import { convertExpire } from '../util';

/**
 * 内存缓存数据 key 值
 */
export type MemoryCacheKey = string | number | symbol;

/**
 * 内存缓存数据的类型
 */
export type MemoryCacheCachedData = {
  /**
   * 缓存内容
   */
  value: any;
  /**
   * 缓存过期时间
   */
  expires: number;
  /**
   * 创建时间
   */
  createTime: number;
};

export type MemoryCache = {
  get(key: MemoryCacheKey, defaultValue?: any): any;
  set(key: MemoryCacheKey, value: any, expires?: number | string): Map<MemoryCacheKey, MemoryCacheCachedData>;
  remove(key: MemoryCacheKey): boolean;
  clear(): void;
};

/**
 * Creates a MemoryCache instance that can be used by a WechatMiniprogram app.
 * 内存缓存工具
 */
export function createMemoryCache(): MemoryCache {
  const memoryCache = new Map<MemoryCacheKey, MemoryCacheCachedData>();

  function get(key: MemoryCacheKey, defaultValue?: any) {
    const data = memoryCache.get(key);

    if (data) {
      const { expires, value } = data;

      if (expires === -1 || expires > Date.now()) return value;

      // delete expired data
      remove(key);
    }

    return defaultValue;
  }

  function set(key: MemoryCacheKey, value: any, expires?: number | string) {
    const timestamp = Date.now();
    const expiresAt = convertExpire(expires || -1) + timestamp;

    const data = {
      value,
      expires: expiresAt,
      createTime: Date.now(),
    };

    return memoryCache.set(key, data);
  }

  function remove(key: MemoryCacheKey) {
    return memoryCache.delete(key);
  }

  function clear() {
    return memoryCache.clear();
  }

  return {
    get,
    set,
    remove,
    clear,
  };
}