//datatypes are: -
//text-p / text-np / date / number / currency
		
//parameters are: -
//field
//fieldname
//data type
//maxlength
//required


var dtCh= "/";
var minYear=1900;
var maxYear=2100;



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

function stripCharsInBag(s, bag){
	var i;
var c;
    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++){   
        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,fieldname)
	{
	var daysInMonth = new DaysArray(12);
	var pos1=dtStr.indexOf(dtCh);
	var pos2=dtStr.indexOf(dtCh,pos1+1);
	var strDay=dtStr.substring(0,pos1);
	var strMonth=dtStr.substring(pos1+1,pos2);
	var strYear=dtStr.substring(pos2+1);
	var 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);}
	}
	var month=parseInt(strMonth,10);
	var day=parseInt(strDay,10);
	var year=parseInt(strYr,10);
	
	if (pos1==-1 || pos2==-1){
		alert("The date format in the " + fieldname + " field should be : dd/mm/yyyy");
		return false;
	}
	if (strDay.length<1 || day<1 || day>31 || (month==2 && day>daysInFebruary(year)) || day > daysInMonth[month]){
		alert("Please enter a valid day in the " + fieldname + " field.");
		return false;
	}
	if (strMonth.length<1 || month<1 || month>12){
		alert("Please enter a valid month in the " + fieldname + " field.");
		return false;
	}
	if (strYear.length != 4 || year===0 || year<minYear || year>maxYear){
		alert("Please enter a valid 4 digit year between "+minYear+" and "+maxYear + " in the " + fieldname + " field.");
		return false;
	}
	if (dtStr.indexOf(dtCh,pos2+1)!=-1|| isInteger(stripCharsInBag(dtStr, dtCh))===false){
		alert("Please enter a valid date in the " + fieldname + " field.");
		return false;
	}
return true;
}

function validatedate(objName,fieldname)
	{
	var dt=objName;
	if (isDate(dt.value,fieldname)===false)
		{
		objName.style.backgroundColor="red";
		return false;
		}
	else
		{
		objName.style.backgroundColor="";
		}
	}
 
function chkcontents(objName,fieldname,symbols)
	{
	var checkOK = symbols;
	var checkStr = objName;
	var allValid = true;
	var decPoints = 0;
	var allNum = "";
        var ch;
        var j;
	for (var i = 0;  i < checkStr.value.length;  i++)
		{
		ch = checkStr.value.charAt(i);
		for (j = 0;  j < checkOK.length;  j++){
		if (ch == checkOK.charAt(j)){
		break;}
		if (j == checkOK.length)
			{
			allValid = false;
			break;
			}
		if (ch != ","){
		allNum += ch;}
}
		}
var alertsay;
	if (!allValid)
		{
		alertsay = "Please enter only the values \"";
		alertsay = alertsay + checkOK + "\" in the " + fieldname + " field.";
		alert(alertsay);
		return (false);
		}
	}


function validate_field(fieldobj,fieldname,datatype,fieldlen,isrequired)
	{
	//alert(fieldlen);
	//Function to validate an individual field	
	if (fieldobj.length>fieldlen)
		{
		alert(fieldname + " value exceeds maximum field length");
		fieldobj.style.backgroundColor="red";
		return false;
		}
	else
		{
		switch(datatype)
			{
					
			case "text-p":
				//text with punctuation - we don't care whats in it
				//just check for required value

				if(isrequired==="True" && fieldobj.value==="")
					{
					alert("No value entered in the " + fieldname + " field");
					fieldobj.style.backgroundColor="red";
					return false;
					}
				else
					{
					fieldobj.style.backgroundColor="";
					}
			break;

			case "text-np":
				//text without punctuation - call chkcontents function
				//then check for required value
				if (chkcontents(fieldobj,fieldname,"ABCDEFGHIJKLMNOPQRSTUVWXYZ abcdefghijklmnopqrstuvwxyz 1234567890") === false)
					{
					fieldobj.style.backgroundColor="red";
					return false;
					}
				else
					{
					if(isrequired==="True" && fieldobj.value==="")
						{
						alert("No value entered in the " + fieldname + " field");
						fieldobj.style.backgroundColor="red";
						return false;
						}
					else
						{
						fieldobj.style.backgroundColor="";
						}
					}
			break;

			case "date":
				if(isrequired==="True")
					{
					if(validatedate(fieldobj,fieldname) === false)
						{
						return false;
						}
					}
				
				if(isrequired==="False" && fieldobj.value!=="")
					{
					if(validatedate(fieldobj,fieldname) === false)
						{
						return false;
						}
					}
				
				if(isrequired==="False" && fieldobj.value==="")
					{
					fieldobj.style.backgroundColor="";
					return true;
					}
			break;

			case "number":
				//For number fields, check the datatype and the required value
				if (chkcontents(fieldobj,fieldname,"0123456789.") === false)
					{
					fieldobj.style.backgroundColor="red";
					return false;
					}
				else
					{
					if(isrequired==="True" && fieldobj.value==="")
						{
						alert("No value entered in the " + fieldname + " field");
						fieldobj.style.backgroundColor="red";
						return false;
						}
					else
						{
						fieldobj.style.backgroundColor="";
						}
					}
			break;

			case "currency":
				//For number fields, check the datatype and the required value
				if (chkcontents(fieldobj,fieldname,"0123456789-.,") === false)
					{
					fieldobj.style.backgroundColor="red";
					return false;
					}
				else
					{
					if(isrequired==="True" && fieldobj.value==="")
						{
						alert("No value entered in the " + fieldname + " field");
						fieldobj.style.backgroundColor="red";
						return false;
						}
					else
						{
						fieldobj.style.backgroundColor="";
						}
					}
			break;
			}	
		}
	
	}