/**
 * Turns a raw ComfyUI node error into something you can act on.
 *
 * Node errors surface verbatim from the engine, which is right for diagnosis
 * and useless for deciding what to do next. These are the ones worth naming.
 */
export function explainJobError(raw: string | null): string | null {
  if (!raw) return null;

  // SheetSage2AudioToABC: Ins: note pitch=83 at 351.06-351.11 cannot be
  // represented on the decoded subbeat grid
  if (/subbeat grid/i.test(raw)) {
    const at = /at\s+(\d+(?:\.\d+)?)/.exec(raw);
    const when = at ? clock(Number(at[1])) : null;
    return when
      ? `The reference could not be transcribed around ${when}. Trim it to exclude that moment, or use a shorter section.`
      : "The reference could not be transcribed. Trim it to a shorter section.";
  }

  if (/out of memory|CUDA out of memory|OutOfMemoryError/i.test(raw)) {
    return "The GPU ran out of memory. Lower the length ceiling, or turn on tiled decode under Sampling and weights.";
  }

  if (/Value not in list/i.test(raw)) {
    return "ComfyUI does not have that model file. Check the checkpoint and transcriber under Sampling and weights.";
  }

  if (/Failed to find C compiler/i.test(raw)) {
    return "The engine image is missing a C compiler, which Triton needs to build kernels. Rebuild the Space.";
  }

  if (/Prompt (outputs )?failed validation/i.test(raw)) {
    return "ComfyUI rejected the graph. The engine and this app are probably out of step; rebuild the Space.";
  }

  return null;
}

function clock(seconds: number): string {
  const safe = Math.max(0, Math.round(seconds));
  return `${Math.floor(safe / 60)}:${String(safe % 60).padStart(2, "0")}`;
}