(function($) {

var jstar_timer = null;
var jstar_index = 0;
var jstar_dindex = 0;
var jstar_image = null;

$.jstars = {};
$.fn.jstars = function(settings)
{
	// check IE. only IE9+ support
	if( $.browser.msie && $.browser.version < 9 ) return;
	// apply default params
	settings = $.extend({}, $.fn.jstars.defaults, settings);
	// define frequency
	settings.frequency = 20 - Math.max(1, Math.min(settings.frequency, 19));
	// save in global
	$.jstars.settings = settings;
	
	return this.each(
		function()
		{
			// preprocess
			if( !jstar_timer ){
				// init timer
				jstar_timer = setInterval(jstar_uptade_star_bg, settings.delay / 9);
				// init image
				jstar_image = new Image();
				jstar_image.src = settings.image_path + '/' + settings.image;
			}
			
			// hover event
			$(this).mousemove(function(e){
				if( (jstar_dindex++ % settings.frequency) != 0) return;
				
				// define what side we need to show stars:
				var sideX = jstar_rand(-1,1);
				var sideY = jstar_rand(-1,1);
				
				var randX = jstar_rand(5, 30);
				var randY = jstar_rand(5, 30);
				
				var opacity = Math.min(Math.random() + 0.4, 1);
				
				// calculate coordinate
				var x = e.pageX + (sideX * randX);
				var y = e.pageY + (sideY * randY);
				
				// show span and launch animate
				var id = 'jstar_' + jstar_index++;
				
				// append style
				if( settings.style != 'rand' ){
					var bg_pos = '0px ' + settings.style_map[ settings.style ] + 'px';
				}
				else{
					var ind = jstar_rand(0, 5);
					var i = 0;
					for(var key in settings.style_map){
						if( i++ == ind ){
							var bg_pos = '0px ' + settings.style_map[ key ] + 'px';
							break;
						}
					}
				}
				
				var span = '<span id="' + id + '" class="jstar_span" style="display:block; width:27px; height:27px; background:url('+jstar_image.src+') no-repeat '+bg_pos+'; margin:0; padding:0; position:absolute; top:-50px; left:0;">&nbsp;</span>';
				$(document.body).append(span);
				
				var star = $('#' + id);
				star
					.css({
						top: y,
						left: x,
						'opacity': opacity
					})
					.animate({ opacity: 0 }, 300, function(){ star.remove(); }); // remove span on finish animate*/
			})
		}
	)
};

/**
 * helper functions
 */

// timer function
function jstar_uptade_star_bg(){
	if( ! $('span.jstar_span').size ) return;
	
	$('span.jstar_span').each(function(){
		var bg_pos = $(this).css('background-position').split(' ');
		var bg_pos_x = parseInt(bg_pos[0]);
		var bg_pos_y = parseInt(bg_pos[1]);
		$(this).css('background-position', (bg_pos_x - $.jstars.settings.width) + 'px ' + bg_pos_y + 'px');
	})
}

// math rand in interval
function jstar_rand(from, to){
	var r = Math.random();
	r = r * (to - from);
	r = r + from;
	r = Math.round(r);
	return r;
}

$.fn.jstars.defaults = {
	image_path: '', // this is requried param
	image: 'jstar-map.png', // this is requried param
	style: 'white',
	frequency: 12,
	style_map: {
		white: 0,
		blue: -27,
		green: -54,
		red: -81,
		yellow: -108
	},
	width: 27,
	height: 27,
	delay: 300
};


})(jQuery);