/*
 * 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.session;


import java.io.BufferedInputStream;
import java.io.BufferedOutputStream;
import java.io.File;
import java.io.FileInputStream;
import java.io.FileNotFoundException;
import java.io.FileOutputStream;
import java.io.IOException;
import java.io.ObjectInputStream;
import java.io.ObjectOutputStream;
import java.util.ArrayList;

import javax.servlet.ServletContext;

import org.apache.catalina.Context;
import org.apache.catalina.Loader;
import org.apache.catalina.Session;
import org.apache.catalina.util.CustomObjectInputStream;


/**
 * Concrete implementation of the <b>Store</b> interface that utilizes
 * a file per saved Session in a configured directory.  Sessions that are
 * saved are still subject to being expired based on inactivity.
 *
 * @author Craig R. McClanahan
 */
public final class FileStore extends StoreBase {


    // ----------------------------------------------------- Constants


    /**
     * The extension to use for serialized session filenames.
     */
    private static final String FILE_EXT = ".session";


    // ----------------------------------------------------- Instance Variables


    /**
     * The pathname of the directory in which Sessions are stored.
     * This may be an absolute pathname, or a relative path that is
     * resolved against the temporary work directory for this application.
     */
    private String directory = ".";


    /**
     * A File representing the directory in which Sessions are stored.
     */
    private File directoryFile = null;


    /**
     * Name to register for this Store, used for logging.
     */
    private static final String storeName = "fileStore";


    /**
     * Name to register for the background thread.
     */
    private static final String threadName = "FileStore";


    // ------------------------------------------------------------- Properties


    /**
     * Return the directory path for this Store.
     */
    public String getDirectory() {

        return (directory);

    }


    /**
     * Set the directory path for this Store.
     *
     * @param path The new directory path
     */
    public void setDirectory(String path) {

        String oldDirectory = this.directory;
        this.directory = path;
        this.directoryFile = null;
        support.firePropertyChange("directory", oldDirectory,
                                   this.directory);

    }


    /**
     * Return the thread name for this Store.
     */
    public String getThreadName() {
        return(threadName);
    }


    /**
     * Return the name for this Store, used for logging.
     */
    @Override
    public String getStoreName() {
        return(storeName);
    }


    /**
     * Return the number of Sessions present in this Store.
     *
     * @exception IOException if an input/output error occurs
     */
    @Override
    public int getSize() throws IOException {

        // Acquire the list of files in our storage directory
        File file = directory();
        if (file == null) {
            return (0);
        }
        String files[] = file.list();

        // Figure out which files are sessions
        int keycount = 0;
        for (int i = 0; i < files.length; i++) {
            if (files[i].endsWith(FILE_EXT)) {
                keycount++;
            }
        }
        return (keycount);

    }


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


    /**
     * Remove all of the Sessions in this Store.
     *
     * @exception IOException if an input/output error occurs
     */
    @Override
    public void clear()
        throws IOException {

        String[] keys = keys();
        for (int i = 0; i < keys.length; i++) {
            remove(keys[i]);
        }

    }


    /**
     * Return an array containing the session identifiers of all Sessions
     * currently saved in this Store.  If there are no such Sessions, a
     * zero-length array is returned.
     *
     * @exception IOException if an input/output error occurred
     */
    @Override
    public String[] keys() throws IOException {

        // Acquire the list of files in our storage directory
        File file = directory();
        if (file == null) {
            return (new String[0]);
        }

        String files[] = file.list();

        // Bugzilla 32130
        if((files == null) || (files.length < 1)) {
            return (new String[0]);
        }

        // Build and return the list of session identifiers
        ArrayList<String> list = new ArrayList<>();
        int n = FILE_EXT.length();
        for (int i = 0; i < files.length; i++) {
            if (files[i].endsWith(FILE_EXT)) {
                list.add(files[i].substring(0, files[i].length() - n));
            }
        }
        return list.toArray(new String[list.size()]);

    }


    /**
     * Load and return the Session associated with the specified session
     * identifier from this Store, without removing it.  If there is no
     * such stored Session, return <code>null</code>.
     *
     * @param id Session identifier of the session to load
     *
     * @exception ClassNotFoundException if a deserialization error occurs
     * @exception IOException if an input/output error occurs
     */
    @Override
    public Session load(String id)
        throws ClassNotFoundException, IOException {

        // Open an input stream to the specified pathname, if any
        File file = file(id);
        if (file == null) {
            return (null);
        }

        if (! file.exists()) {
            return (null);
        }
        if (manager.getContext().getLogger().isDebugEnabled()) {
            manager.getContext().getLogger().debug(sm.getString(getStoreName()+".loading",
                             id, file.getAbsolutePath()));
        }

        ObjectInputStream ois = null;
        Loader loader = null;
        ClassLoader classLoader = null;
        ClassLoader oldThreadContextCL = Thread.currentThread().getContextClassLoader();
        try (FileInputStream fis = new FileInputStream(file.getAbsolutePath());
                BufferedInputStream bis = new BufferedInputStream(fis)) {
            Context context = manager.getContext();
            if (context != null)
                loader = context.getLoader();
            if (loader != null)
                classLoader = loader.getClassLoader();
            if (classLoader != null) {
                Thread.currentThread().setContextClassLoader(classLoader);
                ois = new CustomObjectInputStream(bis, classLoader);
            } else {
                ois = new ObjectInputStream(bis);
            }

            StandardSession session =
                    (StandardSession) manager.createEmptySession();
            session.readObjectData(ois);
            session.setManager(manager);
            return (session);
        } catch (FileNotFoundException e) {
            if (manager.getContext().getLogger().isDebugEnabled())
                manager.getContext().getLogger().debug("No persisted data file found");
            return (null);
        } finally {
            if (ois != null) {
                // Close the input stream
                try {
                    ois.close();
                } catch (IOException f) {
                    // Ignore
                }
            }
            Thread.currentThread().setContextClassLoader(oldThreadContextCL);
        }
    }


    /**
     * Remove the Session with the specified session identifier from
     * this Store, if present.  If no such Session is present, this method
     * takes no action.
     *
     * @param id Session identifier of the Session to be removed
     *
     * @exception IOException if an input/output error occurs
     */
    @Override
    public void remove(String id) throws IOException {

        File file = file(id);
        if (file == null) {
            return;
        }
        if (manager.getContext().getLogger().isDebugEnabled()) {
            manager.getContext().getLogger().debug(sm.getString(getStoreName()+".removing",
                             id, file.getAbsolutePath()));
        }
        file.delete();

    }


    /**
     * Save the specified Session into this Store.  Any previously saved
     * information for the associated session identifier is replaced.
     *
     * @param session Session to be saved
     *
     * @exception IOException if an input/output error occurs
     */
    @Override
    public void save(Session session) throws IOException {

        // Open an output stream to the specified pathname, if any
        File file = file(session.getIdInternal());
        if (file == null) {
            return;
        }
        if (manager.getContext().getLogger().isDebugEnabled()) {
            manager.getContext().getLogger().debug(sm.getString(getStoreName()+".saving",
                             session.getIdInternal(), file.getAbsolutePath()));
        }

        try (FileOutputStream fos = new FileOutputStream(file.getAbsolutePath());
                ObjectOutputStream oos = new ObjectOutputStream(new BufferedOutputStream(fos))) {
            ((StandardSession)session).writeObjectData(oos);
        }
    }


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


    /**
     * Return a File object representing the pathname to our
     * session persistence directory, if any.  The directory will be
     * created if it does not already exist.
     */
    private File directory() throws IOException {

        if (this.directory == null) {
            return (null);
        }
        if (this.directoryFile != null) {
            // NOTE:  Race condition is harmless, so do not synchronize
            return (this.directoryFile);
        }
        File file = new File(this.directory);
        if (!file.isAbsolute()) {
            Context context = manager.getContext();
            if (context != null) {
                ServletContext servletContext = context.getServletContext();
                File work = (File)
                    servletContext.getAttribute(ServletContext.TEMPDIR);
                file = new File(work, this.directory);
            } else {
                throw new IllegalArgumentException
                    ("Parent Container is not a Context");
            }
        }
        if (!file.exists() || !file.isDirectory()) {
            if (!file.delete() && file.exists()) {
                throw new IOException(
                        sm.getString("fileStore.deleteFailed", file));
            }
            if (!file.mkdirs() && !file.isDirectory()) {
                throw new IOException(
                        sm.getString("fileStore.createFailed", file));
            }
        }
        this.directoryFile = file;
        return (file);

    }


    /**
     * Return a File object representing the pathname to our
     * session persistence file, if any.
     *
     * @param id The ID of the Session to be retrieved. This is
     *    used in the file naming.
     */
    private File file(String id) throws IOException {

        if (this.directory == null) {
            return (null);
        }
        String filename = id + FILE_EXT;
        File file = new File(directory(), filename);
        return (file);

    }


}