import { rmSync, statSync } from "node:fs";
import { listRunDirs, tryReadRunState } from "./artifacts";

const DAY_MS = 24 * 60 * 60 * 1000;
const COMPLETED_RUN_TTL_MS = 7 * DAY_MS;
const INTERRUPTED_RUN_TTL_MS = 30 * DAY_MS;

export interface CleanupResult {
  scanned: number;
  removed: number;
  errors: number;
}

/**
 * Sweep state/subagents/ and remove run directories past their TTL.
 *
 * - `phase === "done"` runs expire after COMPLETED_RUN_TTL_MS.
 * - All other phases expire after INTERRUPTED_RUN_TTL_MS.
 * - Malformed run.json or unreadable directories are skipped (not removed).
 * - Errors during rm are counted, not thrown — TTL sweep must never block startup.
 *
 * `now` is injectable for tests.
 */
export async function cleanupOldRuns(now = Date.now()): Promise<CleanupResult> {
  const result: CleanupResult = { scanned: 0, removed: 0, errors: 0 };
  let dirs: string[];
  try {
    dirs = listRunDirs();
  } catch {
    return result;
  }

  for (const dir of dirs) {
    result.scanned += 1;
    const persisted = tryReadRunState(dir);
    if (!persisted) continue;

    let mtime: number;
    try {
      mtime = statSync(dir).mtimeMs;
    } catch {
      continue;
    }

    const ttl = persisted.phase === "done" ? COMPLETED_RUN_TTL_MS : INTERRUPTED_RUN_TTL_MS;
    if (now - mtime < ttl) continue;

    try {
      rmSync(dir, { recursive: true, force: true });
      result.removed += 1;
    } catch {
      result.errors += 1;
    }
  }

  return result;
}

// Exposed for tests; module constants stay private otherwise.
export const __testables = {
  COMPLETED_RUN_TTL_MS,
  INTERRUPTED_RUN_TTL_MS,
  DAY_MS,
};