/**
 *
 * Copyright (c) 2015, Lucee Assosication Switzerland
 *
 * This library is free software; you can redistribute it and/or
 * modify it under the terms of the GNU Lesser General Public
 * License as published by the Free Software Foundation; either 
 * version 2.1 of the License, or (at your option) any later version.
 * 
 * This library is distributed in the hope that it will be useful,
 * but WITHOUT ANY WARRANTY; without even the implied warranty of
 * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the GNU
 * Lesser General Public License for more details.
 * 
 * You should have received a copy of the GNU Lesser General Public 
 * License along with this library.  If not, see <http://www.gnu.org/licenses/>.
 * 
 **/
package lucee.runtime.functions.other;

import java.security.NoSuchAlgorithmException;
import java.security.spec.InvalidKeySpecException;

import javax.crypto.SecretKeyFactory;
import javax.crypto.spec.PBEKeySpec;

import lucee.commons.lang.StringUtil;
import lucee.runtime.PageContext;
import lucee.runtime.coder.Base64Coder;
import lucee.runtime.exp.FunctionException;
import lucee.runtime.exp.PageException;
import lucee.runtime.ext.function.BIF;
import lucee.runtime.op.Caster;

public class GeneratePBKDFKey extends BIF {

	private static final long serialVersionUID = -2558116913822203235L;

	public static String call(PageContext pc,String algorithm, String passPhrase, String salt) throws PageException {
		return call(pc, algorithm, passPhrase, salt, 4096, 128);
	}
	
	public static String call(PageContext pc,String algorithm, String passPhrase, String salt, double iterations) throws PageException {
		return call(pc, algorithm, passPhrase, salt, iterations, 128);
	}
	public static String call(PageContext pc,String algorithm, String passPhrase, String salt, double iterations, double keySize) throws PageException {
		// algo
		if(StringUtil.isEmpty(algorithm))
			throw new FunctionException(pc, "GeneratePBKDFKey", 1, "algorithm", "algorithm argument is empty.");
		algorithm = algorithm.trim();
		if(!StringUtil.startsWithIgnoreCase(algorithm, "PBK"))
			throw new FunctionException(pc, "GeneratePBKDFKey", 1, "algorithm", "algorithm ["+algorithm+"] is not supported.");

		
		// TODO add provider to support addional keys by addin a provider that is supporting it 
		SecretKeyFactory key=null;
		try {
			key = SecretKeyFactory.getInstance(algorithm);
		} catch (NoSuchAlgorithmException e) {
			if(!algorithm.equalsIgnoreCase("PBKDF2WithHmacSHA1"))
				throw new FunctionException(pc, "GeneratePBKDFKey", 1, "algorithm", "only the algorithm [PBKDF2WithHmacSHA1] is supported by the build in .");
			else 
				throw Caster.toPageException(e);

		}
		
		
		try {
			PBEKeySpec spec = new PBEKeySpec(passPhrase.toCharArray(), salt.getBytes(), (int)iterations, (int)keySize);
			return Base64Coder.encode(key.generateSecret(spec).getEncoded());
	    }
	    catch (InvalidKeySpecException ikse) {
	      throw Caster.toPageException(ikse);
	    }
	  }
	
	@Override
	public Object invoke(PageContext pc, Object[] args) throws PageException {
		if ( args.length == 5) return call( pc, Caster.toString(args[0]),Caster.toString(args[1]), Caster.toString(args[2]),Caster.toDoubleValue(args[3]),Caster.toDoubleValue(args[4]));
		if ( args.length == 4) return call( pc, Caster.toString(args[0]),Caster.toString(args[1]), Caster.toString(args[2]),Caster.toDoubleValue(args[3]));
		if ( args.length == 3) return call( pc, Caster.toString(args[0]),Caster.toString(args[1]), Caster.toString(args[2]));
	    
		throw new FunctionException(pc, "GeneratePBKDFKey", 3, 5, args.length);
	}
}