How to build a public Cal.com integration: Building the Auth Flow

Hey there, fellow JavaScript enthusiast! Ready to dive into the world of Cal.com integrations? Today, we're going to walk through building the authorization flow for a user-facing integration. Buckle up, because we're about to make your app play nicely with Cal.com's powerful scheduling features.

Prerequisites

Before we jump in, make sure you've got:

• A basic understanding of OAuth 2.0
• Node.js installed
• Your favorite code editor ready to roll

We'll assume you're comfortable with JavaScript and have some experience with building web applications. If you're nodding along, great! Let's get started.

Setting up the project

First things first, head over to Cal.com and create a new application. You'll need to grab your API credentials – think of them as your app's VIP pass to Cal.com's exclusive club.

Implementing the Authorization Flow

Initiating the OAuth 2.0 flow

Time to kick things off! We'll start by constructing the authorization URL:

const authUrl = `https://api.cal.com/oauth/authorize?client_id=${YOUR_CLIENT_ID}&redirect_uri=${REDIRECT_URI}&response_type=code`;

Now, redirect your user to this URL. They'll land on Cal.com's authorization page, where they can grant your app permission to access their data.

Handling the callback

Once the user gives the thumbs up, Cal.com will redirect them back to your specified redirect URI. Set up an endpoint to catch this callback:

app.get('/callback', (req, res) => {
  const authCode = req.query.code;
  // Time to exchange this code for an access token!
});

Exchanging the code for access token

Now for the good stuff – let's swap that authorization code for an access token:

const tokenResponse = await fetch('https://api.cal.com/oauth/token', {
  method: 'POST',
  headers: { 'Content-Type': 'application/json' },
  body: JSON.stringify({
    client_id: YOUR_CLIENT_ID,
    client_secret: YOUR_CLIENT_SECRET,
    grant_type: 'authorization_code',
    code: authCode,
    redirect_uri: REDIRECT_URI
  })
});

const { access_token, refresh_token } = await tokenResponse.json();

Remember to store these tokens securely. They're your golden tickets to the Cal.com API!

Refreshing the access token

Access tokens don't last forever, so let's implement a refresh mechanism:

async function refreshAccessToken(refresh_token) {
  const response = await fetch('https://api.cal.com/oauth/token', {
    method: 'POST',
    headers: { 'Content-Type': 'application/json' },
    body: JSON.stringify({
      client_id: YOUR_CLIENT_ID,
      client_secret: YOUR_CLIENT_SECRET,
      grant_type: 'refresh_token',
      refresh_token
    })
  });

  return response.json();
}

Making authenticated requests

Now that you've got your access token, it's time to put it to work:

const response = await fetch('https://api.cal.com/v1/schedules', {
  headers: {
    Authorization: `Bearer ${access_token}`
  }
});

const schedules = await response.json();

Error handling and edge cases

Always be prepared for things to go sideways. Handle authorization failures gracefully and be ready to deal with revoked access. A simple try-catch block can go a long way:

try {
  // Make API request
} catch (error) {
  if (error.status === 401) {
    // Time to refresh that token!
  }
}

Best practices and security considerations

Keep those tokens safe! Store them securely and consider implementing PKCE (Proof Key for Code Exchange) for an extra layer of security. Your users will thank you for it.

Testing the integration

Before you pop the champagne, make sure to thoroughly test your auth flow. Try different scenarios: successful logins, token refreshes, and even intentionally breaking things to see how your app handles it.

Conclusion

And there you have it! You've just built a rock-solid authorization flow for your Cal.com integration. Pat yourself on the back – you're well on your way to creating an awesome, Cal.com-powered application.

Remember, this is just the beginning. Now that you've got the auth flow down, the sky's the limit. Happy coding, and may your calendars always be in sync!