import { NextResponse } from "next/server";
import { auth } from "@/auth";
import { getInventoryScan } from "@/lib/inventory-scans";

// Streams the scan's photo on demand straight from Telegram's file storage
// — see prisma/schema.prisma's InventoryScan.photoFileId comment for why
// this app doesn't keep its own copy on disk. Telegram's getFile file_path
// is short-lived, so this re-resolves it on every request rather than
// caching a URL.
export async function GET(
  request: Request,
  { params }: { params: { id: string } }
): Promise<NextResponse> {
  const session = await auth();
  if (!session) {
    return NextResponse.json({ error: "Unauthorized" }, { status: 401 });
  }

  const scan = await getInventoryScan(params.id);
  if (!scan || !scan.photo_file_id) {
    return NextResponse.json({ error: "No photo for this scan" }, { status: 404 });
  }

  const botToken = process.env.BOT_TOKEN;
  if (!botToken) {
    return NextResponse.json({ error: "BOT_TOKEN not configured" }, { status: 500 });
  }

  const fileResp = await fetch(
    `https://api.telegram.org/bot${botToken}/getFile?file_id=${encodeURIComponent(scan.photo_file_id)}`
  );
  const fileJson = await fileResp.json();
  if (!fileJson.ok) {
    return NextResponse.json({ error: "Telegram getFile failed" }, { status: 502 });
  }

  const filePath = fileJson.result.file_path as string;
  const imageResp = await fetch(`https://api.telegram.org/file/bot${botToken}/${filePath}`);
  if (!imageResp.ok || !imageResp.body) {
    return NextResponse.json({ error: "Failed to fetch photo from Telegram" }, { status: 502 });
  }

  // Telegram serves file content as generic application/octet-stream
  // regardless of the actual file type, which makes browsers download
  // instead of display it inline — derive the real content type from the
  // file_path extension instead of trusting imageResp's header.
  const extension = filePath.split(".").pop()?.toLowerCase();
  const contentType =
    extension === "png"
      ? "image/png"
      : extension === "webp"
        ? "image/webp"
        : "image/jpeg";

  return new NextResponse(imageResp.body, {
    status: 200,
    headers: {
      "Content-Type": contentType,
      "Content-Disposition": "inline",
      "Cache-Control": "private, max-age=3600",
    },
  });
}