import { publicBaseUrl } from '@/lib/config';
import { encodeScreen } from '@/lib/screen/encode';
import { parsePreviewTime } from '@/lib/screen/preview-time';
import { renderScreenSvg } from '@/lib/screen/render';
import { buildCurrentScreen } from '@/lib/screen/service';

export const dynamic = 'force-dynamic';

/**
 * The panel as it stands, or as it will stand at a given moment.
 *
 * Deliberately the same pipeline the device is served from — payload, SVG,
 * threshold — so what the admin sees is what the shop window shows, down to
 * the last thresholded pixel. A preview drawn any other way would eventually
 * disagree with reality, and quietly.
 *
 * `?at=` moves the clock. The whole pipeline is already a function of "now",
 * so showing next Tuesday costs nothing but passing a different instant —
 * which is how a holiday closure can be checked before anyone is standing in
 * front of a locked door.
 *
 * Behind /api/admin, so the middleware requires a session.
 */
export async function GET(request: Request) {
  const { at } = parsePreviewTime(new URL(request.url).searchParams.get('at'), new Date());

  const { payload } = await buildCurrentScreen(at, publicBaseUrl(request));
  const png = encodeScreen(await renderScreenSvg(payload), 'png');

  return new Response(new Uint8Array(png), {
    headers: {
      'Content-Type': 'image/png',
      // It reflects live data; a cached preview is a misleading preview.
      'Cache-Control': 'no-store',
    },
  });
}