// $Id: date.js 4 2008-08-18 15:52:41Z damian $

//  Update date script. 

//  Calcate and update the new return date if the entered departure date is previous than the current return date
function update_return_date(depart_date) {

   var return_date = document.getElementById( 'return_date' );

   if (isDate(depart_date) && !isDate(return_date.value)) {
      alert( "in update_return_date(), about to call add_days()" );
      return_date.value = add_days(depart_date, 3);
   }

   if (isDate(return_date.value) && isDate(depart_date) && ( new Date(depart_date) > new Date(return_date.value) )) {
      return_date.value = add_days(depart_date, 3); 
   }

}  

// return date added the passed date to the number of days passed
function add_days(date, days){

   var n_days = new Number(days);
   var dt = new Date(date);
   	
   dt.setDate(dt.getDate() + n_days);
   var month=(dt.getMonth()+1)<= 9 ?"0"+(dt.getMonth()+1):(dt.getMonth()+1);
   var date = dt.getDate()<=9?"0"+dt.getDate():dt.getDate();
   var date_str = month + '/' + date + '/' + dt.getFullYear();

   return date_str;
}

function get_today(){

   var today = new Date();
   var month=(today.getMonth()+1)<= 9 ?"0"+(today.getMonth()+1):(today.getMonth()+1);
   var date = today.getDate()<=9?"0"+today.getDate():today.getDate();
   var date_str = month + '/' + date + '/' + today.getFullYear();
   return date_str;
}

function get_days_after(date){

   if ( date ) {
      var today = new Date(date);
   } else {
      var today = new Date();
   }

   today.setDate(today.getDate()-1);
   var month=(today.getMonth()+1)<= 9 ?"0"+(today.getMonth()+1):(today.getMonth()+1);
   var date = today.getDate()<=9?"0"+today.getDate():today.getDate();
   var date_str = month + '/' + date + '/' + today.getFullYear();
   return date_str;
}

function get_next_year(){

   var today = new Date();

   today.setDate(today.getDate()+330);
   var month=(today.getMonth()+1)<= 9 ?"0"+(today.getMonth()+1):(today.getMonth()+1);
   var date = today.getDate()<=9?"0"+today.getDate():today.getDate();
   var date_str = month + '/' + date + '/' + today.getFullYear();
   return date_str;
}

//  date validation script. 
//  Originate from Courtesy of SmartWebby.com (http://www.smartwebby.com/dhtml/)
//
//  Declaring valid date character, minimum year and maximum year
var dtCh= "/";
var minYear=1900;
var maxYear=2100;

function isInteger(s){
    var i;
    for (i = 0; i < s.length; i++){   
        // Check that current character is number.
        var c = s.charAt(i);
        if (((c < "0") || (c > "9"))) return false;
    }
    // All characters are numbers.
    return true;
}

function stripCharsInBag(s, bag){
    var i;
    var returnString = "";
    // Search through string's characters one by one.
    // If character is not in bag, append to returnString.
    for (i = 0; i < s.length; i++){   
        var c = s.charAt(i);
        if (bag.indexOf(c) == -1) returnString += c;
    }
    return returnString;
}

function daysInFebruary (year){
    // February has 29 days in any year evenly divisible by four,
    // EXCEPT for centurial years which are not also divisible by 400.
    return (((year % 4 == 0) && ( (!(year % 100 == 0)) || (year % 400 == 0))) ? 29 : 28 );
}

function DaysArray(n) {
    for (var i = 1; i <= n; i++) {
        this[i] = 31
        if (i==4 || i==6 || i==9 || i==11) {this[i] = 30}
        if (i==2) {this[i] = 29}
   } 
   return this
}

function isDate(dtStr){

    var daysInMonth = DaysArray(12)
    var pos1=dtStr.indexOf(dtCh)
    var pos2=dtStr.indexOf(dtCh,pos1+1)
    var strMonth=dtStr.substring(0,pos1)
    var strDay=dtStr.substring(pos1+1,pos2)
    var strYear=dtStr.substring(pos2+1)
    strYr=strYear
    if (strDay.charAt(0)=="0" && strDay.length>1) strDay=strDay.substring(1)
    if (strMonth.charAt(0)=="0" && strMonth.length>1) strMonth=strMonth.substring(1)
    for (var i = 1; i <= 3; i++) {
        if (strYr.charAt(0)=="0" && strYr.length>1) strYr=strYr.substring(1)
    }
    month=parseInt(strMonth)
    day=parseInt(strDay)
    year=parseInt(strYr)
    if (pos1==-1 || pos2==-1){
        alert("The date format should be : mm/dd/yyyy")
        return false;
    }
    if (strMonth.length<1 || month<1 || month>12){
        alert("Please enter a valid month")
        return false;
    }
    if (strDay.length<1 || day<1 || day>31 || (month==2 && day>daysInFebruary(year)) || day > daysInMonth[month]){
        alert("Please enter a valid day")
        return false;
    }
    if (strYear.length != 4 || year==0 || year<minYear || year>maxYear){
        alert("Please enter a valid 4 digit year")
        return false;
    }
    if (dtStr.indexOf(dtCh,pos2+1)!=-1 || isInteger(stripCharsInBag(dtStr, dtCh))==false){
        alert("Please enter a valid date")
        return false;
    }
    return true;
}