/*  Snowfall jquery plugin

====================================================================
LICENSE
====================================================================
Licensed under the Apache License, Version 2.0 (the "License");
you may not use this file except in compliance with the License.
You may obtain a copy of the License at

   http://www.apache.org/licenses/LICENSE-2.0

   Unless required by applicable law or agreed to in writing, software
   distributed under the License is distributed on an "AS IS" BASIS,
   WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
   See the License for the specific language governing permissions and
   limitations under the License.


        Version 1.5 Oct 5th 2011
        Added collecting snow! Uses the canvas element to collect snow. In order to initialize snow collection use the following
        
        $(document).snowfall({collection : 'element'});

    element = any valid jquery selector.

        The plugin then creates a canvas above every element that matches the selector, and collects the snow. If there are a varrying amount of elements the 
        flakes get assigned a random one on start they will collide.

        Version 1.4 Dec 8th 2010
        Fixed issues (I hope) with scroll bars flickering due to snow going over the edge of the screen. 
        Added round snowflakes via css, will not work for any version of IE. - Thanks to Luke Barker of http://www.infinite-eye.com/
        Added shadows as an option via css again will not work with IE. The idea behind shadows, is to show flakes on lighter colored web sites - Thanks Yutt
 
        Version 1.3.1 Nov 25th 2010
        Updated script that caused flakes not to show at all if plugin was initialized with no options, also added the fixes that Han Bongers suggested 
        
        Developed by Jason Brown for any bugs or questions email me at loktar69@hotmail
        info on the plugin is located on Somethinghitme.com
        
        values for snow options are
        
        flakeCount,
        flakeColor,
        flakeIndex,
        minSize,
        maxSize,
        minSpeed,
        maxSpeed,
        round,          true or false, makes the snowflakes rounded if the browser supports it.
        shadow          true or false, gives the snowflakes a shadow if the browser supports it.
        
        Example Usage :
        $(document).snowfall({flakeCount : 100, maxSpeed : 10});
        
        -or-
        
        $('#element').snowfall({flakeCount : 800, maxSpeed : 5, maxSize : 5});
        
        -or with defaults-
        
        $(document).snowfall();
        
        - To clear -
        $('#element').snowfall('clear');
*/

(function($){
        $.snowfall = function(element, options){
                var     defaults = {
                                flakeCount : 35,
                                flakeColor : '#ffffff',
                                flakeIndex: 999999,
                                minSize : 1,
                                maxSize : 2,
                                minSpeed : 1,
                                maxSpeed : 5,
                                round : false,
                                shadow : false,
                                collection : false,
                                collectionHeight : 40
                        },
                        options = $.extend(defaults, options),
                        random = function random(min, max){
                                return Math.round(min + Math.random()*(max-min)); 
                        };

                        $(element).data("snowfall", this);                      

                        // Snow flake object
                        function Flake(_x, _y, _size, _speed, _id)
                        {
                                // Flake properties
                                this.id = _id; 
                                this.x  = _x;
                                this.y  = _y;
                                this.size = _size;
                                this.speed = _speed;
                                this.step = 0;
                                this.stepSize = random(1,10) / 100;

                                if(options.collection){
                                        this.target = canvasCollection[random(0,canvasCollection.length-1)];
                                }

                                var flakeMarkup = $(document.createElement("div")).attr({'class': 'snowfall-flakes', 'id' : 'flake-' + this.id}).css({'width' : this.size, 'height' : this.size, 'background' : options.flakeColor, 'position' : 'absolute', 'top' : this.y, 'left' : this.x, 'fontSize' : 0, 'zIndex' : options.flakeIndex});

                                if($(element).get(0).tagName === $(document).get(0).tagName){
                                        $('body').append(flakeMarkup);
                                        element = $('body');
                                }else{
                                        $(element).append(flakeMarkup);
                                }

                                this.element = document.getElementById('flake-' + this.id);

                                // Update function, used to update the snow flakes, and checks current snowflake against bounds
                                this.update = function(){
                                        this.y += this.speed;

                                        if(this.y > (elHeight) - (this.size  + 6)){
                                                this.reset();
                                        }

                                        this.element.style.top = this.y + 'px';
                                        this.element.style.left = this.x + 'px';

                                        this.step += this.stepSize;
                                        this.x += Math.cos(this.step);

                                        // Pileup check
                                        if(options.collection){
                                                if(this.x > this.target.x && this.x < this.target.width + this.target.x && this.y > this.target.y && this.y < this.target.height + this.target.y){
                                                        var ctx = this.target.element.getContext("2d"),
                                                                curX = this.x - this.target.x,
                                                                curY = this.y - this.target.y,
                                                                colData = this.target.colData;

                                                                if(colData[parseInt(curX)][parseInt(curY+this.speed+this.size)] !== undefined || curY+this.speed+this.size > this.target.height){
                                                                        if(curY+this.speed+this.size > this.target.height){
                                                                                while(curY+this.speed+this.size > this.target.height && this.speed > 0){
                                                                                        this.speed *= .5;
                                                                                }

                                                                                ctx.fillStyle = "#fff";

                                                                                if(colData[parseInt(curX)][parseInt(curY+this.speed+this.size)] == undefined){
                                                                                        colData[parseInt(curX)][parseInt(curY+this.speed+this.size)] = 1;
                                                                                        ctx.fillRect(curX, (curY)+this.speed+this.size, this.size, this.size);
                                                                                }else{
                                                                                        colData[parseInt(curX)][parseInt(curY+this.speed)] = 1;
                                                                                        ctx.fillRect(curX, curY+this.speed, this.size, this.size);
                                                                                }
                                                                                this.reset();
                                                                        }else{
                                                                                // flow to the sides
                                                                                this.speed = 1;
                                                                                this.stepSize = 0;

                                                                                if(parseInt(curX)+1 < this.target.width && colData[parseInt(curX)+1][parseInt(curY)+1] == undefined ){
                                                                                        // go left
                                                                                        this.x++;
                                                                                }else if(parseInt(curX)-1 > 0 && colData[parseInt(curX)-1][parseInt(curY)+1] == undefined ){
                                                                                        // go right
                                                                                        this.x--;
                                                                                }else{
                                                                                        //stop
                                                                                        ctx.fillStyle = "#fff";
                                                                                        ctx.fillRect(curX, curY, this.size, this.size);
                                                                                        colData[parseInt(curX)][parseInt(curY)] = 1;
                                                                                        this.reset();
                                                                                }
                                                                        }
                                                                }
                                                }
                                        }

                                        if(this.x > (elWidth) - widthOffset || this.x < widthOffset){
                                                this.reset();
                                        }
                                }

                                // Resets the snowflake once it reaches one of the bounds set
                                this.reset = function(){
                                        this.y = 0;
                                        this.x = random(widthOffset, elWidth - widthOffset);
                                        this.stepSize = random(1,10) / 100;
                                        this.size = random((options.minSize * 100), (options.maxSize * 100)) / 100;
                                        this.speed = random(options.minSpeed, options.maxSpeed);
                                }
                        }

                        // Private vars
                        var flakes = [],
                                flakeId = 0,
                                i = 0,
                                elHeight = $(element).height(),
                                elWidth = $(element).width(),
                                widthOffset = 0,
                                snowTimeout = 0;

                        // Collection Piece ******************************
                        if(options.collection !== false){
                                var testElem = document.createElement('canvas');
                                if(!!(testElem.getContext && testElem.getContext('2d'))){
                                        var canvasCollection = [],
                                                elements = $(options.collection),
                                                collectionHeight = options.collectionHeight;

                                        for(var i =0; i < elements.length; i++){
                                                        var bounds = elements[i].getBoundingClientRect(),
                                                                canvas = document.createElement('canvas'),
                                                                collisionData = [];

                                                        if(bounds.top-collectionHeight > 0){                                                                    
                                                                document.body.appendChild(canvas);
                                                                var jQueryCanvas = $(canvas);
                                                                jQueryCanvas.css('position', 'absolute');
                                                                jQueryCanvas.attr('height', collectionHeight);
                                                                jQueryCanvas.attr('width', bounds.width);
                                                                jQueryCanvas.css('left', bounds.left);
                                                                jQueryCanvas.css('top', bounds.top-collectionHeight);

                                                                for(var w = 0; w < bounds.width; w++){
                                                                        collisionData[w] = [];
                                                                }

                                                                canvasCollection.push({element :canvas, x : bounds.left, y : bounds.top-collectionHeight, width : bounds.width, height: collectionHeight, colData : collisionData});
                                                        }
                                        }
                                }else{
                                        // Canvas element isnt supported
                                        options.collection = false;
                                }
                        }
                        // ************************************************

                        // This will reduce the horizontal scroll bar from displaying, when the effect is applied to the whole page
                        if($(element).get(0).tagName === $(document).get(0).tagName){
                                widthOffset = 25;
                        }

                        // Bind the window resize event so we can get the innerHeight again
                        $(window).bind("resize", function(){  
                                elHeight = $(element).height();
                                elWidth = $(element).width();
                        }); 


                        // initialize the flakes
                        for(i = 0; i < options.flakeCount; i+=1){
                                flakeId = flakes.length;
                                flakes.push(new Flake(random(widthOffset,elWidth - widthOffset), random(0, elHeight), random((options.minSize * 100), (options.maxSize * 100)) / 100, random(options.minSpeed, options.maxSpeed), flakeId));
                        }

                        // This adds the style to make the snowflakes round via border radius property 
                        if(options.round){
                                $('.snowfall-flakes').css({'-moz-border-radius' : options.maxSize, '-webkit-border-radius' : options.maxSize, 'border-radius' : options.maxSize});
                        }

                        // This adds shadows just below the snowflake so they pop a bit on lighter colored web pages
                        if(options.shadow){
                                $('.snowfall-flakes').css({'-moz-box-shadow' : '1px 1px 1px #555', '-webkit-box-shadow' : '1px 1px 1px #555', 'box-shadow' : '1px 1px 1px #555'});
                        }

                        // this controls flow of the updating snow
                        function snow(){
                                for( i = 0; i < flakes.length; i += 1){
                                        flakes[i].update();
                                }

                                snowTimeout = setTimeout(function(){snow()}, 30);
                        }

                        snow();

                // Public Methods

                // clears the snowflakes
                this.clear = function(){
                                                $(element).children('.snowfall-flakes').remove();
                                                flakes = [];
                                                clearTimeout(snowTimeout);
                                        };
        };

        // Initialize the options and the plugin
        $.fn.snowfall = function(options){
                if(typeof(options) == "object" || options == undefined){                
                                 return this.each(function(i){
                                        (new $.snowfall(this, options)); 
                                });     
                }else if (typeof(options) == "string") {
                        return this.each(function(i){
                                var snow = $(this).data('snowfall');
                                if(snow){
                                        snow.clear();
                                }
                        });
                }
        };
})(jQuery);