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

/// Represents a busy intersection.
class Intersection {
  final String name;
  final double latitude;
  final double longitude;

  Intersection(this.name, this.latitude, this.longitude);
}

/// A service that communicates with the OpenAI ChatGPT API.
class ChatGPTService {
  final String apiKey = 'YOUR_API_KEY'; // Replace with your actual API key
  final String apiUrl = 'https://api.openai.com/v1/chat/completions';

  /// Sends a prompt to ChatGPT to find the busiest intersections around the address.
  Future<List<Intersection>> getBusyIntersections({
    required String address,
    required int count,
    required double radiusMiles,
    required String timeOfDay,
  }) async {
    final prompt = '''
Given the address "$address", find the $count busiest intersections within $radiusMiles miles during $timeOfDay on a weekday. Return the results in CSV format with columns: intersection_name, latitude, longitude.
''';

    final response = await http.post(
      Uri.parse(apiUrl),
      headers: {
        'Authorization': 'Bearer $apiKey',
        'Content-Type': 'application/json',
      },
      body: jsonEncode({
        "model": "gpt-4",
        "messages": [
          {
            "role": "system",
            "content": "You are a traffic and mapping expert.",
          },
          {"role": "user", "content": prompt},
        ],
      }),
    );

    if (response.statusCode == 200) {
      final data = jsonDecode(response.body);
      final csvString = data['choices'][0]['message']['content'];
      return _parseCsv(csvString);
    } else {
      throw Exception('Failed to get response from ChatGPT: ${response.body}');
    }
  }

  /// Parses the CSV response into a list of [Intersection] objects.
  List<Intersection> _parseCsv(String csv) {
    final lines = LineSplitter().convert(csv.trim());
    final intersections = <Intersection>[];

    for (var i = 1; i < lines.length; i++) {
      final parts = lines[i].split(',');
      if (parts.length >= 3) {
        final name = parts[0].trim();
        final lat = double.tryParse(parts[1].trim());
        final lng = double.tryParse(parts[2].trim());
        if (lat != null && lng != null) {
          intersections.add(Intersection(name, lat, lng));
        }
      }
    }

    return intersections;
  }
}