// Copyright 2016 The Chromium Authors. All rights reserved.
// Use of this source code is governed by a BSD-style license that can be
// found in the LICENSE file.

// Queue storing asynchronous results received from the Service Worker. Results
// are sent to the test when requested.
function ResultQueue() {
  // Invariant: this.queue.length == 0 || this.pendingGets == 0
  this.queue = [];
  this.pendingGets = 0;
}

// Adds a data item to the queue. Will be sent to the test if there are
// pendingGets.
ResultQueue.prototype.push = function(data) {
  if (this.pendingGets > 0) {
    this.pendingGets--;
    sendResultToTest(data);
  } else {
    this.queue.unshift(data);
  }
};

// Called by native. Sends the next data item to the test if it is available.
// Otherwise increments pendingGets so it will be delivered when received.
ResultQueue.prototype.pop = function() {
  if (this.queue.length) {
    sendResultToTest(this.queue.pop());
  } else {
    this.pendingGets++;
  }
};

// Called by native. Immediately sends the next data item to the test if it is
// available, otherwise sends null.
ResultQueue.prototype.popImmediately = function() {
  sendResultToTest(this.queue.length ? this.queue.pop() : null);
};

// Sends data back to the test. This must be in response to an earlier
// request, but it's ok to respond asynchronously. The request blocks until
// the response is sent.
function sendResultToTest(result) {
  console.log('sendResultToTest: ' + result);
  if (window.domAutomationController) {
    domAutomationController.send('' + result);
  }
}

function sendErrorToTest(error) {
  sendResultToTest(error.name + ' - ' + error.message);
}