import 'dart:convert';

import 'package:firebase_core/firebase_core.dart';
import 'package:flutter/services.dart';

class AppConfigService {
  AppConfigService._();

  static final AppConfigService instance = AppConfigService._();

  bool _initialized = false;

  Future<void> initialize() async {
    if (_initialized) return;

    final configRaw =
        await rootBundle.loadString('assets/config/runtime_config.json');
    final Map<String, dynamic> config = json.decode(configRaw);

    await Firebase.initializeApp(
      options: FirebaseOptions(
        apiKey: _required(config, 'firebase_api_key'),
        appId: _required(config, 'firebase_app_id'),
        messagingSenderId: _required(config, 'firebase_messaging_sender_id'),
        projectId: _required(config, 'firebase_project_id'),
        authDomain: _required(config, 'firebase_auth_domain'),
        storageBucket: _required(config, 'firebase_storage_bucket'),
        measurementId: _optional(config, 'firebase_measurement_id'),
      ),
    );

    _initialized = true;
  }

  String _required(Map<String, dynamic> config, String key) {
    final value = (config[key] ?? '').toString().trim();
    if (value.isEmpty || value.startsWith('replace-with-')) {
      throw StateError('Missing required runtime configuration: $key');
    }
    return value;
  }

  String? _optional(Map<String, dynamic> config, String key) {
    final value = (config[key] ?? '').toString().trim();
    return value.isEmpty ? null : value;
  }
}