/** @license
 * DHTML Snowstorm! JavaScript-based snow for web pages
 * Making it snow on the internets since 2003. You're welcome.
 * -----------------------------------------------------------
 * Version 1.44.20131208 (Previous rev: 1.44.20131125)
 * Copyright (c) 2007, Scott Schiller. All rights reserved.
 * Code provided under the BSD License
 * http://schillmania.com/projects/snowstorm/license.txt
 */

/*jslint nomen: true, plusplus: true, sloppy: true, vars: true, white: true */
/*global window, document, navigator, clearInterval, setInterval */

function snow(flakesMax) {
	// --- common properties ---
  
	this.autoStart = true; // Whether the snow should start automatically or not.
	this.excludeMobile = false; // Snow is likely to be bad news for mobile phones' CPUs (and batteries.) Enable at your own risk.
	this.flakesMax = flakesMax; // Limit total amount of snow made (falling + sticking)
	this.flakesMaxActive = 30; // Limit amount of snow falling at once (less = lower CPU use)
	this.animationInterval = 70; // Theoretical "miliseconds per frame" measurement. 20 = fast + smooth, but high CPU use. 50 = more conservative, but slower
	this.useGPU = true; // Enable transform-based hardware acceleration, reduce CPU load.
	this.className = null; // CSS class name for further customization on snow elements
	this.excludeMobile = true; // Snow is likely to be bad news for mobile phones' CPUs (and batteries.) By default, be nice.
	this.flakeBottom = null; // Integer for Y axis snow limit, 0 or null for "full-screen" snow effect
	this.followMouse = false; // Snow movement can respond to the user's mouse
	this.snowColor = "#fff"; // Don't eat (or use?) yellow snow.
	this.snowCharacter = "•"; // • = bullet, · is square on some systems etc.
	this.snowStick = true; // Whether or not snow should "stick" at the bottom. When off, will never collect.
	this.targetElement = null; // element which snow will be appended to (null = document.body) - can be an element ID eg. 'myDiv', or a DOM node reference
	this.useMeltEffect = true; // When recycling fallen snow (or rarely, when falling), have it "melt" and fade out if browser supports it
	this.useTwinkleEffect = false; // Allow snow to randomly "flicker" in and out of view while falling
	this.usePositionFixed = false; // true = snow does not shift vertically when scrolling. May increase CPU load, disabled by default - if enabled, used only where supported
	this.usePixelPosition = false; // Whether to use pixel values for snow top/left vs. percentages. Auto-enabled if body is position:relative or targetElement is specified.
  
	// --- less-used bits ---
  
	this.freezeOnBlur = true; // Only snow when the window is in focus (foreground.) Saves CPU.
	this.flakeLeftOffset = 0; // Left margin/gutter space on edge of container (eg. browser window.) Bump up these values if seeing horizontal scrollbars.
	this.flakeRightOffset = 0; // Right margin/gutter space on edge of container
	this.flakeWidth = 8; // Max pixel width reserved for snow element
	this.flakeHeight = 8; // Max pixel height reserved for snow element
	this.vMaxX = 5; // Maximum X velocity range for snow
	this.vMaxY = 4; // Maximum Y velocity range for snow
	this.zIndex = 0; // CSS stacking order applied to each snowflake
  
	// --- "No user-serviceable parts inside" past this point, yadda yadda ---
  
	var storm = this,
	  features,
	  // UA sniffing and backCompat rendering mode checks for fixed position, etc.
	  isIE = navigator.userAgent.match(/msie/i),
	  isIE6 = navigator.userAgent.match(/msie 6/i),
	  isMobile = navigator.userAgent.match(/mobile|opera m(ob|in)/i),
	  isBackCompatIE = isIE && document.compatMode === "BackCompat",
	  noFixed = isBackCompatIE || isIE6,
	  screenX = null,
	  screenX2 = null,
	  screenY = null,
	  scrollY = null,
	  docHeight = null,
	  vRndX = null,
	  vRndY = null,
	  windOffset = 1,
	  windMultiplier = 2,
	  flakeTypes = 6,
	  fixedForEverything = false,
	  targetElementIsRelative = false,
	  opacitySupported = (function () {
		try {
		  document.createElement("div").style.opacity = "0.5";
		} catch (e) {
		  return false;
		}
		return true;
	  })(),
	  didInit = false,
	  docFrag = document.createDocumentFragment();
  
	features = (function () {
	  var getAnimationFrame;
  
	  /**
	   * hat tip: paul irish
	   * http://paulirish.com/2011/requestanimationframe-for-smart-animating/
	   * https://gist.github.com/838785
	   */
  
	  function timeoutShim(callback) {
		window.setTimeout(callback, 1000 / (storm.animationInterval || 20));
	  }
  
	  var _animationFrame =
		window.requestAnimationFrame ||
		window.webkitRequestAnimationFrame ||
		window.mozRequestAnimationFrame ||
		window.oRequestAnimationFrame ||
		window.msRequestAnimationFrame ||
		timeoutShim;
  
	  // apply to window, avoid "illegal invocation" errors in Chrome
	  getAnimationFrame = _animationFrame
		? function () {
			return _animationFrame.apply(window, arguments);
		  }
		: null;
  
	  var testDiv;
  
	  testDiv = document.createElement("div");
  
	  function has(prop) {
		// test for feature support
		var result = testDiv.style[prop];
		return result !== undefined ? prop : null;
	  }
  
	  // note local scope.
	  var localFeatures = {
		transform: {
		  ie: has("-ms-transform"),
		  moz: has("MozTransform"),
		  opera: has("OTransform"),
		  webkit: has("webkitTransform"),
		  w3: has("transform"),
		  prop: null // the normalized property value
		},
  
		getAnimationFrame: getAnimationFrame
	  };
  
	  localFeatures.transform.prop =
		localFeatures.transform.w3 ||
		localFeatures.transform.moz ||
		localFeatures.transform.webkit ||
		localFeatures.transform.ie ||
		localFeatures.transform.opera;
  
	  testDiv = null;
  
	  return localFeatures;
	})();
  
	this.timer = null;
	this.flakes = [];
	this.disabled = false;
	this.active = false;
	this.meltFrameCount = 20;
	this.meltFrames = [];
  
	this.setXY = function (o, x, y) {
	  if (!o) {
		return false;
	  }
  
	  if (storm.usePixelPosition || targetElementIsRelative) {
		o.style.left = x - storm.flakeWidth + "px";
		o.style.top = y - storm.flakeHeight + "px";
	  } else if (noFixed) {
		o.style.right = 100 - (x / screenX) * 100 + "%";
		// avoid creating vertical scrollbars
		o.style.top = Math.min(y, docHeight - storm.flakeHeight) + "px";
	  } else {
		if (!storm.flakeBottom) {
		  // if not using a fixed bottom coordinate...
		  o.style.right = 100 - (x / screenX) * 100 + "%";
		  o.style.bottom = 100 - (y / screenY) * 100 + "%";
		} else {
		  // absolute top.
		  o.style.right = 100 - (x / screenX) * 100 + "%";
		  o.style.top = Math.min(y, docHeight - storm.flakeHeight) + "px";
		}
	  }
	};
  
	this.events = (function () {
	  var old = !window.addEventListener && 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]; // prefix
		  if (len > 3) {
			args.pop(); // no capture
		  }
		} else if (len === 3) {
		  args.push(false);
		}
		return args;
	  }
  
	  function apply(args, sType) {
		var element = args.shift(),
		  method = [evt[sType]];
		if (old) {
		  element[method](args[0], args[1]);
		} else {
		  element[method].apply(element, 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 () {
	  var i;
	  vRndX = plusMinus(rnd(storm.vMaxX, 0.2));
	  vRndY = rnd(storm.vMaxY, 0.2);
	  if (this.flakes) {
		for (i = 0; i < this.flakes.length; i++) {
		  if (this.flakes[i].active) {
			this.flakes[i].setVelocities();
		  }
		}
	  }
	};
  
	this.scrollHandler = function () {
	  var i;
	  // "attach" snowflakes to bottom of window if no absolute bottom value was given
	  scrollY = storm.flakeBottom
		? 0
		: parseInt(
			window.scrollY ||
			  document.documentElement.scrollTop ||
			  (noFixed ? document.body.scrollTop : 0),
			10
		  );
	  if (isNaN(scrollY)) {
		scrollY = 0; // Netscape 6 scroll fix
	  }
	  if (!fixedForEverything && !storm.flakeBottom && storm.flakes) {
		for (i = 0; i < storm.flakes.length; i++) {
		  if (storm.flakes[i].active === 0) {
			storm.flakes[i].stick();
		  }
		}
	  }
	};
  
	this.resizeHandler = function () {
	  if (window.innerWidth || window.innerHeight) {
		screenX = window.innerWidth - 16 - storm.flakeRightOffset;
		screenY = storm.flakeBottom || window.innerHeight;
	  } else {
		screenX =
		  (document.documentElement.clientWidth ||
			document.body.clientWidth ||
			document.body.scrollWidth) -
		  (!isIE ? 8 : 0) -
		  storm.flakeRightOffset;
		screenY =
		  storm.flakeBottom ||
		  document.documentElement.clientHeight ||
		  document.body.clientHeight ||
		  document.body.scrollHeight;
	  }
	  docHeight = document.body.offsetHeight;
	  screenX2 = parseInt(screenX / 2, 10);
	};
  
	this.resizeHandlerAlt = function () {
	  screenX = storm.targetElement.offsetWidth - storm.flakeRightOffset;
	  screenY = storm.flakeBottom || storm.targetElement.offsetHeight;
	  screenX2 = parseInt(screenX / 2, 10);
	  docHeight = document.body.offsetHeight;
	};
  
	this.freeze = function () {
	  // pause animation
	  if (!storm.disabled) {
		storm.disabled = 1;
	  } else {
		return false;
	  }
	  storm.timer = null;
	};
  
	this.resume = function () {
	  if (storm.disabled) {
		storm.disabled = 0;
	  } else {
		return false;
	  }
	  storm.timerInit();
	};
  
	this.toggleSnow = function () {
	  if (!storm.flakes.length) {
		// first run
		storm.start();
	  } else {
		storm.active = !storm.active;
		if (storm.active) {
		  storm.show();
		  storm.resume();
		} else {
		  storm.stop();
		  storm.freeze();
		}
	  }
	};
  
	this.stop = function () {
	  var i;
	  this.freeze();
	  for (i = 0; i < this.flakes.length; i++) {
		this.flakes[i].o.style.display = "none";
	  }
	  storm.events.remove(window, "scroll", storm.scrollHandler);
	  storm.events.remove(window, "resize", storm.resizeHandler);
	  if (storm.freezeOnBlur) {
		if (isIE) {
		  storm.events.remove(document, "focusout", storm.freeze);
		  storm.events.remove(document, "focusin", storm.resume);
		} else {
		  storm.events.remove(window, "blur", storm.freeze);
		  storm.events.remove(window, "focus", storm.resume);
		}
	  }
	};
  
	this.show = function () {
	  var i;
	  for (i = 0; i < this.flakes.length; i++) {
		this.flakes[i].o.style.display = "block";
	  }
	};
  
	this.SnowFlake = function (type, x, y) {
	  var s = this;
	  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]; // "amplification" for vX/vY (based on flake size/type)
	  this.vAmp = this.vAmpTypes[this.type] || 1;
	  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;
	  if (storm.className) {
		this.o.setAttribute("class", storm.className);
	  }
	  this.o.style.color = storm.snowColor;
	  this.o.style.position = fixedForEverything ? "fixed" : "absolute";
	  if (storm.useGPU && features.transform.prop) {
		// GPU-accelerated snow.
		this.o.style[features.transform.prop] = "translate3d(0px, 0px, 0px)";
	  }
	  this.o.style.width = storm.flakeWidth + "px";
	  this.o.style.height = storm.flakeHeight + "px";
	  this.o.style.fontFamily = "arial,verdana";
	  this.o.style.cursor = "default";
	  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)) {
		  // safety check
		  return false;
		}
		storm.setXY(s.o, s.x, s.y);
	  };
  
	  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.bottom = "0%";
		  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) {
		  // X-axis scroll check
		  s.x = 0;
		} else if (vX < 0 && s.x - storm.flakeLeftOffset < -storm.flakeWidth) {
		  s.x = screenX - storm.flakeWidth - 1; // flakeWidth;
		}
		s.refresh();
		yDiff = screenY + scrollY - s.y + storm.flakeHeight;
		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
		  ) {
			// ~1/1000 chance of melting mid-air, with each frame
			s.melting = true;
			s.melt();
			// only incrementally melt one frame
			// s.melting = false;
		  }
		  if (storm.useTwinkleEffect) {
			if (s.twinkleFrame < 0) {
			  if (Math.random() > 0.97) {
				s.twinkleFrame = parseInt(Math.random() * 8, 10);
			  }
			} else {
			  s.twinkleFrame--;
			  if (!opacitySupported) {
				s.o.style.visibility =
				  s.twinkleFrame && s.twinkleFrame % 2 === 0
					? "hidden"
					: "visible";
			  } else {
				s.o.style.opacity =
				  s.twinkleFrame && s.twinkleFrame % 2 === 0 ? 0 : 1;
			  }
			}
		  }
		}
	  };
  
	  this.animate = function () {
		// main animation loop
		// move, check status, die etc.
		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.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";
			s.meltFrame++;
		  } 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(); // set up x/y coords etc.
	  this.refresh();
	};
  
	this.snow = function () {
	  var active = 0,
		flake = null,
		i,
		j;
	  for (i = 0, j = storm.flakes.length; i < j; i++) {
		if (storm.flakes[i].active === 1) {
		  storm.flakes[i].move();
		  active++;
		}
		if (storm.flakes[i].melting) {
		  storm.flakes[i].melt();
		}
	  }
	  if (active < storm.flakesMaxActive) {
		flake = storm.flakes[parseInt(rnd(storm.flakes.length), 10)];
		if (flake.active === 0) {
		  flake.melting = true;
		}
	  }
	  if (storm.timer) {
		features.getAnimationFrame(storm.snow);
	  }
	};
  
	this.mouseMove = function (e) {
	  if (!storm.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) {
	  var i;
	  for (i = 0; i < limit; i++) {
		storm.flakes[storm.flakes.length] = new storm.SnowFlake(
		  parseInt(rnd(flakeTypes), 10)
		);
		if (allowInactive || i > storm.flakesMaxActive) {
		  storm.flakes[storm.flakes.length - 1].active = -1;
		}
	  }
	  storm.targetElement.appendChild(docFrag);
	};
  
	this.timerInit = function () {
	  storm.timer = true;
	  storm.snow();
	};
  
	this.init = function () {
	  var i;
	  for (i = 0; i < storm.meltFrameCount; i++) {
		storm.meltFrames.push(1 - i / storm.meltFrameCount);
	  }
	  storm.randomizeWind();
	  storm.createSnow(storm.flakesMax); // create initial batch
	  storm.events.add(window, "resize", storm.resizeHandler);
	  storm.events.add(window, "scroll", storm.scrollHandler);
	  if (storm.freezeOnBlur) {
		if (isIE) {
		  storm.events.add(document, "focusout", storm.freeze);
		  storm.events.add(document, "focusin", storm.resume);
		} else {
		  storm.events.add(window, "blur", storm.freeze);
		  storm.events.add(window, "focus", storm.resume);
		}
	  }
	  storm.resizeHandler();
	  storm.scrollHandler();
	  if (storm.followMouse) {
		storm.events.add(isIE ? document : window, "mousemove", storm.mouseMove);
	  }
	  storm.animationInterval = Math.max(20, storm.animationInterval);
	  storm.timerInit();
	};
  
	this.start = function (bFromOnLoad) {
	  if (!didInit) {
		didInit = true;
	  } else if (bFromOnLoad) {
		// already loaded and running
		return true;
	  }
	  if (typeof storm.targetElement === "string") {
		var targetID = storm.targetElement;
		storm.targetElement = document.getElementById(targetID);
		if (!storm.targetElement) {
		  throw new Error(
			'Snowstorm: Unable to get targetElement "' + targetID + '"'
		  );
		}
	  }
	  if (!storm.targetElement) {
		storm.targetElement = document.body || document.documentElement;
	  }
	  if (
		storm.targetElement !== document.documentElement &&
		storm.targetElement !== document.body
	  ) {
		// re-map handler to get element instead of screen dimensions
		storm.resizeHandler = storm.resizeHandlerAlt;
		//and force-enable pixel positioning
		storm.usePixelPosition = true;
	  }
	  storm.resizeHandler(); // get bounding box elements
	  storm.usePositionFixed =
		storm.usePositionFixed && !noFixed && !storm.flakeBottom; // whether or not position:fixed is to be used
	  if (window.getComputedStyle) {
		// attempt to determine if body or user-specified snow parent element is relatlively-positioned.
		try {
		  targetElementIsRelative =
			window
			  .getComputedStyle(storm.targetElement, null)
			  .getPropertyValue("position") === "relative";
		} catch (e) {
		  // oh well
		  targetElementIsRelative = false;
		}
	  }
	  fixedForEverything = storm.usePositionFixed;
	  if (screenX && screenY && !storm.disabled) {
		storm.init();
		storm.active = true;
	  }
	};
  
	function doDelayedStart() {
	  window.setTimeout(function () {
		storm.start(true);
	  }, 20);
	  // event cleanup
	  storm.events.remove(isIE ? document : window, "mousemove", doDelayedStart);
	}
  
	function doStart() {
	  if (!storm.excludeMobile || !isMobile) {
		doDelayedStart();
	  }
	  // event cleanup
	  storm.events.remove(window, "load", doStart);
	}
  
	// hooks for starting the snow
	if (storm.autoStart) {
	  storm.events.add(window, "load", doStart, false);
	}
  
	return this;
}

snow(80)