import { CookieNames } from "$lib/configuration";
import { detectLocale, i18n, isLocale, locales } from '$lib/i18n/i18n-util'
import type { Handle, RequestEvent } from '@sveltejs/kit'
import { initAcceptLanguageHeaderDetector } from 'typesafe-i18n/detectors'
import { parse, serialize } from "cookie";
import type { Locales } from "$lib/i18n/i18n-types";
import { loadAllLocales } from "$lib/i18n/i18n-util.sync";


loadAllLocales()
const L = i18n()

export const handle: Handle = async ({ event, resolve }) => {
    const cookies = parse(event.request.headers.get("Cookie") ?? '');
    const localeCookie = cookies[CookieNames.locale];
    const preferredLocale = getPreferredLocale(event);
    let finalLocale = localeCookie ?? preferredLocale;

    console.log("Handling locale", {
        locales,
        localeCookie,
        preferredLocale,
        finalLocale
    });

    if (!isLocale(finalLocale)) finalLocale = "en";
    if (!localeCookie) {
        // Set a locale cookie
        event.setHeaders({
            "Set-Cookie": serialize(CookieNames.locale, finalLocale, {
                path: "/",
                expires: new Date(2099, 1, 1, 0, 0, 0, 0),
                sameSite: "strict"
            })
        });
    }

    event.locals.locale = finalLocale as Locales;
    event.locals.LL = L[finalLocale as Locales];

    return resolve(event, { transformPageChunk: ({ html }) => html.replace('%lang%', finalLocale) });
}

function getPreferredLocale(event: RequestEvent) {
    const acceptLanguageDetector = initAcceptLanguageHeaderDetector(event.request);
    return detectLocale(acceptLanguageDetector);
}