FIDO U2F component extension

chrome/browser/resources/cryptotoken/countdown.js

+// Copyright (c) 2014 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.
+
+/**
+ * @fileoverview Provides a countdown-based timer.
+ * @author juanlang@google.com (Juan Lang)
+ */
+'use strict';
+
+/**
+ * A countdown timer.
+ * @interface
+ */
+function Countdown() {}
+
+/**
+ * Sets a new timeout for this timer.
+ * @param {number} timeoutMillis how long, in milliseconds, the countdown lasts.
+ * @param {Function=} cb called back when the countdown expires.
+ * @return {boolean} whether the timeout could be set.
+ */
+Countdown.prototype.setTimeout = function(timeoutMillis, cb) {};
+
+/** Clears this timer's timeout. */
+Countdown.prototype.clearTimeout = function() {};
+
+/**
+ * @return {number} how many milliseconds are remaining until the timer expires.
+ */
+Countdown.prototype.millisecondsUntilExpired = function() {};
+
+/** @return {boolean} whether the timer has expired. */
+Countdown.prototype.expired = function() {};
+
+/**
+ * Constructs a new clone of this timer, while overriding its callback.
+ * @param {Function=} cb callback for new timer.
+ * @return {!Countdown} new clone.
+ */
+Countdown.prototype.clone = function(cb) {};
+
+/**
+ * Constructs a new timer.  The timer has a very limited resolution, and does
+ * not attempt to be millisecond accurate. Its intended use is as a
+ * low-precision timer that pauses while debugging.
+ * @param {number=} timeoutMillis how long, in milliseconds, the countdown
+ *     lasts.
+ * @param {Function=} cb called back when the countdown expires.
+ * @constructor
+ * @implements {Countdown}
+ */
+function CountdownTimer(timeoutMillis, cb) {
+  this.remainingMillis = 0;
+  this.setTimeout(timeoutMillis || 0, cb);
+}
+
+CountdownTimer.TIMER_INTERVAL_MILLIS = 200;
+
+/**
+ * Sets a new timeout for this timer. Only possible if the timer is not
+ * currently active.
+ * @param {number} timeoutMillis how long, in milliseconds, the countdown lasts.
+ * @param {Function=} cb called back when the countdown expires.
+ * @return {boolean} whether the timeout could be set.
+ */
+CountdownTimer.prototype.setTimeout = function(timeoutMillis, cb) {
+  if (this.timeoutId)
+    return false;
+  if (!timeoutMillis || timeoutMillis < 0)
+    return false;
+  this.remainingMillis = timeoutMillis;
+  this.cb = cb;
+  if (this.remainingMillis > CountdownTimer.TIMER_INTERVAL_MILLIS) {
+    this.timeoutId =
+        window.setInterval(this.timerTick.bind(this),
+            CountdownTimer.TIMER_INTERVAL_MILLIS);
+  } else {
+    // Set a one-shot timer for the last interval.
+    this.timeoutId =
+        window.setTimeout(this.timerTick.bind(this), this.remainingMillis);
+  }
+  return true;
+};
+
+/** Clears this timer's timeout. */
+CountdownTimer.prototype.clearTimeout = function() {
+  if (this.timeoutId) {
+    window.clearTimeout(this.timeoutId);
+    this.timeoutId = undefined;
+  }
+};
+
+/**
+ * @return {number} how many milliseconds are remaining until the timer expires.
+ */
+CountdownTimer.prototype.millisecondsUntilExpired = function() {
+  return this.remainingMillis > 0 ? this.remainingMillis : 0;
+};
+
+/** @return {boolean} whether the timer has expired. */
+CountdownTimer.prototype.expired = function() {
+  return this.remainingMillis <= 0;
+};
+
+/**
+ * Constructs a new clone of this timer, while overriding its callback.
+ * @param {Function=} cb callback for new timer.
+ * @return {!Countdown} new clone.
+ */
+CountdownTimer.prototype.clone = function(cb) {
+  return new CountdownTimer(this.remainingMillis, cb);
+};
+
+/** Timer callback. */
+CountdownTimer.prototype.timerTick = function() {
+  this.remainingMillis -= CountdownTimer.TIMER_INTERVAL_MILLIS;
+  if (this.expired()) {
+    window.clearTimeout(this.timeoutId);
+    this.timeoutId = undefined;
+    if (this.cb) {
+      this.cb();
+    }
+  }
+};