var loc_count = 30;
var loc_array = new Array(3);
loc_array[0] = new Array('yyc','yyz','yul','lir','sjo','dub','mbj','kin','mid','tul1','czm','cun','pvr','cme','sxm','sju','anc','phx','lax','den','fll','idr','ksm','mco','mia','pbi','tpa','atl','dfw','sea');
loc_array[1] = new Array();
loc_array[2] = new Array();

function populateDaysOfMonth(objSource,objTarget){
   var daysInMonth = new Array(31,28,31,30,31,30,31,31,30,31,30,31);
   var month = parseInt(objSource.value);
   var htmlCode = "";
   var tarValue = objTarget.value;

   //if month is february
   if (month == 2){
      //determine year
      var d = new Date();
      var year = (objSource.value < d.getMonth()+1) ? d.getFullYear()+1 : d.getFullYear();

      //if is it a leap year make february have 29 days
      if (isLeapYear(year))
         daysInMonth[1] = 29;
   }

   clearDropdown(objTarget);

   //loop thru the number of days for the month
   for (var i=1; i <= daysInMonth[month-1]; i++)
      appendOption(objTarget,i,i);

   objTarget.selectedIndex = getOptionIndex(objTarget,tarValue);
}

//clears the passed dropdown list
function clearDropdown(obj){
   //clear the dropdown list
   for (var i=obj.options.length-1; i >= 0 ; i--)
      obj.remove(i);
}

//add option to dropdown object
function appendOption(obj,value,text){
   //create new option object
   var newOption = document.createElement("option");
   newOption.value = value;
   newOption.text = text;

   //append new option element to the end of the dropdown list
   try {
      obj.add(newOption, null); // standards compliant; doesn't work in IE
   }catch(ex){
      obj.add(newOption); // IE only
   }
}

//determines if the year is a leap year, returns true if leap year
function isLeapYear(year){
   if (year % 4 == 0 && year % 100 != 0 || year % 400 == 0)
      return true;
   else
      return false;
}

function changeHours(obj,tar){
   var loc_code = obj.value;
   var index = 0;
   var tarValue = tar.value;

   while (loc_array[0][index] != loc_code && index < loc_count)
      index++;

   if (index != loc_count)
      populateHoursOfDay(tar,loc_array[1][index],loc_array[2][index]);
   tar.selectedIndex = getOptionIndex(tar,tarValue);
}

function populateHoursOfDay(obj,open,close){
   var tmp_hour, tmp_min, close_hour, close_min, tmp_array;
   tmp_array = open.split(":");
   tmp_hour = parseInt(tmp_array[0]); tmp_min = parseInt(tmp_array[1]);
   tmp_array = close.split(":");
   close_hour = parseInt(tmp_array[0]); close_min = parseInt(tmp_array[1]);

   clearDropdown(obj);
   do{
      appendOption(obj,getTimeStr(tmp_hour,tmp_min),getTimeStr(tmp_hour,tmp_min));
      tmp_min = add30Min(tmp_min);
      if (tmp_min < 30)
         tmp_hour++;
   }while( parseInt(get2DigStr(tmp_hour)+get2DigStr(tmp_min)) <= parseInt(get2DigStr(close_hour)+get2DigStr(close_min)) )
}

//returns 2 digit string, if length of num is 1 append a '0' to the beginning. ex 4 -> '04'
function get2DigStr(num){
   num = num.toString();
   if (num.length == 1)
      num = "0" + num;
   return num;
}

//takes numerical hour ("16") and returns hour string ("4:00 PM")
function getTimeStr(hour,min){
   if (min == 0)
      min = "00";
   return chg24To12HourClock(hour) + ":" + min +" "+ returnAMOrPM(hour);
}

//converts from 24 hour clock to 12 hour clock, 16 to 4
function chg24To12HourClock(hour){
   return (hour % 12 == 0) ? 12 : hour % 12;
}

//returns AM or PM string
function returnAMOrPM(hour){
   return (isAM(hour)) ? "AM" : "PM"
}

//returns true if time is AM, false if PM
function isAM(hour){
   return (hour >= 12) ? false : true;
}

//returns passed minutes + 30
function add30Min(min){
   return (min + 30) % 60;
}

//seaches options in dropdown (obj) for passed value (str)
//returns selected index or false
function getOptionIndex(obj,str){
   var options = obj.options;
   for (var i=0; i < options.length; i++)
      if (options[i].value == str)
         return i;
   return false;
}