/*! Copyright (c) 2011 by Jonas Mosbech - https://github.com/jmosbech/StickyTableHeaders
  MIT license info: https://github.com/jmosbech/StickyTableHeaders/blob/master/license.txt */

;(function ($, window, undefined) {
  'use strict';

  var name = 'stickyTableHeaders',
    id = 0,
    defaults = {
      fixedOffset: 0,
      leftOffset: 0,
      scrollableArea: window
    };

  function Plugin (el, options) {
    // To avoid scope issues, use 'base' instead of 'this'
    // to reference this class from internal events and functions.
    var base = this;

    // Access to jQuery and DOM versions of element
    base.$el = $(el);
    base.el = el;
    base.id = id++;

    // Listen for destroyed, call teardown
    base.$el.bind('destroyed',
      $.proxy(base.teardown, base));

    // Cache DOM refs for performance reasons
    base.$clonedHeader = null;
    base.$originalHeader = null;

    // Keep track of state
    base.isSticky = false;
    base.hasBeenSticky = false;
    base.leftOffset = null;
    base.topOffset = null;

    base.init = function () {
      base.options = $.extend({}, defaults, options);

      base.$el.each(function () {
        var $this = $(this);

        // remove padding on <table> to fix issue #7
        $this.css('padding', 0);

        base.$scrollableArea = $(base.options.scrollableArea);

        base.$originalHeader = $('thead:first', this);
        base.$clonedHeader = base.$originalHeader.clone();
        $this.trigger('clonedHeader.' + name, [base.$clonedHeader]);

        base.$clonedHeader.addClass('tableFloatingHeader');
        base.$clonedHeader.css('display', 'none');

        base.$originalHeader.addClass('tableFloatingHeaderOriginal');

        base.$originalHeader.after(base.$clonedHeader);

        base.$printStyle = $('<style type="text/css" media="print">' +
          '.tableFloatingHeader{display:none !important;}' +
          '.tableFloatingHeaderOriginal{position:static !important;}' +
          '</style>');
        $('head').append(base.$printStyle);
      });

      base.updateWidth();
      base.toggleHeaders();

      base.bind();
    };

    base.destroy = function (){
      base.$el.unbind('destroyed', base.teardown);
      base.teardown();
    };

    base.teardown = function(){
      if (base.isSticky) {
        base.$originalHeader.css('position', 'static');
      }
      $.removeData(base.el, 'plugin_' + name);
      base.unbind();

      base.$clonedHeader.remove();
      base.$originalHeader.removeClass('tableFloatingHeaderOriginal');
      base.$originalHeader.css('visibility', 'visible');
      base.$printStyle.remove();

      base.el = null;
      base.$el = null;
    };

    base.bind = function(){
      base.$scrollableArea.on('scroll.' + name, base.toggleHeaders);
      if (!base.isWindowScrolling()) {
        $(window).on('scroll.' + name + base.id, base.setPositionValues);
        $(window).on('resize.' + name + base.id, base.toggleHeaders);
      }
      base.$scrollableArea.on('resize.' + name, base.toggleHeaders);
      base.$scrollableArea.on('resize.' + name, base.updateWidth);
    };

    base.unbind = function(){
      // unbind window events by specifying handle so we don't remove too much
      base.$scrollableArea.off('.' + name, base.toggleHeaders);
      if (!base.isWindowScrolling()) {
        $(window).off('.' + name + base.id, base.setPositionValues);
        $(window).off('.' + name + base.id, base.toggleHeaders);
      }
      base.$scrollableArea.off('.' + name, base.updateWidth);
      base.$el.off('.' + name);
      base.$el.find('*').off('.' + name);
    };

    base.toggleHeaders = function () {
      if (base.$el) {
        base.$el.each(function () {
          var $this = $(this),
            newLeft,
            newTopOffset = base.isWindowScrolling() ? (
                  isNaN(base.options.fixedOffset) ?
                  base.options.fixedOffset.outerHeight() :
                  base.options.fixedOffset
                ) :
                base.$scrollableArea.offset().top + (!isNaN(base.options.fixedOffset) ? base.options.fixedOffset : 0),
            offset = $this.offset(),

            scrollTop = base.$scrollableArea.scrollTop() + newTopOffset,
            scrollLeft = base.$scrollableArea.scrollLeft(),

            scrolledPastTop = base.isWindowScrolling() ?
                scrollTop > offset.top :
                newTopOffset > offset.top,
            notScrolledPastBottom = (base.isWindowScrolling() ? scrollTop : 0) <
                (offset.top + $this.height() - base.$clonedHeader.height() - (base.isWindowScrolling() ? 0 : newTopOffset));

          if (scrolledPastTop && notScrolledPastBottom) {
            newLeft = offset.left - scrollLeft + base.options.leftOffset;
            base.$originalHeader.css({
              'position': 'fixed',
              'margin-top': 0,
              'left': newLeft,
              'z-index': 1 // #18: opacity bug
            });
            base.isSticky = true;
            base.leftOffset = newLeft;
            base.topOffset = newTopOffset;
            base.$clonedHeader.css('display', '');
            base.setPositionValues();
            // make sure the width is correct: the user might have resized the browser while in static mode
            base.updateWidth();
          } else if (base.isSticky) {
            base.$originalHeader.css('position', 'static');
            base.$clonedHeader.css('display', 'none');
            base.isSticky = false;
            base.resetWidth($("td,th", base.$clonedHeader), $("td,th", base.$originalHeader));
          }
        });
      }
    };

    base.isWindowScrolling = function() {
      return base.$scrollableArea[0] === window;
    };

    base.setPositionValues = function () {
      var winScrollTop = $(window).scrollTop(),
        winScrollLeft = $(window).scrollLeft();
      if (!base.isSticky ||
          winScrollTop < 0 || winScrollTop + $(window).height() > $(document).height() ||
          winScrollLeft < 0 || winScrollLeft + $(window).width() > $(document).width()) {
        return;
      }
      base.$originalHeader.css({
        'top': base.topOffset - (base.isWindowScrolling() ? 0 : winScrollTop),
        'left': base.leftOffset - (base.isWindowScrolling() ? 0 : winScrollLeft)
      });
    };

    base.updateWidth = function () {
      if (!base.isSticky) {
        return;
      }
      // Copy cell widths from clone
      if (!base.$originalHeaderCells) {
        base.$originalHeaderCells = $('th,td', base.$originalHeader);
      }
      if (!base.$clonedHeaderCells) {
        base.$clonedHeaderCells = $('th,td', base.$clonedHeader);
      }
      var cellWidths = base.getWidth(base.$clonedHeaderCells);
      base.setWidth(cellWidths, base.$clonedHeaderCells, base.$originalHeaderCells);

      // Copy row width from whole table
      base.$originalHeader.css('width', base.$clonedHeader.width());
    };

    base.getWidth = function ($clonedHeaders) {
      var widths = [];
      $clonedHeaders.each(function (index) {
        var width, $this = $(this);

        if ($this.css('box-sizing') === 'border-box') {
          width = $this.outerWidth(); // #39: border-box bug
        } else {
          width = $this.width();
        }

        widths[index] = width;
      });
      return widths;
    };

    base.setWidth = function (widths, $clonedHeaders, $origHeaders) {
      $clonedHeaders.each(function (index) {
        var width = widths[index];
        $origHeaders.eq(index).css({
          'min-width': width,
          'max-width': width
        });
      });
    };

    base.resetWidth = function ($clonedHeaders, $origHeaders) {
      $clonedHeaders.each(function (index) {
        var $this = $(this);
        $origHeaders.eq(index).css({
          'min-width': $this.css("min-width"),
          'max-width': $this.css("max-width")
        });
      });
    };

    base.updateOptions = function(options) {
      base.options = $.extend({}, defaults, options);
      base.updateWidth();
      base.toggleHeaders();
    };

    // Run initializer
    base.init();
  }

  // A plugin wrapper around the constructor,
  // preventing against multiple instantiations
  $.fn[name] = function ( options ) {
    return this.each(function () {
      var instance = $.data(this, 'plugin_' + name);
      if (instance) {
        if (typeof options === "string") {
          instance[options].apply(instance);
        } else {
          instance.updateOptions(options);
        }
      } else if(options !== 'destroy') {
        $.data(this, 'plugin_' + name, new Plugin( this, options ));
      }
    });
  };

})(jQuery, window);