(function($) {
var version = '1.5.2',
    optionOverrides = {},
    defaults = {
      exclude: [],
      excludeWithin:[],
      offset: 0,

      // one of 'top' or 'left'
      direction: 'top',

      // jQuery set of elements you wish to scroll (for $.smoothScroll).
      //  if null (default), $('html, body').firstScrollable() is used.
      scrollElement: null,

      // only use if you want to override default behavior
      scrollTarget: null,

      // fn(opts) function to be called before scrolling occurs.
      // `this` is the element(s) being scrolled
      beforeScroll: function() {},

      // fn(opts) function to be called after scrolling occurs.
      // `this` is the triggering element
      afterScroll: function() {},
      easing: 'swing',
      speed: 400,

      // coefficient for "auto" speed
      autoCoefficient: 2,

      // $.fn.smoothScroll only: whether to prevent the default click action
      preventDefault: true
    },

    getScrollable = function(opts) {
      var scrollable = [],
          scrolled = false,
          dir = opts.dir && opts.dir === 'left' ? 'scrollLeft' : 'scrollTop';

      this.each(function() {

        if (this === document || this === window) { return; }
        var el = $(this);
        if ( el[dir]() > 0 ) {
          scrollable.push(this);
        } else {
          // if scroll(Top|Left) === 0, nudge the element 1px and see if it moves
          el[dir](1);
          scrolled = el[dir]() > 0;
          if ( scrolled ) {
            scrollable.push(this);
          }
          // then put it back, of course
          el[dir](0);
        }
      });

      // If no scrollable elements, fall back to <body>,
      // if it's in the jQuery collection
      // (doing this because Safari sets scrollTop async,
      // so can't set it to 1 and immediately get the value.)
      if (!scrollable.length) {
        this.each(function() {
          if (this.nodeName === 'BODY') {
            scrollable = [this];
          }
        });
      }

      // Use the first scrollable element if we're calling firstScrollable()
      if ( opts.el === 'first' && scrollable.length > 1 ) {
        scrollable = [ scrollable[0] ];
      }

      return scrollable;
    };

$.fn.extend({
  scrollable: function(dir) {
    var scrl = getScrollable.call(this, {dir: dir});
    return this.pushStack(scrl);
  },
  firstScrollable: function(dir) {
    var scrl = getScrollable.call(this, {el: 'first', dir: dir});
    return this.pushStack(scrl);
  },

  smoothScroll: function(options, extra) {
    options = options || {};

    if ( options === 'options' ) {
      if ( !extra ) {
        return this.first().data('ssOpts');
      }
      return this.each(function() {
        var $this = $(this),
            opts = $.extend($this.data('ssOpts') || {}, extra);

        $(this).data('ssOpts', opts);
      });
    }

    var opts = $.extend({}, $.fn.smoothScroll.defaults, options),
        locationPath = $.smoothScroll.filterPath(location.pathname);

    this
    .unbind('click.smoothscroll')
    .bind('click.smoothscroll', function(event) {
      var link = this,
          $link = $(this),
          thisOpts = $.extend({}, opts, $link.data('ssOpts') || {}),
          exclude = opts.exclude,
          excludeWithin = thisOpts.excludeWithin,
          elCounter = 0, ewlCounter = 0,
          include = true,
          clickOpts = {},
          hostMatch = ((location.hostname === link.hostname) || !link.hostname),
          pathMatch = thisOpts.scrollTarget || ( $.smoothScroll.filterPath(link.pathname) === locationPath ),
          thisHash = escapeSelector(link.hash);

      if ( !thisOpts.scrollTarget && (!hostMatch || !pathMatch || !thisHash) ) {
        include = false;
      } else {
        while (include && elCounter < exclude.length) {
          if ($link.is(escapeSelector(exclude[elCounter++]))) {
            include = false;
          }
        }
        while ( include && ewlCounter < excludeWithin.length ) {
          if ($link.closest(excludeWithin[ewlCounter++]).length) {
            include = false;
          }
        }
      }

      if ( include ) {

        if ( thisOpts.preventDefault ) {
          event.preventDefault();
        }

        $.extend( clickOpts, thisOpts, {
          scrollTarget: thisOpts.scrollTarget || thisHash,
          link: link
        });

        $.smoothScroll( clickOpts );
      }
    });

    return this;
  }
});

$.smoothScroll = function(options, px) {
  if ( options === 'options' && typeof px === 'object' ) {
    return $.extend(optionOverrides, px);
  }
  var opts, $scroller, scrollTargetOffset, speed, delta,
      scrollerOffset = 0,
      offPos = 'offset',
      scrollDir = 'scrollTop',
      aniProps = {},
      aniOpts = {};

  if (typeof options === 'number') {
    opts = $.extend({link: null}, $.fn.smoothScroll.defaults, optionOverrides);
    scrollTargetOffset = options;
  } else {
    opts = $.extend({link: null}, $.fn.smoothScroll.defaults, options || {}, optionOverrides);
    if (opts.scrollElement) {
      offPos = 'position';
      if (opts.scrollElement.css('position') === 'static') {
        opts.scrollElement.css('position', 'relative');
      }
    }
  }

  scrollDir = opts.direction === 'left' ? 'scrollLeft' : scrollDir;

  if ( opts.scrollElement ) {
    $scroller = opts.scrollElement;
    if ( !(/^(?:HTML|BODY)$/).test($scroller[0].nodeName) ) {
      scrollerOffset = $scroller[scrollDir]();
    }
  } else {
    $scroller = $('html, body').firstScrollable(opts.direction);
  }

  // beforeScroll callback function must fire before calculating offset
  opts.beforeScroll.call($scroller, opts);

  scrollTargetOffset = (typeof options === 'number') ? options :
                        px ||
                        ( $(opts.scrollTarget)[offPos]() &&
                        $(opts.scrollTarget)[offPos]()[opts.direction] ) ||
                        0;

  aniProps[scrollDir] = scrollTargetOffset + scrollerOffset + opts.offset;
  speed = opts.speed;

  // automatically calculate the speed of the scroll based on distance / coefficient
  if (speed === 'auto') {

    // $scroller.scrollTop() is position before scroll, aniProps[scrollDir] is position after
    // When delta is greater, speed will be greater.
    delta = aniProps[scrollDir] - $scroller.scrollTop();
    if(delta < 0) {
      delta *= -1;
    }

    // Divide the delta by the coefficient
    speed = delta / opts.autoCoefficient;
  }

  aniOpts = {
    duration: speed,
    easing: opts.easing,
    complete: function() {
      opts.afterScroll.call(opts.link, opts);
    }
  };

  if (opts.step) {
    aniOpts.step = opts.step;
  }

  if ($scroller.length) {
    $scroller.stop().animate(aniProps, aniOpts);
  } else {
    opts.afterScroll.call(opts.link, opts);
  }
};

$.smoothScroll.version = version;
$.smoothScroll.filterPath = function(string) {
  string = string || '';
  return string
    .replace(/^\//,'')
    .replace(/(?:index|default).[a-zA-Z]{3,4}$/,'')
    .replace(/\/$/,'');
};

// default options
$.fn.smoothScroll.defaults = defaults;

function escapeSelector (str) {
  return str.replace(/(:|\.)/g,'\\$1');
}

})(jQuery);
