S3 Explorer

A modern, offline-first Android application designed to act as a robust, high-performance file explorer for S3-compatible buckets (such as AWS S3, MinIO, and Cloudflare R2).

Built with Jetpack Compose, Kotlin, and following Modern Android Development (MAD) practices, the application features secure local caching, encrypted credential management, and highly-optimized media thumbnail loading.

Core Features

1. Connection & Profile Management

- Multi-Profile Accounts: Add, edit, rename, and manage multiple S3 connections. - Smart Display Names: Fallback chain (Custom Alias > Default Bucket Name > Endpoint URL) ensures neat, readable lists without label duplication. - Rclone Configuration Exporter: Decrypts connection details securely and formats them into a standard .ini config ready for rclone. - Credential Reuse: Quickly pre-fill the connection screen using credential details from an existing profile. - Key Shredding on Delete: Deleting a profile clears all Room caches and shreds keys from the Android Keystore. - Connection Validation: Validate credentials against S3 before saving. - Simplified Fields: Removed extraneous buttons to declutter the form.

2. Multi-Tenant Local S3 Cache

- Profile Isolation: Directory caching indexed via composite primary keys referencing profileId — multiple accounts with identical bucket names never experience data crossover.

3. File Explorer & Navigation

- Connection Drawer: Slide-out panel for active profile details, bucket storage stats, and setup links. - Floating Action Drawer: Bottom sheet for Create New Folder, Upload File, and Take Photo (via FileProvider). - Dynamic View Modes: Toggle between Detailed List, Compact List, Gallery Small (2-column), and Gallery Large (1-column). - Scroll State Preservation: Layout changes occur inside a single LazyVerticalGrid, preserving scroll position. - Interactive Breadcrumbs: Tap-to-navigate path indicator for quick jumps to parent directories. - Selection Mode: Toggle selection from toolbar across both list and gallery views. - Explorer File Sorting & Filtering: Sort by Name, Size, Type, or Last Updated; toggle Ascending/Descending, "Folders first", search via SQLite LIKE, and toggle hidden files visibility. Preferences persisted in DataStore.

4. Settings & Configurations

- Account Settings: Isolated by profileId — configures filename encryption, multipart upload thresholds, upload concurrency, and local cache lifecycle. - Advanced Upload Features: - E2E Encryption: Encrypt payloads with AES-GCM prior to upload using profile passphrase (stored in EncryptedSharedPreferences); IV injected in x-amz-meta-iv. - MD5 Hash Verification: Calculates payload MD5 and transmits Content-MD5 header. - Storage Class Customization: Applies custom storage class headers. - Skip Same File Upload: HEAD checks for files >= 10KB to skip re-uploading identical objects. - Global Settings: Trust insecure SSL/TLS certificates, biometric lock screen, dotfiles visibility, and date format styling.

5. High-Performance Media Thumbnails

- Automatic Media Classifier: Uses Android's MimeTypeMap to detect supported formats from extensions. - Secure Offline Presigning: Generates temporary 1-hour pre-signed URLs locally via HMAC calculations. - Strict Concurrency Throttling: Limits thumbnail requests to 5 concurrent connections. - Video Frame Extraction: Registers VideoFrameDecoder for remote video streams. - Zero-Flicker Scrolling: Presigned URLs stored in in-memory cache; scroll-back loads instantly from memory cache.

6. Dedicated Video Player

- Immersive Playback: Launches videos in dedicated activity using Media3 (ExoPlayer) with full system bar hiding. - Custom Control Overlay: Single-tap to toggle controls; red progress bar with live scrubbing. - Smart Timecodes: Left-aligned elapsed and total duration matching native patterns. - Advanced Player Controls: Loop mode, orientation lock, and fullscreen transitions. - Swipe to Dismiss: Swipe-down gesture to close player and return to explorer.

7. Branding & Theming

- Premium UI Palette: Custom Material 3 colors (Ocean Blue, Sky Blue, Warm Wood). - Native Splash Screen: Android 12 core-splashscreen library. - Watermark Background: Desaturated grayscale watermark logo behind explorer contents.

8. Connections Import, Export, & Management

- JSON/Base64 Portability: Export connections as Base64-encoded JSON array (.dat extension). - System File Picker Integration: Storage Access Framework (SAF) for import/export. - Safe Profile Purge: Bulk-delete with confirmation dialog.

9. AppLock & Biometric Security

- Process-Lifecycle Protection: Uses ProcessLifecycleOwner to detect background/foreground transitions. - Overlay Lock Screen: Blocks user input while preserving navigation graph state. - Unlock Fallback: Manual "Unlock" button for biometric retry.

License

GNU General Public License v3.0