import { instance } from "@/instance";
import { $i } from "@/account";
import { api } from "@/os";
import { lang } from "@/config";

export async function initializeSw() {
	if (!("serviceWorker" in navigator)) return;

	navigator.serviceWorker.register("/sw.js", { scope: "/", type: "classic" });
	navigator.serviceWorker.ready.then((registration) => {
		registration.active?.postMessage({
			msg: "initialize",
			lang,
		});

		if (instance.swPublickey && "PushManager" in window && $i && $i.token) {
			// SEE: https://developer.mozilla.org/en-US/docs/Web/API/PushManager/subscribe#Parameters
			registration.pushManager
				.subscribe({
					userVisibleOnly: true,
					applicationServerKey: urlBase64ToUint8Array(instance.swPublickey),
				})
				.then((subscription) => {
					function encode(buffer: ArrayBuffer | null) {
						return btoa(
							String.fromCharCode.apply(null, new Uint8Array(buffer)),
						);
					}

					// Register
					api("sw/register", {
						endpoint: subscription.endpoint,
						auth: encode(subscription.getKey("auth")),
						publickey: encode(subscription.getKey("p256dh")),
					});
				})
				// When subscribe failed
				.catch(async (err: Error) => {
					// 通知が許可されていなかったとき
					if (err.name === "NotAllowedError") {
						return;
					}

					// 違うapplicationServerKey (または gcm_sender_id)のサブスクリプションが
					// 既に存在していることが原因でエラーになった可能性があるので、
					// そのサブスクリプションを解除しておく
					const subscription = await registration.pushManager.getSubscription();
					if (subscription) subscription.unsubscribe();
				});
		}
	});
}

/**
 * Convert the URL safe base64 string to a Uint8Array
 * @param base64String base64 string
 */
function urlBase64ToUint8Array(base64String: string): Uint8Array {
	const padding = "=".repeat((4 - (base64String.length % 4)) % 4);
	const base64 = (base64String + padding).replace(/-/g, "+").replace(/_/g, "/");

	const rawData = window.atob(base64);
	const outputArray = new Uint8Array(rawData.length);

	for (let i = 0; i < rawData.length; ++i) {
		outputArray[i] = rawData.charCodeAt(i);
	}
	return outputArray;
}