/**
 * @constructor
 * @param {function(string, string)} activeCallback
 * @param {function(string, string)} inactiveCallback
 * @param {webfont.DomHelper} domHelper
 * @param {Object.<string, function(Object): number>} fontSizer
 * @param {function(function(), number=)} asyncCall
 * @param {function(): number} getTime
 * @param {string} fontFamily
 * @param {string} fontDescription
 * @param {string=} opt_fontTestString
 * @extends webfont.FontWatchRunner
 */
webfont.LastResortWebKitFontWatchRunner = function(activeCallback,
    inactiveCallback, domHelper, fontSizer, asyncCall, getTime, fontFamily,
    fontDescription, opt_fontTestString) {
  webfont.LastResortWebKitFontWatchRunner.superCtor_.call(this,
      activeCallback, inactiveCallback, domHelper, fontSizer, asyncCall,
      getTime, fontFamily, fontDescription, opt_fontTestString);
  this.webKitLastResortFontSizes_ = this.setUpWebKitLastResortFontSizes_();
  this.webKitLastResortSizeChange_ = false;
};
webfont.extendsClass(webfont.FontWatchRunner, webfont.LastResortWebKitFontWatchRunner);

webfont.LastResortWebKitFontWatchRunner.METRICS_COMPATIBLE_FONTS = {
    "Arimo": true,
    "Cousine": true,
    "Tinos": true
};

/**
 * While loading a web font webkit applies a last resort fallback font to the
 * element on which the web font is applied.
 * See file: WebKit/Source/WebCore/css/CSSFontFaceSource.cpp.
 * Looking at the different implementation for the different platforms,
 * the last resort fallback font is different. This code uses the default
 * OS/browsers values.
 */
webfont.LastResortWebKitFontWatchRunner.prototype
    .setUpWebKitLastResortFontSizes_ = function() {
  var lastResortFonts = ['Times New Roman', 'Arial', 'Times', 'Sans', 'Serif'];
  var lastResortFontSizes = lastResortFonts.length;
  var webKitLastResortFontSizes = {};
  var element = this.createHiddenElementWithFont_(lastResortFonts[0], true);

  webKitLastResortFontSizes[this.fontSizer_.getWidth(element)] = true;
  for (var i = 1; i < lastResortFontSizes; i++) {
    var font = lastResortFonts[i];
    this.domHelper_.setStyle(element, this.computeStyleString_(font,
        this.fontDescription_, true));
    webKitLastResortFontSizes[this.fontSizer_.getWidth(element)] = true;

    // Another WebKit quirk if the normal weight/style is loaded first,
    // the size of the normal weight is returned when loading another weight.
    if (this.fontDescription_[1] != '4') {
      this.domHelper_.setStyle(element, this.computeStyleString_(font,
        this.fontDescription_[0] + '4', true));
      webKitLastResortFontSizes[this.fontSizer_.getWidth(element)] = true;
    }
  }
  this.domHelper_.removeElement(element);
  return webKitLastResortFontSizes;
};

webfont.LastResortWebKitFontWatchRunner.prototype.check_ = function() {
  var sizeA = this.fontSizer_.getWidth(this.requestedFontA_);
  var sizeB = this.fontSizer_.getWidth(this.requestedFontB_);

  if (!this.webKitLastResortSizeChange_ && sizeA == sizeB &&
      this.webKitLastResortFontSizes_[sizeA]) {
    this.webKitLastResortFontSizes_ = {};
    this.webKitLastResortFontSizes_[sizeA] = true;
    this.webKitLastResortSizeChange_ = true;
  }
  if ((this.originalSizeA_ != sizeA || this.originalSizeB_ != sizeB) &&
      (!this.webKitLastResortFontSizes_[sizeA] &&
       !this.webKitLastResortFontSizes_[sizeB])) {
    this.finish_(this.activeCallback_);
  } else if (this.getTime_() - this.started_ >= 5000) {

    // In order to handle the fact that a font could be the same size as the
    // default browser font on a webkit browser, mark the font as active
    // after 5 seconds if the latest 2 sizes are in webKitLastResortFontSizes_
    // and the font name is known to be metrics compatible.
    if (this.webKitLastResortFontSizes_[sizeA]
        && this.webKitLastResortFontSizes_[sizeB] &&
        webfont.LastResortWebKitFontWatchRunner.METRICS_COMPATIBLE_FONTS[
          this.fontFamily_]) {
      this.finish_(this.activeCallback_);
    } else {
      this.finish_(this.inactiveCallback_);
    }
  } else {
    this.asyncCheck_();
  }
};