import "server-only";
import type { Metadata } from "next";
import { getSeoPage, getSeoSettings } from "@/lib/data";
import { siteConfig } from "@/lib/site-config";

export async function buildMetadata(path: string, fallback?: Metadata): Promise<Metadata> {
  const [settings, override] = await Promise.all([
    getSeoSettings(),
    getSeoPage(path),
  ]);

  const siteName = settings?.site_name || siteConfig.name;
  const siteDesc = settings?.site_description || siteConfig.tagline;
  const ogDefault = settings?.default_og_image || "/logo.png";

  const title =
    override?.title ?? (fallback?.title as string | undefined) ?? siteName;
  const description =
    override?.description ??
    (fallback?.description as string | undefined) ??
    siteDesc;

  // Sayfanın kendi OG bilgisi (blog kapağı, type:"article" vb.) — fallback'ten
  // oku. Öncelik: sayfa SEO override > sayfanın fallback OG görseli > varsayılan.
  const fbOg = fallback?.openGraph as
    | { images?: unknown; type?: string }
    | undefined;
  const fbOgImage = (() => {
    const imgs = fbOg?.images;
    if (typeof imgs === "string") return imgs;
    if (Array.isArray(imgs) && imgs.length) {
      const first = imgs[0];
      if (typeof first === "string") return first;
      if (first && typeof first === "object" && "url" in first)
        return String((first as { url: unknown }).url);
    }
    return undefined;
  })();
  const ogImage = override?.og_image || fbOgImage || ogDefault;
  const ogType = fbOg?.type ?? "website";

  // Anahtar kelimeler: sayfa override + site geneli varsayılan + sayfanın kendi
  // keyword'leri (örn. blog etiketleri) birleştirilir, tekrarlar ayıklanır.
  const fbKeywords = fallback?.keywords;
  const fbKeywordsStr = Array.isArray(fbKeywords)
    ? fbKeywords.join(",")
    : typeof fbKeywords === "string"
      ? fbKeywords
      : "";
  const keywordsRaw = [override?.keywords, settings?.default_keywords, fbKeywordsStr]
    .filter(Boolean)
    .join(",");
  const keywords = keywordsRaw
    ? Array.from(
        new Set(
          keywordsRaw
            .split(",")
            .map((k) => k.trim())
            .filter(Boolean),
        ),
      )
    : undefined;

  return {
    title,
    description,
    keywords,
    metadataBase: new URL(siteConfig.url),
    openGraph: {
      title,
      description,
      images: ogImage ? [{ url: ogImage }] : undefined,
      type: ogType as "website" | "article",
      locale: "tr_TR",
      siteName,
    },
    twitter: {
      card: "summary_large_image",
      title,
      description,
      images: ogImage ? [ogImage] : undefined,
      site: settings?.twitter_handle ?? undefined,
    },
    alternates: override?.canonical
      ? { canonical: override.canonical }
      : undefined,
    robots: override?.noindex
      ? { index: false, follow: false }
      : undefined,
    verification: settings?.google_site_verification
      ? { google: settings.google_site_verification }
      : undefined,
  };
}