copperhead

import { readdir, stat, rm } from 'node:fs/promises';
import { tmpdir } from 'node:os';
import path from 'node:path';

/** Newest local-history entries to keep when capping `.history/` (see
 *  pruneHistoryDir). Enough to preserve a useful recovery window, bounded enough
 *  that the dir cannot grow without limit across a long run. */
export const DEFAULT_HISTORY_KEEP = 200;

/**
 * Cap the growth of a repo's `.history/` directory (4.1). KiCad (and editor
 * local-history) rewrite a snapshot on every project touch, so across a long
 * run `.history/` grows without bound and was a contributor to the disk-fill
 * halt (I8). It is gitignored, so its contents are disposable: keep the newest
 * `keepNewest` files by mtime and remove the rest. Recursive (local history
 * mirrors the workspace tree), best-effort (every error is swallowed — pruning
 * housekeeping must never fail a run), and a no-op when the dir is absent or
 * already under the cap. Returns the number of files removed.
 */
export async function pruneHistoryDir(repoRoot: string, keepNewest = DEFAULT_HISTORY_KEEP): Promise<number> {
  const root = path.join(repoRoot, '.history');
  const files: Array<{ full: string; mtimeMs: number }> = [];
  const walk = async (dir: string): Promise<void> => {
    let entries: Array<{ name: string; isDirectory(): boolean; isFile(): boolean }>;
    try {
      entries = await readdir(dir, { withFileTypes: true });
    } catch {
      return; // unreadable dir — skip it
    }
    for (const e of entries) {
      const full = path.join(dir, e.name);
      if (e.isDirectory()) {
        await walk(full);
      } else if (e.isFile()) {
        try {
          const st = await stat(full);
          files.push({ full, mtimeMs: st.mtimeMs });
        } catch {
          // stat race — skip this file
        }
      }
    }
  };
  await walk(root);
  if (files.length <= keepNewest) return 0;
  files.sort((a, b) => b.mtimeMs - a.mtimeMs); // newest first
  let removed = 0;
  for (const f of files.slice(keepNewest)) {
    try {
      await rm(f.full, { force: true });
      removed++;
    } catch {
      // permission/race — leave it, keep pruning the rest
    }
  }
  return removed;
}

/**
 * Every scratch dir copperhead makes under the OS temp dir shares this prefix:
 * kicad-cli ERC/DRC (`copperhead-`), the KiCad edit probe (`copperhead-validate-`),
 * the failed-run backup (`copperhead-runs-`), and the provider working dirs
 * (`copperhead-cc-`, `copperhead-codex-`). Each site removes its own dir in a
 * `finally`, but a watchdog SIGKILL of the process tree or a hard abort skips
 * that cleanup, so stale dirs accumulate across runs and can eventually fill the
 * disk (I8). A prefix match lets one sweep reclaim all of them.
 */
export const TEMP_PREFIX = 'copperhead-';

/** Default staleness cutoff for the startup sweep: 2h. Safe even for multi-hour
 * runs (10-min turns × per-stage retries × 8 stages): a live run's only
 * long-lived scratch dir is the provider's reused cwd, which is `utimes`-touched
 * every turn (ClaudeCodeProvider.ensureCwd), so its mtime never goes stale while
 * the process is alive; per-call kicad-cli dirs are removed within a turn. A dir
 * older than this therefore belongs to a dead run, and the window is short enough
 * that such a leak is reclaimed on the very next invocation. */
export const DEFAULT_STALE_MS = 2 * 60 * 60 * 1000;

/**
 * Remove leaked `copperhead-*` scratch dirs left in the OS temp dir by earlier
 * runs whose `finally` cleanup was skipped (watchdog kill / hard abort). Only
 * dirs whose mtime is older than `maxAgeMs` are removed, so a concurrent run's
 * fresh scratch dirs are never touched. Best-effort: every error is swallowed
 * (a temp dir we can't stat or remove is not worth failing a run over), and the
 * function returns the paths it removed so a caller can log the reclaim.
 *
 * `now` is injected so the behaviour is deterministically testable; callers pass
 * `Date.now()`.
 */
export async function sweepStaleTempDirs(now: number, maxAgeMs = DEFAULT_STALE_MS): Promise<string[]> {
  const root = tmpdir();
  const removed: string[] = [];
  let entries: string[];
  try {
    entries = await readdir(root);
  } catch {
    return removed; // no temp dir / not readable — nothing to sweep
  }
  for (const name of entries) {
    if (!name.startsWith(TEMP_PREFIX)) continue;
    const full = path.join(root, name);
    try {
      const st = await stat(full);
      if (!st.isDirectory()) continue;
      if (now - st.mtimeMs < maxAgeMs) continue; // too fresh: could be a live run
      await rm(full, { recursive: true, force: true });
      removed.push(full);
    } catch {
      // stat/rm race or permission issue — skip this entry, keep sweeping.
    }
  }
  return removed;
}