/*
 * 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.log4j.config;

import org.apache.log4j.Priority;
import org.apache.log4j.helpers.LogLog;

import java.beans.BeanInfo;
import java.beans.IntrospectionException;
import java.beans.Introspector;
import java.beans.PropertyDescriptor;
import java.io.InterruptedIOException;
import java.lang.reflect.InvocationTargetException;
import java.lang.reflect.Method;

/**
 * Used for inferring configuration information for a log4j's component.
 * 
 * @author Anders Kristensen
 */
public class PropertyGetter {
    protected static final Object[] NULL_ARG = new Object[] {};
    protected Object obj;
    protected PropertyDescriptor[] props;

    public interface PropertyCallback {
	void foundProperty(Object obj, String prefix, String name, Object value);
    }

    /**
     * Create a new PropertyGetter for the specified Object. This is done in
     * prepartion for invoking
     * {@link #getProperties(PropertyGetter.PropertyCallback, String)} one or more
     * times.
     * 
     * @param obj the object for which to set properties
     */
    public PropertyGetter(Object obj) throws IntrospectionException {
	BeanInfo bi = Introspector.getBeanInfo(obj.getClass());
	props = bi.getPropertyDescriptors();
	this.obj = obj;
    }

    public static void getProperties(Object obj, PropertyCallback callback, String prefix) {
	try {
	    new PropertyGetter(obj).getProperties(callback, prefix);
	} catch (IntrospectionException ex) {
	    LogLog.error("Failed to introspect object " + obj, ex);
	}
    }

    public void getProperties(PropertyCallback callback, String prefix) {
	for (int i = 0; i < props.length; i++) {
	    Method getter = props[i].getReadMethod();
	    if (getter == null)
		continue;
	    if (!isHandledType(getter.getReturnType())) {
		// System.err.println("Ignoring " + props[i].getName() +" " +
		// getter.getReturnType());
		continue;
	    }
	    String name = props[i].getName();
	    try {
		Object result = getter.invoke(obj, NULL_ARG);
		// System.err.println("PROP " + name +": " + result);
		if (result != null) {
		    callback.foundProperty(obj, prefix, name, result);
		}
	    } catch (IllegalAccessException ex) {
		LogLog.warn("Failed to get value of property " + name);
	    } catch (InvocationTargetException ex) {
		if (ex.getTargetException() instanceof InterruptedException
			|| ex.getTargetException() instanceof InterruptedIOException) {
		    Thread.currentThread().interrupt();
		}
		LogLog.warn("Failed to get value of property " + name);
	    } catch (RuntimeException ex) {
		LogLog.warn("Failed to get value of property " + name);
	    }
	}
    }

    protected boolean isHandledType(Class type) {
	return String.class.isAssignableFrom(type) || Integer.TYPE.isAssignableFrom(type)
		|| Long.TYPE.isAssignableFrom(type) || Boolean.TYPE.isAssignableFrom(type)
		|| Priority.class.isAssignableFrom(type);
    }
}
