/$layoutId'),
      headers: {'x-api-key': apiKey},
    );
    if (res.statusCode != 200) throw Exception('HTTP ${res.statusCode}');
    return jsonDecode(res.body);
  }

  // Step 2: Get a token
  Future<void> connect() async {
    final res = await http.post(
      Uri.parse('$apiUrl/token'),
      headers: _keyHeaders,
      body: jsonEncode({'layoutId': layoutId}),
    );
    if (res.statusCode != 200) throw Exception('HTTP ${res.statusCode}');
    _token = jsonDecode(res.body)['token'];
  }

  // Step 3: Send actions
  Future<void> sendAction(int lid, String type, [dynamic value]) async {
    await http.post(
      Uri.parse('$apiUrl/action'),
      headers: _tokenHeaders,
      body: jsonEncode({
        'layoutId': layoutId,
        'lid': lid,
        'type': type,
        if (value != null) 'value': value,
      }),
    );
  }

  Future<void> sendButton(int lid) => sendAction(lid, 'Button');
  Future<void> sendSlider(int lid, double value) => sendAction(lid, 'Slider', value);
  Future<void> sendToggle(int lid, bool value) => sendAction(lid, 'Toggle', value);
  Future<void> sendIndex(int lid, int value) => sendAction(lid, 'Index', value);
}

Usage

final client = VoltaClient(
  apiUrl: 'https://your-api-url.execute-api.eu-west-2.amazonaws.com',
  apiKey: 'your-api-key',
  layoutId: 'your-layout-id',
);

await client.connect();
final layout = await client.getLayoutInfo();

// Send interactions
await client.sendButton(1);
await client.sendSlider(2, 0.75);
await client.sendIndex(3, 1);