// Sorting table columns correctly by text, number or date. There are other 
// versions, plugins, etc., for this but they either are restricted to specific 
// date formats, or require EVERY row-element to be given a sort attribute; mine 
// can handle many different date and number formats, and even allows for specific 
// cells that may not conform to the overall date/number format for that column. 
// My version also enables sorting of element hierarchies: such as a DIV containing 
// P-paragraphs and SPANs - this could even be an image-gallery containing prices 
// or dates within spans. Very efficient as well!!
// Example: andrew.dx.am/sortgallerydel.html
// AddSortToTables(); will make the table headers clickable, to sort columns in 
// ascending or descending order, for any tables with class="sortIt".
// SortTable(tbl, col); will sort the table (tbl is an id or table object) by 
// the supplied column index (indexed from 0) in ascending or descending order.
// AddSortByDate(tbl, col, dateMask); enables sorting of a column by date, 
// specified by a date-mask such as 'dd-mmm-yy'.
// AddSortByNumber(tbl, col); enables sorting of a column by number. This assumes a 
// period . as the decimal separator (if present); it ignores any other non-numeric 
// characters.
// SortElements(parentEl, childTag, colTag, colIndex); will sort (non-table) 
// elements in ascending or descending order. For example, an UL containing LIs 
// and SPANs. colIndex specifies which span to sort; there may be more than one in 
// the LI (0 indexed).
// Example: SortElements('divid', 'p', 'span', 2);
// 3rd span within each paragraph.
//
// AddSortByDate2(parentEl, childTag, colTag, colIndex, dateMask); and 
// AddSortByNumber2(parentEl, childTag, colTag, colIndex)
// provide the same feature-set as AddSortByDate and AddSortByNumber does 
// for tables, but for element hierarchies.
// If there are dates or numbers in a column (or element) which don't meet the 
// date-mask or number formatting necessary to sort correctly, then these individual 
// elements can be given the attribute "sort" and they will still sort correctly!
// For example, with a date column <td sort="2012/12/20"> will still sort a 
// cell correctly. (This format 'YYYY/MM/DD' will be converted into a Date() object.)
var MonthNames = ["January", "February", "March", "April", "May", "June", "July", 
  "August", "September", "October", "November", "December"];
var DayNames = [ "Sunday", "Monday", "Tueday", "Wednesday", "Thursday", 
  "Friday", "Saturday" ];
var ShortMths = ["Jan", "Feb", "Mar", "Apr", "May", "Jun", "Jul", "Aug", 
  "Sep", "Oct", "Nov", "Dec"];
var ShortDays = ["Sun", "Mon", "Tue", "Wed", "Thu", "Fri", "Sat"];
var AddEvent = function (elem, eventType, func) {
  // Helper function.
  if ( elem.addEventListener )
    AddEvent = function (elem, eventType, func) {
      elem.addEventListener(eventType, func, false);
    };
  else if ( elem.attachEvent )
    AddEvent = function (elem, eventType, func) {
      elem.attachEvent('on' + eventType, func);
    };
  else
    AddEvent = function (elem, eventType, func) {
      elem['on' + eventType] = func;
    };
  AddEvent(elem, eventType, func);
};
// Sort methods/algorithms attributed:
var SortTable = function (tbl, col) {
  // could be called directly
  SortElements(tbl, 'tr', 'td', col);
};
var SortElements = function (parentEl, childTag, colTag, colIndex) {
  // example use: SortElements('table1','tr','td',2)
  // or SortElements('list1','li')
  // or SortElements('divName','p','span',3)
  var i, j, cTags = {}, startAt = 0, childLen, aChild, elem,
    sortBy, content, elems = [], sortedLen, frag, hdrsLen, hdr;
  var parent = (typeof parentEl === 'string') ? 
    document.getElementById(parentEl) : parentEl;
  var AscText = function (a, b) { // sort() by .data as text
    var x = a.data, y = b.data,
      xNum = parseFloat(x), yNum = parseFloat(y);
      // check if each begin with a number..
    if ( !isNaN(xNum) && !isNaN(yNum) && (xNum - yNum) )
      return xNum - yNum;
    return ((x < y) ? -1 : ((x > y) ? 1 : 0));
  };
  var DescText = function (a, b) { // sort() by .data
    var x = a.data, y = b.data,
      xNum = parseFloat(x), yNum = parseFloat(y);
      // check if each begin with a number..
    if ( !isNaN(xNum) && !isNaN(yNum) && (yNum - xNum) )
      return yNum - xNum;
    return ((x > y) ? -1 : ((x < y) ? 1 : 0));
  };
  var AscNum = function (a, b) { // used with dates as well
    return a.data - b.data;
  };
  var DescNum = function (a, b) {
    return b.data - a.data;
  };
  if (parent.nodeName.toLowerCase() == 'table') {
    if ( childTag == 'tr' ) {
      sortBy = parent.rows[0].cells[colIndex].sortBy || 'text';
    }
    parent = parent.tBodies[0] || parent;
    if ( parent.rows[0].cells[0].nodeName.toLowerCase() == 'th' ) {
      startAt = 1;
    }
  }
  cTags = parent.getElementsByTagName(childTag);
  if ( typeof colIndex == 'undefined' ) {
    sortBy = 'text'; // sort simple lists or paragraphs as text
  }
  for (i = startAt, childLen = cTags.length; i < childLen; i++) {
    // ..go forward examining each child
    aChild = cTags[i];
    elem = (colTag) ? aChild.getElementsByTagName(colTag)[colIndex] : aChild;
    if (elem) {
      if ( !sortBy ) { // sorting non-table columns..
        sortBy = (typeof elem.numberValue != 'undefined') ? 'number' : 
          ((typeof elem.dateValue != 'undefined') ? 'date' : 'text');
      }
      switch (sortBy) {
      // You can supply 'sort' attributes to enable sorting of numbers, etc.
      // For example, <td sort='2011/02/12'> for a date.
        case 'text':
          content = (elem.getAttribute('sort') || 
            elem.firstChild.nodeValue).toLowerCase();
          break;
        case 'number':
          content = elem.numberValue;
          break;
        case 'date':
          content = elem.dateValue;
          break;
        default:
          content = (elem.getAttribute('sort') || 
            elem.firstChild.nodeValue).toLowerCase();
          break;
      }
      j = elems.length;
      if ( !aChild.id ) 
        aChild.id = 'tempSortID' + j;
      elems[j] = { data: content, tempID: aChild.id };
    }
  }
  // The following will determine if the table/etc has already been sorted 
  // by the same column or tag. If so, it will sort in ascending or descending 
  // order. It creates custom element properties to the parent element to 
  // remember the previous sort details.
  if ( typeof colIndex == 'undefined' ) colIndex = 0;
  if ( parent.prevTag && parent.prevTag == ((typeof colTag == 'undefined') ? 
      childTag : colTag) ) {
    if (parent.prevCol == colIndex) {
      // sorting by the same column as previously
      parent.prevSort = (parent.prevSort == 'asc') ? 'desc' : 'asc';
    } else { // sorting by any other column
      parent.prevCol = colIndex;
      parent.prevSort = 'asc';
    }
  } else {
    // sorting for the 1st time or by a different tag
    parent.prevTag = ((typeof colTag == 'undefined') ? childTag : colTag);
    parent.prevCol = colIndex;
    parent.prevSort = 'asc';
  }
  if ( parent.prevSort === 'desc' ) {
    // 'desc' WILL BE the previous sort order..
    switch (sortBy) {
      case 'text': elems.sort(DescText); break;
      case 'number': elems.sort(DescNum); break;
      case 'date': elems.sort(DescNum); break;
      default: elems.sort(DescText); break;
    }
  } else {
    switch (sortBy) {
      case 'text': elems.sort(AscText); break;
      case 'number': elems.sort(AscNum); break;
      case 'date': elems.sort(AscNum); break;
      default: elems.sort(AscText); break;
    }
  }
  frag = document.createDocumentFragment();
  for (i = 0, sortedLen = elems.length; i < sortedLen; i++) {
    elem = document.getElementById(elems[i].tempID);
    frag.appendChild(elem);
    if ( (elem.id).substr(0,10) == 'tempSortID' )
      elem.removeAttribute('id');
  }
  parent.appendChild(frag);
  elems = null;
  return parent.prevSort; // not currently used
};
var AddSortToTables = function () {
  // ..if table has class-name 'sortIt'
  var tables = document.getElementsByTagName('table'), i, j, 
    tblLen, tbl, hdrs, hdrsLen;
  function PreserveSortScope(a,b,c,d) {
    return function () {
      // assign the SortElements fn. to a table header
      SortElements(a, b, c, d);
    }
  }
  // add sorting to table headers
  for ( i = 0, tblLen = tables.length; i < tblLen; i++ ) { 
    tbl = tables[i];
    if ( tbl.className.indexOf('sortIt') + 1) {
      hdrs = tbl.getElementsByTagName('th');
      if ( hdrs ) {
        for ( j = 0, hdrsLen = hdrs.length; j < hdrsLen; j++ ) {
          AddEvent(hdrs[j],'click',PreserveSortScope(tbl,'tr','td',j));
          // if there's no title already, add "Click to sort"
          if ( !hdrs[j].title ) hdrs[j].setAttribute('title',
            'Click to sort');
        }
      }
    }
  }
};
var AddSortByDate = function (tbl, col, dateMask) {
  // Input: the table name (or object), a column index (or array) 
  // and a date mask ('dd-mmm-yy')
  // Adds a sortBy = 'date' property to the first row
  // will ignore the first row, assuming it is a header row
  var i, rLen, cell;
  while ( col.length ) AddSortByDate(tbl,col.pop(),dateMask);
  if ((col instanceof Array) || isNaN(col)) return;
  var tbl = (typeof tbl === 'string') ? document.getElementById(tbl) : tbl;
  tbl.rows[0].cells[col].sortBy = 'date';
  AddSortByDate2(tbl, 'tr', 'td', col, dateMask);
};
var AddSortByDate2 = function (parentEl, childTag, colTag, colIndex, dateMask) {
  var kids, startAt = 0, i, rLen, cell;
  var parent = (typeof parentEl === 'string') ? 
    document.getElementById(parentEl) : parentEl;
  if ( parent.nodeName.toLowerCase() == 'table' ) {
    parent = parent.tBodies[0] || parent;
    startAt = ( parent.rows[0].cells[0].nodeName.toLowerCase() == 'th' ) * 1;
  }
  kids = parent.getElementsByTagName(childTag);
  for ( i = startAt, rLen = kids.length; i < rLen; i++) {
    cell = kids[i].getElementsByTagName(colTag)[colIndex];
    if (cell) {
      if ( typeof cell.numberValue != 'undefined' ) delete cell.numberValue;
      // the above enables switching from a number to a date sort 
      // (although v. unlikely)
      if (cell.getAttribute('sort')) {
        // use sort attribute if present
        cell.dateValue = new Date(cell.getAttribute('sort'));
      } else {
        cell.dateValue = new Date(StringToDate(cell.firstChild.nodeValue, 
          dateMask));
      }
      if (cell.dateValue.toString() == "NaN" || cell.dateValue.toString() == 
          "Invalid Date") {
        cell.dateValue = 0;
      } 
    }
  }
};
var AddSortByNumber = function (tbl, col) {
  // col is a column index or array of indices
  // will ignore the first row, assuming it is a header row
  var i, rLen, cell, tempNum;
  while ( col.length ) AddSortByNumber(tbl,col.pop());
  if ((col instanceof Array) || isNaN(col)) return;
  tbl = (typeof tbl === 'string') ? document.getElementById(tbl) : tbl;
  tbl.rows[0].cells[col].sortBy = 'number';
  AddSortByNumber2(tbl,'tr','td',col);
};
var AddSortByNumber2 = function (parentEl, childTag, colTag, colIndex) {
  var kids, startAt = 0, i, rLen, cell, tempNum;
  var parent = (typeof parentEl === 'string') ? 
    document.getElementById(parentEl) : parentEl;
  if ( parent.nodeName.toLowerCase() == 'table' ) {
    parent = parent.tBodies[0] || parent;
    startAt = (parent.rows[0].cells[0].nodeName.toLowerCase() == 'th') * 1;
  }
  kids = parent.getElementsByTagName(childTag);
  for (i = startAt, rLen = kids.length; i < rLen; i++) {
    cell = kids[i].getElementsByTagName(colTag)[colIndex];
    if (cell) {
      if ( typeof cell.dateValue != 'undefined' ) delete cell.dateValue;
      // the above enables switching from a date to a number sort
      // (although v. unlikely)
      tempNum = cell.getAttribute('sort') || cell.firstChild.nodeValue;
      tempNum = tempNum.replace(/[^0-9.-]/g, '');
      cell.numberValue = parseFloat(tempNum);
      if (isNaN(cell.numberValue)) 
        cell.numberValue = 0.0;
    }
  }
};
var StringToDate = function (sDate, sFormat, cutOff) {
  // Input: a date value as a string, it's format as a string e.g. 'dd-mmm-yy'
  // Optional: a cutoff (integer) for 2 digit years.
  // If no 'd' appears in the format string then the 1st of the month is assumed.
  // If the year is 20 and the cut-off is 30 then the value will be converted 
  // to 2020; if the year is 40 then this will be converted to 1940.
  // If no cut-off is supplied then '20' will be pre-pended to the year (YY).
  // Output: a string in the format 'YYYY/MM/DD' or ''
  // Will not attempt to convert certain combinations e.g. DMM, MDD, DDM, YYYYD.
  var sParsed, fndSingle;
  // sParsed will be constructed in the format 'YYYY/MM/DD'
  sDate = sDate.toString().toUpperCase();
  sFormat = sFormat.toUpperCase();
  if (sFormat.search(/MMMM|MMM/) + 1) { // replace Mar/March with 03, etc.
    sDate = sDate.replace(new RegExp('(' + ShortMths.join('|') + ')[A-Z]*', 'gi'),
      function (m) {
      var i = ShortMths.indexOf(m.charAt(0).toUpperCase() + 
        m.substr(1, 2).toLowerCase()) + 1;
      return ((i < 10) ? "0" + i : "" + i).toString();
    });
    sFormat = sFormat.replace(/MMMM|MMM/g, 'MM');
  }
  if (sFormat.search(/DDDD|DDD/) + 1) { // replace Tue/Tuesday, etc. with ''
    sDate = sDate.replace(new RegExp('(' + ShortDays.join('|') + ')[A-Z]*', 'gi'),'');
    sFormat = sFormat.replace(/DDDD|DDD/g, '');
  }
  sDate = sDate.replace(/(^|\D)(\d)(?=\D|$)/g, function($0, $1, $2) {
    // single digits 2 with 02
    return $1 + '0' + $2;
  });
  sFormat = sFormat.replace(/(^|[^DMY])(D|M)(?=[^DMY]|$)/g, function($0, $1, $2){
    return $1 + $2 + $2; // replace D or M with DD and MM
  });
  // are there still single Ds or Ms?
  fndSingle = sFormat.search(/(^|[^D])D([^D]|$)|(^|[^M])M([^M]|$)/)+1;
  if ( fndSingle ) return ''; // do not attempt to parse, for example, 'DMM'
  sFormat = sFormat.replace(/(^|[^Y])(YY)(?=[^Y]|$)/g, function($0, $1, $2, index) {
    var tempDate = sDate.substr(0, index + 1);
    tempDate += (cutOff) ? ((parseInt(sDate.substr(index + 1, 2),10) > cutOff) ? 
      '19' : '20') : '20';
    tempDate += sDate.substr(index + 1);
    sDate = tempDate;
    return $1 + $2 + $2;
  });
  sParsed = ('YYYY/MM/DD').replace(/YYYY|MM|DD/g, function(m){
    return (sFormat.indexOf(m) + 1) ? 
      sDate.substr(sFormat.indexOf(m), m.length) : '';
  });
  if (sParsed.charAt(0) == '/') {
    // if no year specified, assume the current year
    sParsed = (new Date().getFullYear()) + sParsed;
  }
  if (sParsed.charAt(sParsed.length - 1) == '/') {
    // if no date, assume the 1st of the month
    sParsed += '01';
  }
  // should end up with 10 characters..
  return ( sParsed.length == 10 ) ? sParsed : '';
};