import type { Settings } from "@/db/schema";

export const FEED_PATH = "/feed.xml";

/**
 * Canonical + RSS-autodiscovery alternates for a public page. Next.js
 * merges metadata SHALLOWLY per key, so a page that sets only
 * `alternates.canonical` would wipe the RSS link inherited from the
 * root layout — always set both through this helper.
 */
export function pageAlternates(canonical: string) {
  return {
    canonical,
    types: { "application/rss+xml": FEED_PATH },
  };
}

/**
 * The site's public origin for canonical URLs, feeds, and the sitemap.
 * Preference order: the admin-configured setting, the SITE_URL env var,
 * then localhost so development still produces valid (if wrong) URLs.
 * Always returned without a trailing slash.
 */
export function resolveSiteUrl(settings: Pick<Settings, "siteUrl">): string {
  const configured = settings.siteUrl || process.env.SITE_URL || "http://localhost:3000";
  return configured.replace(/\/+$/, "");
}

export function absoluteUrl(siteUrl: string, path: string): string {
  return `${siteUrl}${path.startsWith("/") ? path : `/${path}`}`;
}

/**
 * Rewrites site-relative src/href attributes ("/uploads/…", "/posts/…")
 * to absolute URLs. Feed readers resolve nothing relative to the feed,
 * so stored HTML must be absolutified before it goes into RSS.
 */
export function absolutifyHtml(html: string, siteUrl: string): string {
  return html.replace(
    /(src|href)="(\/(?!\/)[^"]*)"/g,
    (_m, attr: string, path: string) => `${attr}="${siteUrl}${path}"`,
  );
}