/**
* Functions related to VU meters.
* These functions are intimately tied to the markup defined in the
* VU templates in _vu_meters.html.erb
*/
(function(context, $) {

    "use strict";

    context.JK = context.JK || {};

    // As these are helper functions, just have a single
    // static object with functions. Each function should
    // take all necessary arguments to complete its work.
    context.JK.VuHelpers = {

        /**
        * Render a VU meter into the provided selector.
        * vuType can be either "horizontal" or "vertical"
        */
        renderVU: function(selector, userOptions) {
            selector = $(selector);


            /**
            * The default options for rendering a VU
            */
            var renderVUDefaults = {
                vuType: "vertical",
                lightCount: 12,
                lightWidth: 3,
                lightHeight: 17
            };

            var options = $.extend({}, renderVUDefaults, userOptions);
            var templateSelector = "#template-vu-v";
            if (options.vuType === "horizontal") {
                templateSelector = "#template-vu-h";
            }
            var templateSource = $(templateSelector).html();

            selector.each(function() {
                var $track = $(this);
                $track.empty();
                $track.html(context._.template(templateSource, options, {variable: 'data'}));
            })

        },

        /**
        * Given a selector representing a container for a VU meter and
        * a value between 0.0 and 1.0, light the appropriate lights.
        */
        updateVU: function ($selector, value) {
            // There are 13 VU lights. Figure out how many to
            // light based on the incoming value.
            $selector.each(function() {
                var $track = $(this)
                var countSelector = 'tr';
                var horizontal = ($track.find('table.horizontal').length);
                if (horizontal) {
                    countSelector = 'td';
                }

                var lightCount = $track.find(countSelector).length;
                var i = 0;
                var state = 'on';
                var lights = Math.round(value * lightCount);
                var redSwitch = Math.round(lightCount * 0.6666667);

                var $light = null;
                var colorClass = 'vu-green-';
                var lightSelectorPrefix = $track.find('td.vu');
                var thisLightSelector = null;

                // Remove all light classes from all lights
                var allLightsSelector = $track.find('td.vulight');
                $(allLightsSelector).removeClass('vu-green-off vu-green-on vu-red-off vu-red-on');

                // Set the lights
                for (i = 0; i < lightCount; i++) {
                    colorClass = 'vu-green-';
                    state = 'on';
                    if (i >= redSwitch) {
                        colorClass = 'vu-red-';
                    }
                    if (i >= lights) {
                        state = 'off';
                    }

                    var lightIndex = horizontal ? i : lightCount - i - 1;
                    allLightsSelector.eq(lightIndex).addClass(colorClass + state);
                }
            })

        }

    };

})(window, jQuery);