common-types/src/main/java/org/apache/falcon/entity/v0/DateValidator.java

/**
 * Licensed to the Apache Software Foundation (ASF) under one
 * or more contributor license agreements.  See the NOTICE file
 * distributed with this work for additional information
 * regarding copyright ownership.  The ASF licenses this file
 * to you under the Apache License, Version 2.0 (the
 * "License"); you may not use this file except in compliance
 * with the License.  You may obtain a copy of the License at
 *
 *     http://www.apache.org/licenses/LICENSE-2.0
 *
 * Unless required by applicable law or agreed to in writing, software
 * distributed under the License is distributed on an "AS IS" BASIS,
 * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
 * See the License for the specific language governing permissions and
 * limitations under the License.
 */
package org.apache.falcon.entity.v0;

import org.apache.commons.lang3.StringUtils;

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

/**
 * Date utility class.
 */
public final class DateValidator {

    private static final String DATE_PATTERN =
            "(2\\d\\d\\d|19\\d\\d)-(0[1-9]|1[012])-(0[1-9]|1[0-9]|2[0-9]|3[01])T([0-1][0-9]|2[0-3]):([0-5][0-9])Z";
    private static final Pattern PATTERN = Pattern.compile(DATE_PATTERN);

    private DateValidator() {
    }

    /**
     * Validate date format with regular expression.
     *
     * @param date date address for validation
     * @return true valid date fromat, false invalid date format
     */
    public static boolean validate(final String date) {
        if (StringUtils.isBlank(date)) {
            return false;
        }
        Matcher matcher = PATTERN.matcher(date);

        if (matcher.matches()) {

            matcher.reset();

            if (matcher.find()) {

                int year = Integer.parseInt(matcher.group(1));
                String month = matcher.group(2);
                String day = matcher.group(3);

                if (day.equals("31")
                        && (month.equals("4") || month.equals("6")
                        || month.equals("9") || month.equals("11")
                        || month.equals("04") || month.equals("06") || month.equals("09"))) {
                    return false; // only 1,3,5,7,8,10,12 has 31 days
                } else if (month.equals("2") || month.equals("02")) {
                    // leap year
                    if (year % 4 == 0) {
                        return !(day.equals("30") || day.equals("31"));
                    } else {
                        return !(day.equals("29") || day.equals("30") || day.equals("31"));
                    }
                } else {
                    return true;
                }
            } else {
                return false;
            }
        } else {
            return false;
        }
    }
}