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/*

 * Swipe 2.0

 *

 * Brad Birdsall

 * Copyright 2013, MIT License

 *

*/

function Swipe(container, options) {

  "use strict";

  // utilities

  var noop = function() {}; // simple no operation function

  var offloadFn = function(fn) { setTimeout(fn || noop, 0) }; // offload a functions execution

  // check browser capabilities

  var browser = {

    addEventListener: !!window.addEventListener,

    touch: ('ontouchstart' in window) || window.DocumentTouch && document instanceof DocumentTouch,

    transitions: (function(temp) {

      var props = ['transitionProperty', 'WebkitTransition', 'MozTransition', 'OTransition', 'msTransition'];

      for ( var i in props ) if (temp.style[ props[i] ] !== undefined) return true;

      return false;

    })(document.createElement('swipe'))

  };

  // quit if no root element

  if (!container) return;

  var element = container.children[0];

  var slides, slidePos, width, length;

  options = options || {};

  var index = parseInt(options.startSlide, 10) || 0;

  var speed = options.speed || 300;

  options.continuous = options.continuous !== undefined ? options.continuous : true;

  function setup() {

    // cache slides

    slides = element.children;

    length = slides.length;

    // set continuous to false if only one slide

    if (slides.length < 2) options.continuous = false;

    //special case if two slides

    if (browser.transitions && options.continuous && slides.length < 3) {

      element.appendChild(slides[0].cloneNode(true));

      element.appendChild(element.children[1].cloneNode(true));

      slides = element.children;

    }

    // create an array to store current positions of each slide

    slidePos = new Array(slides.length);

    // determine width of each slide

    width = container.getBoundingClientRect().width || container.offsetWidth;

    element.style.width = (slides.length * width) + 'px';

    // stack elements

    var pos = slides.length;

    while(pos--) {

      var slide = slides[pos];

      slide.style.width = width + 'px';

      slide.setAttribute('data-index', pos);

      if (browser.transitions) {

        slide.style.left = (pos * -width) + 'px';

        move(pos, index > pos ? -width : (index < pos ? width : 0), 0);

      }

    }

    // reposition elements before and after index

    if (options.continuous && browser.transitions) {

      move(circle(index-1), -width, 0);

      move(circle(index+1), width, 0);

    }

    if (!browser.transitions) element.style.left = (index * -width) + 'px';

    container.style.visibility = 'visible';

  }

  function prev() {

    if (options.continuous) slide(index-1);

    else if (index) slide(index-1);

  }

  function next() {

    if (options.continuous) slide(index+1);

    else if (index < slides.length - 1) slide(index+1);

  }

  function circle(index) {

    // a simple positive modulo using slides.length

    return (slides.length + (index % slides.length)) % slides.length;

  }

  function slide(to, slideSpeed) {

    // do nothing if already on requested slide

    if (index == to) return;

    if (browser.transitions) {

      var direction = Math.abs(index-to) / (index-to); // 1: backward, -1: forward

      // get the actual position of the slide

      if (options.continuous) {

        var natural_direction = direction;

        direction = -slidePos[circle(to)] / width;

        // if going forward but to < index, use to = slides.length + to

        // if going backward but to > index, use to = -slides.length + to

        if (direction !== natural_direction) to =  -direction * slides.length + to;

      }

      var diff = Math.abs(index-to) - 1;

      // move all the slides between index and to in the right direction

      while (diff--) move( circle((to > index ? to : index) - diff - 1), width * direction, 0);

      to = circle(to);

      move(index, width * direction, slideSpeed || speed);

      move(to, 0, slideSpeed || speed);

      if (options.continuous) move(circle(to - direction), -(width * direction), 0); // we need to get the next in place

    } else {     

      to = circle(to);

      animate(index * -width, to * -width, slideSpeed || speed);

      //no fallback for a circular continuous if the browser does not accept transitions

    }

    index = to;

    offloadFn(options.callback && options.callback(index, slides[index]));

  }

  function move(index, dist, speed) {

    translate(index, dist, speed);

    slidePos[index] = dist;

  }

  function translate(index, dist, speed) {

    var slide = slides[index];

    var style = slide && slide.style;

    if (!style) return;

    style.webkitTransitionDuration = 

    style.MozTransitionDuration = 

    style.msTransitionDuration = 

    style.OTransitionDuration = 

    style.transitionDuration = speed + 'ms';

    style.webkitTransform = 'translate(' + dist + 'px,0)' + 'translateZ(0)';

    style.msTransform = 

    style.MozTransform = 

    style.OTransform = 'translateX(' + dist + 'px)';

  }

  function animate(from, to, speed) {

    // if not an animation, just reposition

    if (!speed) {

      element.style.left = to + 'px';

      return;

    }

    var start = +new Date;

    var timer = setInterval(function() {

      var timeElap = +new Date - start;

      if (timeElap > speed) {

        element.style.left = to + 'px';

        if (delay) begin();

        options.transitionEnd && options.transitionEnd.call(event, index, slides[index]);

        clearInterval(timer);

        return;

      }

      element.style.left = (( (to - from) * (Math.floor((timeElap / speed) * 100) / 100) ) + from) + 'px';

    }, 4);

  }

  // setup auto slideshow

  var delay = options.auto || 0;

  var interval;

  function begin() {

    interval = setTimeout(next, delay);

  }

  function stop() {

    delay = 0;

    clearTimeout(interval);

  }

  // setup initial vars

  var start = {};

  var delta = {};

  var isScrolling;      

  // setup event capturing

  var events = {

    handleEvent: function(event) {

      switch (event.type) {

        case 'touchstart': this.start(event); break;

        case 'touchmove': this.move(event); break;

        case 'touchend': offloadFn(this.end(event)); break;

        case 'webkitTransitionEnd':

        case 'msTransitionEnd':

        case 'oTransitionEnd':

        case 'otransitionend':

        case 'transitionend': offloadFn(this.transitionEnd(event)); break;

        case 'resize': offloadFn(setup.call()); break;

      }

      if (options.stopPropagation) event.stopPropagation();

    },

    start: function(event) {

      var touches = event.touches[0];

      // measure start values

      start = {

        // get initial touch coords

        x: touches.pageX,

        y: touches.pageY,

        // store time to determine touch duration

        time: +new Date

      };

      // used for testing first move event

      isScrolling = undefined;

      // reset delta and end measurements

      delta = {};

      // attach touchmove and touchend listeners

      element.addEventListener('touchmove', this, false);

      element.addEventListener('touchend', this, false);

    },

    move: function(event) {

      // ensure swiping with one touch and not pinching

      if ( event.touches.length > 1 || event.scale && event.scale !== 1) return

      if (options.disableScroll) event.preventDefault();

      var touches = event.touches[0];

      // measure change in x and y

      delta = {

        x: touches.pageX - start.x,

        y: touches.pageY - start.y

      }

      // determine if scrolling test has run - one time test

      if ( typeof isScrolling == 'undefined') {

        isScrolling = !!( isScrolling || Math.abs(delta.x) < Math.abs(delta.y) );

      }

      // if user is not trying to scroll vertically

      if (!isScrolling) {

        // prevent native scrolling 

        event.preventDefault();

        // stop slideshow

        stop();

        // increase resistance if first or last slide

        if (options.continuous) { // we don't add resistance at the end

          translate(circle(index-1), delta.x + slidePos[circle(index-1)], 0);

          translate(index, delta.x + slidePos[index], 0);

          translate(circle(index+1), delta.x + slidePos[circle(index+1)], 0);

        } else {

          delta.x = 

            delta.x / 

              ( (!index && delta.x > 0               // if first slide and sliding left

                || index == slides.length - 1        // or if last slide and sliding right

                && delta.x < 0                       // and if sliding at all

              ) ?                      

              ( Math.abs(delta.x) / width + 1 )      // determine resistance level

              : 1 );                                 // no resistance if false

          // translate 1:1

          translate(index-1, delta.x + slidePos[index-1], 0);

          translate(index, delta.x + slidePos[index], 0);

          translate(index+1, delta.x + slidePos[index+1], 0);

        }

      }

    },

    end: function(event) {

      // measure duration

      var duration = +new Date - start.time;

      // determine if slide attempt triggers next/prev slide

      var isValidSlide = 

            Number(duration) < 250               // if slide duration is less than 250ms

            && Math.abs(delta.x) > 20            // and if slide amt is greater than 20px

            || Math.abs(delta.x) > width/2;      // or if slide amt is greater than half the width

      // determine if slide attempt is past start and end

      var isPastBounds = 

            !index && delta.x > 0                            // if first slide and slide amt is greater than 0

            || index == slides.length - 1 && delta.x < 0;    // or if last slide and slide amt is less than 0

      if (options.continuous) isPastBounds = false;

      // determine direction of swipe (true:right, false:left)

      var direction = delta.x < 0;

      // if not scrolling vertically

      if (!isScrolling) {

        if (isValidSlide && !isPastBounds) {

          if (direction) {

            if (options.continuous) { // we need to get the next in this direction in place

              move(circle(index-1), -width, 0);

              move(circle(index+2), width, 0);

            } else {

              move(index-1, -width, 0);

            }

            move(index, slidePos[index]-width, speed);

            move(circle(index+1), slidePos[circle(index+1)]-width, speed);

            index = circle(index+1);  

          } else {

            if (options.continuous) { // we need to get the next in this direction in place

              move(circle(index+1), width, 0);

              move(circle(index-2), -width, 0);

            } else {

              move(index+1, width, 0);

            }

            move(index, slidePos[index]+width, speed);

            move(circle(index-1), slidePos[circle(index-1)]+width, speed);

            index = circle(index-1);

          }

          options.callback && options.callback(index, slides[index]);

        } else {

          if (options.continuous) {

            move(circle(index-1), -width, speed);

            move(index, 0, speed);

            move(circle(index+1), width, speed);

          } else {

            move(index-1, -width, speed);

            move(index, 0, speed);

            move(index+1, width, speed);

          }

        }

      }

      // kill touchmove and touchend event listeners until touchstart called again

      element.removeEventListener('touchmove', events, false)

      element.removeEventListener('touchend', events, false)

    },

    transitionEnd: function(event) {

      if (parseInt(event.target.getAttribute('data-index'), 10) == index) {

        if (delay) begin();

        options.transitionEnd && options.transitionEnd.call(event, index, slides[index]);

      }

    }

  }

  // trigger setup

  setup();

  // start auto slideshow if applicable

  if (delay) begin();

  // add event listeners

  if (browser.addEventListener) {

    // set touchstart event on element    

    if (browser.touch) element.addEventListener('touchstart', events, false);

    if (browser.transitions) {

      element.addEventListener('webkitTransitionEnd', events, false);

      element.addEventListener('msTransitionEnd', events, false);

      element.addEventListener('oTransitionEnd', events, false);

      element.addEventListener('otransitionend', events, false);

      element.addEventListener('transitionend', events, false);

    }

    // set resize event on window

    window.addEventListener('resize', events, false);

  } else {

    window.onresize = function () { setup() }; // to play nice with old IE

  }

  // expose the Swipe API

  return {

    setup: function() {

      setup();

    },

    slide: function(to, speed) {

      // cancel slideshow

      stop();

      slide(to, speed);

    },

    prev: function() {

      // cancel slideshow

      stop();

      prev();

    },

    next: function() {

      // cancel slideshow

      stop();

      next();

    },

    getPos: function() {

      // return current index position

      return index;

    },

    getNumSlides: function() {

      // return total number of slides

      return length;

    },

    kill: function() {

      // cancel slideshow

      stop();

      // reset element

      element.style.width = 'auto';

      element.style.left = 0;

      // reset slides

      var pos = slides.length;

      while(pos--) {

        var slide = slides[pos];

        slide.style.width = '100%';

        slide.style.left = 0;

        if (browser.transitions) translate(pos, 0, 0);

      }

      // removed event listeners

      if (browser.addEventListener) {

        // remove current event listeners

        element.removeEventListener('touchstart', events, false);

        element.removeEventListener('webkitTransitionEnd', events, false);

        element.removeEventListener('msTransitionEnd', events, false);

        element.removeEventListener('oTransitionEnd', events, false);

        element.removeEventListener('otransitionend', events, false);

        element.removeEventListener('transitionend', events, false);

        window.removeEventListener('resize', events, false);

      }

      else {

        window.onresize = null;

      }

    }

  }

}

if ( window.jQuery || window.Zepto ) {

  (function($) {

    $.fn.Swipe = function(params) {

      return this.each(function() {

        $(this).data('Swipe', new Swipe($(this)[0], params));

      });

    }

  })( window.jQuery || window.Zepto )

}