import { readFile } from "node:fs/promises";
import { join } from "node:path";
import { NextResponse } from "next/server";
import { getSiteSettings } from "@/lib/db/queries";

export const runtime = "nodejs";
export const dynamic = "force-dynamic";
export const revalidate = 0;

const DEFAULT_CONTENT_TYPE = "image/x-icon";

function noStoreHeaders(contentType: string) {
  return {
    "Content-Type": contentType,
    "Cache-Control": "no-store, no-cache, must-revalidate, proxy-revalidate",
    Pragma: "no-cache",
    Expires: "0",
  };
}

function inferContentType(url: string) {
  const lower = url.toLowerCase();
  if (lower.endsWith(".png")) return "image/png";
  if (lower.endsWith(".svg")) return "image/svg+xml";
  if (lower.endsWith(".jpg") || lower.endsWith(".jpeg")) return "image/jpeg";
  if (lower.endsWith(".webp")) return "image/webp";
  return DEFAULT_CONTENT_TYPE;
}

async function readLocalFallbackFavicon() {
  const file = await readFile(join(process.cwd(), "app", "favicon.ico"));
  return new NextResponse(file, {
    status: 200,
    headers: noStoreHeaders(DEFAULT_CONTENT_TYPE),
  });
}

export async function GET() {
  try {
    const settings = await getSiteSettings();
    const faviconUrl = String(settings?.favicon || "").trim();

    if (!faviconUrl) {
      return await readLocalFallbackFavicon();
    }

    const targetUrl = `${faviconUrl}${faviconUrl.includes("?") ? "&" : "?"}v=${Date.now()}`;
    const upstream = await fetch(targetUrl, { cache: "no-store" });

    if (!upstream.ok) {
      return await readLocalFallbackFavicon();
    }

    const buffer = await upstream.arrayBuffer();
    const contentType =
      upstream.headers.get("content-type") || inferContentType(faviconUrl);

    return new NextResponse(buffer, {
      status: 200,
      headers: noStoreHeaders(contentType),
    });
  } catch (_error) {
    return await readLocalFallbackFavicon();
  }
}