/**
 * Renders the email that greets a new account. `sendWelcomeEmail`
 * (`user-service.ts`) sends it after sign-up, in the instance's style and
 * language. It opens with the instance's `GERBEUR_WELCOME_EMAIL_BODY`, or the
 * built-in body, then says the digests are on, since they are by default, and
 * where to turn them off.
 *
 * @module
 */

import { FRONTEND_URL, OG_SITE_NAME, WELCOME_EMAIL_BODY } from "../config.ts";
import { i18n } from "./i18n.ts";
import {
  EmailKit,
  escMd,
  lookOf,
  mdLink,
  type RenderedEmail,
} from "./layout.ts";

/**
 * Returns the welcome email of `username`. The instance's body has
 * `{{username}}` and `{{site_name}}` filled in; raw HTML in it passes
 * through, since it comes from whoever runs the instance, never from a user.
 */
export function renderWelcomeEmail(username: string): RenderedEmail {
  // A username may hold a `_`, which Markdown would read as emphasis.
  const body = WELCOME_EMAIL_BODY
    ? WELCOME_EMAIL_BODY
      .replaceAll("{{username}}", escMd(username))
      .replaceAll("{{site_name}}", escMd(OG_SITE_NAME))
    : i18n._("email.welcome.body", {
      site: escMd(OG_SITE_NAME),
      username: escMd(username),
    });
  const markdown = [
    body,
    mdLink(
      i18n._("email.welcome.button", { site: OG_SITE_NAME }),
      FRONTEND_URL,
    ),
    `*${escMd(i18n._("email.welcome.digests"))}*`,
    "---",
    escMd(i18n._("email.welcome.reason", { site: OG_SITE_NAME })),
  ].join("\n\n");

  return new EmailKit(lookOf()).render({
    subject: i18n._("email.welcome.subject", { site: OG_SITE_NAME }),
    preheader: i18n._("email.welcome.preheader"),
    markdown,
  });
}