import { IEvent } from "@/types/event.model"; const ANONYMOUS_PARTICIPATIONS_LOCALSTORAGE_KEY = "ANONYMOUS_PARTICIPATIONS"; interface IAnonymousParticipation { token: string; expiration: Date; confirmed: boolean; } class AnonymousParticipationNotFoundError extends Error { constructor(message?: string) { super(message); Object.setPrototypeOf(this, new.target.prototype); this.name = AnonymousParticipationNotFoundError.name; } } /** * Fetch existing anonymous participations saved inside this browser */ function getLocalAnonymousParticipations(): Map { return jsonToMap( localStorage.getItem(ANONYMOUS_PARTICIPATIONS_LOCALSTORAGE_KEY) || mapToJson(new Map()) ); } function mapToJson(map: Map): string { return JSON.stringify([...map]); } function jsonToMap(jsonStr: string): Map { return new Map(JSON.parse(jsonStr)); } /** * Purge participations which expiration has been reached * @param participations Map */ function purgeOldParticipations( participations: Map ): Map { for (const [hashedUUID, { expiration }] of participations) { if (expiration < new Date()) { participations.delete(hashedUUID); } } return participations; } /** * Insert a participation in the list of anonymous participations * @param hashedUUID * @param participation */ function insertLocalAnonymousParticipation( hashedUUID: string, participation: IAnonymousParticipation ) { const participations = purgeOldParticipations(getLocalAnonymousParticipations()); participations.set(hashedUUID, participation); localStorage.setItem(ANONYMOUS_PARTICIPATIONS_LOCALSTORAGE_KEY, mapToJson(participations)); } function buildExpiration(event: IEvent): Date { const expiration = event.endsOn || event.beginsOn; expiration.setMonth(expiration.getMonth() + 3); expiration.setDate(1); return expiration; } async function addLocalUnconfirmedAnonymousParticipation(event: IEvent, cancellationToken: string) { /** * We hash the event UUID so that we can't know which events an anonymous user goes by looking up it's localstorage */ const hashedUUID = await digestMessage(event.uuid); /** * We round expiration to first day of next 3 months so that it's difficult to find event from date */ const expiration = buildExpiration(event); insertLocalAnonymousParticipation(hashedUUID, { token: cancellationToken, expiration, confirmed: false, }); } async function confirmLocalAnonymousParticipation(uuid: string) { const participations = purgeOldParticipations(getLocalAnonymousParticipations()); const hashedUUID = await digestMessage(uuid); const participation = participations.get(hashedUUID); if (participation) { participation.confirmed = true; participations.set(hashedUUID, participation); localStorage.setItem(ANONYMOUS_PARTICIPATIONS_LOCALSTORAGE_KEY, mapToJson(participations)); } } async function isParticipatingInThisEvent(eventUUID: string): Promise { const participation = await getParticipation(eventUUID); return participation !== undefined && participation.confirmed; } async function getParticipation(eventUUID: string): Promise { const hashedUUID = await digestMessage(eventUUID); const participation = purgeOldParticipations(getLocalAnonymousParticipations()).get(hashedUUID); if (participation) { return participation; } throw new AnonymousParticipationNotFoundError("Participation not found"); } async function getLeaveTokenForParticipation(eventUUID: string): Promise { return (await getParticipation(eventUUID)).token; } async function removeAnonymousParticipation(eventUUID: string): Promise { const hashedUUID = await digestMessage(eventUUID); const participations = purgeOldParticipations(getLocalAnonymousParticipations()); participations.delete(hashedUUID); localStorage.setItem(ANONYMOUS_PARTICIPATIONS_LOCALSTORAGE_KEY, mapToJson(participations)); } async function digestMessage(message: string): Promise { const encoder = new TextEncoder(); const data = encoder.encode(message); const hashBuffer = await crypto.subtle.digest("SHA-256", data); const hashArray = Array.from(new Uint8Array(hashBuffer)); return hashArray.map((b) => b.toString(16).padStart(2, "0")).join(""); } export { addLocalUnconfirmedAnonymousParticipation, confirmLocalAnonymousParticipation, getLeaveTokenForParticipation, isParticipatingInThisEvent, removeAnonymousParticipation, AnonymousParticipationNotFoundError, };