Cyberpunk Notes App 🌃

A secure, cyberpunk-themed note-taking application for Android, built with modern Android technologies and a distinct visual style.

Developed live as part of live stream series: https://www.youtube.com/playlist?list=PL0zZBw8Dq429NOr4MPDZHolp8UoFVuNPI

🚀 Technical Stack

• Language: Kotlin
• UI Framework: Jetpack Compose (Material3)
• Architecture: MVP (Model-View-Presenter)
• Database: Room (SQLite abstraction)
• Security: AndroidX Security Crypto (EncryptedSharedPreferences)
• Asynchronous: Kotlin Coroutines & Flow
• Serialization: GSON
• PDF Generation: iText7

🏗 Architecture & Components

The application follows the MVP (Model-View-Presenter) pattern to separate UI logic from business logic.

📱 Key Activities & Screens

1. NotesActivity (Main Entry)

   • Role: Displays and manages the primary note list.
   • Logic:
     • Validates session and passcode state with SessionManager/PreferencesManager.
     • Loads notes via NotesPresenter/NotesRepository and keeps trash-bin visibility in sync.
   • UI: NotesListScreen (Compose) with search, grid/list toggle, JSON import/export, and quick access to settings, trash, pinned notes, and URL-filtered notes.

2. NoteDetailActivity

   • Role: Create, view, and edit individual notes.
   • Features:
     • Auto-save functionality.
     • Export to PDF (FileUtils).
     • Share note content.
   • UI: NoteDetailScreen (Compose).

3. LoginActivity

   • Role: Handles secure access to the application.
   • Modes:
     • SETUP: Create a new passcode.
     • CONFIRM: Verify the new passcode.
     • VALIDATE: Unlock the app.
   • UI: LoginScreen (Compose) with custom 4-digit PIN input and cyberpunk styling.

4. SettingsActivity

   • Role: Manage application settings.
   • Features:
     • Toggle "Require passcode on opening".
     • Initiates the passcode setup flow.

5. TrashBinActivity

   • Role: Shows soft-deleted notes with options to restore individually, restore all, or empty the bin permanently.
   • UI: TrashBinScreen (Compose) driven by TrashBinPresenter/NotesRepository.

6. PinnedNotesActivity

   • Role: Presents notes that have been marked as pinned from the main list.
   • UI: PinnedNotesScreen (Compose) with unpin support and navigation back to details.

7. UrlNotesActivity

   • Role: Filters notes containing URLs for quick link discovery.
   • UI: UrlNotesScreen (Compose) powered by UrlNotesPresenter querying URL-bearing notes.

🔐 Security & Session Management

The app implements a robust security model to protect user notes.

• Storage: Passcodes are stored using EncryptedSharedPreferences (AES256-GCM), ensuring they are encrypted at rest and cannot be read even on rooted devices without the Keystore key.
• Session State:
  • Managed by SessionManager (Singleton).
  • isLoggedIn flag tracks the current session.
  • Session is cleared on process death or when the passcode is disabled.
  • Prevents infinite login loops by checking both the enabled flag and session state.

💾 Data Layer

• AppDatabase: Room database instance.
• Note: Entity representing a note (id, title, content, timestamp) with flags for soft deletion and pinning.
• NoteDao: Data Access Object for database operations including search, trash management, pin toggling, and URL filtering.
• NotesRepository: Abstraction layer between Presenters and the DAO.

🎨 UI & Theming

• Theme: Custom Cyberpunk theme (NotesAppTheme).
• Colors: Neon palette (Cyan, Magenta, Yellow) on dark backgrounds.
• Components: Custom CyberpunkCard, NeonButton, and glitch-effect text styles.

📂 Project Structure

com.dmitryy.notesapp
├── data/           # Room entities, DAO, Database, Repository
├── ui/
│   ├── base/       # Base MVP interfaces
│   ├── list/       # Notes list screen (Activity, Presenter, Contract)
│   ├── detail/     # Note detail screen (Activity, Presenter, Contract)
│   ├── login/      # Login screen (Activity, Presenter, Contract)
│   ├── settings/   # Settings screen (Activity, Presenter, Contract)
│   ├── trash/      # Trash bin screen for soft-deleted notes
│   ├── pinned/     # Pinned notes screen
│   ├── url/        # Notes filtered to links/URLs
│   └── theme/      # Compose theme and color definitions
└── utils/          # Helpers (Logger, FileUtils, PreferencesManager, SessionManager, NavigationUtils)