Mobile App

SafeCall Nav is a Flutter app for indoor navigation using BLE beacons. It supports Android and iOS with a single codebase.

Tech Stack

• Framework: Flutter (Dart ^3.10.3)
• Map Rendering: Flame (^1.35.1) game engine
• BLE: flutter_blue_plus (^2.1.1) for beacon scanning
• QR Scanner: mobile_scanner (^7.1.4)
• State Management: flutter_riverpod (^3.2.1)
• HTTP: http (^1.6.0) package
• Local Storage: sqflite + path_provider

Architecture

mobile/lib/
├── main.dart                     # App entry point
├── screens/
│   ├── home_screen.dart          # Server connection & sync
│   ├── qr_scanner_screen.dart    # QR code scanning
│   └── navigation_screen.dart    # Main map & navigation UI
├── services/
│   ├── api_client.dart           # HTTP client for server API
│   └── ble_scanner.dart          # BLE beacon scanning
├── models/
│   └── navigation_data.dart      # Domain models (bundle, floor, node, edge, beacon)
├── core/
│   ├── navigation_graph.dart     # Dijkstra pathfinding
│   └── positioning.dart          # BLE RSSI → position estimation
└── game/
    └── navigation_game.dart      # Flame map renderer

User Flow

1. Connect: Enter server URL manually or scan QR code
2. Authenticate: Login with email/password or navigation token
3. Sync: Download navigation bundle (floors, nodes, edges, beacons, maps)
4. Navigate: View indoor map, select destination, follow path

Data Flow

QR Code / Manual Input
        │
        ▼
    ApiClient
        │ authenticate + fetch bundle + download maps
        ▼
  NavigationBundle (saved to disk)
        │
        ├── NavigationGraph (Dijkstra pathfinding)
        ├── PositioningEngine (BLE → x,y)
        │       └── BleScanner (RSSI from WTK beacons)
        └── NavigationGame (Flame map renderer)

Key Models

Model	Purpose
NavigationBundle	Complete navigation data for a location (floors, nodes, edges, beacons)
NavigationFloor	One floor's graph, beacons, and map images
FloorData	Floor metadata (compass angle, map scale, ruler calibration)
NavNode	Graph node with x, y coordinates and optional name
NavEdge	Graph edge connecting two nodes with a weight
NavBeacon	BLE beacon with position, MAC, and POI/static flags

Offline Support

The app caches the navigation bundle to disk as nav_bundle.json. Floor map images are saved as floor_{id}.png. On subsequent launches, the app checks the SHA hash against the server and only re-downloads if the data has changed.

Development

cd mobile

# Get dependencies
flutter pub get

# Run on connected device
flutter run

# Run tests
flutter test

# Analyze code
flutter analyze