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import ScriptReceiver from './script_receiver';

/** Builds receivers for JSONP and Script requests.
 *
 * Each receiver is an object with following fields:
 * - number - unique (for the factory instance), numerical id of the receiver
 * - id - a string ID that can be used in DOM attributes
 * - name - name of the function triggering the receiver
 * - callback - callback function
 *
 * Receivers are triggered only once, on the first callback call.
 *
 * Receivers can be called by their name or by accessing factory object
 * by the number key.
 *
 * @param {String} prefix the prefix used in ids
 * @param {String} name the name of the object
 */
export class ScriptReceiverFactory {
  lastId: number;
  prefix: string;
  name: string;

  constructor(prefix: string, name: string) {
    this.lastId = 0;
    this.prefix = prefix;
    this.name = name;
  }

  create(callback: Function): ScriptReceiver {
    this.lastId++;

    var number = this.lastId;
    var id = this.prefix + number;
    var name = this.name + '[' + number + ']';

    var called = false;
    var callbackWrapper = function() {
      if (!called) {
        callback.apply(null, arguments);
        called = true;
      }
    };

    this[number] = callbackWrapper;
    return { number: number, id: id, name: name, callback: callbackWrapper };
  }

  remove(receiver: ScriptReceiver) {
    delete this[receiver.number];
  }
}

export var ScriptReceivers = new ScriptReceiverFactory(
  '_pusher_script_',
  'Pusher.ScriptReceivers'
);