import * as z from "zod";

import { getAdminSession } from "@/lib/auth/server";
import { getMediaVisibility, getReadyMedia } from "@/lib/media/repository";
import { getMediaStorage } from "@/lib/media/storage";
import { parseByteRange } from "@/lib/media/validation";

async function serveMedia(
  request: Request,
  context: { params: Promise<{ id: string }> },
  headOnly: boolean,
) {
  const { id } = await context.params;
  if (!z.string().uuid().safeParse(id).success) {
    return new Response("Not found", { status: 404 });
  }
  const record = await getReadyMedia(id);
  if (!record) return new Response("Not found", { status: 404 });
  const visibility = await getMediaVisibility(id);
  if (!visibility.public && !(await getAdminSession())) {
    return new Response("Not found", { status: 404 });
  }

  const file = (await getMediaStorage()).file(record.objectKey);
  let stat: Awaited<ReturnType<typeof file.stat>>;
  try {
    stat = await file.stat();
  } catch {
    return new Response("Not found", { status: 404 });
  }
  const rangeHeader = request.headers.get("range");
  const range = parseByteRange(rangeHeader, stat.size);
  if (rangeHeader && !range) {
    return new Response(null, {
      status: 416,
      headers: { "Content-Range": `bytes */${stat.size}` },
    });
  }
  const headers = new Headers({
    "Accept-Ranges": "bytes",
    "Content-Type": record.mimeType,
    "Content-Disposition": `inline; filename*=UTF-8''${encodeURIComponent(record.fileName)}`,
    "Cache-Control": visibility.public
      ? "public, max-age=60, must-revalidate"
      : "private, no-store",
    ETag: stat.etag,
    "X-Content-Type-Options": "nosniff",
  });
  if (range) {
    const length = range.end - range.start + 1;
    headers.set("Content-Length", String(length));
    headers.set("Content-Range", `bytes ${range.start}-${range.end}/${stat.size}`);
    return new Response(
      headOnly ? null : file.slice(range.start, range.end + 1).stream(),
      { status: 206, headers },
    );
  }
  headers.set("Content-Length", String(stat.size));
  return new Response(headOnly ? null : file.stream(), { status: 200, headers });
}

export async function GET(
  request: Request,
  context: { params: Promise<{ id: string }> },
) {
  return serveMedia(request, context, false);
}

export async function HEAD(
  request: Request,
  context: { params: Promise<{ id: string }> },
) {
  return serveMedia(request, context, true);
}