var snowStorm = (function(window, document) {
    this.flakesMax = 60;
    this.flakesMaxActive = 60;
    this.animationInterval = 40;
    this.excludeMobile = true;
    this.flakeBottom = null;
    this.followMouse = true;
    this.snowColor = '#fff';
    this.snowCharacter = '•';
    this.snowStick = false;
    this.targetElement = null;
    this.useMeltEffect = true;
    this.useTwinkleEffect = false;
    this.usePositionFixed = false;
    this.freezeOnBlur = true;
    this.flakeLeftOffset = 0;
    this.flakeRightOffset = 0;
    this.flakeWidth = 5;
    this.flakeHeight = 5;
    this.vMaxX = 2.5;
    this.vMaxY = 2.5;
    this.zIndex = 10000;
    var s = this,
    storm = this,
    i, isIE = navigator.userAgent.match(/msie/i),
    isIE6 = navigator.userAgent.match(/msie 6/i),
    isWin98 = navigator.appVersion.match(/windows 98/i),
    isMobile = navigator.userAgent.match(/mobile/i),
    isBackCompatIE = (isIE && document.compatMode === 'BackCompat'),
    noFixed = (isMobile || isBackCompatIE || isIE6),
    screenX = null,
    screenX2 = null,
    screenY = null,
    scrollY = null,
    vRndX = null,
    vRndY = null,
    windOffset = 1,
    windMultiplier = 2,
    flakeTypes = 6,
    fixedForEverything = false,
    opacitySupported = (function() {
        try {
            document.createElement('div').style.opacity = '0.5';
        } catch(e) {
            return false;
        }
        return true;
    } ()),
    didInit = false,
    docFrag = document.createDocumentFragment();
    this.timers = [];
    this.flakes = [];
    this.disabled = false;
    this.active = false;
    this.meltFrameCount = 20;
    this.meltFrames = [];
    this.events = (function() {
        var old = (window.attachEvent),
        slice = Array.prototype.slice,
        evt = {
            add: (old ? 'attachEvent': 'addEventListener'),
            remove: (old ? 'detachEvent': 'removeEventListener')
        };
        function getArgs(oArgs) {
            var args = slice.call(oArgs),
            len = args.length;
            if (old) {
                args[1] = 'on' + args[1];
                if (len > 3) {
                    args.pop();
                }
            } else if (len === 3) {
                args.push(false);
            }
            return args;
        }
        function apply(args, sType) {
            var oFunc = args.shift()[evt[sType]];
            if (old) {
                oFunc(args[0], args[1]);
            } else {
                oFunc.apply(this, args);
            }
        }
        function addEvent() {
            apply(getArgs(arguments), 'add');
        }
        function removeEvent() {
            apply(getArgs(arguments), 'remove');
        }
        return {
            add: addEvent,
            remove: removeEvent
        };
    } ());
    function rnd(n, min) {
        if (isNaN(min)) {
            min = 0;
        }
        return (Math.random() * n) + min;
    }
    function plusMinus(n) {
        return (parseInt(rnd(2), 10) === 1 ? n * -1 : n);
    }
    this.randomizeWind = function() {
        vRndX = plusMinus(rnd(s.vMaxX, 0.2));
        vRndY = rnd(s.vMaxY, 0.2);
        if (this.flakes) {
            for (var i = 0; i < this.flakes.length; i++) {
                if (this.flakes[i].active) {
                    this.flakes[i].setVelocities();
                }
            }
        }
    };
    this.scrollHandler = function() {
        scrollY = (s.flakeBottom ? 0 : parseInt(window.scrollY || document.documentElement.scrollTop || document.body.scrollTop, 10));
        if (isNaN(scrollY)) {
            scrollY = 0;
        }
        if (!fixedForEverything && !s.flakeBottom && s.flakes) {
            for (var i = s.flakes.length; i--;) {
                if (s.flakes[i].active === 0) {
                    s.flakes[i].stick();
                }
            }
        }
    };
    this.resizeHandler = function() {
        if (window.innerWidth || window.innerHeight) {
            screenX = window.innerWidth - (!isIE ? 16 : 2) - s.flakeRightOffset;
            screenY = (s.flakeBottom ? s.flakeBottom: window.innerHeight);
        } else {
            screenX = (document.documentElement.clientWidth || document.body.clientWidth || document.body.scrollWidth) - (!isIE ? 8 : 0) - s.flakeRightOffset;
            screenY = s.flakeBottom ? s.flakeBottom: (document.documentElement.clientHeight || document.body.clientHeight || document.body.scrollHeight);
        }
        screenX2 = parseInt(screenX / 2, 10);
    };
    this.resizeHandlerAlt = function() {
        screenX = s.targetElement.offsetLeft + s.targetElement.offsetWidth - s.flakeRightOffset;
        screenY = s.flakeBottom ? s.flakeBottom: s.targetElement.offsetTop + s.targetElement.offsetHeight;
        screenX2 = parseInt(screenX / 2, 10);
    };
    this.freeze = function() {
        if (!s.disabled) {
            s.disabled = 1;
        } else {
            return false;
        }
        for (var i = s.timers.length; i--;) {
            clearInterval(s.timers[i]);
        }
    };
    this.resume = function() {
        if (s.disabled) {
            s.disabled = 0;
        } else {
            return false;
        }
        s.timerInit();
    };
    this.toggleSnow = function() {
        if (!s.flakes.length) {
            s.start();
        } else {
            s.active = !s.active;
            if (s.active) {
                s.show();
                s.resume();
            } else {
                s.stop();
                s.freeze();
            }
        }
    };
    this.stop = function() {
        this.freeze();
        for (var i = this.flakes.length; i--;) {
            this.flakes[i].o.style.display = 'none';
        }
        s.events.remove(window, 'scroll', s.scrollHandler);
        s.events.remove(window, 'resize', s.resizeHandler);
        if (s.freezeOnBlur) {
            if (isIE) {
                s.events.remove(document, 'focusout', s.freeze);
                s.events.remove(document, 'focusin', s.resume);
            } else {
                s.events.remove(window, 'blur', s.freeze);
                s.events.remove(window, 'focus', s.resume);
            }
        }
    };
    this.show = function() {
        for (var i = this.flakes.length; i--;) {
            this.flakes[i].o.style.display = 'block';
        }
    };
    this.SnowFlake = function(parent, type, x, y) {
        var s = this,
        storm = parent;
        this.type = type;
        this.x = x || parseInt(rnd(screenX - 20), 10);
        this.y = (!isNaN(y) ? y: -rnd(screenY) - 12);
        this.vX = null;
        this.vY = null;
        this.vAmpTypes = [1, 1.2, 1.4, 1.6, 1.8];
        this.vAmp = this.vAmpTypes[this.type];
        this.melting = false;
        this.meltFrameCount = storm.meltFrameCount;
        this.meltFrames = storm.meltFrames;
        this.meltFrame = 0;
        this.twinkleFrame = 0;
        this.active = 1;
        this.fontSize = (10 + (this.type / 5) * 10);
        this.o = document.createElement('div');
        this.o.innerHTML = storm.snowCharacter;
        this.o.style.color = storm.snowColor;
        this.o.style.position = (fixedForEverything ? 'fixed': 'absolute');
        this.o.style.width = storm.flakeWidth + 'px';
        this.o.style.height = storm.flakeHeight + 'px';
        this.o.style.fontFamily = 'arial,verdana';
        this.o.style.overflow = 'hidden';
        this.o.style.fontWeight = 'normal';
        this.o.style.zIndex = storm.zIndex;
        docFrag.appendChild(this.o);
        this.refresh = function() {
            if (isNaN(s.x) || isNaN(s.y)) {
                return false;
            }
            s.o.style.left = s.x + 'px';
            s.o.style.top = s.y + 'px';
        };
        this.stick = function() {
            if (noFixed || (storm.targetElement !== document.documentElement && storm.targetElement !== document.body)) {
                s.o.style.top = (screenY + scrollY - storm.flakeHeight) + 'px';
            } else if (storm.flakeBottom) {
                s.o.style.top = storm.flakeBottom + 'px';
            } else {
                s.o.style.display = 'none';
                s.o.style.top = 'auto';
                s.o.style.bottom = '0px';
                s.o.style.position = 'fixed';
                s.o.style.display = 'block';
            }
        };
        this.vCheck = function() {
            if (s.vX >= 0 && s.vX < 0.2) {
                s.vX = 0.2;
            } else if (s.vX < 0 && s.vX > -0.2) {
                s.vX = -0.2;
            }
            if (s.vY >= 0 && s.vY < 0.2) {
                s.vY = 0.2;
            }
        };
        this.move = function() {
            var vX = s.vX * windOffset,
            yDiff;
            s.x += vX;
            s.y += (s.vY * s.vAmp);
            if (s.x >= screenX || screenX - s.x < storm.flakeWidth) {
                s.x = 0;
            } else if (vX < 0 && s.x - storm.flakeLeftOffset < 0 - storm.flakeWidth) {
                s.x = screenX - storm.flakeWidth - 1;
            }
            s.refresh();
            yDiff = screenY + scrollY - s.y;
            if (yDiff < storm.flakeHeight) {
                s.active = 0;
                if (storm.snowStick) {
                    s.stick();
                } else {
                    s.recycle();
                }
            } else {
                if (storm.useMeltEffect && s.active && s.type < 3 && !s.melting && Math.random() > 0.998) {
                    s.melting = true;
                    s.melt();
                }
                if (storm.useTwinkleEffect) {
                    if (!s.twinkleFrame) {
                        if (Math.random() > 0.9) {
                            s.twinkleFrame = parseInt(Math.random() * 20, 10);
                        }
                    } else {
                        s.twinkleFrame--;
                        s.o.style.visibility = (s.twinkleFrame && s.twinkleFrame % 2 === 0 ? 'hidden': 'visible');
                    }
                }
            }
        };
        this.animate = function() {
            s.move();
        };
        this.setVelocities = function() {
            s.vX = vRndX + rnd(storm.vMaxX * 0.12, 0.1);
            s.vY = vRndY + rnd(storm.vMaxY * 0.12, 0.1);
        };
        this.setOpacity = function(o, opacity) {
            if (!opacitySupported) {
                return false;
            }
            o.style.opacity = opacity;
        };
        this.melt = function() {
            if (!storm.useMeltEffect || !s.melting) {
                s.recycle();
            } else {
                if (s.meltFrame < s.meltFrameCount) {
                    s.meltFrame++;
                    s.setOpacity(s.o, s.meltFrames[s.meltFrame]);
                    s.o.style.fontSize = s.fontSize - (s.fontSize * (s.meltFrame / s.meltFrameCount)) + 'px';
                    s.o.style.lineHeight = storm.flakeHeight + 2 + (storm.flakeHeight * 0.75 * (s.meltFrame / s.meltFrameCount)) + 'px';
                } else {
                    s.recycle();
                }
            }
        };
        this.recycle = function() {
            s.o.style.display = 'none';
            s.o.style.position = (fixedForEverything ? 'fixed': 'absolute');
            s.o.style.bottom = 'auto';
            s.setVelocities();
            s.vCheck();
            s.meltFrame = 0;
            s.melting = false;
            s.setOpacity(s.o, 1);
            s.o.style.padding = '0px';
            s.o.style.margin = '0px';
            s.o.style.fontSize = s.fontSize + 'px';
            s.o.style.lineHeight = (storm.flakeHeight + 2) + 'px';
            s.o.style.textAlign = 'center';
            s.o.style.verticalAlign = 'baseline';
            s.x = parseInt(rnd(screenX - storm.flakeWidth - 20), 10);
            s.y = parseInt(rnd(screenY) * -1, 10) - storm.flakeHeight;
            s.refresh();
            s.o.style.display = 'block';
            s.active = 1;
        };
        this.recycle();
        this.refresh();
    };
    this.snow = function() {
        var active = 0,
        used = 0,
        waiting = 0,
        flake = null,
        i;
        for (i = s.flakes.length; i--;) {
            if (s.flakes[i].active === 1) {
                s.flakes[i].move();
                active++;
            } else if (s.flakes[i].active === 0) {
                used++;
            } else {
                waiting++;
            }
            if (s.flakes[i].melting) {
                s.flakes[i].melt();
            }
        }
        if (active < s.flakesMaxActive) {
            flake = s.flakes[parseInt(rnd(s.flakes.length), 10)];
            if (flake.active === 0) {
                flake.melting = true;
            }
        }
    };
    this.mouseMove = function(e) {
        if (!s.followMouse) {
            return true;
        }
        var x = parseInt(e.clientX, 10);
        if (x < screenX2) {
            windOffset = -windMultiplier + (x / screenX2 * windMultiplier);
        } else {
            x -= screenX2;
            windOffset = (x / screenX2) * windMultiplier;
        }
    };
    this.createSnow = function(limit, allowInactive) {
        for (var i = 0; i < limit; i++) {
            s.flakes[s.flakes.length] = new s.SnowFlake(s, parseInt(rnd(flakeTypes), 10));
            if (allowInactive || i > s.flakesMaxActive) {
                s.flakes[s.flakes.length - 1].active = -1;
            }
        }
        storm.targetElement.appendChild(docFrag);
    };
    this.timerInit = function() {
        s.timers = (!isWin98 ? [setInterval(s.snow, s.animationInterval)] : [setInterval(s.snow, s.animationInterval * 3), setInterval(s.snow, s.animationInterval)]);
    };
    this.init = function() {
        for (var i = 0; i < s.meltFrameCount; i++) {
            s.meltFrames.push(1 - (i / s.meltFrameCount));
        }
        s.randomizeWind();
        s.createSnow(s.flakesMax);
        s.events.add(window, 'resize', s.resizeHandler);
        s.events.add(window, 'scroll', s.scrollHandler);
        if (s.freezeOnBlur) {
            if (isIE) {
                s.events.add(document, 'focusout', s.freeze);
                s.events.add(document, 'focusin', s.resume);
            } else {
                s.events.add(window, 'blur', s.freeze);
                s.events.add(window, 'focus', s.resume);
            }
        }
        s.resizeHandler();
        s.scrollHandler();
        if (s.followMouse) {
            s.events.add(isIE ? document: window, 'mousemove', s.mouseMove);
        }
        s.animationInterval = Math.max(20, s.animationInterval);
        s.timerInit();
    };
    this.start = function(bFromOnLoad) {
        if (!didInit) {
            didInit = true;
        } else if (bFromOnLoad) {
            return true;
        }
        if (typeof s.targetElement === 'string') {
            var targetID = s.targetElement;
            s.targetElement = document.getElementById(targetID);
            if (!s.targetElement) {
                throw new Error('Snowstorm: Unable to get targetElement "' + targetID + '"');
            }
        }
        if (!s.targetElement) {
            s.targetElement = (!isIE ? (document.documentElement ? document.documentElement: document.body) : document.body);
        }
        if (s.targetElement !== document.documentElement && s.targetElement !== document.body) {
            s.resizeHandler = s.resizeHandlerAlt;
        }
        s.resizeHandler();
        s.usePositionFixed = (s.usePositionFixed && !noFixed);
        fixedForEverything = s.usePositionFixed;
        if (screenX && screenY && !s.disabled) {
            s.init();
            s.active = true;
        }
    };
    function doStart() {
        if ((this.excludeMobile && !isMobile) || !this.excludeMobile) {
            window.setTimeout(function() {
                s.start(true);
            },
            20);
        }
        s.events.remove(window, 'load', doStart);
    }
    s.events.add(window, 'load', doStart, false);
    return this;
} (window, document));