feat(seo): add localized route metadata

lib/seo.ts

@@ -0,0 +1,127 @@
+import type { Metadata } from "next";
+import { getTranslations } from "next-intl/server";
+
+export const SITE_URL = (
+  process.env.NEXT_PUBLIC_SITE_URL || "https://poyrazavsever.com"
+).replace(/\/$/, "");
+
+export type SiteLocale = "tr" | "en";
+
+type LocalePaths = Partial<Record<SiteLocale, string>>;
+
+type StaticSeoPage =
+  | "home"
+  | "about"
+  | "references"
+  | "volunteerCommunity"
+  | "blog"
+  | "projects"
+  | "content"
+  | "gallery"
+  | "links"
+  | "contact";
+
+function normalizePath(path: string) {
+  if (!path || path === "/") return "/";
+  return `/${path.replace(/^\/+|\/+$/g, "")}`;
+}
+
+export function getLocalizedPath(locale: SiteLocale, path: string) {
+  const normalizedPath = normalizePath(path);
+
+  if (locale === "tr") return normalizedPath;
+  return normalizedPath === "/" ? "/en" : `/en${normalizedPath}`;
+}
+
+export function getAbsoluteUrl(path: string) {
+  return new URL(path, `${SITE_URL}/`).toString();
+}
+
+export function getLocalizedUrl(locale: SiteLocale, path: string) {
+  return getAbsoluteUrl(getLocalizedPath(locale, path));
+}
+
+export function createAlternates(
+  locale: SiteLocale,
+  paths: LocalePaths,
+): Metadata["alternates"] {
+  const currentPath = paths[locale];
+  if (!currentPath) return undefined;
+
+  const languages: Record<string, string> = {};
+
+  if (paths.tr) {
+    languages["tr-TR"] = getLocalizedUrl("tr", paths.tr);
+  }
+  if (paths.en) {
+    languages["en-US"] = getLocalizedUrl("en", paths.en);
+  }
+
+  languages["x-default"] = paths.tr
+    ? getLocalizedUrl("tr", paths.tr)
+    : getLocalizedUrl(locale, currentPath);
+
+  return {
+    canonical: getLocalizedUrl(locale, currentPath),
+    languages,
+  };
+}
+
+export function createPageMetadata({
+  locale,
+  title,
+  description,
+  path,
+  absoluteTitle = false,
+}: {
+  locale: SiteLocale;
+  title: string;
+  description: string;
+  path: string;
+  absoluteTitle?: boolean;
+}): Metadata {
+  const url = getLocalizedUrl(locale, path);
+
+  return {
+    title: absoluteTitle ? { absolute: title } : title,
+    description,
+    alternates: createAlternates(locale, { tr: path, en: path }),
+    openGraph: {
+      type: "website",
+      locale: locale === "tr" ? "tr_TR" : "en_US",
+      alternateLocale: locale === "tr" ? ["en_US"] : ["tr_TR"],
+      url,
+      title,
+      description,
+    },
+    twitter: {
+      card: "summary_large_image",
+      title,
+      description,
+      creator: "@poyrazavsever",
+    },
+  };
+}
+
+export async function getStaticPageMetadata({
+  locale,
+  page,
+  path,
+  absoluteTitle = false,
+}: {
+  locale: string;
+  page: StaticSeoPage;
+  path: string;
+  absoluteTitle?: boolean;
+}) {
+  const siteLocale = locale === "en" ? "en" : "tr";
+  const t = await getTranslations({ locale: siteLocale, namespace: "Seo" });
+
+  return createPageMetadata({
+    locale: siteLocale,
+    title: t(`${page}.title`),
+    description: t(`${page}.description`),
+    path,
+    absoluteTitle,
+  });
+}