/*!
 * jQCloud Plugin for jQuery
 *
 * Version 0.1.5
 *
 * Copyright 2011, Luca Ongaro
 * Licensed under the MIT license.
 *
 * Date: Tue Mar 1 11:09:37 +0100 2011
 */ 
 
(function ($) {
    $.fn.jQCloud = function (word_array, callback_function) {
        // Reference to the container element
        var $this = this;
        // Reference to the ID of the container element
        var container_id = $this.attr('id');

        // Add the "jqcloud" class to the container for easy CSS styling
        $this.addClass("jqcloud");

        var drawWordCloud = function () {
            // Helper function to test if an element overlaps others
            var hitTest = function (elem, other_elems) {
                // Pairwise overlap detection
                var overlapping = function (a, b) {
                    if (Math.abs(2.0 * a.offsetLeft + a.offsetWidth - 2.0 * b.offsetLeft - b.offsetWidth) < a.offsetWidth + b.offsetWidth) {
                        if (Math.abs(2.0 * a.offsetTop + a.offsetHeight - 2.0 * b.offsetTop - b.offsetHeight) < a.offsetHeight + b.offsetHeight) {
                            return true;
                        }
                    }
                    return false;
                };
                var i = 0;
                // Check elements for overlap one by one, stop and return false as soon as an overlap is found
                for (i = 0; i < other_elems.length; i++) {
                    if (overlapping(elem, other_elems[i])) {
                        return true;
                    }
                }
                return false;
            };

            // Sort word_array from the word with the highest weight to the one with the lowest
            word_array.sort(function (a, b) { if (a.weight < b.weight) { return 1; } else if (a.weight > b.weight) { return -1; } else { return 0; } });

            var step = 2.0;
            var already_placed_words = [];
            var aspect_ratio = $this.width() / $this.height();
            var origin_x = $this.width() / 2.0;
            var origin_y = $this.height() / 2.0;

            // Move each word in spiral until it finds a suitable empty place
            $.each(word_array, function (index, word) {

                // Define the ID element of the span that will wrap the word, and the associated jquery selector string
                var word_id = container_id + "_word_" + index;
                var word_selector = "#" + word_id;

                var angle = 6.28 * Math.random();
                var radius = 0.0;
                // Linearly map the original weight to a discrete scale from 1 to 10
                var weight = Math.round((word.weight - word_array[word_array.length - 1].weight) / (word_array[0].weight - word_array[word_array.length - 1].weight) * 9.0) + 1;
                if (word.url == null)
                    word.url = '#';                
                var inner_html = word.url != "undefined" ? "<a id=" + word.wordId + " class='myword' style='cursor:pointer;'>" + word.text + "</a></span>" : word.text;
                $this.append("<span id='" + word_id + "' class='w" + weight + "' title='" + (word.title || "") + "'>" + inner_html + "</span>");

                var width = $(word_selector).width();
                var height = $(word_selector).height();
                var left = origin_x - width / 2.0;
                var top = origin_y - height / 2.0;
                $(word_selector).css("position", "absolute");
                $(word_selector).css("left", left + "px");
                $(word_selector).css("top", top + "px");

                while (hitTest(document.getElementById(word_id), already_placed_words)) {
                    radius += step;
                    angle += (index % 2 === 0 ? 1 : -1) * step;

                    left = origin_x + (radius * Math.cos(angle) - (width / 2.0)) * aspect_ratio;
                    top = origin_y + radius * Math.sin(angle) - (height / 2.0);

                    $(word_selector).css('left', left + "px");
                    $(word_selector).css('top', top + "px");
                }
                already_placed_words.push(document.getElementById(word_id));
            });

            if (typeof callback_function === 'function') {
                callback_function.call(this);
            }
        };

        // Delay execution so that the browser can render the page before the computatively intensive word cloud drawing
        setTimeout(function () { drawWordCloud(); }, 100);
        return this;
    };
})(jQuery);