PYQ clone

A working full-stack copy of the ZenithPrep PYQ practice app: build a paper from JEE Main style questions, take it on a timed CBT screen with +4 / −1 marking, then read the analysis and progress dashboard.

Rust + Axum + SQLite. Server-rendered HTML, vanilla JS, no frontend framework.

Run

cargo run

Then open http://127.0.0.1:8080 and sign in with any name and email.

Environment:

var	default	meaning
PYQ_ADDR	127.0.0.1:8080	listen address
PYQ_DB	pyq.db	SQLite file, created if absent
PYQ_BASE	empty	URL prefix when mounted in a subpath
GOOGLE_CLIENT_ID	empty	enables Google sign-in; unset hides the button
GOOGLE_CLIENT_SECRET	empty	needed only by the full-page fallback

Google sign-in

Set a client id and the button appears on /student. Without it the page says Google is off and offers the email form instead.

GOOGLE_CLIENT_ID=1234-ab.apps.googleusercontent.com \
GOOGLE_CLIENT_SECRET=... \
cargo run

In the Google Cloud console add an OAuth 2.0 Client ID / Web application, then list every origin this runs on, for example http://127.0.0.1:8080 and http://localhost:8080. The callback URL is derived from the incoming request, so it follows the port you are on and follows x-forwarded-proto behind a proxy. Register each of those origins rather than trying to predict one URL.

Two paths lead to the same session:

• Popup. Google Identity Services returns an ID token to the page, which posts it to POST /student/google.
• Full page. Where a popup is refused, the link beside the button starts an authorization-code flow with PKCE. The code is redeemed server side at GET /student/google/callback, so the client secret never reaches the browser.

Either way the ID token is verified here, not in the browser. The signature is checked against the keys Google publishes at https://www.googleapis.com/oauth2/v3/certs, and the audience must be this client, the issuer must be a Google issuer, the expiry must hold, and the email must be verified. A token failing any of that is rejected and no session is created. The state parameter is single use and expires after ten minutes.

To confirm the rejection path without a real Google account:

cargo run --example forge_google_token -- YOUR_CLIENT_ID attacker@example.com

That prints a correctly signed token from a key the server has never seen. Posting it to /student/google returns 401 and creates no user.

Routes

route	what it does
GET /	landing page with live bank counts
GET /student, POST /student	email sign-in, sets an HttpOnly session cookie
POST /student/google	verifies a Google ID token, signs in
GET /student/google/callback	redeems the authorization code for the full-page flow
GET /logout	clears the session
GET /build, POST /build	chapter picker and paper generation
POST /attempt/:paper	starts or resumes an attempt
GET /attempt/:paper	the CBT screen
POST /attempt/:id/answer	JSON autosave of one answer
POST /attempt/:id/submit	grades and closes the paper
GET /result/:attempt	score, accuracy and per-question analysis
GET /history	every submitted paper
GET /dashboard	cross-paper trend, weak subtopics, coach notes
GET /s/:token	public paper view, never a score
GET /api/attempt/:id/state	autosaved answers as JSON

Marking

+4 for a correct answer, −1 for a wrong one, 0 for a blank. Numerical answers compare against a 0.1 percent tolerance so 20.01 is accepted for 20.

Question selection

A paper is drawn from the chosen chapters, shuffled with a seed derived from the request, and trimmed to the requested length. With "unseen questions only" the query excludes anything already answered by that user, so the same question does not come back by accident.

Tests

cargo test

Covers the marking rules, numerical tolerance, and the urlencoded form decoding that shapes the build endpoint.