/*
 * Swipe 2.0
 *
 * Brad Birdsall
 * Copyright 2012, Licensed GPL & MIT
 *
*/

window.Swipe = function(element, options) {

  var _this = this;

  // return immediately if element doesn't exist
  if (!element) return;

  // reference dom elements
  this.container = element;
  this.element = this.container.children[0];

  // simple feature detection
  this.browser = {
    touch: (function() {
      return ('ontouchstart' in window) || window.DocumentTouch && document instanceof DocumentTouch;
    })(),
    transitions: (function() {
      var temp = document.createElement('swipe'),
          props = ['perspectiveProperty', 'WebkitPerspective', 'MozPerspective', 'OPerspective', 'msPerspective'];
      for ( var i in props ) {
        if (temp.style[ props[i] ] !== undefined) return true;
      }
      return false;
    })()
  };

  // retreive options
  options = options || {};
  this.index = options.startSlide || 0;
  this.speed = options.speed || 300;
  this.callback = options.callback || function() {};
  this.transitionEnd = options.transitionEnd || function() {};
  this.delay = options.auto || 0;
  this.cont = (options.continuous != undefined) ? !!options.continuous : true;
  this.disableScroll = !!options.disableScroll;

  // verify index is a number not string
  this.index = parseInt(this.index,10);

  // trigger slider initialization
  this.setup();

  // begin auto slideshow
  this.begin();

  // add event listeners
  if (this.element.addEventListener) {
    if (!!this.browser.touch) {
      this.element.addEventListener('touchstart', this, false);
      this.element.addEventListener('touchmove', this, false);
      this.element.addEventListener('touchend', this, false);
    }
    if (!!this.browser.transitions) {
      this.element.addEventListener('webkitTransitionEnd', this, false);
      this.element.addEventListener('msTransitionEnd', this, false);
      this.element.addEventListener('oTransitionEnd', this, false);
      this.element.addEventListener('transitionend', this, false);
    }
    window.addEventListener('resize', this, false);
  }

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

};

Swipe.prototype = {

  setup: function() {
    // get and measure amt of slides
    this.slides = this.element.children;
    this.length = this.slides.length;
    this.cache = new Array(this.length);
	
    // return immediately if their are less than two slides
    //if (this.length < 2) return;

    // determine width of each slide
    this.width = this.container.getBoundingClientRect().width || this.container.offsetWidth;

    // return immediately if measurement fails
    if (!this.width) return;

    // store array of slides before, current, and after
    var refArray = [[],[],[]];

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

    // stack elements
    for (var index = this.length - 1; index > -1; index--) {

      var elem = this.slides[index];

      elem.style.width = this.width + 'px';
      elem.setAttribute('data-index', index);

      if (this.browser.transitions) {
        elem.style.left = (index * -this.width) + 'px';
      }

      // add this index to the reference array    0:before 1:equal 2:after
      refArray[this.index > index ? 0 : (this.index < index ? 2 : 1)].push(index);

    }

    if (this.browser.transitions) {
      
      // stack left, current, and right slides
      this._stack(refArray[0],-1);
      this._stack(refArray[1],0);
      this._stack(refArray[2],1);

    }

    this.container.style.visibility = 'visible';

  },

  kill: function() {

    // cancel slideshow
    this.delay = 0;
    clearTimeout(this.interval);

    // clear all translations
    var slideArray = [];
    for (var i = this.slides.length - 1; i >= 0; i--) {
      this.slides[i].style.width = '';
      slideArray.push(i);
    }
    this._stack(slideArray,0);

    var elem = this.element;
    elem.className = elem.className.replace('swipe-active','');

    // remove event listeners
    if (this.element.removeEventListener) {
      if (!!this.browser.touch) {
        this.element.removeEventListener('touchstart', this, false);
        this.element.removeEventListener('touchmove', this, false);
        this.element.removeEventListener('touchend', this, false);
      }
      if (!!this.browser.transitions) {
        this.element.removeEventListener('webkitTransitionEnd', this, false);
        this.element.removeEventListener('msTransitionEnd', this, false);
        this.element.removeEventListener('oTransitionEnd', this, false);
        this.element.removeEventListener('transitionend', this, false);
      }
      window.removeEventListener('resize', this.resize, false);
    }

    // kill old IE! you can quote me on that ;)
    else {
      window.onresize = null;
    }

  },  

  getPos: function() {
    
    // return current index position
    return this.index;

  },

  prev: function(delay) {

    // cancel slideshow
    this.delay = delay || 0;
    clearTimeout(this.interval);

    // if not at first slide
    if (this.index) this.slide(this.index-1, this.speed);
    else if (this.cont) this.slide(this.length-1, this.speed);

  },

  next: function(delay) {

    // cancel slideshow
    this.delay = delay || 0;
    clearTimeout(this.interval);

    if (this.index < this.length - 1) this.slide(this.index+1, this.speed); // if not last slide
    else if (this.cont) this.slide(0, this.speed); //if last slide return to start

  },

  begin: function() {

    var _this = this;

    this.interval = (this.delay)
      ? setTimeout(function() { 
        _this.next(_this.delay);
      }, this.delay)
      : 0;
    
  },

  handleEvent: function(e) {
    switch (e.type) {
      case 'touchstart': this.onTouchStart(e); break;
      case 'touchmove': this.onTouchMove(e); break;
      case 'touchend': this.onTouchEnd(e); break;
      case 'webkitTransitionEnd':
      case 'msTransitionEnd':
      case 'oTransitionEnd':
      case 'transitionend': this.onTransitionEnd(e); break;
      case 'resize': this.setup(); break;
    }
    
    e.stopPropagation();
  },

  onTouchStart: function(e) {

    var _this = this;
    
    _this.start = {

      // get touch coordinates for delta calculations in onTouchMove
      pageX: e.touches[0].pageX,
      pageY: e.touches[0].pageY,

      // set initial timestamp of touch sequence
      time: Number( new Date() )

    };

    // used for testing first onTouchMove event
    _this.isScrolling = undefined;
    
    // reset deltaX
    _this.deltaX = 0;

  },

  onTouchMove: function(e) {

    var _this = this;

    // ensure swiping with one touch and not pinching
    if(e.touches.length > 1 || e.scale && e.scale !== 1) return;

    _this.deltaX = e.touches[0].pageX - _this.start.pageX;

    // determine if scrolling test has run - one time test
    if ( typeof _this.isScrolling == 'undefined') {
      _this.isScrolling = !!( _this.isScrolling || Math.abs(_this.deltaX) < Math.abs(e.touches[0].pageY - _this.start.pageY) );
    }

    // if user is not trying to scroll vertically
    if (!_this.isScrolling) {

      // prevent native scrolling 
      e.preventDefault();

      // cancel slideshow
      _this.delay = 0;
      clearTimeout(_this.interval);

      // increase resistance if first or last slide
      _this.deltaX = 
        _this.deltaX / 
          ( (!_this.index && _this.deltaX > 0               // if first slide and sliding left
            || _this.index == _this.length - 1              // or if last slide and sliding right
            && _this.deltaX < 0                            // and if sliding at all
          ) ?                      
          ( Math.abs(_this.deltaX) / _this.width + 1 )      // determine resistance level
          : 1 );                                          // no resistance if false
      
      // translate immediately 1:1
      _this._move([_this.index-1,_this.index,_this.index+1],_this.deltaX);

    } else if (_this.disableScroll) {

      // prevent native scrolling 
      e.preventDefault();

    }

  },

  onTouchEnd: function(e) {

    var _this = this;

    // determine if slide attempt triggers next/prev slide
    var isValidSlide = 
          Number(new Date()) - _this.start.time < 250      // if slide duration is less than 250ms
          && Math.abs(_this.deltaX) > 20                   // and if slide amt is greater than 20px
          || Math.abs(_this.deltaX) > _this.width/2,        // or if slide amt is greater than half the width

    // determine if slide attempt is past start and end
        isPastBounds = 
          !_this.index && _this.deltaX > 0                          // if first slide and slide amt is greater than 0
          || _this.index == _this.length - 1 && _this.deltaX < 0,    // or if last slide and slide amt is less than 0
        
        direction = _this.deltaX < 0; // true:right false:left

    // if not scrolling vertically
    if (!_this.isScrolling) {

      if (isValidSlide && !isPastBounds) {
        if (direction) {
          _this._stack([_this.index-1],-1);
          _this._slide([_this.index,_this.index+1],-_this.width,_this.speed);
          _this.index += 1;
        } else {
          _this._stack([_this.index+1],1);
          _this._slide([_this.index-1,_this.index],_this.width,_this.speed);
          _this.index += -1;
        }
        _this.callback(_this.index, _this.slides[_this.index]);
      } else {
        _this._slide([_this.index-1,_this.index,_this.index+1],0,_this.speed);
      }

    }

  },

  onTransitionEnd: function(e) {

    if (this._getElemIndex(e.target) == this.index) { // only call transition end on the main slide item

      if (this.delay) this.begin();

      this.transitionEnd(this.index, this.slides[this.index]);

    }

  },

  slide: function(to, speed) {
    
    var from = this.index;

    if (from == to) return; // do nothing if already on requested slide
    
    if (this.browser.transitions) {
      var toStack = Math.abs(from-to) - 1,
          direction = Math.abs(from-to) / (from-to), // 1:right -1:left
          inBetween = [];

      while (toStack--) inBetween.push( (to > from ? to : from) - toStack - 1 );

      // stack em
      this._stack(inBetween,direction);

      // now slide from and to in the proper direction
      this._slide([from,to],this.width * direction,this.speed);
    }
    else {
      this._animate(from*-this.width, to * -this.width, this.speed)
    }

    this.index = to;

    this.callback(this.index, this.slides[this.index]);

  },

  _slide: function(nums, dist, speed) {

    var _slides = this.slides,
        l = nums.length;

    while(l--) {

      this._translate(_slides[nums[l]], dist + this.cache[nums[l]], speed ? speed : 0);

      this.cache[nums[l]] += dist;

    }

  },

  _stack: function(nums, pos) {  // pos: -1:left 0:center 1:right

    var _slides = this.slides,
        l = nums.length,
        dist = this.width * pos;

    while(l--) {
      
      this._translate(_slides[nums[l]], dist, 0);

      this.cache[nums[l]] = dist;

    }

  },

  _move: function(nums, dist) { // 1:1 scrolling

    var _slides = this.slides,
        l = nums.length;

    while(l--) this._translate(_slides[nums[l]], dist + this.cache[nums[l]], 0);

  },

  _translate: function(elem, xval, speed) {
    
    if (!elem) return;

    var style = elem.style;

    // set duration speed to 0
    style.webkitTransitionDuration = 
    style.MozTransitionDuration = 
    style.msTransitionDuration = 
    style.OTransitionDuration = 
    style.transitionDuration = speed + 'ms';

    // translate to given position
    style.webkitTransform = 'translate(' + xval + 'px,0)' + 'translateZ(0)';
    style.msTransform = 
    style.MozTransform = 
    style.OTransform = 'translateX(' + xval + 'px)';

  },

  _animate: function(from, to, speed) {

    var elem = this.element;

    if (!speed) { // if not an animation, just reposition
      
      elem.style.left = to + 'px';

      return;

    }
    
    var _this = this,
        start = new Date(),
        timer = setInterval(function() {

          var timeElap = new Date() - start;

          if (timeElap > speed) {

            elem.style.left = to + 'px';  // callback after this line

            if (_this._getElemIndex(elem) == _this.index) { // only call transition end on the main slide item

              if (_this.delay) _this.begin();
            
              _this.transitionEnd(_this.index, _this.slides[_this.index]);

            }

            clearInterval(timer);

            return;

          }

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

        }, 4);

  },

  _getElemIndex: function(elem) {
    
    return parseInt(elem.getAttribute('data-index'),10);

  }

};


if ( window.jQuery || window.Zepto ) {
  (function($) {
    $.fn.Swipe = function(params) {
      return this.each(function() {
        var _this = $(this);
        _this.data('Swipe', new Swipe(_this[0], params));
      });
    }
  })( window.jQuery || window.Zepto )
}