import type { Metadata } from "next";
import { SITE_URL } from "@/lib/routes";

/** Metadata for an entity / index page: title, description, canonical + OG/Twitter mirror (OG image comes from the segment's opengraph-image.tsx). */
export function pageMetadata({ title, description, path, absoluteTitle }: { title: string; description: string; path: string; absoluteTitle?: boolean }): Metadata {
  const desc = description.length > 300 ? `${description.slice(0, 297)}…` : description;
  return {
    title: absoluteTitle ? { absolute: title } : title,
    description: desc,
    alternates: { canonical: path },
    openGraph: { title, description: desc, url: `${SITE_URL}${path}`, type: "website" },
    twitter: { card: "summary_large_image", title, description: desc },
  };
}

/** Metadata for an entity that does not exist (still renders 404 body via notFound()). */
export const NOT_FOUND_METADATA: Metadata = { title: "Not found", robots: { index: false, follow: false } };

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

/** Drop null / undefined / empty values from a JSON-LD object (Google ignores empty props but it keeps the payload tidy). */
export function compactJsonLd<T extends Record<string, unknown>>(obj: T): Partial<T> {
  const out: Record<string, unknown> = {};
  for (const [k, v] of Object.entries(obj)) {
    if (v === null || v === undefined || v === "") continue;
    if (Array.isArray(v) && v.length === 0) continue;
    out[k] = v;
  }
  return out as Partial<T>;
}

export function breadcrumbJsonLd(items: Array<{ name: string; href: string }>) {
  return {
    "@context": "https://schema.org",
    "@type": "BreadcrumbList",
    itemListElement: items.map((it, i) => ({ "@type": "ListItem", position: i + 1, name: it.name, item: absoluteUrl(it.href) })),
  };
}