hermes-mcp/src/multitenancy/webhook-router.ts

import redis from '../redis.js';
import { getCredential, WhatsAppCredentials } from './credential-store.js';

// Call this at customer onboarding when they connect their WhatsApp Business number
export async function registerWhatsAppNumber(
  customerId: string,
  phoneNumberId: string
): Promise<void> {
  await redis.set(`wa_phone_id:${phoneNumberId}`, customerId);
}

export async function unregisterWhatsAppNumber(phoneNumberId: string): Promise<void> {
  await redis.del(`wa_phone_id:${phoneNumberId}`);
}

export async function resolveCustomerFromPhoneNumberId(
  phoneNumberId: string
): Promise<string | null> {
  return redis.get(`wa_phone_id:${phoneNumberId}`);
}

// WhatsApp Cloud API webhook payload types
interface WhatsAppWebhookEntry {
  id: string;
  changes: Array<{
    value: {
      messaging_product: string;
      metadata: {
        display_phone_number: string;
        phone_number_id: string;
      };
      messages?: WhatsAppInboundMessage[];
      statuses?: WhatsAppStatus[];
    };
    field: string;
  }>;
}

export interface WhatsAppInboundMessage {
  from: string;
  id: string;
  timestamp: string;
  text?: { body: string };
  type: string;
}

interface WhatsAppStatus {
  id: string;
  status: string;
  timestamp: string;
  recipient_id: string;
}

export interface RoutedWebhookEvent {
  customerId: string;
  phoneNumberId: string;
  message: WhatsAppInboundMessage;
  credentials: WhatsAppCredentials;
}

// Parse the incoming webhook and return one routed event per message
export async function routeWhatsAppWebhook(
  body: Record<string, unknown>
): Promise<RoutedWebhookEvent[]> {
  const events: RoutedWebhookEvent[] = [];

  if (body.object !== 'whatsapp_business_account') return events;

  const entries = (body.entry as WhatsAppWebhookEntry[]) ?? [];

  for (const entry of entries) {
    for (const change of entry.changes) {
      if (change.field !== 'messages') continue;

      const { phone_number_id } = change.value.metadata;
      const messages = change.value.messages ?? [];

      if (messages.length === 0) continue;

      // Resolve which customer owns this phone number
      const customerId = await resolveCustomerFromPhoneNumberId(phone_number_id);
      if (!customerId) {
        console.warn(`[webhook-router] Unroutable WhatsApp message to phone_number_id=${phone_number_id}`);
        continue;
      }

      // Load that customer's WhatsApp credentials
      const credentials = await getCredential<WhatsAppCredentials>(customerId, 'whatsapp');
      if (!credentials) {
        console.error(`[webhook-router] No WhatsApp credentials for customerId=${customerId}`);
        continue;
      }

      for (const message of messages) {
        events.push({ customerId, phoneNumberId: phone_number_id, message, credentials });
      }
    }
  }

  return events;
}