### 1) State -> UI trace (user taps one booking item on Home)
- Tap on a booking row triggers `_Booking.onTap` and navigates via `Routes.bookingWithId`.
- Inside the booking `GoRoute` builder in `router.dart`, the booking ID is parsed, the `BookingViewModel` is created, and `viewModel.loadBooking.execute(id)` is called before rendering `BookingScreen`.
- In `booking_viewmodel.dart`, the load command fetches data through the repository abstraction (`BookingRepository`).
- In the remote implementation (`BookingRepositoryRemote.getBooking`), the repository composes booking details using API calls (destinations and destination activities).
- Back in the view model, `Result` (`Ok`/`Error`) is handled and UI state is updated.
- In `booking_screen.dart`, `ListenableBuilder` reacts to command state, showing loading while running and body content when completed.
- In `booking_body.dart`, once booking data is available, header and activities are rendered.
### 2) Routing and auth gate
- In `router.dart`, `GoRouter` is configured with `redirect` and `refreshListenable`.
- `AuthRepository` extends `ChangeNotifier`, so auth changes are observable by the router.
- On `login()` and `logout()`, the auth repo calls `notifyListeners()`.
- That refresh triggers `_redirect()` immediately, which enforces route guards:
- unauthenticated user -> `/login`
- authenticated user on `/login` -> `/home`
- otherwise no redirect
### 3) Data boundary
- UI/domain layers depend on repository interfaces (for example `BookingRepository`) rather than direct HTTP/local services.
- Remote path: repositories call `ApiClient` for network requests.
- Local/dummy path: repositories read from `LocalDataService`/memory-backed sources.
- Provider selection happens in `dependencies.dart` (`providersRemote` vs `providersLocal`), and each flavor main entrypoint chooses the provider set.
- This design is testable because view models/use cases receive injected interfaces, so tests can supply fakes/mocks.
### 4) Possible enhancement
- Add API-boundary caching for read-heavy GET endpoints.
- Strategy: return cached data first, refresh in background, and invalidate with TTL/auth changes.
- Add metrics/logging to validate hit rate, latency reduction, and stale-data behavior.
### app_booking_flow_test.dart
`integration_test/app_booking_flow_test.dart` is an end-to-end integration test that validates:
- auth-gated entry (starts logged out and lands on Login)
- It runs on `providersLocal` for deterministic local data.
- It overrides only `AuthRepository` with a test implementation (`TestAuthRepository`) to simulate logged-out -> logged-in transitions while still exercising the real navigation, view models, and local repositories.
Run command:
```bash
cd app
flutter test integration_test/app_booking_flow_test.dart
```
## Part 4 Answers
### 1) What was the hardest part of this codebase to understand, and how did you figure it out?
- It was the chosen state management. While it wasn't hard to decipher, all of the Flutter projects that I handled were using BLoC/Cubit pattern and so I'm more used to it. I still have yet to figure it out completely but I have a good overview. Two things. First I started with the API calls then tracing them up to the repos then VMs then to widgets and screens. Second, I checked/mapped out the builders in the widgets which is similar to the BlocBuilders in Cubit.
### 2) If you owned this app for the next year, what's the first thing you'd change?
- Since this app already has a solid foundation code-wise, I'll prepare for better scaling. It would be a set of changes though and not a single one. Changes would be like implementing CI/CD, more helpful logging (ideally utiilizing Firebase Crashlytics), and API resilience (timeouts, retries, etc.).
### 3) What three questions would you ask the team before starting?
- Do we have some technical or feature scope overview documentation?
- How's the current feedback of our app in production (from end-users and key stakeholders)?
- What are the high priority goals for the next couple of months?
Henry Domingo Jr
2 weeks ago