/*
 * The Apache Software License, Version 1.1
 *
 * Copyright (c) 1999 The Apache Software Foundation.  All rights
 * reserved.
 *
 * Redistribution and use in source and binary forms, with or without
 * modification, are permitted provided that the following conditions
 * are met:
 *
 * 1. Redistributions of source code must retain the above copyright
 *    notice, this list of conditions and the following disclaimer.
 *
 * 2. Redistributions in binary form must reproduce the above copyright
 *    notice, this list of conditions and the following disclaimer in
 *    the documentation and/or other materials provided with the
 *    distribution.
 *
 * 3. The end-user documentation included with the redistribution, if
 *    any, must include the following acknowlegement:
 *       "This product includes software developed by the
 *        Apache Software Foundation (http://www.apache.org/)."
 *    Alternately, this acknowlegement may appear in the software itself,
 *    if and wherever such third-party acknowlegements normally appear.
 *
 * 4. The names "The Jakarta Project", "Tomcat", and "Apache Software
 *    Foundation" must not be used to endorse or promote products derived
 *    from this software without prior written permission. For written
 *    permission, please contact apache@apache.org.
 *
 * 5. Products derived from this software may not be called "Apache"
 *    nor may "Apache" appear in their names without prior written
 *    permission of the Apache Group.
 *
 * THIS SOFTWARE IS PROVIDED ``AS IS'' AND ANY EXPRESSED OR IMPLIED
 * WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE IMPLIED WARRANTIES
 * OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE ARE
 * DISCLAIMED.  IN NO EVENT SHALL THE APACHE SOFTWARE FOUNDATION OR
 * ITS CONTRIBUTORS BE LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL,
 * SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT
 * LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS OF
 * USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND
 * ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY,
 * OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT
 * OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF
 * SUCH DAMAGE.
 * ====================================================================
 *
 * This software consists of voluntary contributions made by many
 * individuals on behalf of the Apache Software Foundation.  For more
 * information on the Apache Software Foundation, please see
 * <http://www.apache.org/>.
 */
package org.apache.tools.ant.taskdefs.optional.ejb;

import java.io.File;
import java.io.FileInputStream;
import java.io.ObjectInputStream;
import java.io.IOException;
import java.io.PrintWriter;
import java.io.FileWriter;

import javax.ejb.deployment.EntityDescriptor;
import javax.ejb.deployment.DeploymentDescriptor;


/**
 * A helper class which performs the actual work of the ejbc task.
 *
 * This class is run with a classpath which includes the weblogic tools and the home and remote
 * interface class files referenced in the deployment descriptors being processed.
 *
 * @author <a href="mailto:conor@cortexebusiness.com.au">Conor MacNeill</a>, Cortex ebusiness Pty Limited
 */
public class EjbcHelper {
    /**
     * The root directory of the tree containing the serialised deployment desciptors.
     */
    private File descriptorDirectory;

    /**
     * The directory where generated files are placed.
     */
    private File generatedFilesDirectory;

    /**
     * The name of the manifest file generated for the EJB jar.
     */
    private File manifestFile;

    /**
     * The classpath to be used in the weblogic ejbc calls. It must contain the weblogic
     * classes <b>and</b> the implementation classes of the home and remote interfaces.
     */
    private String classpath;

    /**
     * The source directory for the home and remote interfaces. This is used to determine if
     * the generated deployment classes are out of date.
     */
    private File sourceDirectory;

    /**
     * The names of the serialised deployment descriptors
     */
    String[] descriptors;

    /**
     * Command line interface for the ejbc helper task.
     */
    public static void main(String[] args) throws Exception {
        EjbcHelper helper = new EjbcHelper(args);
        helper.process();
    }

    /**
     * Initialise the EjbcHelper by reading the command arguments.
     */
    private EjbcHelper(String[] args) {
        int index = 0;
        descriptorDirectory = new File(args[index++]);
        generatedFilesDirectory = new File(args[index++]);
        sourceDirectory = new File(args[index++]);
        manifestFile = new File(args[index++]);

        descriptors = new String[args.length - index];
        for (int i = 0; index < args.length; ++i) {
            descriptors[i] = args[index++];
        }
    }

    /**
     * Determine if the weblogic EJB support classes need to be regenerated
     * for a given deployment descriptor.
     *
     * This process attempts to determine if the support classes need to be
     * rebuilt. It does this by examining only some of the support classes
     * which are typically generated. If the ejbc task is interrupted generating
     * the support classes for a bean, all of the support classes should be removed
     * to force regeneration of the support classes.
     *
     * @param descriptorFile the serialised deployment descriptor
     *
     * @return true if the support classes need to be regenerated.
     *
     * @throws IOException if the descriptor file cannot be closed.
     */
    private boolean isRegenRequired(File descriptorFile) throws IOException {
        // read in the descriptor. Under weblogic, the descriptor is a weblogic
        // specific subclass which has references to the implementation classes.
        // These classes must, therefore, be in the classpath when the deployment
        // descriptor is loaded from the .ser file
        FileInputStream fis = null;
        try {
            fis = new FileInputStream(descriptorFile);
            ObjectInputStream ois = new ObjectInputStream(fis);
            DeploymentDescriptor dd = (DeploymentDescriptor)ois.readObject();
            fis.close();

            String homeInterfacePath = dd.getHomeInterfaceClassName().replace('.', '/') + ".java";
            String remoteInterfacePath = dd.getRemoteInterfaceClassName().replace('.', '/') + ".java";
            String primaryKeyClassPath = null;
            if (dd instanceof EntityDescriptor) {
                primaryKeyClassPath = ((EntityDescriptor)dd).getPrimaryKeyClassName().replace('.', '/') + ".java";;
            }

            File homeInterfaceSource = new File(sourceDirectory, homeInterfacePath);
            File remoteInterfaceSource = new File(sourceDirectory, remoteInterfacePath);
            File primaryKeyClassSource = null;
            if (primaryKeyClassPath != null) {
                primaryKeyClassSource = new File(sourceDirectory, remoteInterfacePath);
            }

            // are any of the above out of date.
            // we find the implementation classes and see if they are older than any
            // of the above or the .ser file itself.
            String beanClassBase = dd.getEnterpriseBeanClassName().replace('.', '/');
            File ejbImplentationClass
                = new File(generatedFilesDirectory, beanClassBase + "EOImpl.class");
            File homeImplementationClass
                = new File(generatedFilesDirectory, beanClassBase + "HomeImpl.class");
            File beanStubClass
                = new File(generatedFilesDirectory, beanClassBase + "EOImpl_WLStub.class");

            // if the implementation classes don;t exist regenerate
            if (!ejbImplentationClass.exists() || !homeImplementationClass.exists() ||
                    !beanStubClass.exists()) {
                return true;
            }

            // Is the ser file or any of the source files newer then the class files.
            // firstly find the oldest of the two class files.
            long classModificationTime = ejbImplentationClass.lastModified();
            if (homeImplementationClass.lastModified() < classModificationTime) {
                classModificationTime = homeImplementationClass.lastModified();
            }
            if (beanStubClass.lastModified() < classModificationTime) {
                classModificationTime = beanStubClass.lastModified();
            }

            if (descriptorFile.lastModified() > classModificationTime ||
                    homeInterfaceSource.lastModified() > classModificationTime ||
                    remoteInterfaceSource.lastModified() > classModificationTime) {
                return true;
            }

            if (primaryKeyClassSource != null &&
                    primaryKeyClassSource.lastModified() > classModificationTime) {
                return true;
            }
        }
        catch (Throwable descriptorLoadException) {
            System.out.println("Exception occurred reading " + descriptorFile.getName() + " - continuing");
            // any problems - just regenerate
            return true;
        }
        finally {
            if (fis != null) {
                fis.close();
            }
        }

        return false;
    }

    /**
     * Process the descriptors in turn generating support classes for each and a manifest
     * file for all of the beans.
     */
    private void process() throws Exception {
        boolean isManifestRegenRequired = false;
        String manifest = "Manifest-Version: 1.0\n\n";
        for (int i = 0; i < descriptors.length; ++i) {
            String descriptorName = descriptors[i];
            File descriptorFile = new File(descriptorDirectory, descriptorName);

            if (isRegenRequired(descriptorFile)) {
                System.out.println("Running ejbc for " + descriptorFile.getName());
                regenerateSupportClasses(descriptorFile);
                isManifestRegenRequired = true;
            }
            else {
                System.out.println(descriptorFile.getName() + " is up to date");
            }
            manifest += "Name: " + descriptorFile.getName() + "\nEnterprise-Bean: True\n\n";
        }

        if(isManifestRegenRequired){
            FileWriter fw = new FileWriter(manifestFile);
            PrintWriter pw = new PrintWriter(fw);
            pw.print(manifest);
            fw.flush();
            fw.close();
        }
    }

    /**
     * Perform the weblogic.ejbc call to regenerate the support classes.
     *
     * Note that this method relies on an undocumented -noexit option to the
     * ejbc tool to stop the ejbc tool exiting the VM altogether.
     */
    private void regenerateSupportClasses(File descriptorFile) throws Exception {
        // create a Java task to do the rebuild

        String[] args = {"-noexit",
                         "-keepgenerated",
                         "-d", generatedFilesDirectory.getPath(),
                         descriptorFile.getPath()};

        try {
            weblogic.ejbc.main(args);
        }
        catch (Exception e) {
            // run with no exit for better reporting
            String[] newArgs = {"-keepgenerated",
                         "-d", generatedFilesDirectory.getPath(),
                         descriptorFile.getPath()};
            weblogic.ejbc.main(newArgs);
        }
    }
}