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/*
 * Copyright (c) 2015 by Oli B.
 *
 * Licensed 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 orimplied.
 * See the License for the specific language governing permissions and
 * limitations under the License.
 *
 * (c)reated 04.11.2015 by Oli B. ([email protected])
 */

package patterntesting.runtime.junit;

import static org.junit.Assert.assertEquals;

import java.security.*;
import java.util.Set;

import org.slf4j.*;

import patterntesting.runtime.exception.DetailedAssertionError;
import patterntesting.runtime.junit.internal.XrayClassLoader;

/**
 * This tester examines classes. E.g. if looks if classes can be loaded
 * independent from other classes.
 * 
 * If you want to test some dependencies to a given class you can use this
 * tester here. This functionality was moved from the old ClassTester class
 * in the experimental package to here.
 * 
 *
 * @author oboehm ([email protected])
 * @since 1.6 (04.11.2015)
 */
public class ClassTester extends AbstractTester {

	private static final Logger LOG = LoggerFactory.getLogger(ClassTester.class);
	private static final ClassTester INSTANCE = new ClassTester();

	private final Class clazz;
	private final XrayClassLoader classLoader = AccessController
	        .doPrivileged(new PrivilegedAction() {
		        public XrayClassLoader run() {
            return new XrayClassLoader();
        }
    });

    /** Private constructor for internal use. */
	private ClassTester() {
		this.clazz = this.getClass();
	}

    /**
     * Instantiates a new class tester.
     *
     * @param classname the classname
     * @throws ClassNotFoundException the class not found exception
     */
    public ClassTester(final String classname) throws ClassNotFoundException {
        this.clazz = this.classLoader.loadClass(classname);
        if (clazz == null) {
            throw new ClassNotFoundException(classname);
        }
    }

    /**
     * Gets the class name.
     *
     * @return the class name
     */
    public String getClassName() {
        return this.clazz.getName();
    }

    /**
     * Gets the dependencies of the class name.
     * To get all dependencies we load all declared methods, fields and
     * other stuff.
     *
     * @return the dependencies of
     */
    public Set> getDependencies() {
        this.clazz.getDeclaredAnnotations();
        this.clazz.getDeclaredClasses();
        this.clazz.getDeclaredConstructors();
        this.clazz.getDeclaredFields();
        this.clazz.getDeclaredMethods();
        return classLoader.getLoadedClasses();
    }

    /**
     * Checks if the stored class depends on another class.
     * Because the given otherClass is using probably another class loader
     * we compare the class name to decide if it is loaded.
     *
     * @param otherClass the other class
     * @return true, if successful
     */
    public boolean dependsOn(final Class otherClass) {
        return dependsOn(otherClass.getName());
    }

    /**
     * Checks if the stored class depends on another class.
     *
     * @param otherClassname the other classname
     * @return true, if successful
     */
    public boolean dependsOn(final String otherClassname) {
        Set> dependencies = this.getDependencies();
        for (Class cl : dependencies) {
            if (otherClassname.equals(cl.getName())) {
                return true;
            }
        }
        return false;
    }



    /////   STATIC UTILITY METHODS   //////////////////////////////////////////

    /**
     * Gets the dependencies of the given class name.
     *
     * @param classname the classname
     * @return the dependencies of
     * @throws ClassNotFoundException the class not found exception
     */
    public static Set> getDependenciesOf(final String classname) throws ClassNotFoundException {
        return new ClassTester(classname).getDependencies();
    }

    /**
     * Checks if the given class depends on another class.
     *
     * @param classname the classname
     * @param otherClass the other class
     * @return true, if successful
     * @throws ClassNotFoundException the class not found exception
     */
    public static boolean dependsOn(final String classname, final Class otherClass)
            throws ClassNotFoundException {
        return new ClassTester(classname).dependsOn(otherClass);
    }

	/**
	 * Every class has an static initializer which will be called after a class
	 * is loaded. To find problems with such initializers or with dependencies
	 * to other classes which cannot be solved this method tries to load the
	 * class with an isolated classloader and will throw an
	 * {@link AssertionError} if it can't.
	 * 
	 * We expect a String as parameter and not a class because if we receive
	 * a class as parameter this class was already loaded before and we need
	 * not to check it again if it can be loaded.
	 * 
	 *
	 * @param classname the class name.
	 * @throws ClassNotFoundException the class not found exception
	 */
	public static void tryStaticInitializer(final String classname) throws ClassNotFoundException {
		try {
			INSTANCE.load(classname);
		} catch (ExceptionInInitializerError ex) {
			throw new DetailedAssertionError("cannot initialize class " + classname, ex);
		} catch (NoClassDefFoundError ex) {
			throw new DetailedAssertionError("cannot find class definition of " + classname, ex);
		}
	}

	private void load(final String classname) throws ClassNotFoundException {
		Class loaded = Class.forName(classname);
		assertEquals(classname, loaded.getName());
		LOG.trace("{} was loaded by name.", loaded);
		loadClassWith(Thread.currentThread().getContextClassLoader(), classname);
		loadClassWith(classLoader, classname);
	}

	private static void loadClassWith(final ClassLoader classloader, final String classname) throws ClassNotFoundException {
		Class initialized = Class.forName(classname, true, classloader);
		assertEquals(initialized.getName(), classname);
		LOG.trace("{} was loaded and initialized by {}.", initialized, classloader);
		Class loaded = classloader.loadClass(classname);
		assertEquals(initialized, loaded);
	}

}