Configuring EVI

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{
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  "type": "session_settings",
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  "audio": {
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    "channels": 1,
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    "encoding": "linear16",
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    "sample_rate": 48000
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  }
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}

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curl -X POST https://api.hume.ai/v0/evi/configs \
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  -H "X-Hume-Api-Key: <YOUR_API_KEY>" \
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  -H "Content-Type: application/json" \
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  -d '{
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    "evi_version": "2",
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    "name": "Sample Webhook Config",
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    "webhooks": [{
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      "url": <YOUR_WEBHOOK_URL>,
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      "events": ["chat_started", "chat_ended"]
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    }]
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  }'

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import { WebhookEvent } from "hume/serialization/resources/empathicVoice/types/WebhookEvent";
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// Route to handle webhook events
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app.post("/hume-webhook", (req: Request, res: Response) => {
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  // Validate and parse using WebhookEvent
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  const event = WebhookEvent.parseOrThrow(JSON.parse(req.body));
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  try {
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    // Handle the specific event type
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    switch (event.eventName) {
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      case 'chat_started':
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        console.info('Processing chat_started event:', event);
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        // Add additional chat_started processing logic here
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        break;
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      case 'chat_ended':
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        console.info("Processing chat_ended event:", event);
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        // Add additional chat_ended processing logic here
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        break;
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      default:
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        console.warn(`[Event Handling] Unsupported event type: '${event.eventName}'`);
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        res.status(400).json({ error: `Unsupported event type: '${event.eventName}'` });
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        return;
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    }
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    res.json({ status: "success", message: `${event.event_name} processed` });
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  } catch (error) {
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    console.error("Error processing event:", error);
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    res.status(500).json({ error: "Internal server error" });
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  }
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});

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import * as crypto from 'crypto';
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export function validateHmacSignature(payload: string, headers: IncomingHttpHeaders): void {
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  // Retrieve the timestamp and signature from headers
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  const timestamp = headers['x-hume-ai-webhook-timestamp'];
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  if (!timestamp) {
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    console.error('Error: Missing timestamp in the request headers.');
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    throw new Error('Missing timestamp header');
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  }
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  const signature = headers['x-hume-ai-webhook-signature'] as string;
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  if (!signature) {
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    console.error('Error: Missing signature in the request headers.');
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    throw new Error('Missing signature header');
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  }
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  // 2. Retrieve the API key from environment variables
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  const apiKey = process.env.HUME_API_KEY;
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  if (!apiKey) {
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    console.error('Error: HUME_API_KEY is not set in environment variables.');
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    throw new Error('Missing API key');
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  }
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  // 3. Construct the message to be hashed by concatenating the payload and the timestamp
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  const message = `${payload}.${timestamp}`;
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  const expectedSig = crypto
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    .createHmac('sha256', apiKey)
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    .update(message)
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    .digest('hex');
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  // 4. Compare the provided signature with the expected one using timing-safe comparison
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  const signatureBuffer = Buffer.from(signature, 'utf8');
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  const expectedSigBuffer = Buffer.from(expectedSig, 'utf8');
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  const validSignature =
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    signatureBuffer.length === expectedSigBuffer.length &&
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    crypto.timingSafeEqual(signatureBuffer, expectedSigBuffer);
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  // 5. If the signatures do not match, throw an error
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  if (!validSignature) {
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    console.error(`Error: Invalid HMAC signature. Expected: ${expectedSig}, Received: ${signature}`);
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    throw new Error('Invalid HMAC signature');
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  }
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  console.info('HMAC validation successful!');
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}

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export function validateTimestamp(headers: IncomingHttpHeaders): void {
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  // 1. Retrieve the timestamp from the headers
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  const timestamp = headers['x-hume-ai-webhook-timestamp'] as string;
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  if (!timestamp) {
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    console.error('Error: Missing timestamp.');
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    throw new Error('Missing timestamp');
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  }
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  // 2. Attempt to parse the timestamp to a number
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  let timestampInt: number;
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  try {
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    timestampInt = parseInt(timestamp, 10);
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    if (isNaN(timestampInt)) {
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      // parseInt can return NaN if the string isn't a valid integer
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      throw new Error();
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    }
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  } catch (err) {
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    console.error(`Error: Invalid timestamp format: ${timestamp}`);
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    throw new Error('Invalid timestamp format');
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  }
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  // 3. Get the current time in seconds
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  const currentTime = Math.floor(Date.now() / 1000);
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  // 4. Check if the timestamp is more than 180 seconds behind the current time
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  const TIMESTAMP_VALIDATION_WINDOW = 180;
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  if (currentTime - timestampInt > TIMESTAMP_VALIDATION_WINDOW) {
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    console.error(`Error: The timestamp on the request is too old. Current time: ${currentTime}, Timestamp: ${timestamp}`);
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    throw new Error('The timestamp on the request is too old');
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  }
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  console.info('Timestamp validation successful!');
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}