/*

* Copyright (c) 2006 Nokia Corporation and/or its subsidiary(-ies). 

* All rights reserved.

* This component and the accompanying materials are made available

* under the terms of "Eclipse Public License v1.0"

* which accompanies this distribution, and is available

* at the URL "http://www.eclipse.org/legal/epl-v10.html".

*

* Initial Contributors:

* Nokia Corporation - initial contribution.

*

* Contributors:

*

* Description:

*

*/

package com.nokia.s60tools.util.debug;

import com.nokia.s60tools.util.internal.Messages;

/**

 * Simple console debug utility that can be configured

 * via property settings given as command line parameter 

 * to JVM (-Dproperty=value).

 * 

 * JVM parameter usage example:

 * 

 * <code>

 * <pre>

 *  -Dcom.nokia.s60tools.debug=true -Dcom.nokia.s60tools.debugpriority=class|operation

 * </pre>

 * </code>

 * 

 * The aforementioned JVM arguments enable debugging, and print out

 * all the debug messages with priority <code>PRIORITY_CLASS</code> 

 * and <code>PRIORITY_OPERATION</code> but omit debug prints 

 * with <code>PRIORITY_LOOP</code>.<br><br> 

 * 

 * After the following parameter is added in the end of the previous parameters

 * 

 * <code>

 * <pre> 

 *  -Dcom.nokia.s60tools.debugfilter=MyClass

 * </pre>

 * </code>

 * 

 * only those debug messages that start with string "MyClass" are printed to stdout.

 * 

 */

public class DbgUtility {

	/**

	 * Debug prints using this priority generate lots of information because priority

	 * should be used only when debugging happens in a tight loop.

	 */

	public static String PRIORITY_LOOP = "loop"; //$NON-NLS-1$

	/**

	 * Debug prints using this priority generate a moderate amount of information because priority 

	 * should be used only when there is need to debug operation level information.

	 */

	public static String PRIORITY_OPERATION = "operation"; //$NON-NLS-1$

	/**

	 * Debug prints using this priority generate a small amount of information because priority 

	 * should be used only when a class is initialized or deinitialized.

	 */	

	public static String PRIORITY_CLASS = "class";	 //$NON-NLS-1$

	/**

	 * Value for this property can be any OR-combination of 

	 * the priority types that are declared above.

	 * 

	 *  For example, <code>loop | operation | class</code>

	 *   

	 * The default value is <code>class</code>. 

	 */

	private static String PROPERTY_PRIORITY = "com.nokia.s60tools.debugpriority"; //$NON-NLS-1$

	/**

	 * Value for this property can be either <code>true</code> or <code>false</code>.

	 */

	private static String PROPERTY_DEBUG = "com.nokia.s60tools.debug"; //$NON-NLS-1$

	/**

	 * This property filters messages in a such way that it passes through

	 * only the mesages starting with the string defined in this property.

	 */

	private static String PROPERTY_DEBUG_FILTER = "com.nokia.s60tools.debugfilter"; //$NON-NLS-1$

	//

	// Setting up the default values.

	//

	private static String DEFAULT_DEBUG_PRIORITY = "class"; //$NON-NLS-1$

	private static String DEFAULT_DEBUG_FILTER = "";	 //$NON-NLS-1$

	private static String CURRENT_DEBUG_PRIORITY = System.getProperty(PROPERTY_PRIORITY, DEFAULT_DEBUG_PRIORITY);

	private static String CURRENT_DEBUG_FILTER = System.getProperty(PROPERTY_DEBUG_FILTER, DEFAULT_DEBUG_FILTER);		

	/**

	 * Prints message to stdout if it is higher or equal with the current 

	 * debug priority and passes the currently used debugging filter.

	 * @param priorityString Priority type of the message.

	 * @param msg Message string.

	 */

	public static void println(String priorityString, String msg){

		if (Boolean.getBoolean(PROPERTY_DEBUG)

			&&

			priorityMatchesWithCurrentDebugSetting(priorityString)

			&&

			passesFilter(msg)

			) {

			System.out.println(msg);

		}

	}

	/**

	 * Sets a new debug priority.

	 * @param priority New debug priority

	 */

	public static void setCurrentDebugPriority(String priority){

		if(

			(priority.compareToIgnoreCase(PRIORITY_CLASS)== 0)

			||

			(priority.compareToIgnoreCase(PRIORITY_LOOP)== 0)

			||

			(priority.compareToIgnoreCase(PRIORITY_OPERATION)== 0)

			){

			CURRENT_DEBUG_PRIORITY = priority;

		}

		else

		{

			throw new IllegalArgumentException(Messages.getString("DbgUtility.Invalid_Debug_Priority_RunTime_Exception_Msg")); //$NON-NLS-1$

		}

	}

	/**

	 * Debug priority filter.

	 * @param priorityString Priority of the currently handled message.

	 * @return Returns <code>true</code> if the debug message passes 

	 *                 the filter, otherwise return <code>false</code>.

	 */

	private static boolean priorityMatchesWithCurrentDebugSetting(String priorityString){

		return (CURRENT_DEBUG_PRIORITY.toLowerCase()).indexOf(priorityString) >= 0;	

	}

	/**

	 * Debug string start prefix filter.

	 * @param msg Debug message to be checked for filtering.

	 * @return Returns <code>true</code> if the debug message passes 

	 *                 the filter, otherwise return <code>false</code>.

	 */

	private static boolean passesFilter(String msg){

		if(!CURRENT_DEBUG_FILTER.equalsIgnoreCase("")){ //$NON-NLS-1$

			return msg.startsWith(CURRENT_DEBUG_FILTER);	

		}

		else{

			return true;

		}

	}

}