Daumi’s Debt — EmailJS Notification System

Overview

Add email notifications to Daumi’s Debt so that when one user adds an expense, records a payment, or completes a duel, the partner receives an email with the event details, current balance, and a link to the app. Uses EmailJS (client-side) to send emails without a server.

User Profiles in Firestore

New users collection. On Google sign-in, upsert a document keyed by UID:

users/{uid}: {
  email: string,        // from Firebase Auth profile
  displayName: string,  // from Firebase Auth profile
  updatedAt: timestamp
}

The partner is determined by querying the users collection for any document whose UID differs from the current user. Since this is a two-person app, there will be at most one result.

Email Notification Module

New file: js/notifications.js

Exports

• initNotifications() — Dynamically loads the EmailJS SDK script and calls emailjs.init(publicKey). Called once at app startup after auth.
• saveUserProfile(user) — Takes a Firebase Auth user object, writes { email, displayName, updatedAt } to users/{uid} with setDoc (merge). Called on every login to keep email/name current.
• getPartnerEmail() — Queries the users collection, returns the email and displayName of the user whose UID is not the current user. Returns null if no partner profile exists yet.
• notifyPartner({ type, details }) — Builds template parameters from the event type and details, calls emailjs.send(). Fire-and-forget: logs a warning on failure, never blocks the UI or throws to the caller.

EmailJS Configuration

Three constants at the top of notifications.js:

const EMAILJS_PUBLIC_KEY = '...';  // from EmailJS dashboard
const EMAILJS_SERVICE_ID = '...';  // from EmailJS dashboard
const EMAILJS_TEMPLATE_ID = '...'; // from EmailJS dashboard

These are public-safe values (EmailJS is designed for client-side use).

Email Template

A single EmailJS template handles all three event types via dynamic fields:

Subject: Daumi's Debt:

Body (configured in EmailJS dashboard):

Hi ,

 : 



Open Daumi's Debt → 

Trigger Points

1. Expense Added (app.js — expense form submit handler)

After the Firestore write succeeds, call:

notifyPartner({
  type: 'expense',
  details: { description, amount, currency, splitType, usdAmount }
});

Formats as: “added a $25.00 USD expense” / “Dinner — split evenly”

2. Payment Recorded (app.js — payment form submit handler)

After the Firestore write succeeds, call:

notifyPartner({
  type: 'payment',
  details: { amount, currency, usdAmount }
});

Formats as: “recorded a $50.00 USD payment” / “Settle-up payment”

3. Duel Completed (duel.js — after result is saved)

After the duel result is written to Firestore, call:

notifyPartner({
  type: 'duel',
  details: { game, balanceAdjust, favoredUser }
});

Formats as: “completed a duel” / “Wheel of Fortune — $10.00 forgiven”

Balance in Email

Each notification includes the current balance. The existing computeBalance() function in balance.js returns the net USD balance. The notification module calls this and formats it from the partner’s perspective:

• Positive (partner owes current user): “You owe {currentUser} ${amount}”
• Negative (current user owes partner): “{currentUser} owes you ${amount}”
• Zero: “All settled up!”

Service Worker Updates

In sw.js:

• Add /daumis-debt/js/notifications.js to the cached assets list
• Remove three phantom files that don’t exist: expenses.js, payments.js, history.js

Error Handling

• Email sending is fire-and-forget. On failure, console.warn() with the error. No user-facing error, no retry.
• If the partner hasn’t signed in yet (no profile in users collection), getPartnerEmail() returns null and notifyPartner() silently skips sending.
• If EmailJS SDK fails to load (network issue), notifyPartner() silently skips.

Manual Setup Required

These steps must be done manually in the EmailJS dashboard before the integration works:

1. Create a free EmailJS account at https://www.emailjs.com
2. Add an email service (Gmail recommended)
3. Create an email template matching the fields above
4. Copy the public key, service ID, and template ID into js/notifications.js

Files Changed