// This source code is now part of the PHPLint project, see:
// http://cvs.icosaedro.it:8080/viewvc/public/phplint/stdlib/it/icosaedro/web
// Test code also available under the test/ directory of that project.

/**
 * Class for Italian Codice Fiscale normalization, formatting and checking.
 * @author Umberto Salsi <salsi@icosaedro.it>
 * @version $Date: 2020/01/23 10:35:20 $
 */
class CodiceFiscale
{

	/**
	 * Normalizes a CF by removing white spaces and converting to upper-case.
	 * @param string cf Raw CF, possibly with spaces.
	 * @return string Normalized CF.
	 */
	static normalize(cf)
	{
		return cf.replace(/\s/g, "").toUpperCase();
	}



	/**
	 * Returns the formatted CF. Currently does nothing but normalization.
	 * @param string cf Raw CF, possibly with spaces.
	 * @return string Formatted CF.
	 */
	static format(cf)
	{
		return this.normalize(cf);
	}
	
	
	/**
	 * Validates a regular CF.
	 * @param string cf Normalized, 16 characters CF.
	 * @return string Null if valid, or string describing why this CF must be
	 * rejected.
	 */
	static PRIVATE_validate_regular(cf)
	{
		if( ! /^[0-9A-Z]{16}$/.test(cf) )
			return "Invalid characters.";
		var s = 0;
		var even_map = "BAFHJNPRTVCESULDGIMOQKWZYX";
		for(var i = 0; i < 15; i++){
			var c = cf[i];
			var n = 0;
			if( "0" <= c && c <= "9" )
				n = c.charCodeAt(0) - "0".charCodeAt(0);
			else
				n = c.charCodeAt(0) - "A".charCodeAt(0);
			if( (i & 1) === 0 )
				n = even_map.charCodeAt(n) - "A".charCodeAt(0);
			s += n;
		}
		if( s%26 + "A".charCodeAt(0) !== cf.charCodeAt(15) )
			return "Invalid checksum.";
		return null;
	}
	
	
	/**
	 * Validates a temporary CF.
	 * @param string cf Normalized, 11 characters CF.
	 * @return string Null if valid, or string describing why this CF must be
	 * rejected.
	 */
	static PRIVATE_validate_temporary(cf)
	{
		if( ! /^[0-9]{11}$/.test(cf) )
			return "Invalid characters.";
		var s = 0;
		for(var i = 0; i < 11; i++ ){
			var n = cf.charCodeAt(i) - "0".charCodeAt(0);
			if( (i & 1) === 1 ){
				n *= 2;
				if( n > 9 )
					n -= 9;
			}
			s += n;
		}
		if( s % 10 !== 0 )
			return "Invalid checksum.";
		return null;
	}
	
	
	/**
	 * Verifies the basic syntax, length and control code of the given CF.
	 * @param string cf Raw CF, possibly with spaces.
	 * @return string Null if valid, or string describing why this CF must be
	 * rejected.
	 */
	static validate(cf)
	{
		cf = this.normalize(cf);
		if( cf.length === 0 )
			return "Empty.";
		else if( cf.length === 16 )
			return this.PRIVATE_validate_regular(cf);
		else if( cf.length === 11 )
			return this.PRIVATE_validate_temporary(cf);
		else
			return "Invalid length.";
	}

}