/*******************************************************************************
 * Copyright 2013 SAP AG
 * 
 * Licensed 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 com.sap.core.odata.api;

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

/**
 * This class is a container for the supported ODataServiceVersions.
 * @author SAP AG
 *
 */
public class ODataServiceVersion {

  private static final Pattern DATASERVICEVERSIONPATTERN = Pattern.compile("(\\p{Digit}+\\.\\p{Digit}+)(:?;.*)?");

  /**
   * ODataServiceVersion 1.0
   */
  public static final String V10 = "1.0";
  /**
   * ODataServiceVersion 2.0
   */
  public static final String V20 = "2.0";
  /**
   * ODataServiceVersion 3.0
   */
  public static final String V30 = "3.0";

  /**
   * Validates format and range of a data service version string.
   * @param version version string
   * @return <code>true</code> for a valid version
   */
  public static boolean validateDataServiceVersion(final String version) {
    final Matcher matcher = DATASERVICEVERSIONPATTERN.matcher(version);
    if (matcher.matches()) {
      final String possibleDataServiceVersion = matcher.group(1);
      return V10.equals(possibleDataServiceVersion)
          || V20.equals(possibleDataServiceVersion)
          || V30.equals(possibleDataServiceVersion);
    } else {
      throw new IllegalArgumentException(version);
    }
  }

  /**
   * actual > comparedTo
   * @param actual
   * @param comparedTo
   * @return <code>true</code> if actual is bigger than comparedTo
   */
  public static boolean isBiggerThan(final String actual, final String comparedTo) {
    if (!validateDataServiceVersion(comparedTo) || !validateDataServiceVersion(actual)) {
      throw new IllegalArgumentException("Illegal arguments: " + comparedTo + " and " + actual);
    }

    final double me = Double.parseDouble(extractDataServiceVersionString(actual));
    final double other = Double.parseDouble(extractDataServiceVersionString(comparedTo));

    return me > other;
  }

  private static String extractDataServiceVersionString(final String rawDataServiceVersion) {
    if (rawDataServiceVersion != null) {
      final String[] pattern = rawDataServiceVersion.split(";");
      return pattern[0];
    }

    return null;
  }

}