/*
 * 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;

import java.lang.ref.Reference;
import java.lang.reflect.Field;

import org.apache.log4j.helpers.VersionUtil;

import junit.framework.TestCase;

/**
 * Test for MDC
 *
 * @author Maarten Bosteels
 */
public class MDCTestCase extends TestCase {

    public void setUp() {
        MDC.clear();
    }

    public void tearDown() {
        MDC.clear();
    }

    public void testPut() throws Exception {
        MDC.put("key", "some value");
        assertEquals("some value", MDC.get("key"));
        assertEquals(1, MDC.getContext().size());
    }

    public void testRemoveLastKey() throws Exception {
        MDC.put("key", "some value");

        MDC.remove("key");

        int majorJavaVersion = VersionUtil.getJavaMajorVersion();
        System.out.println("majorJavaVersion=" + majorJavaVersion);
        // test fails on newer JDKS
        if (majorJavaVersion <= 9) {

            checkThreadLocalsForLeaks();
        } else {
            System.out.println("Skipping checkThreadLocalsForLeaks() call");
        }
    }

    @SuppressWarnings("unused")
    private void checkThreadLocalsForLeaks() throws Exception {

        // this code is heavily based on code in
        // org.apache.catalina.loader.WebappClassLoader

        // Make the fields in the Thread class that store ThreadLocals accessible
        Field threadLocalsField = Thread.class.getDeclaredField("threadLocals");
        threadLocalsField.setAccessible(true);
        Field inheritableThreadLocalsField = Thread.class.getDeclaredField("inheritableThreadLocals");
        inheritableThreadLocalsField.setAccessible(true);
        // Make the underlying array of ThreadLoad.ThreadLocalMap.Entry objects
        // accessible
        Class<?> tlmClass = Class.forName("java.lang.ThreadLocal$ThreadLocalMap");
        Field tableField = tlmClass.getDeclaredField("table");
        tableField.setAccessible(true);

        Thread thread = Thread.currentThread();

        Object threadLocalMap;
        threadLocalMap = threadLocalsField.get(thread);
        // Check the first map
        checkThreadLocalMapForLeaks(threadLocalMap, tableField);
        // Check the second map
        threadLocalMap = inheritableThreadLocalsField.get(thread);
        checkThreadLocalMapForLeaks(threadLocalMap, tableField);

    }

    private void checkThreadLocalMapForLeaks(Object map, Field internalTableField)
            throws IllegalAccessException, NoSuchFieldException {
        if (map != null) {
            Object[] table = (Object[]) internalTableField.get(map);
            if (table != null) {
                for (int j = 0; j < table.length; j++) {
                    if (table[j] != null) {

                        // Check the key
                        Object key = ((Reference<?>) table[j]).get();
                        String keyClassName = key.getClass().getName();

                        if (key.getClass() == org.apache.log4j.helpers.ThreadLocalMap.class) {
                            fail("Found a ThreadLocal with key of type [" + keyClassName + "]");
                        }
                    }
                }
            }
        }
    }
}
