/**
 * Phone-first signup still has to put something in `users.email` — better-auth
 * requires it to be present and unique. We mint a synthetic address on a domain
 * we control and never deliver to.
 *
 * For a plumber-and-electrician marketplace this will be MOST client accounts,
 * so every outbound-mail path must check `isSyntheticEmail` first. Sending to
 * one is not merely useless: it is a bounce against our sending reputation, and
 * at volume that costs us delivery to the addresses that are real.
 *
 * Pros are required to supply a genuine address during onboarding — they need
 * payout statements, tax records and dispute notices. Clients may never have one
 * and are served over SMS instead.
 */
export const SYNTHETIC_EMAIL_DOMAIN = 'phone.linkder.local';

export function syntheticEmailFor(phoneE164: string): string {
  return `${phoneE164}@${SYNTHETIC_EMAIL_DOMAIN}`;
}

export function isSyntheticEmail(email: string | null | undefined): boolean {
  if (!email) return true; // nothing to send to is, for our purposes, the same thing
  return email.toLowerCase().endsWith(`@${SYNTHETIC_EMAIL_DOMAIN}`);
}

/** True when we can actually put a message in front of this person by email. */
export function isContactableEmail(email: string | null | undefined): email is string {
  return !isSyntheticEmail(email);
}

/**
 * Recover the phone number a synthetic address was minted from.
 * Useful in support tooling; returns null for a real address.
 */
export function phoneFromSyntheticEmail(email: string): string | null {
  if (!isSyntheticEmail(email)) return null;
  const [local] = email.split('@');
  return local && local.startsWith('+') ? local : null;
}