nv.utils.windowSize = function() {
    // Sane defaults
    var size = {width: 640, height: 480};

    // Earlier IE uses Doc.body
    if (document.body && document.body.offsetWidth) {
        size.width = document.body.offsetWidth;
        size.height = document.body.offsetHeight;
    }

    // IE can use depending on mode it is in
    if (document.compatMode=='CSS1Compat' &&
        document.documentElement &&
        document.documentElement.offsetWidth ) {
        size.width = document.documentElement.offsetWidth;
        size.height = document.documentElement.offsetHeight;
    }

    // Most recent browsers use
    if (window.innerWidth && window.innerHeight) {
        size.width = window.innerWidth;
        size.height = window.innerHeight;
    }
    return (size);
};



// Easy way to bind multiple functions to window.onresize
// TODO: give a way to remove a function after its bound, other than removing all of them
nv.utils.windowResize = function(fun){
  if (fun === undefined) return;
  var oldresize = window.onresize;

  window.onresize = function(e) {
    if (typeof oldresize == 'function') oldresize(e);
    fun(e);
  }
}

// Backwards compatible way to implement more d3-like coloring of graphs.
// If passed an array, wrap it in a function which implements the old default
// behavior
nv.utils.getColor = function(color) {
    if (!arguments.length) return nv.utils.defaultColor(); //if you pass in nothing, get default colors back

    if( Object.prototype.toString.call( color ) === '[object Array]' )
        return function(d, i) { return d.color || color[i % color.length]; };
    else
        return color;
        //can't really help it if someone passes rubbish as color
}

// Default color chooser uses the index of an object as before.
nv.utils.defaultColor = function() {
    var colors = d3.scale.category20().range();
    return function(d, i) { return d.color || colors[i % colors.length] };
}


// Returns a color function that takes the result of 'getKey' for each series and
// looks for a corresponding color from the dictionary,
nv.utils.customTheme = function(dictionary, getKey, defaultColors) {
  getKey = getKey || function(series) { return series.key }; // use default series.key if getKey is undefined
  defaultColors = defaultColors || d3.scale.category20().range(); //default color function

  var defIndex = defaultColors.length; //current default color (going in reverse)

  return function(series, index) {
    var key = getKey(series);

    if (!defIndex) defIndex = defaultColors.length; //used all the default colors, start over

    if (typeof dictionary[key] !== "undefined")
      return (typeof dictionary[key] === "function") ? dictionary[key]() : dictionary[key];
    else
      return defaultColors[--defIndex]; // no match in dictionary, use default color
  }
}



// From the PJAX example on d3js.org, while this is not really directly needed
// it's a very cool method for doing pjax, I may expand upon it a little bit,
// open to suggestions on anything that may be useful
nv.utils.pjax = function(links, content) {
  d3.selectAll(links).on("click", function() {
    history.pushState(this.href, this.textContent, this.href);
    load(this.href);
    d3.event.preventDefault();
  });

  function load(href) {
    d3.html(href, function(fragment) {
      var target = d3.select(content).node();
      target.parentNode.replaceChild(d3.select(fragment).select(content).node(), target);
      nv.utils.pjax(links, content);
    });
  }

  d3.select(window).on("popstate", function() {
    if (d3.event.state) load(d3.event.state);
  });
}

/* For situations where we want to approximate the width in pixels for an SVG:text element.
Most common instance is when the element is in a display:none; container. 
Forumla is : text.length * font-size * constant_factor
*/
nv.utils.calcApproxTextWidth = function (svgTextElem) {
    if (svgTextElem instanceof d3.selection) {
        var fontSize = parseInt(svgTextElem.style("font-size").replace("px",""));
        var textLength = svgTextElem.text().length;

        return textLength * fontSize * 0.5; 
    }
    return 0;
};

/* Numbers that are undefined, null or NaN, convert them to zeros.
*/
nv.utils.NaNtoZero = function(n) {
    if (typeof n !== 'number' 
        || isNaN(n) 
        || n === null
        || n === Infinity) return 0;

    return n;
};

/*
Snippet of code you can insert into each nv.models.* to give you the ability to
do things like:
chart.options({
  showXAxis: true,
  tooltips: true
});

To enable in the chart:
chart.options = nv.utils.optionsFunc.bind(chart);
*/
nv.utils.optionsFunc = function(args) {
    if (args) {
      d3.map(args).forEach((function(key,value) {
        if (typeof this[key] === "function") {
           this[key](value);
        }
      }).bind(this));
    }
    return this;
};