expo-media-control/Requirements.md

Comprehensive media control module for Expo and React Native with background audio support, lock screen controls, and system integration

# React Native Music Control Module Requirements

## Overview
This document outlines the requirements for creating a modern implementation of this module using Kotlin for Android and Swift for iOS. The module will be built as an Expo module package and will support React Native's new architecture.

## Core Requirements

### 1. Functionality
- Remote media controls integration for both Android and iOS
- Background audio playback support
- Notification with media controls
- Lock screen media controls
- Remote control events handling (play/pause/stop/next/previous)
- Album artwork display in notifications and lock screen
- Support for rating controls
- Skip forward/backward functionality
- Audio interruption handling
- Volume control integration

### 2. Technology Stack
- **Android**: Kotlin with MediaSessionCompat and Notification APIs
- **iOS**: Swift with MediaPlayer framework
- **JavaScript/TypeScript**: Modern TypeScript with proper type definitions
- **React Native**: Support for the new architecture and backwards compatibility

### 3. Module Structure

#### Android (Kotlin)
- Replace Java implementations with Kotlin equivalents:
  - MediaSessionCompat management
  - Notification creation and management
  - Event handling and broadcasting to JavaScript
  - Audio focus management
  - Volume control

#### iOS (Swift)
- Replace Objective-C implementation with Swift:
  - MPNowPlayingInfoCenter integration
  - MPRemoteCommandCenter for remote controls
  - Event handling and broadcasting to JavaScript

#### JavaScript/TypeScript
- Clean TypeScript API with comprehensive type definitions
- Expo module configuration

## Detailed Requirements

### Android Implementation

1. **Media Session Management**
   - Create and manage MediaSessionCompat
   - Handle media button events
   - Update playback state and metadata

2. **Notification**
   - Create media style notifications
   - Support customization (icons, colors)
   - Handle notification actions
   - Support notification channels for Android 8+

3. **Audio Focus**
   - Request and release audio focus
   - React to audio focus changes (e.g., pause on audio focus loss)

4. **Event Handling**
   - Bridge native events to JavaScript
   - Support all control events (play, pause, stop, next, previous, etc.)

### iOS Implementation

1. **Now Playing Info**
   - Update MPNowPlayingInfoCenter with track information
   - Support artwork loading and caching
   - Handle playback state and position updates

2. **Remote Commands**
   - Register handlers for MPRemoteCommandCenter
   - Support all relevant commands (play, pause, next, previous, seek, etc.)
   - Handle command events and bridge to JavaScript

3. **Background Mode**
   - Configure and manage audio background mode
   - Handle interruptions and route changes

### JavaScript API

1. **Main Interface**
   - Maintain compatibility with existing API
   - Enhance with TypeScript type definitions
   - Support promise-based async operations where appropriate

2. **Events**
   - Implement event system for receiving control commands
   - Support event subscription and cleanup

### Expo Integration

1. **Module Structure**
   - Follow Expo module structure guidelines
   - Support auto-linking and configuration

2. **Configuration**
   - Support configuration through app.json/app.config.js
   - Handle permissions automatically

3. **Documentation**
   - Provide comprehensive documentation for Expo usage
   - Include examples for common use cases

## Non-Functional Requirements

1. **Performance**
   - Minimize battery impact during background playback
   - Efficient handling of artwork loading and caching

2. **Compatibility**
   - Support Android 5.0+ (API level 21+)
   - Support iOS 11.0+
   - Support React Native 0.64+

3. **Testing**
   - Unit tests for core functionality
   - Integration tests with sample audio playback
   - Cross-device testing

4. **Code Quality**
   - Follow Kotlin and Swift best practices
   - Clear documentation and comments
   - Consistent error handling

## Migration Considerations

1. **API Compatibility**
   - Maintain the same JavaScript API interface where possible
   - Document any breaking changes

2. **Upgrade Path**
   - Provide migration guide for users of the older module
   - Support gradual adoption of new features

## Implementation Notes

- Use Kotlin coroutines for asynchronous operations on Android
- Use Swift concurrency features for iOS where appropriate
- Follow React Native's new architecture guidelines for native modules
- Implement proper cleanup to prevent memory leaks
- Consider backward compatibility with older React Native versions