/**
 * OmniCard AI (CRMmp) - 移动端名片离线多媒体缓存与本地持久化策略
 * 严格遵循 AGENTS.md 规范与 uts 跨端强类型语法
 */

export interface MediaCacheEntry {
  url: string;
  localPath: string;
  cachedAt: number;
  expireAt: number;
  sizeBytes?: number;
}

export interface CachedMediaResult {
  localPath: string;
  isExpired: boolean;
}

export interface MediaCacheStats {
  totalEntries: number;
  oldestEntryAt?: number;
}

const STORAGE_CACHE_KEY = 'omni_media_cache_index';

/**
 * 获取底层全部缓存索引映射
 */
function getIndexMap(): Record<string, MediaCacheEntry> {
  try {
    const raw = uni.getStorageSync(STORAGE_CACHE_KEY);
    if (!raw) return {};
    return JSON.parse(String(raw)) || {};
  } catch (e) {
    return {};
  }
}

/**
 * 保存索引映射
 */
function saveIndexMap(map: Record<string, MediaCacheEntry>): void {
  try {
    uni.setStorageSync(STORAGE_CACHE_KEY, JSON.stringify(map));
  } catch (e) {}
}

/**
 * 获取指定多媒体 URL 的本地缓存
 */
export function getCachedMedia(url?: string): CachedMediaResult | null {
  if (!url || typeof url !== 'string') return null;

  const map = getIndexMap();
  const entry = map[url];
  if (!entry) return null;

  const now = Date.now();
  const isExpired = now > entry.expireAt;

  return {
    localPath: entry.localPath,
    isExpired,
  };
}

/**
 * 存入多媒体缓存索引
 */
export function saveMediaToCache(
  url: string,
  localPath: string,
  expireHours: number = 72
): void {
  if (!url || !localPath) return;

  const map = getIndexMap();
  const now = Date.now();
  const expireAt = now + expireHours * 3600 * 1000;

  map[url] = {
    url,
    localPath,
    cachedAt: now,
    expireAt,
  };

  saveIndexMap(map);
}

/**
 * 定期/按需淘汰清理过期缓存条目
 */
export function pruneExpiredMediaCache(): number {
  const map = getIndexMap();
  const now = Date.now();
  let prunedCount = 0;

  const newMap: Record<string, MediaCacheEntry> = {};
  for (const [key, entry] of Object.entries(map)) {
    if (now > entry.expireAt) {
      prunedCount++;
    } else {
      newMap[key] = entry;
    }
  }

  saveIndexMap(newMap);
  return prunedCount;
}

/**
 * 获取多媒体缓存状态统计
 */
export function getMediaCacheStats(): MediaCacheStats {
  const map = getIndexMap();
  const entries = Object.values(map);

  let oldest: number | undefined = undefined;
  for (const e of entries) {
    if (oldest === undefined || e.cachedAt < oldest) {
      oldest = e.cachedAt;
    }
  }

  return {
    totalEntries: entries.length,
    oldestEntryAt: oldest,
  };
}

/**
 * 清空全部多媒体缓存
 */
export function clearAllMediaCache(): void {
  try {
    uni.removeStorageSync(STORAGE_CACHE_KEY);
  } catch (e) {}
}