better-auth/docs/lib/metadata.ts

import type { Metadata } from "next";

export function createMetadata(override: Metadata): Metadata {
	return {
		...override,
		metadataBase: baseUrl,
		openGraph: {
			title: override.title ?? undefined,
			description: override.description ?? undefined,
			url: "https://better-auth.com",
			images: "/og.png",
			siteName: "Better Auth",
			...override.openGraph,
		},
		twitter: {
			card: "summary_large_image",
			title: override.title ?? undefined,
			description: override.description ?? undefined,
			images: "/og.png",
			...override.twitter,
		},
		icons: {
			icon: [
				{ url: "/favicon/favicon.ico", sizes: "any" },
				{
					url: "/favicon/favicon-32x32.png",
					sizes: "32x32",
					type: "image/png",
				},
				{
					url: "/favicon/favicon-16x16.png",
					sizes: "16x16",
					type: "image/png",
				},
			],
			apple: "/favicon/apple-touch-icon.png",
		},
	};
}

export const baseUrl =
	process.env.NODE_ENV === "development" ||
	(!process.env.VERCEL_PROJECT_PRODUCTION_URL && !process.env.VERCEL_URL)
		? new URL("http://localhost:3000")
		: new URL(
				`https://${process.env.VERCEL_PROJECT_PRODUCTION_URL || process.env.VERCEL_URL}`,
			);