import { absOf, pickWindow, resolveClip, windowsFor } from "@/lib/report/serve.mjs";
import { ENV_RATE, analyseMedia } from "@/lib/media";

export const dynamic = "force-dynamic";

// The envelope of a cached source window, in ABSOLUTE SOURCE SECONDS.
//
// Everything in the bench is in source seconds -- the manifest's, the cues',
// the QR's. The file's own start is the only relative number, and it is added
// here so nothing downstream has to remember to.
//
// analyseMedia decodes once and caches to MIX_CACHE keyed by mtime and size. A
// raw clip's window is IN ITS NAME, so the file is immutable and that cache can
// never miss twice for the same window.

export async function GET(request: Request) {
  const url = new URL(request.url);
  const r = await resolveClip(url.searchParams.get("project") ?? "", url.searchParams.get("clip") ?? "");
  if ("error" in r) return Response.json({ error: r.error }, { status: r.status });

  const windows = await windowsFor(r.project, r.clip);
  const win = pickWindow(windows, url.searchParams.get("file"));
  if (!win) return Response.json({ error: "no cached window for this clip" }, { status: 404 });
  const abs = absOf(win);
  if (!abs) return Response.json({ error: "outside the roots" }, { status: 400 });

  const buckets = Math.max(64, Math.min(4000, Number(url.searchParams.get("n") ?? 1200)));

  let analysis;
  try {
    analysis = await analyseMedia(abs);
  } catch (e) {
    return Response.json({ error: e instanceof Error ? e.message : String(e) }, { status: 500 });
  }

  const env = analysis.peak;
  const n = env.length;
  const min: number[] = [];
  const max: number[] = [];
  for (let b = 0; b < buckets; b += 1) {
    const i0 = Math.floor((b / buckets) * n);
    const i1 = Math.max(i0 + 1, Math.floor(((b + 1) / buckets) * n));
    let p = 0;
    for (let i = i0; i < i1 && i < n; i += 1) if (env[i] > p) p = env[i];
    max.push(p);
    // analyseMedia's envelope is positive-only. Mirroring it is what makes the
    // canvas draw the symmetric shape a waveform is expected to be, rather than
    // a row of upward spikes.
    min.push(-p);
  }

  return Response.json(
    {
      from: win.from,
      to: win.from + (n / ENV_RATE),
      duration: analysis.duration,
      fetchStart: win.from,
      window: win.name,
      min,
      max,
    },
    { headers: { "cache-control": "private, max-age=3600" } },
  );
}