import EventEmitter from 'events';
import * as types from '../types';

export default abstract class Subscription {
  /**
   * The date of the last query.
   *
   * @var {String}
   */
  lastQueryTime: String;

  /**
   * Request currently in progress.
   *
   * @var {Boolean}
   */
  requesting: Boolean = false;

  /**
   * @constructor
   * @param {Object} connection
   * @param {EventEmitter} eventEmitter
   */
  constructor(private connection: any, private eventEmitter: EventEmitter) {}

  /**
   * Run the subscription query.
   *
   *
   */
  run() {
    // Don't queue another request if one for this event is already in progress.
    if (this.requesting) return;

    this.requesting = true;

    this.connection.query(this.getQuery(), (err: string, res: any) => {
      if (err) {
        return this.eventEmitter.emit('error', err);
      }

      this.setLastQueryTime();
      this.requesting = false;

      res.records.forEach((record: object) => {
        this.eventEmitter.emit('data.parsed', record, this.getContext());
      });

      if (res.records.length) {
        this.eventEmitter.emit('info', `Sent ${res.records.length} message${res.records.length !== 1 ? 's' : ''} to output`);
      }
    });
  }

  /**
   * Get the subscription context.
   *
   * @returns {types.Context}
   */
  getContext(): types.Context {
    return {
      name: 'salesforce',
      subscription: '',
    };
  }

  /**
   * Get the last query time.
   *
   * @returns {String}
   */
  getLastQueryTime(): String {
    return this.lastQueryTime;
  }

  /**
   * Get the subscription name.
   *
   * @returns {String}
   */
  getName(): String {
    return '';
  }

  /**
   * Get the subscription query.
   *
   * @returns {String}
   */
  getQuery(): String {
    return '';
  }

  /**
   * Set the DateTime for when we last queried the login events.
   */
  setLastQueryTime() {
    this.lastQueryTime = new Date().toISOString();
  }
}