// The encode profiles, in ONE place.
//
// These came off `share-report-clips/reencode.py` in ~/reports/elfpire-eva,
// which is where the first share batch was actually encoded and therefore the
// only honest source for "what the last batch looked like". Ported rather than
// spawned: a python file living beside one project's deliverables is not a
// profile the next project can reach, and two copies of an x264 command line
// is exactly the drift that makes batch 2 not match batch 1.
//
// `std` and `small` are that script's two profiles, argument for argument.
// `accurate` is neither: it is the re-encode a CUT falls back to when the cut
// cannot be stream-copied, and it deliberately keeps the source's geometry --
// an `orig/` file is "the window as fetched", and rescaling it here would make
// the folder's own description untrue.
import { execFile } from "node:child_process";
import { promisify } from "node:util";
import { FFPROBE_BIN } from "umtool-report-to-video/build-video";

const execFileP = promisify(execFile);

/** Scale-and-pad to an exact frame, the shape both share profiles use. */
const box = (w, h) =>
  `scale=w=${w}:h=${h}:force_original_aspect_ratio=decrease,` +
  `pad=${w}:${h}:(ow-iw)/2:(oh-ih)/2,format=yuv420p`;

export const SHARE_PROFILES = {
  // Exactly 1280x720, faststart, a level every phone and every forum player
  // will take. This is the one people download.
  std: {
    label: "1280x720 · crf 23",
    args: [
      "-vf", box(1280, 720),
      "-c:v", "libx264", "-profile:v", "high", "-level", "4.0",
      "-preset", "medium", "-crf", "23", "-r", "30", "-g", "60",
      "-c:a", "aac", "-b:a", "128k", "-ar", "44100", "-ac", "2",
      "-movflags", "+faststart",
    ],
  },
  // 640x360 under a 300k ceiling: the copy that survives an upload limit.
  small: {
    label: "640x360 · crf 28 · 300k cap",
    args: [
      "-vf", box(640, 360),
      "-c:v", "libx264", "-profile:v", "main", "-level", "3.1",
      "-preset", "medium", "-crf", "28", "-maxrate", "300k", "-bufsize", "600k",
      "-r", "30", "-g", "60",
      "-c:a", "aac", "-b:a", "64k", "-ar", "44100", "-ac", "2",
      "-movflags", "+faststart",
    ],
  },
};

/** The encode names a batch produces, beside the untouched `orig`. */
export const SHARE_VARIANTS = ["orig", ...Object.keys(SHARE_PROFILES)];

/**
 * The re-encode a cut falls back to when the window's keyframes are in the
 * wrong places. No scaling and no frame-rate change: the point of this file is
 * that its first and last frames are the seconds that were asked for.
 */
export const ACCURATE_CUT_ARGS = [
  "-c:v", "libx264", "-preset", "veryfast", "-crf", "20", "-pix_fmt", "yuv420p",
  "-c:a", "aac", "-b:a", "160k",
  "-movflags", "+faststart",
];

/**
 * A file's duration in seconds, from the container.
 *
 * build-video's probeDuration() counts VIDEO FRAMES, because a rendered
 * segment's length has to agree with the timeline it is concatenated into.
 * Nothing here is concatenated: the question is "did this cut come out the
 * length it was asked for", and the container's own answer is the one a
 * downloader will see.
 */
export async function probeSeconds(file) {
  const { stdout } = await execFileP(FFPROBE_BIN, [
    "-v", "error", "-show_entries", "format=duration",
    "-of", "default=nw=1:nk=1", file,
  ]);
  const n = Number(String(stdout).trim());
  return Number.isFinite(n) ? n : null;
}