# RCWeb Viewer Control App

The **RCWeb Viewer Control App** (`app/c`) is the remote control interface within the RCWeb ecosystem. It demonstrates the **Asymmetric Pattern**, allowing a user on a mobile device or another browser to send JavaScript commands to a target viewer application operating in the same virtual room.

![icon](pwa-512x512.png "Viewer Control App Icon")

## Screenshot
![screenshot](screenshot.png "Viewer Control App")

## What it does

- **Remote Control Interface**: Provides a user-friendly UI with different tabs to quickly push custom Colors, Images, Videos, HTML, and raw JavaScript straight to the viewer screen.
- **Send Execution Payloads**: Under the hood, the app dynamically constructs JavaScript blocks and uses WebSockets to seamlessly transport these execution payloads to the web browsers running the viewer app.
- **File Upload & Streaming**: Users can easily select local images or videos to display remotely. To save memory and bypass WebSocket payload limits, larger files (1MB or greater) are intelligently chunked and streamed peer-to-peer using proxy requests, while smaller ones are swiftly embedded as Base64 data URLs.
- **Room Management**: Gives the controller the power to instantly redirect all connected viewer displays to different mini-apps (like Spacewar or Chat) within the RCWeb environment or reset them back to the default viewer waiting screen.

## How it works

The core logic is orchestrated within `script.js` which relies entirely on the robust peer-to-peer foundation provided by the `comms.js` library.

- **Initialization**: Upon loading, `loadControls()` initializes default input values (like sample image/video URLs) and connects the controller interface to the server via `rc.connect()`.
- **Command Construction**: When a user clicks an action button—such as `showColor()`, `showImage()`, or `showHtml()`—the app generates the precise DOM manipulation code required. This generated string is then dispatched to the room via `rc.send(js, "v")` or `sendJavaScript()`.
- **Dynamic File Processing**: The `createDynamicFileUrl()` function coordinates file sharing. For large files, it generates a proxy URL (`/x-file/...`) and relies on `sendFileChunk()` and `sendChunk()` to slice the file and upload bytes incrementally via HTTP PUT requests as the viewer requests them. The controller must keep the tab open for the stream to stay alive (`promptExit()`).
- **Callbacks & Feedback**: The script actively listens for `rc.onViewUpdateSuccess` and `rc.onViewUpdateError` broadcasts from the viewer app. This surfaces real-time execution feedback (success or error notices) back to the user within the control interface UI.
- **PWA Experience**: The script checks if it's currently running as an installed Progressive Web App (`insideInstalledApp()`). If true, it automatically restricts the desktop window to resemble a mobile view size by applying `window.resizeTo(430, 500)`.