/*
 * Copyright (c) 2006 Henri Sivonen
 *
 * Permission is hereby granted, free of charge, to any person obtaining a 
 * copy of this software and associated documentation files (the "Software"), 
 * to deal in the Software without restriction, including without limitation 
 * the rights to use, copy, modify, merge, publish, distribute, sublicense, 
 * and/or sell copies of the Software, and to permit persons to whom the 
 * Software is furnished to do so, subject to the following conditions:
 *
 * The above copyright notice and this permission notice shall be included in 
 * all copies or substantial portions of the Software.
 *
 * THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS OR 
 * IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY, 
 * FITNESS FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT. IN NO EVENT SHALL 
 * THE AUTHORS OR COPYRIGHT HOLDERS BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER 
 * LIABILITY, WHETHER IN AN ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING 
 * FROM, OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER 
 * DEALINGS IN THE SOFTWARE.
 */

package nu.validator.datatype;

import java.util.regex.Matcher;
import java.util.regex.Pattern;

import nu.validator.vendor.relaxng.datatype.DatatypeException;

/**
 * 
 * 
 * @version $Id$
 * @author hsivonen
 */
public final class Month extends AbstractDatatype {

    /**
     * The singleton instance.
     */
    public static final Month THE_INSTANCE = new Month();

    /**
     * The rexexp for this datatype.
     */
    private static final Pattern THE_PATTERN = Pattern.compile("^([0-9]{4,})-([0-9]{2})$");

    /**
     * Constructor.
     */
    private Month() {
        super();
    }

    private void checkMonth(String year, String month)
            throws DatatypeException {
        checkMonth(Integer.parseInt(year), Integer.parseInt(month));
    }

    private void checkMonth(int year, int month)
            throws DatatypeException {
        if (year < 1) {
            throw newDatatypeException("Year cannot be less than 1.");
        }
        if (month < 1) {
            throw newDatatypeException("Month cannot be less than 1.");
        }
        if (month > 12) {
            throw newDatatypeException("Month cannot be greater than 12.");
        }
    }

    @Override
    public void checkValid(CharSequence literal)
            throws DatatypeException {
        Matcher m = THE_PATTERN.matcher(literal);
        if (m.matches()) {
            checkMonth(m.group(1), m.group(2));
        } else {
            throw newDatatypeException(
                    "The literal did not satisfy the format for month.");
        }
    }

    @Override
    public String getName() {
        return "month";
    }

}
