/*
 * 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.util;

import java.io.File;
import java.io.FileInputStream;
import java.io.IOException;
import java.io.InputStream;
import java.util.ArrayList;
import java.util.List;
import java.util.Locale;
import java.util.StringTokenizer;
import java.util.jar.JarInputStream;
import java.util.jar.Manifest;

import org.apache.catalina.Context;
import org.apache.catalina.WebResource;
import org.apache.catalina.WebResourceRoot;
import org.apache.juli.logging.Log;
import org.apache.juli.logging.LogFactory;
import org.apache.tomcat.util.res.StringManager;


/**
 * Ensures that all extension dependencies are resolved for a WEB application are met. This class builds a list of
 * extensions available to an application and then validates those extensions. See
 * http://docs.oracle.com/javase/1.4.2/docs/guide/extensions/spec.html for a detailed explanation of the extension
 * mechanism in Java.
 */
public final class ExtensionValidator {

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

    /**
     * The string resources for this package.
     */
    private static final StringManager sm = StringManager.getManager("org.apache.catalina.util");

    private static volatile List<Extension> containerAvailableExtensions = null;
    private static final List<ManifestResource> containerManifestResources = new ArrayList<>();


    // ----------------------------------------------------- Static Initializer


    /*
     * This static initializer loads the container level extensions that are available to all web applications. This
     * method scans all extension directories available via the "java.ext.dirs" System property.
     *
     * The System Class-Path is also scanned for jar files that may contain available extensions.
     */
    static {

        // check for container level optional packages
        String systemClasspath = System.getProperty("java.class.path");

        StringTokenizer strTok = new StringTokenizer(systemClasspath, File.pathSeparator);

        // build a list of jar files in the classpath
        while (strTok.hasMoreTokens()) {
            String classpathItem = strTok.nextToken();
            if (classpathItem.toLowerCase(Locale.ENGLISH).endsWith(".jar")) {
                File item = new File(classpathItem);
                if (item.isFile()) {
                    try {
                        addSystemResource(item);
                    } catch (IOException e) {
                        log.error(sm.getString("extensionValidator.failload", item), e);
                    }
                }
            }
        }

        // add specified folders to the list
        addFolderList("java.ext.dirs");
    }


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


    /**
     * Runtime validation of a Web Application. This method uses JNDI to look up the resources located under a
     * <code>DirContext</code>. It locates Web Application MANIFEST.MF file in the /META-INF/ directory of the
     * application and all MANIFEST.MF files in each JAR file located in the WEB-INF/lib directory and creates an
     * <code>ArrayList</code> of <code>ManifestResource</code> objects. These objects are then passed to the
     * validateManifestResources method for validation.
     *
     * @param resources The resources configured for this Web Application
     * @param context   The context from which the Logger and path to the application
     *
     * @return true if all required extensions satisfied
     *
     * @throws IOException Error reading resources needed for validation
     */
    public static synchronized boolean validateApplication(WebResourceRoot resources, Context context)
            throws IOException {

        String appName = context.getName();
        List<ManifestResource> appManifestResources = new ArrayList<>();

        // Web application manifest
        WebResource resource = resources.getResource("/META-INF/MANIFEST.MF");
        if (resource.isFile()) {
            try (InputStream inputStream = resource.getInputStream()) {
                Manifest manifest = new Manifest(inputStream);
                ManifestResource mre = new ManifestResource(sm.getString("extensionValidator.web-application-manifest"),
                        manifest, ManifestResource.WAR);
                appManifestResources.add(mre);
            }
        }

        // Web application library manifests
        WebResource[] manifestResources = resources.getClassLoaderResources("/META-INF/MANIFEST.MF");
        for (WebResource manifestResource : manifestResources) {
            if (manifestResource.isFile()) {
                // Primarily used for error reporting
                String jarName = manifestResource.getURL().toExternalForm();
                Manifest jmanifest = manifestResource.getManifest();
                if (jmanifest != null) {
                    ManifestResource mre = new ManifestResource(jarName, jmanifest, ManifestResource.APPLICATION);
                    appManifestResources.add(mre);
                }
            }
        }

        return validateManifestResources(appName, appManifestResources);
    }


    /**
     * Checks to see if the given system JAR file contains a MANIFEST, and adds it to the container's manifest
     * resources.
     *
     * @param jarFile The system JAR whose manifest to add
     *
     * @throws IOException Error reading JAR file
     */
    public static void addSystemResource(File jarFile) throws IOException {
        try (InputStream is = new FileInputStream(jarFile)) {
            Manifest manifest = getManifest(is);
            if (manifest != null) {
                ManifestResource mre =
                        new ManifestResource(jarFile.getAbsolutePath(), manifest, ManifestResource.SYSTEM);
                containerManifestResources.add(mre);
            }
        }
    }


    // -------------------------------------------------------- Private Methods


    /**
     * Validates an <code>ArrayList</code> of <code>ManifestResource</code> objects. This method requires an application
     * name (which is the context root of the application at runtime). <code>false</code> is returned if the extension
     * dependencies represented by any given <code>ManifestResource</code> objects is not met. This method should also
     * provide static validation of a Web Application if provided with the necessary parameters.
     *
     * @param appName   The name of the Application that will appear in the error messages
     * @param resources A list of <code>ManifestResource</code> objects to be validated.
     *
     * @return true if manifest resource file requirements are met
     */
    private static boolean validateManifestResources(String appName, List<ManifestResource> resources) {
        boolean passes = true;
        int failureCount = 0;
        List<Extension> availableExtensions = null;

        for (ManifestResource mre : resources) {
            ArrayList<Extension> requiredList = mre.getRequiredExtensions();
            if (requiredList == null) {
                continue;
            }

            // build the list of available extensions if necessary
            if (availableExtensions == null) {
                availableExtensions = buildAvailableExtensionsList(resources);
            }

            // load the container level resource map if it has not been built
            // yet
            if (containerAvailableExtensions == null) {
                containerAvailableExtensions = buildAvailableExtensionsList(containerManifestResources);
            }

            // iterate through the list of required extensions
            for (Extension requiredExt : requiredList) {
                boolean found = false;
                // check the application itself for the extension
                if (availableExtensions != null) {
                    for (Extension targetExt : availableExtensions) {
                        if (targetExt.isCompatibleWith(requiredExt)) {
                            requiredExt.setFulfilled(true);
                            found = true;
                            break;
                        }
                    }
                }
                // check the container level list for the extension
                if (!found && containerAvailableExtensions != null) {
                    for (Extension targetExt : containerAvailableExtensions) {
                        if (targetExt.isCompatibleWith(requiredExt)) {
                            requiredExt.setFulfilled(true);
                            found = true;
                            break;
                        }
                    }
                }
                if (!found) {
                    // Failure
                    log.info(sm.getString("extensionValidator.extension-not-found-error", appName,
                            mre.getResourceName(), requiredExt.getExtensionName()));
                    passes = false;
                    failureCount++;
                }
            }
        }

        if (!passes) {
            log.info(sm.getString("extensionValidator.extension-validation-error", appName, failureCount + ""));
        }

        return passes;
    }

    /*
     * Build this list of available extensions so that we do not have to re-build this list every time we iterate
     * through the list of required extensions. All available extensions in all of the <code>ManifestResource</code>
     * objects will be added to a <code>HashMap</code> which is returned on the first dependency list processing pass.
     *
     * The key is the name + implementation version.
     *
     * NOTE: A list is built only if there is a dependency that needs to be checked (performance optimization).
     *
     * @param resources A list of <code>ManifestResource</code> objects
     *
     * @return HashMap Map of available extensions
     */
    private static List<Extension> buildAvailableExtensionsList(List<ManifestResource> resources) {

        List<Extension> availableList = null;

        for (ManifestResource mre : resources) {
            ArrayList<Extension> list = mre.getAvailableExtensions();
            if (list != null) {
                for (Extension ext : list) {
                    if (availableList == null) {
                        availableList = new ArrayList<>();
                        availableList.add(ext);
                    } else {
                        availableList.add(ext);
                    }
                }
            }
        }

        return availableList;
    }

    /**
     * Return the Manifest from a jar file or war file
     *
     * @param inStream Input stream to a WAR or JAR file
     *
     * @return The WAR's or JAR's manifest
     */
    private static Manifest getManifest(InputStream inStream) throws IOException {
        Manifest manifest = null;
        try (JarInputStream jin = new JarInputStream(inStream)) {
            manifest = jin.getManifest();
        }
        return manifest;
    }


    /**
     * Add the JARs specified to the extension list.
     */
    private static void addFolderList(String property) {

        // get the files in the extensions directory
        String extensionsDir = System.getProperty(property);
        if (extensionsDir != null) {
            StringTokenizer extensionsTok = new StringTokenizer(extensionsDir, File.pathSeparator);
            while (extensionsTok.hasMoreTokens()) {
                File targetDir = new File(extensionsTok.nextToken());
                if (!targetDir.isDirectory()) {
                    continue;
                }
                File[] files = targetDir.listFiles();
                if (files == null) {
                    continue;
                }
                for (File file : files) {
                    if (file.getName().toLowerCase(Locale.ENGLISH).endsWith(".jar") && file.isFile()) {
                        try {
                            addSystemResource(file);
                        } catch (IOException e) {
                            log.error(sm.getString("extensionValidator.failload", file), e);
                        }
                    }
                }
            }
        }

    }
}