Run WhatsApp for your users

import { Wassist } from "@wassist/sdk";

const wassist = new Wassist({ apiKey: process.env.WASSIST_API_KEY });

app.post("/whatsapp/connect", async (req, res) => {
  const tenant = req.user.tenant;

  // Snapshot the accounts you already have, so you can spot the new one later
  const knownAccountIds = (await wassist.whatsappAccounts.list().all()).map((a) => a.id);

  const session = await wassist.whatsappLinkSessions.create({
    successUrl: `https://app.example.com/whatsapp/connected/${tenant.id}`,
    returnUrl: "https://app.example.com/settings/whatsapp",
  });

  await db.linkSessions.insert({ id: session.id, tenantId: tenant.id, knownAccountIds });
  res.redirect(session.linkUrl);
});

app.get("/whatsapp/connected/:tenantId", async (req, res) => {
  const pending = await db.linkSessions.get(req.query.session_id);
  if (!pending || pending.tenantId !== req.params.tenantId) return res.sendStatus(404);

  const session = await wassist.whatsappLinkSessions.get(pending.id);
  if (session.status !== "SUCCESS") return res.redirect("/settings/whatsapp?error=link_failed");

  const accounts = await wassist.whatsappAccounts.list().all();
  const account = accounts.find((a) => !pending.knownAccountIds.includes(a.id));

  await db.tenants.update(pending.tenantId, { whatsappAccountId: account.id });
  await registerNumbers(account.id); // step 3
  res.redirect("/settings/whatsapp?connected=1");
});

async function api(path, init = {}) {
  const res = await fetch(`https://backend.wassist.app/api/v1${path}`, {
    ...init,
    headers: {
      "X-API-Key": process.env.WASSIST_API_KEY,
      "Content-Type": "application/json",
    },
  });
  if (!res.ok) throw new Error(`${res.status}: ${await res.text()}`);
  return res.json();
}

async function registerNumbers(accountId) {
  // Numbers on the account at Meta, flagged with whether Wassist already handles them
  const { data } = await api(`/whatsapp-accounts/${accountId}/phone-numbers/`);

  for (const number of data.filter((n) => !n.isLinkedToWassist)) {
    await api(`/whatsapp-accounts/${accountId}/manage/`, {
      method: "POST",
      body: JSON.stringify({ phoneNumber: number.display_phone_number }),
    });
  }

  const account = await wassist.whatsappAccounts.get(accountId);
  return account.phoneNumbers; // [{ id, number, bot }]
}

// Take over one chat: your webhook now gets its messages, and the agent stops replying
await wassist.conversations.subscribe(conversationId, { webhookId: process.env.WASSIST_WEBHOOK_ID });

// Hand it back to the number's default (the agent)
await wassist.conversations.unsubscribe(conversationId);