/* Example

  const q = new Queue();

  q.enQueue(async () => {
    [CODE HERE]
  });
*/

export default class Queue {
  constructor() {
    this.tasksQueue = [];
    this.deQueuedTask = null;
    this.currentTaskStatus = "INIT"; /* INIT, ADDING, WORKING, DONE */
  }

  EN_QUEUE = task => {
    this.tasksQueue.unshift(task);
  };

  DE_QUEUE = () => {
    this.deQueuedTask = this.tasksQueue.pop();
  };

  UPDATE_CURRENT_TASK_STATUS = status => {
    this.currentTaskStatus = status;
  };

  enQueue = async task => {
    this.EN_QUEUE(task);

    if (this.currentTaskStatus === "INIT") {
      this.UPDATE_CURRENT_TASK_STATUS("WORKING");

      while (this.tasksQueue.length) {
        this.DE_QUEUE();
        await this.runTask(this.deQueuedTask);

        if (!this.tasksQueue.length) {
          this.UPDATE_CURRENT_TASK_STATUS("INIT");
          break;
        }
      }
    }
  };

  runTask = async deQueuedTask => {
    try {
      await deQueuedTask();
    } catch (error) {
      console.log(error);
    }
  };
}