# Authentication Troubleshooting Guide

**Date**: October 10, 2025

---

## Issue: Login Successful But No Navigation

### Symptoms
- Login API call succeeds
- Token is saved
- But app doesn't navigate to MainScreen
- AuthWrapper doesn't react to state change

### Root Causes Fixed

#### 1. **GetIt Dependency Injection Error** ✅ FIXED
- **Problem**: AuthRepository was trying to use GetIt but wasn't registered
- **Solution**: Migrated to pure Riverpod dependency injection
- **Files Changed**: `lib/features/auth/presentation/providers/auth_provider.dart`

#### 2. **Circular Dependency in Auth Provider** ✅ FIXED
- **Problem**: `Auth.build()` was calling async `_checkAuthStatus()` causing circular dependency
- **Solution**: Moved initialization to separate `initialize()` method
- **Files Changed**: `lib/features/auth/presentation/providers/auth_provider.dart`, `lib/app.dart`

#### 3. **Provider Not Kept Alive** ✅ FIXED
- **Problem**: Auth state provider was being disposed between rebuilds
- **Solution**: Added `@Riverpod(keepAlive: true)` to Auth provider
- **Files Changed**: `lib/features/auth/presentation/providers/auth_provider.dart`

#### 4. **State Not Updating Properly** ✅ FIXED
- **Problem**: `copyWith` method wasn't properly setting `isAuthenticated: true`
- **Solution**: Updated login/register methods to create new `AuthState` with explicit values
- **Files Changed**: `lib/features/auth/presentation/providers/auth_provider.dart`

---

## How Auth Flow Should Work

### 1. App Startup
```
main()
  → ProviderScope created
  → RetailApp builds
  → initState() schedules auth initialization
  → auth.initialize() checks for saved token
  → If token found: loads user profile, sets isAuthenticated = true
  → If no token: sets isAuthenticated = false
```

### 2. Login Flow
```
User enters credentials
  → Taps Login button
  → _handleLogin() called
  → ref.read(authProvider.notifier).login(email, password)
  → API call to /api/auth/login
  → Success: saves token, sets user, sets isAuthenticated = true
  → AuthWrapper watches authProvider
  → isAuthenticated changes to true
  → AuthWrapper rebuilds
  → Shows MainScreen instead of LoginPage
```

### 3. Logout Flow
```
User taps Logout in Settings
  → Confirmation dialog shown
  → ref.read(authProvider.notifier).logout()
  → Token cleared from secure storage
  → DioClient token cleared
  → State set to isAuthenticated = false
  → AuthWrapper rebuilds
  → Shows LoginPage
```

---

## Debug Checklist

If auth flow still not working, check these:

### 1. Verify Provider State
```dart
// Add this to login_page.dart _handleLogin after login success
final authState = ref.read(authProvider);
print('🔐 Auth State after login:');
print('  isAuthenticated: ${authState.isAuthenticated}');
print('  user: ${authState.user?.name}');
print('  isLoading: ${authState.isLoading}');
print('  errorMessage: ${authState.errorMessage}');
```

### 2. Verify AuthWrapper Reaction
```dart
// Add this to auth_wrapper.dart build method
@override
Widget build(BuildContext context, WidgetRef ref) {
  final authState = ref.watch(authProvider);

  print('🔄 AuthWrapper rebuild:');
  print('  isAuthenticated: ${authState.isAuthenticated}');
  print('  isLoading: ${authState.isLoading}');
  print('  user: ${authState.user?.name}');

  // ... rest of build method
}
```

### 3. Verify Token Saved
```dart
// Add this to auth_repository_impl.dart login method after saving token
print('💾 Token saved: ${authResponse.accessToken.substring(0, 20)}...');
print('💾 DioClient token set');
```

### 4. Verify API Response
```dart
// Add this to auth_remote_datasource.dart login method
print('📡 Login API response:');
print('  Status: ${response.statusCode}');
print('  User: ${response.data['user']?['name']}');
print('  Token length: ${response.data['accessToken']?.length}');
```

---

## Common Issues and Solutions

### Issue: State Updates But UI Doesn't Rebuild

**Cause**: Using `ref.read()` instead of `ref.watch()` in AuthWrapper

**Solution**: Ensure AuthWrapper uses `ref.watch(authProvider)`
```dart
final authState = ref.watch(authProvider);  // ✅ Correct - watches for changes
// NOT ref.read(authProvider)  // ❌ Wrong - doesn't rebuild
```

### Issue: Login Success But isAuthenticated = false

**Cause**: State update not explicitly setting `isAuthenticated: true`

**Solution**: Create new AuthState with explicit values
```dart
state = AuthState(
  user: authResponse.user,
  isAuthenticated: true,  // ✅ Explicit value
  isLoading: false,
  errorMessage: null,
);
```

### Issue: Provider Disposes Between Rebuilds

**Cause**: Provider not marked as `keepAlive`

**Solution**: Add `@Riverpod(keepAlive: true)` to Auth provider
```dart
@Riverpod(keepAlive: true)  // ✅ Keeps state alive
class Auth extends _$Auth {
  // ...
}
```

### Issue: Circular Dependency Error

**Cause**: Calling async operations in `build()` method

**Solution**: Use separate initialization method
```dart
@override
AuthState build() {
  return const AuthState();  // ✅ Sync only
}

Future<void> initialize() async {
  // ✅ Async operations here
}
```

---

## Testing the Fix

### Test 1: Fresh App Start (No Token)
1. **Clear app data** or use fresh install
2. **Run app**: `flutter run`
3. **Expected**: Shows LoginPage immediately
4. **Result**: ✅ Pass / ❌ Fail

### Test 2: Login Flow
1. **Start at LoginPage**
2. **Enter credentials**: admin@retailpos.com / Admin123!
3. **Tap Login**
4. **Expected**:
   - Loading indicator appears
   - On success: Navigate to MainScreen with bottom tabs
5. **Result**: ✅ Pass / ❌ Fail

### Test 3: Token Persistence
1. **Login successfully**
2. **Close app completely**
3. **Restart app**
4. **Expected**:
   - Shows loading briefly
   - Automatically goes to MainScreen (no login needed)
5. **Result**: ✅ Pass / ❌ Fail

### Test 4: Logout Flow
1. **While logged in, go to Settings tab**
2. **Tap Logout button**
3. **Confirm logout**
4. **Expected**: Navigate back to LoginPage
5. **Result**: ✅ Pass / ❌ Fail

### Test 5: Invalid Credentials
1. **Enter wrong email/password**
2. **Tap Login**
3. **Expected**:
   - Shows error SnackBar
   - Stays on LoginPage
   - Error message displayed
5. **Result**: ✅ Pass / ❌ Fail

---

## Architecture Diagram

```
┌─────────────────────────────────────────────────┐
│              ProviderScope                      │
│  ┌───────────────────────────────────────────┐ │
│  │           RetailApp                       │ │
│  │  (initializes auth on startup)            │ │
│  │  ┌─────────────────────────────────────┐  │ │
│  │  │      MaterialApp                    │  │ │
│  │  │  ┌───────────────────────────────┐  │  │ │
│  │  │  │     AuthWrapper              │  │  │ │
│  │  │  │  (watches authProvider)      │  │  │ │
│  │  │  │                              │  │  │ │
│  │  │  │  if isAuthenticated:         │  │  │ │
│  │  │  │  ┌─────────────────────────┐ │  │  │ │
│  │  │  │  │   MainScreen            │ │  │  │ │
│  │  │  │  │   (with bottom tabs)    │ │  │  │ │
│  │  │  │  └─────────────────────────┘ │  │  │ │
│  │  │  │                              │  │  │ │
│  │  │  │  else:                       │  │  │ │
│  │  │  │  ┌─────────────────────────┐ │  │  │ │
│  │  │  │  │   LoginPage             │ │  │  │ │
│  │  │  │  │   (login form)          │ │  │  │ │
│  │  │  │  └─────────────────────────┘ │  │  │ │
│  │  │  └───────────────────────────────┘  │  │ │
│  │  └─────────────────────────────────────┘  │ │
│  └───────────────────────────────────────────┘ │
└─────────────────────────────────────────────────┘
                      ↕
              ┌───────────────┐
              │  authProvider │
              │  (keepAlive)  │
              └───────────────┘
                      ↕
          ┌───────────────────────┐
          │  authRepository       │
          │  ↓                    │
          │  authRemoteDataSource │
          │  ↓                    │
          │  dioClient            │
          │  ↓                    │
          │  secureStorage        │
          └───────────────────────┘
```

---

## Files Modified

### Core Auth Files
- ✅ `lib/features/auth/presentation/providers/auth_provider.dart`
  - Added `@Riverpod(keepAlive: true)` to Auth provider
  - Fixed `copyWith` method with `clearUser` and `clearError` flags
  - Updated login/register to explicitly set `isAuthenticated: true`
  - Moved auth check to `initialize()` method

- ✅ `lib/app.dart`
  - Changed from `ConsumerWidget` to `ConsumerStatefulWidget`
  - Added `initState()` to call `auth.initialize()`

- ✅ `lib/main.dart`
  - Removed GetIt initialization
  - Using pure Riverpod for DI

- ✅ `lib/features/auth/presentation/widgets/auth_wrapper.dart`
  - Already correct - uses `ref.watch(authProvider)`

- ✅ `lib/features/auth/presentation/pages/login_page.dart`
  - Already correct - login logic properly calls provider

---

## Expected Behavior After Fixes

1. ✅ App starts → auth initializes → shows LoginPage (if no token)
2. ✅ Login success → state updates → AuthWrapper rebuilds → shows MainScreen
3. ✅ Token persists → app restart → auto-login works
4. ✅ Logout → state clears → AuthWrapper rebuilds → shows LoginPage
5. ✅ All tabs accessible after login (Home, Products, Categories, Settings)

---

## Next Steps If Still Not Working

1. **Add Debug Logs**: Add print statements to trace state changes
2. **Check Backend**: Ensure API endpoints are working and returning correct data
3. **Verify Token Format**: Check that JWT token is valid format
4. **Check API Response Structure**: Ensure response matches model expectations
5. **Test with Hot Restart**: Try `r` (hot reload) vs `R` (hot restart) in Flutter

---

**Status**: All known issues fixed. Auth flow should work correctly now.

If issues persist, add debug logging as described above to trace the exact point of failure.