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/*
 *  Copyright Technophobia Ltd 2012
 *
 *   This file is part of Substeps.
 *
 *    Substeps is free software: you can redistribute it and/or modify
 *    it under the terms of the GNU Lesser General Public License as published by
 *    the Free Software Foundation, either version 3 of the License, or
 *    (at your option) any later version.
 *
 *    Substeps is distributed in the hope that it will be useful,
 *    but WITHOUT ANY WARRANTY; without even the implied warranty of
 *    MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
 *    GNU Lesser General Public License for more details.
 *
 *    You should have received a copy of the GNU Lesser General Public License
 *    along with Substeps.  If not, see .
 */
package com.technophobia.substeps.scanner;

import java.io.File;
import java.io.FileFilter;
import java.io.IOException;
import java.lang.annotation.Annotation;
import java.util.ArrayList;
import java.util.Enumeration;
import java.util.List;
import java.util.jar.JarEntry;
import java.util.jar.JarFile;

/**
 * @author imoore
 */
public class ClasspathScanner {

    public List> getClassesWithAnnotation(final Class desiredAnnotation,
                                                   final ClassLoader classLoader, final String[] cpElements) {

        final List> classList = new ArrayList>();

        final List classNameList = new ArrayList();

        for (final String cpElement : cpElements) {
            final File f = new File(cpElement);

            if (f.exists() && f.isDirectory()) {
                final List files = getAllFiles(f, "class");

                for (final File classFile : files) {
                    classNameList.add(convertFileToClass(classFile, f));
                }

            } else {
                // jar file
                JarFile jarFile = null;
                try {
                    jarFile = new JarFile(f);

                    final Enumeration entries = jarFile.entries();

                    while (entries.hasMoreElements()) {
                        final JarEntry nextElement = entries.nextElement();

                        if (!nextElement.isDirectory()) {
                            final String name = nextElement.getName();

                            if (name.endsWith(".class")) {
                                final String classname = name.replace(File.separatorChar, '.');
                                classNameList.add(classname.substring(0, classname.length() - 6));
                            }
                        }
                    }
                } catch (final IOException e) {
                    // don't care
                } finally {
                    if (jarFile != null) {
                        try {
                            jarFile.close();
                        } catch (IOException e) {
                            // don't care
                        }
                    }
                }

                // load up contents of jar

            }

        }

        for (final String className : classNameList) {
            try {
                if (!className.contains("$")) {
                    // no inner classes here thanks
                    final Class clazz = classLoader.loadClass(className);

                    if (clazz.isAnnotationPresent(desiredAnnotation)) {
                        classList.add(clazz);
                    }
                }
            } catch (final NoClassDefFoundError e) {
                // don't care
            } catch (final ClassNotFoundException e) {
                // don't care about that either
            }

        }

        return classList;

    }

    public List> getClassesWithAnnotation(final Class desiredAnnotation,
                                                   final ClassLoader classLoader) {
        // scan the classpath and look for classes with that annotation
        // any dirs on the classpath - recursively look into them

        final String cp = System.getProperty("java.class.path");

        // chop up the path into constituent parts

        final String[] cpElements = cp.split(String.valueOf(File.pathSeparatorChar));

        return getClassesWithAnnotation(desiredAnnotation, classLoader, cpElements);
    }

    private static String convertFileToClass(final File f, final File root) {
        final String fqp = f.getAbsolutePath().substring(root.getAbsolutePath().length() + 1,
                f.getAbsolutePath().length() - 6);
        return fqp.replace(File.separatorChar, '.');
    }

    private static List getAllFiles(final File root, final String extension) {
        final FileFilter filter = f -> f.isDirectory() || (f.isFile() && f.getName().endsWith(extension));

        final List files = new ArrayList();

        if (root.exists()) {
            final File[] children = root.listFiles(filter);
            if (children != null) {
                for (final File child : children) {
                    if (child != null && child.exists()) {
                        if (child.isDirectory()) {
                            // recurse
                            final List childsFiles = getAllFiles(child, extension);
                            files.addAll(childsFiles);
                        } else {
                            files.add(child);
                        }
                    }
                }
            }
        }
        return files;
    }

}