gradido/dlt-connector/src/client/BackendClient.ts

/* eslint-disable @typescript-eslint/no-unsafe-assignment */
/* eslint-disable @typescript-eslint/no-unsafe-member-access */
import { gql, GraphQLClient } from 'graphql-request'
import { SignJWT } from 'jose'

import { CONFIG } from '@/config'
import { CommunityDraft } from '@/graphql/input/CommunityDraft'
import { logger } from '@/logging/logger'
import { LogError } from '@/server/LogError'

const homeCommunity = gql`
  query {
    homeCommunity {
      uuid
      foreign
      creationDate
    }
  }
`
interface Community {
  homeCommunity: {
    uuid: string
    foreign: boolean
    creationDate: string
  }
}
// Source: https://refactoring.guru/design-patterns/singleton/typescript/example
// and ../federation/client/FederationClientFactory.ts
/**
 * A Singleton class defines the `getInstance` method that lets clients access
 * the unique singleton instance.
 */
// eslint-disable-next-line @typescript-eslint/no-extraneous-class
export class BackendClient {
  // eslint-disable-next-line no-use-before-define
  private static instance: BackendClient
  client: GraphQLClient
  /**
   * The Singleton's constructor should always be private to prevent direct
   * construction calls with the `new` operator.
   */
  // eslint-disable-next-line no-useless-constructor, @typescript-eslint/no-empty-function
  private constructor() {}

  /**
   * The static method that controls the access to the singleton instance.
   *
   * This implementation let you subclass the Singleton class while keeping
   * just one instance of each subclass around.
   */
  public static getInstance(): BackendClient | undefined {
    if (!BackendClient.instance) {
      BackendClient.instance = new BackendClient()
    }
    if (!BackendClient.instance.client) {
      try {
        BackendClient.instance.client = new GraphQLClient(CONFIG.BACKEND_SERVER_URL, {
          headers: {
            'content-type': 'application/json',
          },
          method: 'GET',
          jsonSerializer: {
            parse: JSON.parse,
            stringify: JSON.stringify,
          },
        })
      } catch (e) {
        logger.error("couldn't connect to backend: ", e)
        return
      }
    }
    return BackendClient.instance
  }

  public async getHomeCommunityDraft(): Promise<CommunityDraft> {
    logger.info('check home community on backend')
    const { data, errors } = await this.client.rawRequest<Community>(
      homeCommunity,
      {},
      {
        authorization: 'Bearer ' + (await this.createJWTToken()),
      },
    )
    if (errors) {
      throw new LogError('error getting home community from backend', errors)
    }
    const communityDraft = new CommunityDraft()
    communityDraft.uuid = data.homeCommunity.uuid
    communityDraft.foreign = data.homeCommunity.foreign
    communityDraft.createdAt = data.homeCommunity.creationDate
    return communityDraft
  }

  private async createJWTToken(): Promise<string> {
    const secret = new TextEncoder().encode(CONFIG.JWT_SECRET)
    const token = await new SignJWT({ gradidoID: 'dlt-connector', 'urn:gradido:claim': true })
      .setProtectedHeader({ alg: 'HS256' })
      .setIssuedAt()
      .setIssuer('urn:gradido:issuer')
      .setAudience('urn:gradido:audience')
      .setExpirationTime('1m')
      .sign(secret)
    return token
  }
}