import fs from "node:fs";
import { normalizeStoredCronJobs } from "../store-migration.js";
import { loadCronStore, saveCronStore } from "../store.js";
import type { CronJob } from "../types.js";
import { recomputeNextRuns } from "./jobs.js";
import type { CronServiceState } from "./state.js";

async function getFileMtimeMs(path: string): Promise<number | null> {
  try {
    const stats = await fs.promises.stat(path);
    return stats.mtimeMs;
  } catch {
    return null;
  }
}

export async function ensureLoaded(
  state: CronServiceState,
  opts?: {
    forceReload?: boolean;
    /** Skip recomputing nextRunAtMs after load so the caller can run due
     *  jobs against the persisted values first (see onTimer). */
    skipRecompute?: boolean;
  },
) {
  // Fast path: store is already in memory. Other callers (add, list, run, …)
  // trust the in-memory copy to avoid a stat syscall on every operation.
  if (state.store && !opts?.forceReload) {
    return;
  }
  // Force reload always re-reads the file to avoid missing cross-service
  // edits on filesystems with coarse mtime resolution.

  const fileMtimeMs = await getFileMtimeMs(state.deps.storePath);
  const loaded = await loadCronStore(state.deps.storePath);
  const jobs = (loaded.jobs ?? []) as unknown as Array<Record<string, unknown>>;
  const { mutated } = normalizeStoredCronJobs(jobs);
  state.store = { version: 1, jobs: jobs as unknown as CronJob[] };
  state.storeLoadedAtMs = state.deps.nowMs();
  state.storeFileMtimeMs = fileMtimeMs;

  if (!opts?.skipRecompute) {
    recomputeNextRuns(state);
  }

  if (mutated) {
    await persist(state, { skipBackup: true });
  }
}

export function warnIfDisabled(state: CronServiceState, action: string) {
  if (state.deps.cronEnabled) {
    return;
  }
  if (state.warnedDisabled) {
    return;
  }
  state.warnedDisabled = true;
  state.deps.log.warn(
    { enabled: false, action, storePath: state.deps.storePath },
    "cron: scheduler disabled; jobs will not run automatically",
  );
}

export async function persist(state: CronServiceState, opts?: { skipBackup?: boolean }) {
  if (!state.store) {
    return;
  }
  await saveCronStore(state.deps.storePath, state.store, opts);
  // Update file mtime after save to prevent immediate reload
  state.storeFileMtimeMs = await getFileMtimeMs(state.deps.storePath);
}