/*
 * 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.catalina.startup;

import java.io.File;
import java.io.IOException;
import java.net.MalformedURLException;
import java.net.URL;
import java.net.URLClassLoader;
import java.security.AccessController;
import java.security.PrivilegedAction;
import java.util.LinkedHashSet;
import java.util.List;
import java.util.Locale;
import java.util.Set;

import org.apache.juli.logging.Log;
import org.apache.juli.logging.LogFactory;

Utility class for building class loaders for Catalina.  The factory
method requires the following parameters in order to build a new class
loader (with suitable defaults in all cases):

A set of directories containing unpacked classes (and resources)
    that should be included in the class loader's
    repositories.
A set of directories containing classes and resources in JAR files.
    Each readable JAR file discovered in these directories will be
    added to the class loader's repositories.
ClassLoader instance that should become the parent of
    the new class loader.

Author:
Craig R. McClanahan/**
 * <p>Utility class for building class loaders for Catalina.  The factory
 * method requires the following parameters in order to build a new class
 * loader (with suitable defaults in all cases):</p>
 * <ul>
 * <li>A set of directories containing unpacked classes (and resources)
 *     that should be included in the class loader's
 *     repositories.</li>
 * <li>A set of directories containing classes and resources in JAR files.
 *     Each readable JAR file discovered in these directories will be
 *     added to the class loader's repositories.</li>
 * <li><code>ClassLoader</code> instance that should become the parent of
 *     the new class loader.</li>
 * </ul>
 *
 * @author Craig R. McClanahan
 */
public final class ClassLoaderFactory {


    private static final Log log = LogFactory.getLog(ClassLoaderFactory.class);

    // --------------------------------------------------------- Public Methods


    
Create and return a new class loader, based on the configuration
defaults and the specified directory paths:
Params:
unpacked – Array of pathnames to unpacked directories that should
 be added to the repositories of the class loader, or null
for no unpacked directories to be considered
packed – Array of pathnames to directories containing JAR files
 that should be added to the repositories of the class loader,
or null for no directories of JAR files to be considered
parent – Parent class loader for the new class loader, or
 null for the system class loader.
Throws:
Exception – if an error occurs constructing the class loader
Returns:
the new class loader/**
     * Create and return a new class loader, based on the configuration
     * defaults and the specified directory paths:
     *
     * @param unpacked Array of pathnames to unpacked directories that should
     *  be added to the repositories of the class loader, or <code>null</code>
     * for no unpacked directories to be considered
     * @param packed Array of pathnames to directories containing JAR files
     *  that should be added to the repositories of the class loader,
     * or <code>null</code> for no directories of JAR files to be considered
     * @param parent Parent class loader for the new class loader, or
     *  <code>null</code> for the system class loader.
     * @return the new class loader
     *
     * @exception Exception if an error occurs constructing the class loader
     */
    public static ClassLoader createClassLoader(File unpacked[],
                                                File packed[],
                                                final ClassLoader parent)
        throws Exception {

        if (log.isDebugEnabled())
            log.debug("Creating new class loader");

        // Construct the "class path" for this class loader
        Set<URL> set = new LinkedHashSet<>();

        // Add unpacked directories
        if (unpacked != null) {
            for (File file : unpacked) {
                if (!file.canRead()) {
                    continue;
                }
                file = new File(file.getCanonicalPath() + File.separator);
                URL url = file.toURI().toURL();
                if (log.isDebugEnabled()) {
                    log.debug("  Including directory " + url);
                }
                set.add(url);
            }
        }

        // Add packed directory JAR files
        if (packed != null) {
            for (File directory : packed) {
                if (!directory.isDirectory() || !directory.canRead()) {
                    continue;
                }
                String filenames[] = directory.list();
                if (filenames == null) {
                    continue;
                }
                for (String s : filenames) {
                    String filename = s.toLowerCase(Locale.ENGLISH);
                    if (!filename.endsWith(".jar")) {
                        continue;
                    }
                    File file = new File(directory, s);
                    if (log.isDebugEnabled()) {
                        log.debug("  Including jar file " + file.getAbsolutePath());
                    }
                    URL url = file.toURI().toURL();
                    set.add(url);
                }
            }
        }

        // Construct the class loader itself
        final URL[] array = set.toArray(new URL[0]);
        return AccessController.doPrivileged(
                (PrivilegedAction<URLClassLoader>) () -> {
                    if (parent == null) {
                        return new URLClassLoader(array);
                    } else {
                        return new URLClassLoader(array, parent);
                    }
                });
    }


    
Create and return a new class loader, based on the configuration
defaults and the specified directory paths:
Params:
repositories – List of class directories, jar files, jar directories
                    or URLS that should be added to the repositories of
                    the class loader.
parent – Parent class loader for the new class loader, or
 null for the system class loader.
Throws:
Exception – if an error occurs constructing the class loader
Returns:
the new class loader/**
     * Create and return a new class loader, based on the configuration
     * defaults and the specified directory paths:
     *
     * @param repositories List of class directories, jar files, jar directories
     *                     or URLS that should be added to the repositories of
     *                     the class loader.
     * @param parent Parent class loader for the new class loader, or
     *  <code>null</code> for the system class loader.
     * @return the new class loader
     *
     * @exception Exception if an error occurs constructing the class loader
     */
    public static ClassLoader createClassLoader(List<Repository> repositories,
                                                final ClassLoader parent)
        throws Exception {

        if (log.isDebugEnabled())
            log.debug("Creating new class loader");

        // Construct the "class path" for this class loader
        Set<URL> set = new LinkedHashSet<>();

        if (repositories != null) {
            for (Repository repository : repositories)  {
                if (repository.getType() == RepositoryType.URL) {
                    URL url = buildClassLoaderUrl(repository.getLocation());
                    if (log.isDebugEnabled())
                        log.debug("  Including URL " + url);
                    set.add(url);
                } else if (repository.getType() == RepositoryType.DIR) {
                    File directory = new File(repository.getLocation());
                    directory = directory.getCanonicalFile();
                    if (!validateFile(directory, RepositoryType.DIR)) {
                        continue;
                    }
                    URL url = buildClassLoaderUrl(directory);
                    if (log.isDebugEnabled())
                        log.debug("  Including directory " + url);
                    set.add(url);
                } else if (repository.getType() == RepositoryType.JAR) {
                    File file=new File(repository.getLocation());
                    file = file.getCanonicalFile();
                    if (!validateFile(file, RepositoryType.JAR)) {
                        continue;
                    }
                    URL url = buildClassLoaderUrl(file);
                    if (log.isDebugEnabled())
                        log.debug("  Including jar file " + url);
                    set.add(url);
                } else if (repository.getType() == RepositoryType.GLOB) {
                    File directory=new File(repository.getLocation());
                    directory = directory.getCanonicalFile();
                    if (!validateFile(directory, RepositoryType.GLOB)) {
                        continue;
                    }
                    if (log.isDebugEnabled())
                        log.debug("  Including directory glob "
                            + directory.getAbsolutePath());
                    String filenames[] = directory.list();
                    if (filenames == null) {
                        continue;
                    }
                    for (String s : filenames) {
                        String filename = s.toLowerCase(Locale.ENGLISH);
                        if (!filename.endsWith(".jar"))
                            continue;
                        File file = new File(directory, s);
                        file = file.getCanonicalFile();
                        if (!validateFile(file, RepositoryType.JAR)) {
                            continue;
                        }
                        if (log.isDebugEnabled())
                            log.debug("    Including glob jar file "
                                    + file.getAbsolutePath());
                        URL url = buildClassLoaderUrl(file);
                        set.add(url);
                    }
                }
            }
        }

        // Construct the class loader itself
        final URL[] array = set.toArray(new URL[0]);
        if (log.isDebugEnabled())
            for (int i = 0; i < array.length; i++) {
                log.debug("  location " + i + " is " + array[i]);
            }

        return AccessController.doPrivileged(
                (PrivilegedAction<URLClassLoader>) () -> {
                    if (parent == null)
                        return new URLClassLoader(array);
                    else
                        return new URLClassLoader(array, parent);
                });
    }

    private static boolean validateFile(File file,
            RepositoryType type) throws IOException {
        if (RepositoryType.DIR == type || RepositoryType.GLOB == type) {
            if (!file.isDirectory() || !file.canRead()) {
                String msg = "Problem with directory [" + file +
                        "], exists: [" + file.exists() +
                        "], isDirectory: [" + file.isDirectory() +
                        "], canRead: [" + file.canRead() + "]";

                File home = new File (Bootstrap.getCatalinaHome());
                home = home.getCanonicalFile();
                File base = new File (Bootstrap.getCatalinaBase());
                base = base.getCanonicalFile();
                File defaultValue = new File(base, "lib");

                // Existence of ${catalina.base}/lib directory is optional.
                // Hide the warning if Tomcat runs with separate catalina.home
                // and catalina.base and that directory is absent.
                if (!home.getPath().equals(base.getPath())
                        && file.getPath().equals(defaultValue.getPath())
                        && !file.exists()) {
                    log.debug(msg);
                } else {
                    log.warn(msg);
                }
                return false;
            }
        } else if (RepositoryType.JAR == type) {
            if (!file.canRead()) {
                log.warn("Problem with JAR file [" + file +
                        "], exists: [" + file.exists() +
                        "], canRead: [" + file.canRead() + "]");
                return false;
            }
        }
        return true;
    }


    /*
     * These two methods would ideally be in the utility class
     * org.apache.tomcat.util.buf.UriUtil but that class is not visible until
     * after the class loaders have been constructed.
     */
    private static URL buildClassLoaderUrl(String urlString) throws MalformedURLException {
        // URLs passed to class loaders may point to directories that contain
        // JARs. If these URLs are used to construct URLs for resources in a JAR
        // the URL will be used as is. It is therefore necessary to ensure that
        // the sequence "!/" is not present in a class loader URL.
        String result = urlString.replaceAll("!/", "%21/");
        return new URL(result);
    }


    private static URL buildClassLoaderUrl(File file) throws MalformedURLException {
        // Could be a directory or a file
        String fileUrlString = file.toURI().toString();
        fileUrlString = fileUrlString.replaceAll("!/", "%21/");
        return new URL(fileUrlString);
    }


    public enum RepositoryType {
        DIR,
        GLOB,
        JAR,
        URL
    }

    public static class Repository {
        private final String location;
        private final RepositoryType type;

        public Repository(String location, RepositoryType type) {
            this.location = location;
            this.type = type;
        }

        public String getLocation() {
            return location;
        }

        public RepositoryType getType() {
            return type;
        }
    }
}