/*******************************************************************************
 * Copyright 2014 Federal Chancellery Austria
 * MOA-ID has been developed in a cooperation between BRZ, the Federal
 * Chancellery Austria - ICT staff unit, and Graz University of Technology.
 *
 * Licensed under the EUPL, Version 1.1 or - as soon they will be approved by
 * the European Commission - subsequent versions of the EUPL (the "Licence");
 * You may not use this work except in compliance with the Licence.
 * You may obtain a copy of the Licence at:
 * http://www.osor.eu/eupl/
 *
 * Unless required by applicable law or agreed to in writing, software
 * distributed under the Licence is distributed on an "AS IS" basis,
 * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
 * See the Licence for the specific language governing permissions and
 * limitations under the Licence.
 *
 * This product combines work with different licenses. See the "NOTICE" text
 * file for details on the various modules and licenses.
 * The "NOTICE" text file is part of the distribution. Any derivative works
 * that you distribute must include a readable copy of the "NOTICE" text file.
 *******************************************************************************/
package at.gv.egovernment.moa.id.configuration.validation;

import org.apache.commons.lang.StringUtils;

import at.gv.egovernment.moa.id.configuration.Constants;

public class CompanyNumberValidator implements IdentificationNumberValidator {

	public boolean validate(String commercialRegisterNumber) {
		
		String normalizedNumber = commercialRegisterNumber.replaceAll(" ", "");
		if(normalizedNumber.startsWith(Constants.IDENIFICATIONTYPE_FN))
			normalizedNumber = normalizedNumber.substring(2);
		
		return checkCommercialRegisterNumber(normalizedNumber);
	}

	private boolean checkCommercialRegisterNumber(String commercialRegisterNumber) {
		if (commercialRegisterNumber == null) {
			return false;
		}
		commercialRegisterNumber = StringUtils.leftPad(commercialRegisterNumber, 7,
		    '0');
		if (!commercialRegisterNumber.matches("\\d{6}[abdfghikmpstvwxzy]")) {
			return false;
		}
		String digits = commercialRegisterNumber.substring(0,
		    commercialRegisterNumber.length() - 1);
		char checkDigit = commercialRegisterNumber.charAt(commercialRegisterNumber
		    .length() - 1);
		boolean result = calcCheckDigitFromCommercialRegisterNumber(digits) == checkDigit;
		return result;
	}

	public static char calcCheckDigitFromCommercialRegisterNumber(
	    String commercialRegisterDigits) {
		final int[] WEIGHT = { 6, 4, 14, 15, 10, 1 };
		final char[] CHECKDIGIT = { 'a', 'b', 'd', 'f', 'g', 'h', 'i', 'k', 'm',
		    'p', 's', 't', 'v', 'w', 'x', 'y', 'z' };
		if (commercialRegisterDigits == null) {
			throw new NullPointerException("Commercial register number missing.");
		}
		commercialRegisterDigits = StringUtils.leftPad(commercialRegisterDigits, 6,
		    '0');
		if (!commercialRegisterDigits.matches("\\d{6}")) {
			throw new IllegalArgumentException(
			    "Invalid commercial register number provided.");
		}
		int sum = 0;
		for (int i = 0; i < commercialRegisterDigits.length(); i++) {
			int value = commercialRegisterDigits.charAt(i) - '0';
			sum += WEIGHT[i] * value;
		}
		return CHECKDIGIT[sum % 17];
	}
}