import { DateUtil } from '../utils';
import { CacheDriver } from './cache.symbols';

export class InMemoryDriver implements CacheDriver {

  private readonly cache: Record<string, { val: string, ttl?: DateUtil }> = {};

  async get(key: string): Promise<string | null> {

    const property = this.cache[key];

    if (!property || !property.ttl?.isInTheFuture()) {
      return null;
    }

    return property.val;
  }
  set(key: string, val: string): Promise<'OK'> {
    this.cache[key] = { val };
    return Promise.resolve('OK');
  }

  exists(...keys: string[]): Promise<number> {
    return Promise.resolve(
      keys.reduce((acc, k) => {
        if (k in this.cache) {
          return acc + 1;
        }
        return acc;
      }, 0)
    );
  }

  async expire(key: string, seconds: number): Promise<number> {
    const dateUtil = DateUtil.fromDate(new Date()).addNSeconds(seconds);
    const property = this.cache[key];

    if (!property) {
      return 0;
    }

    property.ttl = dateUtil;
    return 1;
  }

  del(key: string): Promise<number> {
    delete this.cache[key];
    return Promise.resolve(1);
  }
}