refactor: break down AppInstallProcessor into collaborator classes

Description

This MR refactors AppInstallProcessor into smaller, tightly scoped, unit-testable components while preserving current behaviour and keeping the public API (mostly) unchanged.

Please review the MR commit by commit to understand how the refactoring evolved. Otherwise, you can review the changes at once; for your aid in the review process, a diagram, and a guide have been added in the Technical details section.

Technical details

Before refactor

Before the refactor, AppInstallProcessor was effectively the central class for almost all install-related responsibilities.

classDiagram
    class AppInstallProcessor_PreRefactor {
        +initAppInstall(...)
        +enqueueFusedDownload(...)
        +canEnqueue(...)
        +validateAgeLimit(...)
        +awaitInvokeAgeLimitEvent(...)
        +updateDownloadUrls(...)
        +processInstall(...)
        +checkDownloadingState(...)
        +startAppInstallationProcess(...)
        +handleFusedDownloadStatus(...)
        +checkUpdateWork(...)
        +showNotificationOnUpdateEnded(...)
    }

    class EventBus
    class StorageComputer
    class ParentalControlAuthenticator
    class UpdatesDao
    class UpdatesNotifier
    class AppInstallComponents
    class ApplicationRepository
    class AppLoungeDataStore
    class StorageNotificationManager
    class DownloadManagerUtils
    class AppManager
    class ValidateAppAgeLimitUseCase

    AppInstallProcessor_PreRefactor --> AppInstallComponents
    AppInstallProcessor_PreRefactor --> ApplicationRepository
    AppInstallProcessor_PreRefactor --> AppLoungeDataStore
    AppInstallProcessor_PreRefactor --> StorageNotificationManager
    AppInstallProcessor_PreRefactor --> DownloadManagerUtils
    AppInstallProcessor_PreRefactor --> AppManager
    AppInstallProcessor_PreRefactor --> ValidateAppAgeLimitUseCase
    AppInstallProcessor_PreRefactor --> EventBus
    AppInstallProcessor_PreRefactor --> StorageComputer
    AppInstallProcessor_PreRefactor --> ParentalControlAuthenticator
    AppInstallProcessor_PreRefactor --> UpdatesDao
    AppInstallProcessor_PreRefactor --> UpdatesNotifier

After refactor

The refactor improves the codebase in these ways:

• smaller classes with tighter responsibilities
• more focused unit tests
• better organization of classes based on their role

This diagram gives a reviewer-friendly starting point for the install/update flow under:

• app/src/main/java/foundation/e/apps/data/install/core/
• app/src/main/java/foundation/e/apps/data/install/wrapper/

classDiagram
direction LR

class AppInstallationFacade
class InstallationRequest
class InstallationEnqueuer
class PreEnqueueChecker
class DownloadUrlRefresher
class AgeLimitGate
class DevicePreconditions
class InstallationProcessor
class InstallationCompletionHandler
class AppEventDispatcher
class NetworkStatusChecker
class ParentalControlAuthGateway
class StorageSpaceChecker
class UpdatesTracker
class UpdatesNotificationSender

AppInstallationFacade --> InstallationRequest : builds install request
AppInstallationFacade --> InstallationEnqueuer : starts enqueue path
AppInstallationFacade --> InstallationProcessor : starts processing path

InstallationEnqueuer --> PreEnqueueChecker : runs checks
PreEnqueueChecker --> DownloadUrlRefresher
PreEnqueueChecker --> AgeLimitGate
PreEnqueueChecker --> DevicePreconditions

AgeLimitGate --> ParentalControlAuthGateway
AgeLimitGate --> AppEventDispatcher
DevicePreconditions --> NetworkStatusChecker
DevicePreconditions --> StorageSpaceChecker
DevicePreconditions --> AppEventDispatcher

InstallationProcessor --> AppEventDispatcher : status events
InstallationProcessor --> InstallationCompletionHandler : finishes update flow
InstallationCompletionHandler --> UpdatesTracker
InstallationCompletionHandler --> UpdatesNotificationSender

Reading guide

• Start at AppInstallationFacade.
• Follow the enqueue side first: InstallationRequest -> InstallationEnqueuer -> PreEnqueueChecker.
• PreEnqueueChecker fans out into the three main checks: URL refresh, age-limit check, and device checks.
• The wrapper classes shown are the main system-facing collaborators used during checks and completion.
• Then review the runtime side: InstallationProcessor -> InstallationCompletionHandler.

Tests

Issues

https://gitlab.e.foundation/e/os/backlog/-/issues/4177

https://gitlab.e.foundation/e/os/backlog/-/issues/4165

10 commandments of code review

👪 ❤️ code review guidelines