import { sequence } from '@sveltejs/kit/hooks';
import type { Handle } from '@sveltejs/kit';
import { apiFetch } from '$lib/server/api';
import { rememberRequestLocale } from '$lib/i18n/strategy.server';
import { paraglideMiddleware } from '$lib/paraglide/server';
import { getTextDirection } from '$lib/paraglide/runtime';

// The only auth logic in the frontend: forward the session cookie to the
// backend and expose the result as locals.user.
const auth: Handle = async ({ event, resolve }) => {
	event.locals.user = null;
	if (event.cookies.get('pablan_session')) {
		try {
			const response = await apiFetch(event.fetch, event.cookies, '/api/auth/me');
			if (response.ok) {
				event.locals.user = await response.json();
			}
		} catch {
			// Backend unreachable: treat as logged out instead of failing the page.
			event.locals.user = null;
		}
	}
	// Hand the account's language to the custom locale strategy, which only
	// sees the request. Runs before the i18n handle, hence the order below.
	rememberRequestLocale(event.request, event.locals.user?.locale ?? null);
	return resolve(event);
};

// Resolves the locale through the configured strategy chain and stamps the
// result into the document, so the very first server-rendered byte already
// carries the right language.
const i18n: Handle = ({ event, resolve }) =>
	paraglideMiddleware(event.request, ({ request: localizedRequest, locale }) => {
		event.request = localizedRequest;
		return resolve(event, {
			transformPageChunk: ({ html }) =>
				html.replace('%lang%', locale).replace('%dir%', getTextDirection(locale))
		});
	});

// auth first: it is what tells the locale strategy which user is asking.
export const handle: Handle = sequence(auth, i18n);