import { RuntimeError } from '../../error';

/**
 * @description 计数插销工具类
 * @export
 * @class CountLatch
 */
export class CountLatch {
  private promise: Promise<void> | null = null;

  private resolve: ((value: void) => void) | null = null;

  /**
   * @description 计数，当前等待的异步逻辑个数
   * @type {number}
   * @memberof CountLatch
   */
  count: number = 0;

  /**
   * @description 开启promise
   * @private
   * @memberof CountLatch
   */
  private startPromise(): void {
    this.promise = new Promise(resolve => {
      this.resolve = resolve;
    });
  }

  /**
   * @description 结束promise
   * @private
   * @memberof CountLatch
   */
  private endPromise(): void {
    if (this.resolve) {
      this.resolve();
      this.resolve = null;
      this.promise = null;
    }
  }

  /**
   * @description 上锁，计数加一，第一次计数，开启异步
   * @memberof CountLatch
   */
  lock(): void {
    this.count += 1;
    if (!this.promise) {
      this.startPromise();
    }
  }

  /**
   * @description 解锁，计数减一，归零时结束异步
   * @memberof CountLatch
   */
  unlock(): void {
    if (this.count < 1) {
      throw new RuntimeError(ibiz.i18n.t('core.utils.notMatchLockUnlock'));
    }
    this.count -= 1;
    if (this.count === 0) {
      this.endPromise();
    }
  }

  /**
   * @description 等待，计数归零异步结束
   * @returns {*}  {Promise<void>}
   * @memberof CountLatch
   */
  async await(): Promise<void> {
    if (this.promise) {
      await this.promise;
    }
  }
}