import { IObject } from "./type"; const request = require('request-promise-native'); export default class Resolver { private history: Set; constructor() { this.history = new Set(); } public async resolveCollection(value) { const collection = typeof value === 'string' ? await this.resolve(value) : value; switch (collection.type) { case 'Collection': collection.objects = collection.object.items; break; case 'OrderedCollection': collection.objects = collection.object.orderedItems; break; default: throw new Error(`unknown collection type: ${collection.type}`); } return collection; } public async resolve(value): Promise { if (typeof value !== 'string') { return value; } if (this.history.has(value)) { throw new Error('cannot resolve already resolved one'); } this.history.add(value); const object = await request({ url: value, headers: { Accept: 'application/activity+json, application/ld+json' }, json: true }); if (object === null || ( Array.isArray(object['@context']) ? !object['@context'].includes('https://www.w3.org/ns/activitystreams') : object['@context'] !== 'https://www.w3.org/ns/activitystreams' )) { throw new Error('invalid response'); } return object; } }