import "server-only";
import { getDefaultStorageConfig } from "@/lib/db/queries";
import { findImageArchiveDownloadTask } from "./image-archive-db";
import { inferOriginalImageUrl } from "@/lib/image-url";
import { getImageDownloadExtension } from "@/lib/image-delivery";
import { sanitizeCanvasDownloadFileName } from "@/lib/canvas/photoshop-safe-download";

/** Resolve the archived original without waiting for a separate PNG conversion. */
export async function resolveOriginalCdnDownload(source: string, name: string, signal: AbortSignal) {
  const config = await getDefaultStorageConfig();
  if (config?.type !== "qiniu-kodo" || !config.isEnabled || !config.publicUrl) return null;
  const base = new URL(config.publicUrl);
  const origin = process.env.CANVAS_QINIU_ORIGIN_URL;
  let target = new URL(source);
  if (target.origin !== base.origin && (!origin || target.origin !== new URL(origin).origin)) {
    const task = await findImageArchiveDownloadTask([...new Set([source, inferOriginalImageUrl(source)])]);
    target = new URL(task?.targetUrl || source);
  }
  if (origin && target.origin === new URL(origin).origin && !target.searchParams.has("token")) {
    target.host = base.host;
    target.protocol = base.protocol;
  }
  if (base.protocol !== "https:" || target.origin !== base.origin ||
      !target.pathname.startsWith(base.pathname.replace(/\/$/, "") + "/")) return null;
  // A Kodo download token signs the complete URL; adding attname would invalidate it.
  if (target.searchParams.has("token")) return null;

  // Only metadata crosses the application server. The browser receives the file
  // from the CDN, including when cross-origin fetch is disabled by storage CORS.
  const response = await fetch(target, {
    method: "HEAD", cache: "no-store",
    signal: AbortSignal.any([signal, AbortSignal.timeout(10_000)]),
  });
  if (!response.ok) throw new Error(`HTTP ${response.status}`);
  const contentType = response.headers.get("content-type") || "";
  if (!contentType.toLowerCase().startsWith("image/")) throw new Error("Source is not an image");
  const extension = getImageDownloadExtension(contentType);
  if (!extension) return null;
  const basename = sanitizeCanvasDownloadFileName(name || target.pathname.split("/").pop() || "image", "image")
    .replace(/\.(?:png|jpe?g|webp|avif|gif|svg|bmp|tiff?)$/i, "");
  const filename = `${basename}.${extension}`;
  target.searchParams.set("attname", filename);
  return { delivery: "cdn" as const, downloadUrl: target.toString(), filename,
    bytes: Number(response.headers.get("content-length")) || 0 };
}