# Android Chat Client

This is the Android client for the SCAR Chat application.

## Requirements

- Android SDK 24+ (API level 24)
- Android Studio 4.0+ or Gradle 8.1+
- Java JDK 11+
- Minimum Android device: Android 7.0 (API 24)

## Project Structure

```
android_client/
├── app/
│   ├── src/
│   │   └── main/
│   │       ├── java/com/scar/chat/
│   │       │   ├── MainActivity.java           # Main activity with tabs
│   │       │   ├── ChatConnection.java         # SSL/TLS connection handler
│   │       │   ├── ChatFragment.java           # Chat UI fragment
│   │       │   ├── VideoFragment.java          # Video/camera UI fragment
│   │       │   └── TabLayoutMediator.java      # Tab mediator
│   │       ├── res/
│   │       │   ├── layout/
│   │       │   │   ├── activity_main.xml       # Main activity layout
│   │       │   │   ├── fragment_chat.xml       # Chat tab layout
│   │       │   │   └── fragment_video.xml      # Video tab layout
│   │       │   └── values/
│   │       │       ├── strings.xml             # String resources
│   │       │       └── colors.xml              # Color resources
│   │       └── AndroidManifest.xml             # App manifest
│   └── build.gradle                            # App-level build config
├── build.gradle                                # Project-level build config
├── settings.gradle                             # Gradle settings
├── gradle/wrapper/                             # Gradle wrapper
└── build.sh                                    # Build script

```

## Features

- **TLS/SSL Encryption**: Secure connection to chat server
- **Multi-tab Interface**: Chat tab for messaging, Video tab for camera
- **Camera Support**: Enable/disable camera with device selection
- **Real-time Chat**: Send and receive messages in real-time
- **Customization**: Background color, text color, and transparency controls (UI ready)
- **Multi-client Support**: Connect multiple Android devices to same server

## Building

### Prerequisites

1. **Install Android Studio** or **Android SDK + Gradle**
2. **Java JDK 11+** installed and in PATH
3. **ANDROID_HOME** environment variable set to SDK location

On Linux/macOS:
```bash
export ANDROID_HOME=$HOME/Android/Sdk
export PATH=$PATH:$ANDROID_HOME/tools:$ANDROID_HOME/platform-tools
```

On Windows (PowerShell):
```powershell
$env:ANDROID_HOME = "$env:USERPROFILE\AppData\Local\Android\Sdk"
$env:PATH += ";$env:ANDROID_HOME\tools;$env:ANDROID_HOME\platform-tools"
```

### Using Android Studio (Recommended)

1. Open Android Studio
2. File → Open and select `android_client/` directory
3. Wait for Gradle sync to complete
4. Select "Build" → "Make Project"
5. APK will be generated in `app/build/outputs/apk/debug/`

### Using Gradle (Command Line)

**Linux/macOS:**
```bash
cd android_client
./gradlew build
```

**Windows:**
```cmd
cd android_client
gradlew.bat build
```

If you don't have Gradle installed system-wide, the wrapper will handle it.

## Running

### On Physical Device

1. Enable USB debugging on your Android device (Settings → Developer Options)
2. Connect via USB
3. Run:
   ```bash
   ./gradlew installDebug        # Linux/macOS
   gradlew.bat installDebug      # Windows
   ```
4. App will be installed automatically
5. Launch "SCAR Chat" from your app drawer

### On Emulator

1. Start Android Emulator from Android Studio (AVD Manager)
2. Wait for emulator to fully boot
3. Run:
   ```bash
   ./gradlew installDebug        # Linux/macOS
   gradlew.bat installDebug      # Windows
   ```
4. App will be installed automatically
5. Launch "SCAR Chat" from emulator app drawer

## Usage

1. **Connect to Server**:
   - Enter server hostname (e.g., `192.168.1.100` or `localhost`)
   - Enter port (default: `42317`)
   - Tap "Connect"

2. **Chat**:
   - Go to "Chat" tab
   - Type message in text field
   - Tap "Send"
   - View chat history in display area

3. **Camera**:
   - Go to "Video" tab
   - Select camera from dropdown (if multiple available)
   - Check "Enable Camera" to start camera
   - Server will receive `CAMERA_ENABLE` message
   - Remote users will see camera status

## Permissions

The app requires the following permissions (Android 6.0+):
- `INTERNET`: Network communication with server
- `CAMERA`: Camera access for video capture
- `RECORD_AUDIO`: Audio recording capability

Permissions are requested at runtime on Android 6.0+.

## Connection Protocol

- **Protocol**: TLS/SSL over TCP
- **Port**: 42317 (default)
- **Message Format**: Text messages ending with newline (`\n`)
- **Camera Status**: `CAMERA_ENABLE` / `CAMERA_DISABLE` messages

## Dependencies

- **androidx.appcompat**: Support library for backward compatibility
- **com.google.android.material**: Material Design components
- **androidx.constraintlayout**: Layout constraints
- **androidx.recyclerview**: List/grid view components
- **androidx.viewpager2**: Tab paging
- **org.bouncycastle**: SSL/TLS support

## Troubleshooting

### Connection Failed
- Verify server is running and accessible
- Check hostname/IP and port number
- Ensure firewall allows connection to port 42317
- Check SSL certificate is valid (app accepts self-signed certs)

### Camera Not Working
- Verify camera permission is granted (Settings → Permissions)
- Check device has a camera
- Try reconnecting or restarting app

### Build Errors
- Update Android Studio to latest version
- Run `./gradlew clean` before rebuilding
- Delete `build/` and `.gradle/` directories
- Ensure Java JDK 11+ is installed

## Security Notes

- The app currently accepts self-signed SSL certificates (for development)
- For production, implement proper certificate validation
- Enable ProGuard/R8 obfuscation in release builds (configured)

## Future Enhancements

- [ ] Full video frame encoding/transmission (H.264)
- [ ] Video frame decoding and display
- [ ] Audio/VoIP support
- [ ] Message persistence/history
- [ ] User authentication
- [ ] Emoji/sticker support
- [ ] File transfer
- [ ] Group chat support
- [ ] Certificate pinning for enhanced security

## Building APK for Distribution

```bash
cd android_client

# Create signed release build
./gradlew bundleRelease
# OR for APK
./gradlew assembleRelease
```

Output files:
- AAB: `app/build/outputs/bundle/release/app-release.aab`
- APK: `app/build/outputs/apk/release/app-release.apk`

## License

Part of the SCAR Chat project. See main project README for details.