/*
 * 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); 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();

    },
    stop: function() {

      // cancel slideshow
      stop();

    },
    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 = '';
      element.style.left = '';

      // reset slides
      var pos = slides.length;
      while(pos--) {

        var slide = slides[pos];
        slide.style.width = '';
        slide.style.left = '';

        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 )
}