/*
 * @author gs
 * @date 2020/11/26 13:50
 */

import { RedisClient } from '../common/cache/redis.client';

export abstract class CacheBaseService<T> {
  expirationTime = 3600; // seconds

  abstract async getFromDatabase(dataId?: string): Promise<T>;

  abstract set cacheKey(key: string);

  public async getData(dataId?: string): Promise<T | undefined> {
    let value = await this.getFromCache(this.getCacheKey(dataId));
    if (!value) {
      value = await this.getFromDatabase(dataId);
    }
    if (!value) {
      return undefined;
    }
    this.setToCache(value, dataId).then();
    return value as T;
  }

  public async setToCache(data: T, dataId?: string): Promise<void> {
    await RedisClient.getInstance().setExpire({
      key: this.getCacheKey(dataId),
      value: JSON.stringify(data),
      time: this.expirationTime
    });
  }

  private async getFromCache(cacheKey: string): Promise<T | undefined> {
    const value = await RedisClient.getInstance().get(cacheKey);
    return value ? (JSON.parse(value) as T) : undefined;
  }

  private getCacheKey(dataId?: string): string {
    return dataId ? `${this.cacheKey}${dataId}` : this.cacheKey;
  }
}