sentinel_flutter/lib/services/api_client.dart

import 'dart:convert';
import 'dart:math';
import 'package:flutter/foundation.dart';
import 'package:http/http.dart' as http;
import '../models/sensor_snapshot.dart';
import '../models/frame_analysis.dart';
import '../models/cost_dashboard.dart';
import '../models/health_status.dart';

class ApiClient extends ChangeNotifier {
  static const String defaultSpaceUrl = "https://com-sentinel-ai.hf.space";

  final http.Client _client;
  String spaceUrl;
  String? modalUrl;
  final String? hfToken;

  bool isOnline = true;

  // Cached Cost Metrics for backward compatibility
  int totalFrames = 0;
  int totalVlmCalls = 0;
  int totalTokens = 0;
  double estimatedCost = 0.0;
  double naiveCost = 0.0;
  double savingsPct = 0.0;
  double avgLatency = 0.0;

  // Connection/Retry Tracking State
  int _consecutiveFailures = 0;
  DateTime? _retryTime;
  int _retryDelaySeconds = 1;

  ApiClient({
    required this.spaceUrl,
    this.modalUrl,
    this.hfToken,
  }) : _client = http.Client();

  void updateSpaceUrl(String url) {
    if (url.endsWith('/')) {
      spaceUrl = url.substring(0, url.length - 1);
    } else {
      spaceUrl = url;
    }
    notifyListeners();
  }

  void _recordSuccess() {
    _consecutiveFailures = 0;
    _retryDelaySeconds = 1;
    if (!isOnline) {
      isOnline = true;
      notifyListeners();
    }
  }

  void _recordFailure() {
    _consecutiveFailures++;
    if (_consecutiveFailures >= 3 && isOnline) {
      isOnline = false;
      notifyListeners();
    }
    _retryTime = DateTime.now().add(Duration(seconds: _retryDelaySeconds));
    _retryDelaySeconds = min(_retryDelaySeconds * 2, 10);
  }

  bool _shouldBypassCall() {
    if (!isOnline) {
      if (_retryTime != null && DateTime.now().isAfter(_retryTime!)) {
        // Retry period expired, attempt connection
        return false;
      }
      return true; // Under cooldown, switch to local offline directly
    }
    return false;
  }

  String buildQuestion(SensorSnapshot sensors) {
    final headingStr = sensors.heading != null ? "${sensors.heading!.toStringAsFixed(0)}°" : "Unknown";
    final lightStr = sensors.lightLevel != null ? "${sensors.lightLevel!.toStringAsFixed(1)} lx" : "Unknown";
    final batteryStr = sensors.batteryPct != null ? "${sensors.batteryPct!.toStringAsFixed(0)}%" : "Unknown";

    String motion = "unknown";
    if (sensors.accelerometer != null && sensors.accelerometer!.length >= 3) {
      final double ax = sensors.accelerometer![0];
      final double ay = sensors.accelerometer![1];
      final double az = sensors.accelerometer![2];
      final double mag = sqrt(ax * ax + ay * ay + az * az) - 9.8;
      if (mag.abs() < 1.0) {
        motion = "stationary";
      } else if (mag.abs() < 3.0) {
        motion = "walking pace";
      } else {
        motion = "running or shaking";
      }
    }

    final String location = (sensors.gps != null) ? "outdoor" : "indoor";
    final gpsStr = sensors.gps != null
        ? "GPS: ${sensors.gps![0].toStringAsFixed(4)}, ${sensors.gps![1].toStringAsFixed(4)}"
        : "GPS: Unavailable";

    return "Describe what you see and any dangers. "
        "User heading: $headingStr. Light: $lightStr. Battery: $batteryStr. "
        "Motion: $motion. Location: $location. $gpsStr.";
  }

  Future<FrameAnalysis> analyzeFrame(String base64Image, SensorSnapshot sensors) async {
    if (_shouldBypassCall()) {
      return _generateOfflineAnalysis(sensors, "System offline (consecutive connection failures).");
    }

    final headers = {
      'Content-Type': 'application/json',
      if (hfToken != null) 'Authorization': 'Bearer $hfToken',
    };

    // 1. Prefer Modal Direct Call (Faster, persistent container)
    if (modalUrl != null && modalUrl!.isNotEmpty) {
      try {
        final url = Uri.parse('$modalUrl/see');
        final response = await _client.post(
          url,
          headers: {'Content-Type': 'application/json'},
          body: jsonEncode({
            "image_base64": base64Image,
            "question": buildQuestion(sensors),
          }),
        ).timeout(const Duration(seconds: 30));

        if (response.statusCode == 200) {
          _recordSuccess();
          final data = jsonDecode(response.body);
          return FrameAnalysis.fromJson(data);
        }
      } catch (e) {
        debugPrint("Modal see request failed: $e. Falling back to Gradio.");
      }
    }

    // 2. Fallback to Gradio Space API
    try {
      final url = Uri.parse('$spaceUrl/call/analyze_frame');
      final response = await _client.post(
        url,
        headers: headers,
        body: jsonEncode({
          "data": [base64Image, sensors.toJson()]
        }),
      ).timeout(const Duration(seconds: 30));

      if (response.statusCode == 200) {
        _recordSuccess();
        final body = jsonDecode(response.body);

        // Gradio async event returns event_id:
        if (body is Map && body.containsKey('event_id')) {
          final eventId = body['event_id'];
          final resultResponse = await _client.get(
            Uri.parse('$spaceUrl/call/analyze_frame/$eventId'),
            headers: headers,
          ).timeout(const Duration(seconds: 30));

          if (resultResponse.statusCode == 200) {
            final lines = resultResponse.body.split('\n');
            for (var line in lines) {
              if (line.startsWith('data: ')) {
                final jsonStr = line.substring(6).trim();
                final List<dynamic> dataList = jsonDecode(jsonStr);
                if (dataList.isNotEmpty) {
                  return FrameAnalysis.fromJson(dataList.first);
                }
              }
            }
          }
        } else if (body is Map && body.containsKey('data')) {
          final List<dynamic> dataList = body['data'];
          if (dataList.isNotEmpty) {
            return FrameAnalysis.fromJson(dataList.first);
          }
        }
      }
    } catch (e) {
      debugPrint("Gradio Space call failed: $e");
    }

    // Both primary routes failed
    _recordFailure();
    return _generateOfflineAnalysis(sensors, "Connection timeout. Switched to offline.");
  }

  Future<String> generateAlertAudio(String text, String level) async {
    if (modalUrl != null && modalUrl!.isNotEmpty && isOnline) {
      try {
        final url = Uri.parse('$modalUrl/generate_alert_audio');
        final response = await _client.post(
          url,
          headers: {'Content-Type': 'application/json'},
          body: jsonEncode({"text": text}),
        ).timeout(const Duration(seconds: 30));

        if (response.statusCode == 200) {
          final data = jsonDecode(response.body);
          return data['audio_base64'] ?? '';
        }
      } catch (e) {
        debugPrint("Error generating alert audio from Modal: $e");
      }
    }
    return '';
  }

  Future<CostDashboard> getCostStats() async {
    final headers = {
      if (hfToken != null) 'Authorization': 'Bearer $hfToken',
    };

    if (isOnline) {
      try {
        final response = await _client.get(
          Uri.parse('$spaceUrl/call/get_stats'),
          headers: headers,
        ).timeout(const Duration(seconds: 30));

        if (response.statusCode == 200) {
          final body = jsonDecode(response.body);
          if (body is Map) {
            if (body.containsKey('event_id')) {
              final eventId = body['event_id'];
              final resultResponse = await _client.get(
                Uri.parse('$spaceUrl/call/get_stats/$eventId'),
                headers: headers,
              ).timeout(const Duration(seconds: 30));

              if (resultResponse.statusCode == 200) {
                final lines = resultResponse.body.split('\n');
                for (var line in lines) {
                  if (line.startsWith('data: ')) {
                    final jsonStr = line.substring(6).trim();
                    final List<dynamic> dataList = jsonDecode(jsonStr);
                    if (dataList.isNotEmpty) {
                      final parsed = CostDashboard.fromJson(dataList.first);
                      _updateLocalCostStats(parsed);
                      return parsed;
                    }
                  }
                }
              }
            } else if (body.containsKey('data')) {
              final List<dynamic> dataList = body['data'];
              if (dataList.isNotEmpty) {
                final parsed = CostDashboard.fromJson(dataList.first);
                _updateLocalCostStats(parsed);
                return parsed;
              }
            }
          }
        }
      } catch (e) {
        debugPrint("Error fetching cost stats: $e");
      }
    }

    return CostDashboard(
      vlmCalls: totalVlmCalls,
      totalTokens: totalTokens,
      totalInferenceMs: (avgLatency * totalVlmCalls).toInt(),
      estimatedCostUsd: estimatedCost,
      naiveCostUsd: naiveCost,
      savingsPct: savingsPct,
      framesProcessed: totalFrames,
      uptimeHours: 0.0,
    );
  }

  Future<HealthStatus> checkHealth() async {
    if (modalUrl != null && modalUrl!.isNotEmpty) {
      try {
        final response = await _client.get(
          Uri.parse('$modalUrl/health'),
        ).timeout(const Duration(seconds: 30));

        if (response.statusCode == 200) {
          final data = jsonDecode(response.body);
          return HealthStatus.fromJson(data);
        }
      } catch (e) {
        debugPrint("Modal health check failed: $e");
      }
    }
    return HealthStatus(status: 'unhealthy', uptime: 0.0);
  }

  void _updateLocalCostStats(CostDashboard stats) {
    totalFrames = stats.framesProcessed;
    totalVlmCalls = stats.vlmCalls;
    totalTokens = stats.totalTokens;
    estimatedCost = stats.estimatedCostUsd;
    naiveCost = stats.naiveCostUsd;
    savingsPct = stats.savingsPct;
    avgLatency = stats.vlmCalls > 0 ? stats.totalInferenceMs / stats.vlmCalls : 0.0;
    notifyListeners();
  }

  FrameAnalysis _generateOfflineAnalysis(SensorSnapshot sensors, String offlineReason) {
    String level = "none";
    String text = "System operating in local offline fallback mode.";

    if (sensors.accelerometer != null && sensors.accelerometer!.length >= 3) {
      final double ax = sensors.accelerometer![0];
      final double ay = sensors.accelerometer![1];
      final double az = sensors.accelerometer![2];
      final double mag = sqrt(ax * ax + ay * ay + az * az);
      if (mag > 26.0) {
        level = "critical";
        text = "Local Alert: High Impact G-Force detected ($mag m/s²)! Possible fall.";
      }
    }

    if (level == "none" && sensors.batteryPct != null && sensors.batteryPct! < 15.0) {
      level = "warning";
      text = "Local Warning: Low Battery level (${sensors.batteryPct!.toStringAsFixed(0)}%).";
    }

    return FrameAnalysis(
      frameId: -1,
      timestamp: DateTime.now().millisecondsSinceEpoch / 1000.0,
      changePct: 0.0,
      yoloDetections: [],
      audioClasses: [],
      vlmTriggered: false,
      alertLevel: level,
      alertText: "$text ($offlineReason)",
    );
  }

  @override
  void dispose() {
    _client.close();
    super.dispose();
  }
}