OTP and sign-up guard

export function decideOtpChannel(row) {
  if (row.number_status !== "valid") {
    return { action: "fix_number", suggestion: row.suggestion ?? "Enter your number with the country code." };
  }
  const lineType = row.checks?.["network.carrier"]?.attributes?.line_type;
  const extraVerification = ["voip", "premium_rate", "toll_free", "shared_cost"].includes(lineType);
  const wa = row.checks?.["whatsapp.registered"];
  if (wa?.registered === true) return { action: "send_whatsapp", extraVerification };
  if (wa?.registered === false) return { action: "send_sms", reason: "whatsapp_not_registered", extraVerification };
  return { action: "send_sms", reason: "whatsapp_unknown", extraVerification }; // null is not "no"
}

// app/api/otp/route.ts
import { MobileValidate } from "mobilevalidate";
import { decideOnError, decideOtpChannel } from "../../../lib/otp-decision.ts";

const mv = process.env.MOBILEVALIDATE_API_KEY ? new MobileValidate() : new MobileValidate({ sandbox: true });

export async function POST(req: Request) {
  const { phone, country } = await req.json();
  const { data, error } = await mv.lookup(phone, {
    checks: ["whatsapp", "carrier"], defaultCountry: country, wait: 5, waitTimeoutMs: 8_000,
  });
  const decision = error ? decideOnError(error) : decideOtpChannel(data.results[0]);
  return Response.json(decision, { status: decision.action === "fix_number" ? 422 : 200 });
}