/*******************************************************************************
 * Copyright (c) 1998, 2015 Oracle and/or its affiliates. All rights reserved.
 * This program and the accompanying materials are made available under the
 * terms of the Eclipse Public License v1.0 and Eclipse Distribution License v. 1.0
 * which accompanies this distribution.
 * The Eclipse Public License is available at http://www.eclipse.org/legal/epl-v10.html
 * and the Eclipse Distribution License is available at
 * http://www.eclipse.org/org/documents/edl-v10.php.
 *
 * Contributors:
 *     Oracle - initial API and implementation from Oracle TopLink
******************************************************************************/
package org.eclipse.persistence.tools.workbench.utility.classfile.tools;

import java.io.File;
import java.io.IOException;
import java.util.Iterator;
import java.util.jar.JarFile;

import org.eclipse.persistence.tools.workbench.utility.Classpath;
import org.eclipse.persistence.tools.workbench.utility.classfile.ClassFile;


/**
 * This iterator will convert all the Java .class files found on a specified
 * classpath entry (which can be either a directory or a JAR) to ClassFiles.
 */
public class ClassFileIterator
    implements Iterator
{
    /** the classpath entry */
    private File file;

    /** the JAR file corresponding to the classpath entry, if appropriate */
    private JarFile jarFile;

    /** true if the classpath entry is a .jar or .zip file */
    private boolean archive;

    /** the names of the classes found in the classpath entry */
    private Iterator classNames;


    // ********** constructor/initialization **********

    /**
     * Construct a class file iterator on the specified classpath
     * entry, which can be either a JAR or a directory.
     */
    public ClassFileIterator(String classpathEntry) {
        super();
        this.file = new File(classpathEntry);
        this.archive = Classpath.fileNameIsArchive(classpathEntry);
        if (this.archive) {
            this.jarFile = this.buildJarFile();
        }
        this.classNames = this.buildClassNames(classpathEntry);
    }

    private JarFile buildJarFile() {
        try {
            return new JarFile(this.file);
        } catch (IOException ex) {
            throw new RuntimeException(ex);
        }
    }

    protected Iterator buildClassNames(String classpathEntry) {
        Classpath cp = new Classpath(new String[] {classpathEntry});
        return cp.classNamesStream();
    }


    // ********** Iterator implementation **********

    /**
     * @see java.util.Iterator#hasNext()
     */
    public boolean hasNext() {
        return this.classNames.hasNext();
    }

    /**
     * @see java.util.Iterator#next()
     */
    public Object next() {
        String className = (String) this.classNames.next();
        ClassFile classFile = null;
        try {
            if (this.archive) {
                classFile = this.buildClassFileFromArchive(className);
            } else {
                classFile = this.buildClassFileFromDirectory(className);
            }
        } catch (IOException ex) {
            throw new RuntimeException(className, ex);
        }
        // close the JAR if necessary
        if (this.archive && ( ! this.hasNext())) {
            this.closeJarFile();
        }
        return classFile;
    }

    /**
     * @see java.util.Iterator#remove()
     */
    public void remove() {
        throw new UnsupportedOperationException();
    }


    // ********** internal methods **********

    private ClassFile buildClassFileFromArchive(String className) throws IOException {
        return ClassFile.fromArchiveEntry(this.jarFile, className);
    }

    private ClassFile buildClassFileFromDirectory(String className) throws IOException {
        return ClassFile.fromClassFile(this.file, className);
    }

    private void closeJarFile() {
        try {
            this.jarFile.close();
        } catch (IOException ex) {
            throw new RuntimeException(ex);
        }
    }

}