import { env } from '$env/dynamic/private';
import nodemailer from 'nodemailer';

let transporter: ReturnType<typeof nodemailer.createTransport> | undefined;

function mailer() {
  if (!env.SMTP_HOST || !env.SMTP_FROM) {
    throw new Error('Email delivery is not configured.');
  }
  if (!transporter) {
    transporter = nodemailer.createTransport({
      host: env.SMTP_HOST,
      port: Number(env.SMTP_PORT || 587),
      secure: env.SMTP_SECURE === 'true',
      auth: env.SMTP_USER
        ? { user: env.SMTP_USER, pass: env.SMTP_PASSWORD }
        : undefined,
      requireTLS: env.SMTP_SECURE !== 'true',
      disableFileAccess: true,
      disableUrlAccess: true,
    });
  }
  return transporter;
}

export function applicationOrigin(): string {
  return (env.APP_ORIGIN || 'http://localhost:5173').replace(/\/+$/, '');
}

export function emailDeliveryConfigured(): boolean {
  return Boolean(env.SMTP_HOST && env.SMTP_FROM);
}

export async function sendAuthenticationLink(
  email: string,
  token: string,
  purpose: 'login' | 'verify_email',
): Promise<void> {
  const url = `${applicationOrigin()}/auth/magic-link?token=${encodeURIComponent(token)}`;
  const subject =
    purpose === 'login'
      ? 'Sign in to SHD.build'
      : 'Verify your SHD.build email';
  const action =
    purpose === 'login' ? 'SIGN IN TO SHD.BUILD' : 'VERIFY EMAIL ADDRESS';
  await mailer().sendMail({
    from: env.SMTP_FROM,
    to: email,
    subject,
    text: `${subject}\n\nOpen this one-time link within 15 minutes:\n${url}\n\nIf you did not request this, you can ignore this message.`,
    html: `<div style="background:#0a0c0d;color:#ecebe5;padding:28px;font-family:Arial,sans-serif"><p style="color:#f6a821;font-size:12px;letter-spacing:2px">SHD IDENTITY NETWORK</p><h1 style="font-size:24px">${subject}</h1><p style="color:#a5aaab">This one-time link expires in 15 minutes.</p><p><a href="${url}" style="display:inline-block;background:#f6a821;color:#111;padding:14px 20px;text-decoration:none;font-weight:800">${action}</a></p><p style="color:#737a7c;font-size:12px">If you did not request this, you can ignore this message.</p></div>`,
  });
}

export async function sendNotificationEmail(
  email: string,
  title: string,
  body: string,
  link: string | null,
): Promise<void> {
  const url = link
    ? `${applicationOrigin()}${link.startsWith('/') ? link : `/${link}`}`
    : `${applicationOrigin()}/account/notifications`;
  await mailer().sendMail({
    from: env.SMTP_FROM,
    to: email,
    subject: `${title} — SHD.build`,
    text: `${title}\n\n${body}\n\nOpen SHD.build: ${url}`,
    html: `<div style="background:#0a0c0d;color:#ecebe5;padding:28px;font-family:Arial,sans-serif"><p style="color:#f6a821;font-size:12px;letter-spacing:2px">SHD NOTIFICATION NETWORK</p><h1 style="font-size:24px">${escapeHtml(title)}</h1><p style="color:#a5aaab;line-height:1.6">${escapeHtml(body)}</p><p><a href="${url}" style="display:inline-block;background:#f6a821;color:#111;padding:14px 20px;text-decoration:none;font-weight:800">OPEN SHD INBOX</a></p></div>`,
  });
}

function escapeHtml(value: string) {
  return value.replace(
    /[&<>"']/g,
    (character) =>
      ({ '&': '&amp;', '<': '&lt;', '>': '&gt;', '"': '&quot;', "'": '&#39;' })[
        character
      ]!,
  );
}