/* 	
 	This JavasScript is meant to be a library of commonly used JS functions for use on the Hamilton College Web site.
 
 	Created by Jason Quatrino, 5/3/2006
	
	CONTENTS:
	
	+ isDate(datevalue)
		- checks whether date is properly formatted as mm/dd/yyyy
		
	+ trim(string)
		- trims whitespace from string	
		
	+ randomString(len)
		- creates a random string of length 'len' (8 mixed case alphanumeric characters by default)
		
	+ togglediv(elementid)
		- toggles element display
		
	
 */


/*
  DHTML date validation script. 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 between "+minYear+" and "+maxYear);
		return false;
		}
	if (dtStr.indexOf(dtCh,pos2+1)!=-1 || isInteger(stripCharsInBag(dtStr, dtCh))==false){
		alert("Please enter a valid date");
		return false;
		}
	return true;
	}

/* trims whitespace from submitted string */
function trim(str) { 
	str = str.replace(/^\s*|\s*$/g,'');
	return str;
	}
			
/* creates a random string of mixed case letters and numbers */
function randomString(len) {
	var chars = "0123456789ABCDEFGHIJKLMNOPQRSTUVWXTZabcdefghiklmnopqrstuvwxyz";
	if (!len || len == '')
		len = 8;
	var string_length = len;
	var randomstring = '';
	for (var i=0; i<string_length; i++) {
		var rnum = Math.floor(Math.random() * chars.length);
		randomstring += chars.substring(rnum,rnum+1);
		}
		
	return randomstring;
	}
	
/* toggles element display */
function togglediv(elementid){
	var elementref = document.getElementById(elementid);
	if (elementref.style.display == 'block' || elementref.style.display == 'inline' || elementref.style.display == '')
		elementref.style.display = 'none';
	else
		elementref.style.display = 'block';
	}