// Jim Stiles
// www.jdstiles.com

setCal();

function leapYear(year) {
  if (year % 4 == 0) {// basic rule
    return true; // is leap year
  }
  /* else */ // else not needed when statement is "return"
  return false; // is not leap year
}

function getDays(month, year) {
  // create array to hold number of days in each month
  var ar = new Array(12);
  ar[0] = 31; // January
  ar[1] = (leapYear(year)) ? 29 : 28; // February
  ar[2] = 31; // March
  ar[3] = 30; // April
  ar[4] = 31; // May
  ar[5] = 30; // June
  ar[6] = 31; // July
  ar[7] = 31; // August
  ar[8] = 30; // September
  ar[9] = 31; // October
  ar[10] = 30; // November
  ar[11] = 31; // December

  // return number of days in the specified month (parameter)
  return ar[month];
}

function getMonthName(month) {
  // create array to hold name of each month
  var ar = new Array(12);
  ar[0] = "January";
  ar[1] = "February";
  ar[2] = "March";
  ar[3] = "April";
  ar[4] = "May";
  ar[5] = "June";
  ar[6] = "July";
  ar[7] = "August";
  ar[8] = "September";
  ar[9] = "October";
  ar[10] = "November";
  ar[11] = "December";

  // return name of specified month (parameter)
  return ar[month];
}

function setCal() {
  // standard time attributes
  var now = new Date();
  var year = now.getFullYear();
  var month = now.getMonth();
  var monthName = getMonthName(month);
  var date = now.getDate();
  now = null;

  // create instance of first day of month, and extract the day on which it occurs
  var firstDayInstance = new Date(year, month, 1);
  var firstDay = firstDayInstance.getDay();
  firstDayInstance = null;

  // number of days in current month
  var days = getDays(month, year);

  // call function to draw calendar
  drawCal(firstDay + 1, days, date, monthName, year);
}

function drawCal(firstDay, lastDate, date, monthName, year) {
  // constant table settings
  var headerHeight = 0 // height of the table's header cell
  var border = 0; // 3D height of table's border
  var cellspacing = 0; // width of table's border
  var headerColor = "#DCEBDF"; // color of table's header
  var headerMonthSize = "2"; // size of tables header font
  var weekSize = "1"; // size of tables cell font
  var cellSize = "1"; // size of tables cell font
  var colWidth = 0; // width of columns in table
  var dayCellHeight = 0; // height of cells containing days of the week
  var dayColor = "#DCEBDF"; // color of font representing week days
  var cellHeight = 0; // height of cells representing dates in the calendar
  var todayColor = "red"; // color specifying today's date in the calendar
  var timeColor = "darkred"; // color of font representing current time

  // create basic table structure
  var text = ""; // initialize accumulative variable to empty string
  text += '<TABLE class="calendar" CELLPADDING=0 BORDER="' + border + '" CELLSPACING=' + cellspacing + '>'; // table settings
  text += '<TH class="month" style="align:center;" CELLPADDING=0  COLSPAN=7 HEIGHT=' + headerHeight + '>'; // create table header cell
  text += '<center>' + monthName + ' ' + year + '</center>'; 
  text += '</TH>'; // close header cell

  // variables to hold constant settings
  var openCol = '<TD class="day"  CELLPADDING=0  BGCOLOR="#AAA087" WIDTH=' + colWidth + ' HEIGHT=' + dayCellHeight + '>';
  var closeCol = '</TD>';

  var openColwd = '<TD class="weekday"  CELLPADDING=0  BGCOLOR="#1D1C1F" WIDTH=' + colWidth + ' HEIGHT=' + dayCellHeight + '>';
  var closeColwd = '</TD>';

  // create array of abbreviated day names
  var weekDay = new Array(7);
  weekDay[0] = "S";
  weekDay[1] = "M";
  weekDay[2] = "T";
  weekDay[3] = "W";
  weekDay[4] = "T";
  weekDay[5] = "F";
  weekDay[6] = "S";
	
  // create first row of table to set column width and specify week day
  text += '<TR class="weekday"  ALIGN="center" VALIGN="center">';
  for (var dayNum = 0; dayNum < 7; ++dayNum) {
    text += openColwd + weekDay[dayNum] + closeColwd; 
  }
  text += '</TR>';
	
  // declaration and initialization of two variables to help with tables
  var dayOfMonth = 1;
  var curCell = 1;
	
  for (var row = 1; row <= Math.ceil((lastDate + firstDay - 1) / 7); ++row) {
    text += '<TR class="day"  CELLPADDING=0  ALIGN="right" VALIGN="top">';
    for (var col = 1; col <= 7; ++col) {
      if ((curCell < firstDay) || (dayOfMonth > lastDate)) {
        text += '<TD class="day" HEIGHT='+ dayCellHeight + ' BGCOLOR="#AAA087"> </TD>';
        curCell++
      } else {
          if (dayOfMonth == date) { // current cell represents today's date
            text += '<TD class="today" cellpadding=0  HEIGHT='+ dayCellHeight + ' BGCOLOR="pink">' +  dayOfMonth + '</TD>';
          } else {
              text += '<TD class="day"  HEIGHT='+ dayCellHeight + ' BGCOLOR="#DCEBDF">' + dayOfMonth + '</TD>';
            }
            dayOfMonth++;
        }
    }
    text += '</TR>';
  }
	
  // close all basic table tags
  text += '</TABLE>';
  text += '</CENTER>';

  // print accumulative HTML string
  document.write(text); 
}