#!/usr/bin/env node
/**
 * Watches a Schulcloud session to confirm it is actually being held.
 *
 * The session is a Valkey whitelist entry with a 7200 s TTL that every
 * authenticated request re-sets, so the keepalive should hold it to the JWT's
 * 30-day ceiling. The thing that breaks it is not a clock: a Schulportal tab
 * left open shares the same token and its client-side auto-logout issues
 * `POST /api/v3/logout` ~2 h after login, deleting the shared key. See
 * docs/AUTH.md.
 *
 * This calls refresh-session every 10 minutes and logs the reported budget, so
 * the shape of the log at death tells you which it was:
 *
 *   budget steady at 7200, then an abrupt 401   → revoked (open tab, or logout)
 *   budget decaying 7200 → 0 across pings       → extension not taking effect
 *
 * Read-only with respect to user data. Usage: `npm run session-diagnose [minutes]`
 * (default 150 — enough to pass the ~2 h mark where an open tab would strike).
 */
import { loadConfig } from '../dist/config.js';
import { SchulcloudClient, SchulcloudApiError } from '../dist/schulcloud/client.js';

const totalMinutes = Number(process.argv[2] ?? 150);
const INTERVAL_MS = 10 * 60_000;

const config = loadConfig();
const client = new SchulcloudClient(config);

const payload = JSON.parse(Buffer.from(config.jwt.split('.')[1], 'base64url').toString('utf8'));
const login = new Date(payload.iat * 1000);
const start = Date.now();

const stamp = () => {
	const now = new Date();
	const sinceStart = ((Date.now() - start) / 60000).toFixed(1);
	const sinceLogin = ((Date.now() - login.getTime()) / 60000).toFixed(1);
	return `${now.toISOString().slice(11, 19)}Z  t+${sinceStart.padStart(6)}min  login+${sinceLogin.padStart(6)}min`;
};

console.log(`session diagnosis — instance ${config.baseUrl}`);
console.log(`token jti ${payload.jti}`);
console.log(`login (iat) ${login.toISOString()}  →  login+2h = ${new Date(login.getTime() + 7200_000).toISOString()}`);
console.log(`pinging refresh-session every ${INTERVAL_MS / 60000} min for ${totalMinutes} min\n`);

const samples = [];
const deadline = start + totalMinutes * 60_000;

while (Date.now() < deadline) {
	try {
		const { expiresInSeconds } = await client.extendSession();
		samples.push(expiresInSeconds);
		console.log(`${stamp()}  budget ${expiresInSeconds}s (${Math.round(expiresInSeconds / 60)} min)`);
	} catch (error) {
		const status = error instanceof SchulcloudApiError ? error.status : '—';
		console.log(`${stamp()}  FAILED ${status} — session is gone`);
		verdict(samples, true);
		process.exit(0);
	}
	await new Promise((resolve) => setTimeout(resolve, Math.min(INTERVAL_MS, deadline - Date.now())));
}

console.log(`\n${stamp()}  reached the end of the window with the session still alive`);
verdict(samples, false);

function verdict(series, died) {
	const minutesAlive = (Date.now() - login.getTime()) / 60000;
	console.log('\n--- verdict ---');
	console.log(`budget series: ${series.join(', ')}`);
	if (!died) {
		console.log(`PASS: session survived ${minutesAlive.toFixed(0)} min since login with refresh-session pings.`);
		console.log('=> refresh-session DOES hold the session. The keepalive works; ship it.');
		return;
	}
	const decayed = series.length >= 2 && series.at(-1) < series[0] - 60;
	if (decayed) {
		console.log(`Session ended ${minutesAlive.toFixed(0)} min after login, and the budget was DECAYING.`);
		console.log('=> the extension is not taking effect. Shorten KEEPALIVE_INTERVAL_MS; the');
		console.log('   series above shows the real decay rate.');
	} else {
		console.log(`Session ended ${minutesAlive.toFixed(0)} min after login while the budget still read ${series.at(-1)}s.`);
		console.log('=> REVOKED from outside, not expired. The budget was healthy right up to the 401.');
		if (minutesAlive > 100 && minutesAlive < 160) {
			console.log('   ~2h after login is the signature of a Schulportal tab left open on this');
			console.log('   token: its auto-logout calls POST /api/v3/logout and deletes the shared');
			console.log('   key. Close every Schulportal window and use a fresh token (docs/AUTH.md).');
		} else {
			console.log('   Check for an explicit logout, or an IDP back-channel logout.');
		}
	}
}