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/* VersionMatcher.java
 * $Id: ServerVersionMatcher.java,v 1.4 2007/05/05 05:36:26 tcfujii Exp $
 * $Revision: 1.4 $
 * $Date: 2007/05/05 05:36:26 $
 * Indentation Information:
 * 0. Please (try to) preserve these settings.
 * 1. Tabs are preferred over spaces.
 * 2. In vi/vim -
 *		:set tabstop=4 :set shiftwidth=4 :set softtabstop=4
 * 3. In S1 Studio -
 *		1. Tools->Options->Editor Settings->Java Editor->Tab Size = 4
 *		2. Tools->Options->Indentation Engines->Java Indentation Engine->Expand Tabs to Spaces = False.
 *		3. Tools->Options->Indentation Engines->Java Indentation Engine->Number of Spaces per Tab = 4.
 */

package com.sun.enterprise.admin.jmx.remote.server;

import java.util.logging.Logger;
import com.sun.enterprise.admin.jmx.remote.protocol.Version;
/**
 *
 * @author  <a href="mailto:Kedar.Mhaswade@sun.com">Kedar Mhaswade</a>
 * @since S1AS8.0
 * @version $Revision: 1.4 $
 */
public class ServerVersionMatcher {
	
	private static final ServerVersionMatcher matcher = new ServerVersionMatcher();
	private static final Logger logger = Logger.getLogger("com.sun.enterprise.admin.jmx.remote.finer.logger");
	private ServerVersionMatcher() {
	}
	
	public static ServerVersionMatcher getMatcher() {
		return ( matcher );
	}
	/**
	 * Returns true if and only if the client version and server version are
	 * compatible. The server version matches with client version if and only if
	 * <ul>
	 * <li> Client Major Version is <= Server Major Version </li>
	 * <li> Client Minor Version is <= Server Minor Version </li>
	 * <li> Upgrade Data is compatible in both the versions </li>
	 * </ul>
	 */
	public boolean match(Version client, Version server) {
		return (majorCompatible(client, server) &&
				minorCompatible(client, server) &&
				upgradeCompatible(client, server) );
	}
	
	boolean majorCompatible(Version c, Version s) {
		//client version can at most equal server version
		boolean compatible = false;
		final int cmv = c.getMajorVersion();
		final int smv = s.getMajorVersion();
		if (cmv < smv) {
			logger.finer("S1AS JSR 160 - Using Backword compatibility, as client version: " +
			cmv + " is smaller than server version: " + smv);
			logger.finer("It is better to upgrade the client software");
			compatible = true;
		}
		else if (cmv == smv) {
			compatible = true;
		}
		else {
			logger.finer("S1AS JSR 160 - Version Compatibility failed, as client version: " +
			cmv + " is higher than server version: " + smv);
			logger.finer("Server software has to be upgraded to atleast major version: " + cmv);
			compatible = false;
		}
		return ( compatible );
	}

	boolean minorCompatible(Version c, Version s) {
		//client version can at most equal server version
		boolean compatible = false;
		final int cmv = c.getMinorVersion();
		final int smv = s.getMinorVersion();
		if (cmv < smv) {
			logger.finer("S1AS JSR 160 - Using Backword compatibility, as client version: " +
			cmv + " is smaller than server version: " + smv);
			logger.finer("It is better to upgrade the client software");
			compatible = true;
		}
		else if (cmv == smv) {
			compatible = true;
		}
		else {
			logger.finer("S1AS JSR 160 - Version Compatibility failed, as client version: " +
			cmv + " is higher than server version: " + smv);
			logger.finer("Server software has to be upgraded to atleast major version: " + cmv);
			compatible = false;
		}
		return ( compatible );
	}
	
	boolean upgradeCompatible(Version c, Version s) {
		final String[] cud = c.getUpgradeData();
		final String[] sud = s.getUpgradeData();
		boolean uc = true;
		uc = uc && (cud.length == sud.length); //lengths must be the same
		if (uc) {
			for (int i = 0 ; i < cud.length ; i++) {
				if (cud[i] != null && sud[i] != null) {
					uc = uc && cud[i].equals(sud[i]);
					if (!uc) {
						break;
					}
				}
			}
		}
		return ( uc );
	}
}