class PaypalClient {
  appId: string
  dryRun: boolean
  environment: any | null

  constructor(appId: string) {
    this.appId = appId
    this.dryRun = Boolean(process.env.NODE_ENV !== 'production')
  }
  public setup = async () => {
	// ...
  }

  public createOrder = async (orderDetails: CreateOrderRequestBody) => {
    // ...
  }

  public captureOrder = async (paypalOrderId: string) => {
   // ...
  }
}

// ...
      const host = await getAppHost(appId)
      const paypalClient = new PaypalClient(appId)
      try {
        await paypalClient.setup()
      } catch (error) {
        return res.redirect(`https://${host}/orders/${orderId}?code=E_SETUP_PAYPAL&error=${error.message}`)
      }

      // capture order
      let capturedOrderResponse: OrderResponse | any
      try {
        capturedOrderResponse = await paypalClient.captureOrder(paymentId)
      } catch (error) {
        return res.redirect(`https://${host}/orders/${orderId}?code=E_PAYPAL_CAPTURE&error=${error.message}`)
      }

class VitalClient {
  appId: string
  private _baseUri: string = ''
  private _storeName: string = ''
  private _apiKey: string = ''
  private _apiBaseCaller: AxiosInstance = axios
  constructor(appId: string) {
    this.appId = appId
  }
  public init = async () => {
    const appModules = await getAppModules(this.appId)
    if (!appModules.includes('vital_crm')) {
      throw new Error(`app: ${this.appId} did not support vital crm. Please add vital_crm module`)
    }
    // ...
    this._baseUri = 'https://www.videgree.com/' + this._storeName
    this._apiBaseCaller = axios.create({
      headers: {
        Authorization: `ApiKey ${this._apiKey}`,
      },
      baseURL: this._baseUri,
    })
  }

  private _composeMemberData = (memberData: { email: string; name: string; id: string }) => {
	// ...
  }
  private _composeOrderData = (orderData) => {
	// ...
  }
  public insertMember = async (memberData: { [key: string]: any }) => {
    // memberData to vital req.body
  }
  public updateMember = async (memberData: { [key: string]: any }) => {
	// ...
  }
  public insertOrUpdateOrder = async (orderData) => {
   // ...
  }
}

// ...  
private static _handleMemberInsertOrUpdate = async (event: TriggerEvent) => {
    // get app Id if there have vital_crm module
    const appId = event.data.new?.app_id
    const appModules = await getAppModules(appId)
    if (!appModules.includes('vital_crm')) return

    // get vitalClient
    const vitalClient = new VitalClient(appId)
    try {
      await vitalClient.init()
    } catch (error) {
      throw new Error(`vital Client init failed: ${error.stack}`)
    }

    const newMemberData = event.data.new || {}
    const vitalCustomerNo = newMemberData?.metadata?.vital?.CustomerNo
    // insert
    if (!vitalCustomerNo) {
      await vitalClient.insertMember(newMemberData)
      return
    }

    // update
    await vitalClient.updateMember(newMemberData)
  }