/**
 * Compare observed per-file counts with a counted baseline. A file may not
 * exceed its recorded count. A count below the baseline is stale; with
 * `shrink`, the returned baseline lowers it (and drops zero entries) but never
 * raises any count; `lowered` says whether it did, so callers rewrite a
 * baseline only when it changed.
 */
export const compareCountedBaseline = (counts, baseline, shrink) => {
  const grown = [];
  const stale = [];
  for (const [path, count] of counts) {
    const allowed = baseline[path] ?? 0;
    if (count > allowed) grown.push({ path, count, allowed });
  }
  for (const [path, allowed] of Object.entries(baseline)) {
    const count = counts.get(path) ?? 0;
    if (count < allowed) stale.push({ path, count, allowed });
  }
  if (!shrink || stale.length === 0)
    return { grown, stale, baseline, lowered: false };
  const shrunk = { ...baseline };
  for (const { path, count } of stale)
    if (count === 0) delete shrunk[path];
    else shrunk[path] = count;
  return { grown, stale: [], baseline: shrunk, lowered: true };
};

/**
 * Record a comparison's lowered baseline under `key` in the full baseline
 * map. Returns whether the map changed, so the caller rewrites the file only
 * then. A key whose last count was removed is deleted rather than kept empty.
 */
export const recordLoweredBaseline = (baselines, key, compared) => {
  if (!compared.lowered) return false;
  if (Object.keys(compared.baseline).length === 0) delete baselines[key];
  else baselines[key] = compared.baseline;
  return true;
};