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

/// Provides AI-powered activity suggestions using an external endpoint.
///
/// The endpoint is expected to accept POST JSON:
/// { "city": "...", "interests": ["food","art"], "budget": "low|mid|high" }
/// and return { "suggestions": [ { "title": "...", "detail": "..." }, ... ] }
///
/// This class is a thin client and can be wired to a custom backend that
/// proxies LLM calls (to avoid shipping secrets in the app).
class AiActivityService {
  /// Base URL of the AI suggestion endpoint.
  final String baseUrl;

  /// Optional API key if your backend requires it.
  final String? apiKey;

  /// Creates an AI activity service client.
  const AiActivityService({required this.baseUrl, this.apiKey});

  /// Fetches suggestions for the given [city] with optional [interests] and [budget].
  ///
  /// Returns a list of string suggestions. In case of error, returns an empty list
  /// to keep the UI responsive.
  Future<List<String>> fetchSuggestions({
    required String city,
    List<String> interests = const [],
    String budget = 'mid',
  }) async {
    final uri = Uri.parse('$baseUrl/ai/suggestions');
    try {
      final response = await http.post(
        uri,
        headers: {
          'Content-Type': 'application/json',
          if (apiKey != null) 'Authorization': 'Bearer $apiKey',
        },
        body: json.encode({
          'city': city,
          'interests': interests,
          'budget': budget,
        }),
      );

      if (response.statusCode == 200) {
        final data = json.decode(response.body) as Map<String, dynamic>;
        final list = (data['suggestions'] as List<dynamic>? ?? [])
            .cast<Map<String, dynamic>>();
        return list
            .map((item) => item['title'] as String? ?? 'Suggestion')
            .toList();
      }
      return const [];
    } catch (_) {
      return const [];
    }
  }
}