Command Channel

+-------------------------------------------------------------------+
|                    COMMAND CHANNEL FLOW (Web)                      |
+-------------------------------------------------------------------+
|  Setup:                                                           |
|    client.join() -> client.getCommandClient()                     |
|                                                                   |
|  Sender:                                                          |
|    cmdClient.send(message)           [broadcast to all]           |
|    cmdClient.send(message, userId)   [targeted]                   |
|                                                                   |
|  Receiver:                                                        |
|    client.on('command-channel-message', callback)                 |
|                                                                   |
|  IMPORTANT: Command channel is SESSION-SCOPED.                    |
|  It does NOT span across different sessions.                      |
+-------------------------------------------------------------------+

// CORRECT: Everything after join
await client.join(topic, jwt, userName);
const cmdClient = client.getCommandClient();
client.on('command-channel-status', (status) => { /* ... */ });
client.on('command-channel-message', (payload) => { /* ... */ });

// WRONG: Registering before join — command channel not active yet
await client.init('en-US', 'Global', { patchJsMedia: true });
client.on('command-channel-message', handler);  // WILL NOT RECEIVE MESSAGES
await client.join(topic, jwt, userName);

import ZoomVideo from '@zoom/videosdk';

const client = ZoomVideo.createClient();

async function joinAndSetupCommandChannel(topic, jwt, userName) {
    // 1. Initialize
    await client.init('en-US', 'Global', { patchJsMedia: true });

    // 2. Join session
    await client.join(topic, jwt, userName);

    // 3. Activate command channel (MUST be after join)
    const cmdClient = client.getCommandClient();

    // 4. Listen for connection status
    client.on('command-channel-status', (status) => {
        console.log('Command channel status:', status);
        if (status === true) {
            console.log('Command channel connected - ready to send');
        }
    });

    // 5. Listen for incoming commands
    client.on('command-channel-message', (payload) => {
        try {
            const data = JSON.parse(payload.text);
            console.log('Command received:', data);
            handleCommand(data);
        } catch (e) {
            console.log('Raw command received:', payload.text);
        }
    });

    return cmdClient;
}

// Send a command (broadcast to all participants in session)
function sendCommand(cmdClient, type, data) {
    const message = JSON.stringify({ type, data });
    cmdClient.send(message);
}

// Send to a specific participant
function sendCommandToUser(cmdClient, userId, type, data) {
    const message = JSON.stringify({ type, data });
    cmdClient.send(message, userId);
}

// Handle incoming commands
function handleCommand(data) {
    switch (data.type) {
        case 'ping':
            console.log('Received ping');
            break;
        case 'transfer':
            console.log('Transfer info:', data);
            break;
        default:
            console.log('Unknown command type:', data.type);
    }
}

client.on('command-channel-status', (status) => {
    // status: boolean - true when connected, false when disconnected
    if (status) {
        // Safe to send commands now
    }
});

client.on('command-channel-message', (payload) => {
    // payload.text: string - the command message content
    // payload.senderId: number - user ID of the sender
    const message = payload.text;
    console.log('Received:', message);
});

const pollTimer = setInterval(async () => {
    const res = await fetch(`/api/status/${sessionName}`);
    const data = await res.json();
    if (data.ready) {
        clearInterval(pollTimer);
        handleData(data);
    }
}, 3000);