Copyright (c) 2006 IBM Corporation and others.
All rights reserved. This program and the accompanying materials 
are made available under the terms of the Eclipse Public License v1.0
which accompanies this distribution, and is available at
http://www.eclipse.org/legal/epl-v10.html
Contributors:
    Matthew Webster - initial implementation
/*******************************************************************************
 * Copyright (c) 2006 IBM Corporation and others.
 * All rights reserved. This program and the accompanying materials 
 * are made available under the terms of the Eclipse Public License v1.0
 * which accompanies this distribution, and is available at
 * http://www.eclipse.org/legal/epl-v10.html
 * 
 * Contributors:
 *     Matthew Webster - initial implementation
 *******************************************************************************/
package org.aspectj.weaver.tools;

import org.aspectj.util.LangUtil;

public abstract class TraceFactory {
    
	public final static String DEBUG_PROPERTY = "org.aspectj.tracing.debug";
	public final static String FACTORY_PROPERTY = "org.aspectj.tracing.factory";
	public final static String DEFAULT_FACTORY_NAME = "default";
	
    protected static boolean debug = getBoolean(DEBUG_PROPERTY,false); 
    private static TraceFactory instance;
    
    public Trace getTrace (Class clazz) {
    	return instance.getTrace(clazz);
    }
    
    public static TraceFactory getTraceFactory () {
    	return instance;
    }
    
    protected static boolean getBoolean(String name, boolean def) {
		String defaultValue = String.valueOf(def);
		String value = System.getProperty(name,defaultValue);
		return Boolean.valueOf(value).booleanValue();
	}

	static {
		
		/*
		 * Allow user to override default behaviour or specify their own factory 
		 */
		String factoryName = System.getProperty(FACTORY_PROPERTY);
		if (factoryName != null) try {
			if (factoryName.equals(DEFAULT_FACTORY_NAME)) {
				instance = new DefaultTraceFactory();
			}
			else {
	    		Class factoryClass = Class.forName(factoryName);
	    		instance = (TraceFactory)factoryClass.newInstance();
			}
		}
    	catch (Throwable th) {
    		if (debug) th.printStackTrace();
    	}
    	
		/*
		 * Try to load external trace infrastructure using supplied factories
		 */
    	if (instance == null) try {
			if (LangUtil.is15VMOrGreater()) {
	    		Class factoryClass = Class.forName("org.aspectj.weaver.tools.Jdk14TraceFactory");
	    		instance = (TraceFactory)factoryClass.newInstance();
			} else {
	    		Class factoryClass = Class.forName("org.aspectj.weaver.tools.CommonsTraceFactory");
	    		instance = (TraceFactory)factoryClass.newInstance();
			}
    	}
    	catch (Throwable th) {
    		if (debug) th.printStackTrace();
    	}

    	/*
		 * Use default trace 
		 */
    	if (instance == null) {
    	    instance = new DefaultTraceFactory();
    	}
    	
    	if (debug) System.err.println("TraceFactory.instance=" + instance);
    }

}