Primora/apps/auth/src/lib/mail.ts

import nodemailer from "nodemailer";
import { Resend } from "resend";

import { env } from "./env.js";

const resend = env.RESEND_API_KEY ? new Resend(env.RESEND_API_KEY) : null;

const transporter =
  !resend && env.SMTP_HOST
    ? nodemailer.createTransport({
        host: env.SMTP_HOST,
        port: env.SMTP_PORT,
        secure: false,
        auth: env.SMTP_USER
          ? {
              user: env.SMTP_USER,
              pass: env.SMTP_PASSWORD,
            }
          : undefined,
      })
    : null;

export async function sendTransactionalEmail(input: {
  to: string;
  subject: string;
  text: string;
  html: string;
}) {
  if (resend) {
    await resend.emails.send({
      from: env.MAIL_FROM,
      to: [input.to],
      subject: input.subject,
      text: input.text,
      html: input.html,
    });
    return;
  }

  if (!transporter) {
    throw new Error("No mail transport configured for auth service.");
  }

  await transporter.sendMail({
    from: env.MAIL_FROM,
    to: input.to,
    subject: input.subject,
    text: input.text,
    html: input.html,
  });
}