/**
 * Per-client `localStorage` cache for the in-flight content-generation job id
 * and the last terminal status snapshot.
 *
 * Used by the Content Generator page so the progress UI survives page reloads
 * and cross-page navigation. The cached id is treated as authoritative only
 * after `getActiveContentGenJob` confirms Redis still holds the lock; the
 * cached snapshot is the fallback when the lock is gone (terminal cleanup
 * already wiped Redis) so the UI can still show the "Job Complete" card
 * after a refresh. See `src/pages/ContentGenerator.tsx`.
 */

import type { ContentGeneratorStatusResponse } from './content-generator.interface';

const KEY_PREFIX = 'recomaze:content-gen:job-id';
const SNAPSHOT_PREFIX = 'recomaze:content-gen:snapshot';

// 7 days. Beyond that, surfacing the previous completion on refresh is more
// confusing than helpful (the user has likely moved on).
const SNAPSHOT_TTL_MS = 7 * 24 * 60 * 60 * 1000;

const buildKey = (clientId: string): string => `${KEY_PREFIX}:${clientId}`;
const buildSnapshotKey = (clientId: string): string =>
  `${SNAPSHOT_PREFIX}:${clientId}`;

export const loadCachedJobId = (clientId: string): string | null => {
  if (typeof window === 'undefined' || !clientId) return null;
  try {
    return window.localStorage.getItem(buildKey(clientId));
  } catch {
    return null;
  }
};

export const saveCachedJobId = (clientId: string, jobId: string): void => {
  if (typeof window === 'undefined' || !clientId) return;
  try {
    window.localStorage.setItem(buildKey(clientId), jobId);
  } catch {
    /* quota / private mode - non-fatal */
  }
};

export const clearCachedJobId = (clientId: string): void => {
  if (typeof window === 'undefined' || !clientId) return;
  try {
    window.localStorage.removeItem(buildKey(clientId));
  } catch {
    /* non-fatal */
  }
};

interface CachedSnapshotPayload {
  status: ContentGeneratorStatusResponse;
  savedAt: number;
}

export const saveCachedJobSnapshot = (
  clientId: string,
  status: ContentGeneratorStatusResponse
): void => {
  if (typeof window === 'undefined' || !clientId) return;
  try {
    const payload: CachedSnapshotPayload = { status, savedAt: Date.now() };
    window.localStorage.setItem(
      buildSnapshotKey(clientId),
      JSON.stringify(payload)
    );
  } catch {
    /* non-fatal */
  }
};

export const loadCachedJobSnapshot = (
  clientId: string
): ContentGeneratorStatusResponse | null => {
  if (typeof window === 'undefined' || !clientId) return null;
  try {
    const raw = window.localStorage.getItem(buildSnapshotKey(clientId));
    if (!raw) return null;
    const payload = JSON.parse(raw) as CachedSnapshotPayload | null;
    if (!payload?.status) return null;
    if (Date.now() - payload.savedAt > SNAPSHOT_TTL_MS) {
      window.localStorage.removeItem(buildSnapshotKey(clientId));
      return null;
    }
    return payload.status;
  } catch {
    return null;
  }
};

export const clearCachedJobSnapshot = (clientId: string): void => {
  if (typeof window === 'undefined' || !clientId) return;
  try {
    window.localStorage.removeItem(buildSnapshotKey(clientId));
  } catch {
    /* non-fatal */
  }
};