/******************************************************************************
 * http://ajas.us/
 * The way I want to do CreditCards (Apr 27, 2007) rev. (May 14, 2007)
 * If you find an error, or improvement, let me know: dev at ajas dot us
 * This file is free for use
 *
 * ajas.ui.magicCreditCard()           - call this onblur, scrubs and validates
 * ajas.validator.creditCard.validate()- call for true/false validation
 * ajas.validator.creditCard.parse()   - don't call this
 * ajas.validator.creditCard.infer()   - just because I could, has ambiguity 
 * ajas.validator.creditCard.aCards    - details for each card type to check 
 * 
 * based on: http://www.braemoor.co.uk/software/creditcard.shtml
 *****************************************************************************/

if(!ajas)var ajas={};
if(!ajas.ui)ajas.ui={};
if(!ajas.validator)ajas.validator={};
if(!ajas.validator.creditCard)ajas.validator.creditCard={};


// use this function for form feedback
ajas.ui.magicCreditCard=function(oInput, sType, bStrict) {
	// Set preferred defaults here.
	// bStrict=false will remove invalid characters
	// bStrict=true will fail on invalid characters
	if(arguments.length < 3) var bStrict=true;

	var sLabel = oInput.id + 'Msg';
	oInput.className = oInput.className.replace(/ajas_credit_error/g, '');
	try {
		if (oInput.value == '') {
			document.getElementById(sLabel).innerHTML = 'Enter Credit Card';
			return;
		}
		var sCC = ajas.validator.creditCard.parse(oInput.value, sType, bStrict);
		document.getElementById(sLabel).innerHTML = oInput.value = sCC;
	} catch (e) {
		oInput.className += ' ajas_credit_error';
		var message = e.message;
		// Fix for IE6 bug
		if (message.indexOf('is null or not an object') > -1) {
			message = 'Invalid Phone string';
		}
		document.getElementById(sLabel).innerHTML = message;
	}
}

//use this function to get a quiet true/false response
ajas.validator.creditCard.validate=function(sCC, sType) {
	try {
		ajas.validator.creditCard.parse(sCC, sType, true); //bStrict=true
	} catch (e) {
		return false;
	}
	return true;
}

ajas.validator.creditCard.parse=function(sCC, sType, bStrict) {
	if(arguments.length < 3) var bStrict=true;

	if (false==bStrict) {
		//strip non-digits
		sCC=sCC.replace(/[^\d]/g,'');
	} else {
		//strip only spaces and dashes
		sCC=sCC.replace(/[\s\-]/g,'');
		
		// verify number is actually numeric
		if (!/^\d*$/.exec(sCC)) {
			throw new Error("Invalid Credit Card #");
		}
	}
	
	if (sCC.length == 0) {
		throw new Error("Enter Credit Card #");
	}

	//verify specified type is known valide
	if (!ajas.validator.creditCard.aCards[sType]) {
		throw new Error("Unsupported Card Type");
	}
	
	//verify specified number matches card type prefix
	if (!new RegExp('^'+ajas.validator.creditCard.aCards[sType].prefixes).test(sCC)) {
		throw new Error("Invalid "+sType+" #");
	}
	
	//verify specified number is of valid length for type
	if (!new RegExp('^'+ajas.validator.creditCard.aCards[sType].len).test(sCC.length)) {
		throw new Error("Invalid Number Length");
	}

	//verify check-digit, if card type specifies
	if (ajas.validator.creditCard.aCards[sType].bChkDig) {
		var iSum=0;
		for(var i=sCC.length-1,j=true;i>=0;i--,j=!j) {
			l=0;
			if (j) {
				iSum+=parseInt(sCC.charAt(i));
			} else { // add the sum of the digits
				if ((k=parseInt(sCC.charAt(i))) > 4) {
					iSum+=2*k-9;
				} else {
					iSum+=2*k;
				}
			}
		}
		if (iSum%10!=0) {
			throw new Error("Invalid CC (checksum)"+iSum);
		}
	}
	return sCC;
}

ajas.validator.creditCard.infer=function(sCC) {
	//strip non-digits
	sCC=sCC.replace(/[^\d]/g,'');

	var aCandidates = new Array();
	var i=0;
	
	//Find which cards' prefixes match supplied card
	for(var s in ajas.validator.creditCard.aCards) {
		if (new RegExp('^'+ajas.validator.creditCard.aCards[s].prefixes).test(sCC)) {
			aCandidates[i++]=s;
		}
	}
	
	if (aCandidates.length==0) return '[No Prefix Match]';
	var aCandidates2 = new Array();
	i=0;
	
	//Find which cards' lengths match remaining candidates
	for(var j in aCandidates) {
		if (new RegExp('^'+ajas.validator.creditCard.aCards[aCandidates[j]].len).test(sCC.length)) {
			aCandidates2[i++]=aCandidates[j];
		}
	}

	if (aCandidates2.length==0) return '[No Length Match]';
	var aCandidates = new Array();
	var bChk = false;
	
	//verify check-digit
	var iSum=0;
	for(var i=sCC.length-1,j=true;i>=0;i--,j=!j) {
		l=0;
		if (j) {
			iSum+=parseInt(sCC.charAt(i));
		} else { // add the sum of the digits
			if ((k=parseInt(sCC.charAt(i))) > 4) {
				iSum+=2*k-9;
			} else {
				iSum+=2*k;
			}
		}
	}
	if (iSum%10==0) {
		bChk=true;
	}
	
	i=0;
	
	// if the checkdigit fails, remove candidates that require it
	if (!bChk) {
		for(var j in aCandidates2) {
			if (!ajas.validator.creditCard.aCards[j].bChkDig) {
				aCandidates[i++]=aCandidates2[j];
			}
		}
	} else {
		aCandidates=aCandidates2;
	}

	if (aCandidates.length==0) return '[No Parity Match]';

	return aCandidates.join(',');
}

// define known valid card types
ajas.validator.creditCard.aCards={
	"Visa"        :{bChkDig:true,len:"13|16"   ,prefixes:"4"},
	"MasterCard"  :{bChkDig:true,len:"16"      ,prefixes:"51|52|53|54|55"},
	"DinersClub"  :{bChkDig:true,len:"14|16"   ,prefixes:"300|301|302|303|304|305|36|38|55"},
	"CarteBlanche":{bChkDig:true,len:"14"      ,prefixes:"300|301|302|303|304|305|36|38"},
	"AmEx"        :{bChkDig:true,len:"15"      ,prefixes:"34|37"},
	"Discover"    :{bChkDig:true,len:"16"      ,prefixes:"6011|650"},
	"JCB"         :{bChkDig:true,len:"15|16"   ,prefixes:"3|1800|2131"},
	"enRoute"     :{bChkDig:true,len:"15"      ,prefixes:"2014|2149"},
	"Solo"        :{bChkDig:true,len:"16|18|19",prefixes:"6334|6767"},
	"Switch"      :{bChkDig:true,len:"16|18|19",prefixes:"4903|4905|4911|4936|564182|633110|6333|6759"},
	"Maestro"     :{bChkDig:true,len:"16"      ,prefixes:"5020|6"},
	"VisaElectron":{bChkDig:true,len:"16"      ,prefixes:"417500|4917|4913"}
};