/**
 * jQuery || Zepto Parallax Plugin
 * @author Matthew Wagerfield - @wagerfield
 * @description Creates a parallax effect between an array of layers,
 *              driving the motion from the gyroscope output of a smartdevice.
 *              If no gyroscope is available, the cursor position is used.
 */
 ;(function($, window, document, undefined) {

    // Strict Mode
    'use strict';
  
    // Constants
    var NAME = 'parallax';
    var MAGIC_NUMBER = 30;
    var DEFAULTS = {
      relativeInput: false,
      clipRelativeInput: false,
      calibrationThreshold: 100,
      calibrationDelay: 500,
      supportDelay: 500,
      calibrateX: false,
      calibrateY: true,
      invertX: true,
      invertY: true,
      limitX: false,
      limitY: false,
      scalarX: 10.0,
      scalarY: 10.0,
      frictionX: 0.1,
      frictionY: 0.1,
      originX: 0.5,
      originY: 0.5,
      pointerEvents: true,
      precision: 1
    };
  
    function Plugin(element, options) {
  
      // DOM Context
      this.element = element;
  
      // Selections
      this.$context = $(element).data('api', this);
      this.$layers = this.$context.find('.layer');
  
      // Data Extraction
      var data = {
        calibrateX: this.$context.data('calibrate-x') || null,
        calibrateY: this.$context.data('calibrate-y') || null,
        invertX: this.$context.data('invert-x') || null,
        invertY: this.$context.data('invert-y') || null,
        limitX: parseFloat(this.$context.data('limit-x')) || null,
        limitY: parseFloat(this.$context.data('limit-y')) || null,
        scalarX: parseFloat(this.$context.data('scalar-x')) || null,
        scalarY: parseFloat(this.$context.data('scalar-y')) || null,
        frictionX: parseFloat(this.$context.data('friction-x')) || null,
        frictionY: parseFloat(this.$context.data('friction-y')) || null,
        originX: parseFloat(this.$context.data('origin-x')) || null,
        originY: parseFloat(this.$context.data('origin-y')) || null,
        pointerEvents: this.$context.data('pointer-events') || true,
        precision: parseFloat(this.$context.data('precision')) || 1
      };
  
      // Delete Null Data Values
      for (var key in data) {
        if (data[key] === null) delete data[key];
      }
  
      // Compose Settings Object
      $.extend(this, DEFAULTS, options, data);
  
      // States
      this.calibrationTimer = null;
      this.calibrationFlag = true;
      this.enabled = false;
      this.depthsX = [];
      this.depthsY = [];
      this.raf = null;
  
      // Element Bounds
      this.bounds = null;
      this.ex = 0;
      this.ey = 0;
      this.ew = 0;
      this.eh = 0;
  
      // Element Center
      this.ecx = 0;
      this.ecy = 0;
  
      // Element Range
      this.erx = 0;
      this.ery = 0;
  
      // Calibration
      this.cx = 0;
      this.cy = 0;
  
      // Input
      this.ix = 0;
      this.iy = 0;
  
      // Motion
      this.mx = 0;
      this.my = 0;
  
      // Velocity
      this.vx = 0;
      this.vy = 0;
  
      // Callbacks
      this.onMouseMove = this.onMouseMove.bind(this);
      this.onDeviceOrientation = this.onDeviceOrientation.bind(this);
      this.onOrientationTimer = this.onOrientationTimer.bind(this);
      this.onCalibrationTimer = this.onCalibrationTimer.bind(this);
      this.onAnimationFrame = this.onAnimationFrame.bind(this);
      this.onWindowResize = this.onWindowResize.bind(this);
  
      // Initialise
      this.initialise();
    }
  
    Plugin.prototype.transformSupport = function(value) {
      var element = document.createElement('div');
      var propertySupport = false;
      var propertyValue = null;
      var featureSupport = false;
      var cssProperty = null;
      var jsProperty = null;
      for (var i = 0, l = this.vendors.length; i < l; i++) {
        if (this.vendors[i] !== null) {
          cssProperty = this.vendors[i][0] + 'transform';
          jsProperty = this.vendors[i][1] + 'Transform';
        } else {
          cssProperty = 'transform';
          jsProperty = 'transform';
        }
        if (element.style[jsProperty] !== undefined) {
          propertySupport = true;
          break;
        }
      }
      switch(value) {
        case '2D':
          featureSupport = propertySupport;
          break;
        case '3D':
          if (propertySupport) {
            var body = document.body || document.createElement('body');
            var documentElement = document.documentElement;
            var documentOverflow = documentElement.style.overflow;
            var isCreatedBody = false;
            if (!document.body) {
              isCreatedBody = true;
              documentElement.style.overflow = 'hidden';
              documentElement.appendChild(body);
              body.style.overflow = 'hidden';
              body.style.background = '';
            }
            body.appendChild(element);
            element.style[jsProperty] = 'translate3d(1px,1px,1px)';
            propertyValue = window.getComputedStyle(element).getPropertyValue(cssProperty);
            featureSupport = propertyValue !== undefined && propertyValue.length > 0 && propertyValue !== "none";
            documentElement.style.overflow = documentOverflow;
            body.removeChild(element);
            if ( isCreatedBody ) {
              body.removeAttribute('style');
              body.parentNode.removeChild(body);
            }
          }
          break;
      }
      return featureSupport;
    };
  
    Plugin.prototype.ww = null;
    Plugin.prototype.wh = null;
    Plugin.prototype.wcx = null;
    Plugin.prototype.wcy = null;
    Plugin.prototype.wrx = null;
    Plugin.prototype.wry = null;
    Plugin.prototype.portrait = null;
    Plugin.prototype.desktop = !navigator.userAgent.match(/(iPhone|iPod|iPad|Android|BlackBerry|BB10|mobi|tablet|opera mini|nexus 7)/i);
    Plugin.prototype.vendors = [null,['-webkit-','webkit'],['-moz-','Moz'],['-o-','O'],['-ms-','ms']];
    Plugin.prototype.motionSupport = !!window.DeviceMotionEvent;
    Plugin.prototype.orientationSupport = !!window.DeviceOrientationEvent;
    Plugin.prototype.orientationStatus = 0;
    Plugin.prototype.transform2DSupport = Plugin.prototype.transformSupport('2D');
    Plugin.prototype.transform3DSupport = Plugin.prototype.transformSupport('3D');
    Plugin.prototype.propertyCache = {};
  
    Plugin.prototype.initialise = function() {
  
      // Configure Styles
      if (this.$context.css('position') === 'static') {
        this.$context.css({
          position:'relative'
        });
      }
  
      // Pointer events
      if(!this.pointerEvents){
        this.$context.css({
          pointerEvents: 'none'
        });
      }
  
      // Hardware Accelerate Context
      this.accelerate(this.$context);
  
      // Setup
      this.updateLayers();
      this.updateDimensions();
      this.enable();
      this.queueCalibration(this.calibrationDelay);
    };
  
    Plugin.prototype.updateLayers = function() {
  
      // Cache Layer Elements
      this.$layers = this.$context.find('.layer');
      this.depthsX = [];
      this.depthsY = [];
  
      // Configure Layer Styles
      this.$layers.css({
        position:'absolute',
        display:'block',
        left: 0,
        top: 0
      });
      this.$layers.first().css({
        position:'relative'
      });
  
      // Hardware Accelerate Layers
      this.accelerate(this.$layers);
  
      // Cache Depths
      this.$layers.each($.proxy(function(index, element) {
        //Graceful fallback on depth if depth-x or depth-y is absent
        var depth = $(element).data('depth') || 0;
        this.depthsX.push($(element).data('depth-x') || depth);
        this.depthsY.push($(element).data('depth-y') || depth);
      }, this));
    };
  
    Plugin.prototype.updateDimensions = function() {
      this.ww = window.innerWidth;
      this.wh = window.innerHeight;
      this.wcx = this.ww * this.originX;
      this.wcy = this.wh * this.originY;
      this.wrx = Math.max(this.wcx, this.ww - this.wcx);
      this.wry = Math.max(this.wcy, this.wh - this.wcy);
    };
  
    Plugin.prototype.updateBounds = function() {
      this.bounds = this.element.getBoundingClientRect();
      this.ex = this.bounds.left;
      this.ey = this.bounds.top;
      this.ew = this.bounds.width;
      this.eh = this.bounds.height;
      this.ecx = this.ew * this.originX;
      this.ecy = this.eh * this.originY;
      this.erx = Math.max(this.ecx, this.ew - this.ecx);
      this.ery = Math.max(this.ecy, this.eh - this.ecy);
    };
  
    Plugin.prototype.queueCalibration = function(delay) {
      clearTimeout(this.calibrationTimer);
      this.calibrationTimer = setTimeout(this.onCalibrationTimer, delay);
    };
  
    Plugin.prototype.enable = function() {
      if (!this.enabled) {
        this.enabled = true;
        if (this.orientationSupport) {
          this.portrait = null;
          window.addEventListener('deviceorientation', this.onDeviceOrientation);
          setTimeout(this.onOrientationTimer, this.supportDelay);
        } else {
          this.cx = 0;
          this.cy = 0;
          this.portrait = false;
          window.addEventListener('mousemove', this.onMouseMove);
        }
        window.addEventListener('resize', this.onWindowResize);
        this.raf = requestAnimationFrame(this.onAnimationFrame);
      }
    };
  
    Plugin.prototype.disable = function() {
      if (this.enabled) {
        this.enabled = false;
        if (this.orientationSupport) {
          window.removeEventListener('deviceorientation', this.onDeviceOrientation);
        } else {
          window.removeEventListener('mousemove', this.onMouseMove);
        }
        window.removeEventListener('resize', this.onWindowResize);
        cancelAnimationFrame(this.raf);
      }
    };
  
    Plugin.prototype.calibrate = function(x, y) {
      this.calibrateX = x === undefined ? this.calibrateX : x;
      this.calibrateY = y === undefined ? this.calibrateY : y;
    };
  
    Plugin.prototype.invert = function(x, y) {
      this.invertX = x === undefined ? this.invertX : x;
      this.invertY = y === undefined ? this.invertY : y;
    };
  
    Plugin.prototype.friction = function(x, y) {
      this.frictionX = x === undefined ? this.frictionX : x;
      this.frictionY = y === undefined ? this.frictionY : y;
    };
  
    Plugin.prototype.scalar = function(x, y) {
      this.scalarX = x === undefined ? this.scalarX : x;
      this.scalarY = y === undefined ? this.scalarY : y;
    };
  
    Plugin.prototype.limit = function(x, y) {
      this.limitX = x === undefined ? this.limitX : x;
      this.limitY = y === undefined ? this.limitY : y;
    };
  
    Plugin.prototype.origin = function(x, y) {
      this.originX = x === undefined ? this.originX : x;
      this.originY = y === undefined ? this.originY : y;
    };
  
    Plugin.prototype.clamp = function(value, min, max) {
      value = Math.max(value, min);
      value = Math.min(value, max);
      return value;
    };
  
    Plugin.prototype.css = function(element, property, value) {
      var jsProperty = this.propertyCache[property];
      if (!jsProperty) {
        for (var i = 0, l = this.vendors.length; i < l; i++) {
          if (this.vendors[i] !== null) {
            jsProperty = $.camelCase(this.vendors[i][1] + '-' + property);
          } else {
            jsProperty = property;
          }
          if (element.style[jsProperty] !== undefined) {
            this.propertyCache[property] = jsProperty;
            break;
          }
        }
      }
      element.style[jsProperty] = value;
    };
  
    Plugin.prototype.accelerate = function($element) {
      for (var i = 0, l = $element.length; i < l; i++) {
        var element = $element[i];
        this.css(element, 'transform', 'translate3d(0,0,0)');
        this.css(element, 'transform-style', 'preserve-3d');
        this.css(element, 'backface-visibility', 'hidden');
      }
    };
  
    Plugin.prototype.setPosition = function(element, x, y) {
      x += 'px';
      y += 'px';
      if (this.transform3DSupport) {
        this.css(element, 'transform', 'translate3d('+x+','+y+',0)');
      } else if (this.transform2DSupport) {
        this.css(element, 'transform', 'translate('+x+','+y+')');
      } else {
        element.style.left = x;
        element.style.top = y;
      }
    };
  
    Plugin.prototype.onOrientationTimer = function(event) {
      if (this.orientationSupport && this.orientationStatus === 0) {
        this.disable();
        this.orientationSupport = false;
        this.enable();
      }
    };
  
    Plugin.prototype.onCalibrationTimer = function(event) {
      this.calibrationFlag = true;
    };
  
    Plugin.prototype.onWindowResize = function(event) {
      this.updateDimensions();
    };
  
    Plugin.prototype.onAnimationFrame = function() {
      this.updateBounds();
      var dx = this.ix - this.cx;
      var dy = this.iy - this.cy;
      if ((Math.abs(dx) > this.calibrationThreshold) || (Math.abs(dy) > this.calibrationThreshold)) {
        this.queueCalibration(0);
      }
      if (this.portrait) {
        this.mx = this.calibrateX ? dy : this.iy;
        this.my = this.calibrateY ? dx : this.ix;
      } else {
        this.mx = this.calibrateX ? dx : this.ix;
        this.my = this.calibrateY ? dy : this.iy;
      }
      this.mx *= this.ew * (this.scalarX / 100);
      this.my *= this.eh * (this.scalarY / 100);
      if (!isNaN(parseFloat(this.limitX))) {
        this.mx = this.clamp(this.mx, -this.limitX, this.limitX);
      }
      if (!isNaN(parseFloat(this.limitY))) {
        this.my = this.clamp(this.my, -this.limitY, this.limitY);
      }
      this.vx += (this.mx - this.vx) * this.frictionX;
      this.vy += (this.my - this.vy) * this.frictionY;
      for (var i = 0, l = this.$layers.length; i < l; i++) {
        var depthX = this.depthsX[i];
        var depthY = this.depthsY[i];
        var layer = this.$layers[i];
        var xOffset = this.vx * (depthX * (this.invertX ? -1 : 1));
        var yOffset = this.vy * (depthY * (this.invertY ? -1 : 1));
        this.setPosition(layer, xOffset, yOffset);
      }
      this.raf = requestAnimationFrame(this.onAnimationFrame);
    };
  
    Plugin.prototype.onDeviceOrientation = function(event) {
  
      // Validate environment and event properties.
      if (!this.desktop && event.beta !== null && event.gamma !== null) {
  
        // Set orientation status.
        this.orientationStatus = 1;
  
        // Extract Rotation
        var x = (event.beta  || 0) / MAGIC_NUMBER; //  -90 :: 90
        var y = (event.gamma || 0) / MAGIC_NUMBER; // -180 :: 180
  
        // Detect Orientation Change
        var portrait = window.innerHeight > window.innerWidth;
        if (this.portrait !== portrait) {
          this.portrait = portrait;
          this.calibrationFlag = true;
        }
  
        // Set Calibration
        if (this.calibrationFlag) {
          this.calibrationFlag = false;
          this.cx = x;
          this.cy = y;
        }
  
        // Set Input
        this.ix = x;
        this.iy = y;
      }
    };
  
    Plugin.prototype.onMouseMove = function(event) {
  
      // Cache mouse coordinates.
      var clientX = event.clientX;
      var clientY = event.clientY;
  
      // Calculate Mouse Input
      if (!this.orientationSupport && this.relativeInput) {
  
        // Clip mouse coordinates inside element bounds.
        if (this.clipRelativeInput) {
          clientX = Math.max(clientX, this.ex);
          clientX = Math.min(clientX, this.ex + this.ew);
          clientY = Math.max(clientY, this.ey);
          clientY = Math.min(clientY, this.ey + this.eh);
        }
  
        // Calculate input relative to the element.
        this.ix = (clientX - this.ex - this.ecx) / this.erx;
        this.iy = (clientY - this.ey - this.ecy) / this.ery;
  
      } else {
  
        // Calculate input relative to the window.
        this.ix = (clientX - this.wcx) / this.wrx;
        this.iy = (clientY - this.wcy) / this.wry;
      }
    };
  
    var API = {
      enable: Plugin.prototype.enable,
      disable: Plugin.prototype.disable,
      updateLayers: Plugin.prototype.updateLayers,
      calibrate: Plugin.prototype.calibrate,
      friction: Plugin.prototype.friction,
      invert: Plugin.prototype.invert,
      scalar: Plugin.prototype.scalar,
      limit: Plugin.prototype.limit,
      origin: Plugin.prototype.origin
    };
  
    $.fn[NAME] = function (value) {
      var args = arguments;
      return this.each(function () {
        var $this = $(this);
        var plugin = $this.data(NAME);
        if (!plugin) {
          plugin = new Plugin(this, value);
          $this.data(NAME, plugin);
        }
        if (API[value]) {
          plugin[value].apply(plugin, Array.prototype.slice.call(args, 1));
        }
      });
    };
  
  })(window.jQuery || window.Zepto, window, document);