# Google Navigation Flutter - Implementation Summary

## Overview
Complete implementation of Google Navigation Flutter for the Plan B Logistics app with full support for turn-by-turn navigation, location permissions, and internationalization.

## Configuration Changes

### Android (android/app/build.gradle.kts)
- Set `minSdk = 23` (required for Google Navigation)
- Added desugaring dependency for Java NIO support
- Kotlin version already at 2.1.0 (meets 2.0+ requirement)

### iOS (ios/Runner/Info.plist)
- Added `NSLocationAlwaysUsageDescription` for background location tracking
- Background modes already configured for location
- API key already configured in AppDelegate.swift

## New Services Created

### 1. LocationPermissionService (`lib/services/location_permission_service.dart`)
Handles location permission requests with pattern matching:
- `requestLocationPermission()` - Request user permission
- `hasLocationPermission()` - Check current status
- `openAppSettings()` - Open app settings

Returns `LocationPermissionResult` sealed class with states:
- `granted()` - Permission granted
- `denied()` - Permission denied
- `permanentlyDenied()` - Need to open settings
- `error(message)` - System error occurred

### 2. NavigationSessionService (`lib/services/navigation_session_service.dart`)
Singleton service for managing Google Navigation session:
- `initializeSession()` - Initialize navigation session
- `setController(controller)` - Set view controller
- `calculateRoute(...)` - Calculate route from A to B
- `startNavigation()` - Start turn-by-turn guidance
- `stopNavigation()` - Stop current navigation
- `addLocationListener(callback)` - Track location updates
- `addArrivalListener(callback)` - Handle destination arrival
- `addRemainingDistanceListener(callback)` - Track remaining distance
- `cleanup()` - Cleanup resources

Returns `NavigationRoute` with location and route info.

## New UI Components

### 1. NavigationTermsAndConditionsDialog (`lib/components/navigation_tc_dialog.dart`)
Material 3 themed dialog for T&C acceptance:
- Displays navigation service description
- Shows Google Maps attribution
- Accept/Decline buttons with callbacks
- Fully internationalized

### 2. NavigationPage (`lib/pages/navigation_page.dart`)
Complete turn-by-turn navigation screen:
- Full-screen Google Navigation View
- Automatic location permission handling
- Destination markers and route visualization
- Navigation UI controls enabled
- Arrival notifications
- Error handling dialogs
- Loading states with spinners

Features:
- Initializes navigation session
- Requests location permissions if needed
- Sets delivery destination
- Shows T&C dialog on first use
- Handles navigation events (arrival, location updates)
- Provides completion/cancellation callbacks

## Internationalization

Added translation keys for both English and French:

### Navigation Service Keys
- `navigationTcTitle` - Service name
- `navigationTcDescription` - Service description
- `navigationTcAttribution` - Google Maps attribution
- `navigationTcTerms` - Terms acceptance text

### Permission Keys
- `locationPermissionRequired` - Title
- `locationPermissionMessage` - Permission request message
- `locationPermissionDenied` - Denial message
- `permissionPermanentlyDenied` - Title for settings needed
- `openSettingsMessage` - Settings message
- `openSettings` - Open settings button

### Navigation Keys
- `navigationArrived` - Arrival notification
- `navigatingTo` - Navigation header text
- `initializingNavigation` - Loading message

### General Keys
- `accept`, `decline` - Button labels
- `cancel`, `ok`, `requestPermission` - Common buttons

## File Structure

```
lib/
├── services/
│   ├── location_permission_service.dart (NEW)
│   ├── navigation_session_service.dart (NEW)
│   └── auth_service.dart (existing)
├── pages/
│   ├── navigation_page.dart (NEW)
│   ├── deliveries_page.dart (existing)
│   └── ...
├── components/
│   ├── navigation_tc_dialog.dart (NEW)
│   └── ...
└── l10n/
    ├── app_en.arb (UPDATED)
    └── app_fr.arb (UPDATED)

android/
└── app/
    └── build.gradle.kts (UPDATED)

ios/
├── Podfile (already configured)
└── Runner/
    └── Info.plist (UPDATED)
```

## Key Features Implemented

1. **Location Permissions**
   - Runtime permission request with user dialogs
   - Handles denied and permanently denied states
   - Opens app settings for permanently denied case
   - Uses permission_handler package

2. **Navigation Session Management**
   - Singleton pattern for session lifecycle
   - Route calculation from start to destination
   - Event listeners for location and arrival
   - Proper error handling with custom exceptions

3. **Turn-by-Turn Navigation**
   - Full-screen Google Navigation View
   - Real-time location tracking
   - Destination arrival notifications
   - Navigation UI with zoom and scroll controls
   - Marker clustering for multiple waypoints

4. **User Dialogs**
   - Location permission request
   - T&C acceptance for navigation services
   - Error notifications
   - Settings access for denied permissions

5. **Error Handling**
   - Initialization errors
   - Permission errors
   - Route calculation failures
   - Navigation start/stop errors
   - User-friendly error messages

## Integration Steps

To integrate into deliveries page:

```dart
// Add navigation button to delivery item
FloatingActionButton(
  onPressed: () => Navigator.of(context).push(
    MaterialPageRoute(
      builder: (context) => NavigationPage(
        delivery: delivery,
        destinationLatitude: delivery.latitude,
        destinationLongitude: delivery.longitude,
        onNavigationComplete: () {
          // Update delivery status
          ref.refresh(deliveriesProvider(routeFragmentId));
        },
      ),
    ),
  ),
  child: const Icon(Icons.navigation),
)
```

## Configuration Requirements

Before testing/releasing:

1. **Add API Keys**
   - Android: Add to AndroidManifest.xml or build.gradle
   - iOS: Update AppDelegate.swift (already configured)

2. **Update AndroidManifest.xml** (if not using build.gradle)
   ```xml
   <meta-data
       android:name="com.google.android.geo.API_KEY"
       android:value="YOUR_API_KEY" />
   ```

3. **Verify Permissions** in AndroidManifest.xml
   - `INTERNET`
   - `ACCESS_FINE_LOCATION`
   - `ACCESS_COARSE_LOCATION`

4. **Test on Devices**
   - Android 6.0+ (API 23+)
   - iOS 16.0+
   - Real devices (emulator may have limited GPS)

## Design System Compliance

All components follow Svrnty design system:
- Material 3 theme colors (Primary: #C44D58, Secondary: #475C6C)
- Montserrat typography
- Dark/light theme support
- High contrast variants compatible

## Code Quality

- Strict typing enforced (no `dynamic` or untyped `var`)
- Sealed classes for type-safe pattern matching
- Result pattern for error handling
- Proper resource cleanup in dispose
- Comprehensive null safety

## Testing Recommendations

### Android
- Test on API 23+ device
- Verify GPS works
- Check location permission dialog
- Verify navigation UI displays correctly
- Test arrival notifications

### iOS
- Test on iOS 16.0+ device
- Verify location permission dialog
- Check background location mode
- Test with navigation UI
- Verify arrival notification

## Known Limitations

- Package is in Beta (expect potential breaking changes)
- Don't combine with other Google Maps SDK versions
- EEA developers subject to regional terms (effective July 8, 2025)
- Navigation requires actual GPS for best results

## Documentation

Comprehensive setup guide provided in `GOOGLE_NAVIGATION_SETUP.md` including:
- API key configuration for both platforms
- Integration examples
- Service usage documentation
- Error handling patterns
- Production considerations
- Testing checklist

## Next Steps

1. Add your Google Cloud API keys
2. Test location permissions flow
3. Integrate navigation button into delivery items
4. Test on real Android and iOS devices
5. Monitor navigation start/completion rates
6. Gather user feedback on navigation experience
