/**
 * Best-effort client-side video duration probe. Resolves null when the browser
 * cannot decode the container's metadata — callers must not block the upload in
 * that case (SH-116: duration is a client-side check only).
 */
export const VIDEO_DURATION_PROBE_TIMEOUT_MS = 10_000;

export function probeVideoDurationSeconds(file: File): Promise<number | null> {
  return new Promise((resolve) => {
    const url = URL.createObjectURL(file);
    const video = document.createElement("video");
    let settled = false;

    const done = (value: number | null) => {
      if (settled) return;
      settled = true;
      video.removeAttribute("src");
      video.load();
      URL.revokeObjectURL(url);
      resolve(value);
    };

    const timeout = window.setTimeout(() => done(null), VIDEO_DURATION_PROBE_TIMEOUT_MS);

    video.preload = "metadata";
    video.onloadedmetadata = () => {
      window.clearTimeout(timeout);
      done(Number.isFinite(video.duration) ? video.duration : null);
    };
    video.onerror = () => {
      window.clearTimeout(timeout);
      done(null);
    };
    video.src = url;
  });
}