/*
 * 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.commons.vfs2.impl;

import java.io.File;
import java.util.ArrayList;
import java.util.Random;

import org.apache.commons.io.FileUtils;
import org.apache.commons.logging.Log;
import org.apache.commons.logging.LogFactory;
import org.apache.commons.vfs2.FileObject;
import org.apache.commons.vfs2.FileSelector;
import org.apache.commons.vfs2.FileSystemException;
import org.apache.commons.vfs2.VfsLog;
import org.apache.commons.vfs2.provider.AbstractVfsComponent;
import org.apache.commons.vfs2.provider.FileReplicator;
import org.apache.commons.vfs2.provider.TemporaryFileStore;
import org.apache.commons.vfs2.provider.UriParser;
import org.apache.commons.vfs2.util.Messages;

/**
 * A simple file replicator and temporary file store.
 */
public class DefaultFileReplicator extends AbstractVfsComponent implements FileReplicator, TemporaryFileStore {

    private static final Log log = LogFactory.getLog(DefaultFileReplicator.class);
    private static final int MASK = 0xffff;

    private static final Random RANDOM = new Random();

    private static final char[] TMP_RESERVED_CHARS = {'?', '/', '\\', ' ', '&', '"', '\'', '*', '#', ';', ':', '<', '>', '|'};

    private final ArrayList<Object> copies = new ArrayList<>();
    private long fileCount;
    private File tempDir;
    private boolean tempDirMessageLogged;

    /**
     * Constructs a new instance.
     */
    public DefaultFileReplicator() {
    }

    /**
     * Constructor to set the location of the temporary directory.
     *
     * @param tempDir The temporary directory.
     */
    public DefaultFileReplicator(final File tempDir) {
        this.tempDir = tempDir;
    }

    /**
     * Adds a file.
     *
     * @param file the file to add.
     */
    protected void addFile(final Object file) {
        synchronized (copies) {
            copies.add(file);
        }
    }

    /**
     * Allocates a new temporary file.
     *
     * @param baseName the base file name.
     * @return The created File.
     * @throws FileSystemException if an error occurs.
     */
    @Override
    public File allocateFile(final String baseName) throws FileSystemException {
        // Create a unique-ish file name
        final String actualBaseName = createFilename(baseName);
        synchronized (this) {
            fileCount++;
        }

        return createAndAddFile(tempDir, actualBaseName);
    }

    /**
     * Closes the replicator, deleting all temporary files.
     */
    @Override
    public void close() {
        // Delete the temporary files
        synchronized (copies) {
            while (!copies.isEmpty()) {
                deleteFile((File) removeFile());
            }
        }

        // Clean up the temp directory, if it is empty
        if (tempDir != null && tempDir.exists()) {
            final String[] list = tempDir.list();
            if (list != null && list.length == 0) {
                tempDir.delete();
                tempDir = null;
            }
        }
    }

    /**
     * Adds a file.
     *
     * @param parent ignored.
     * @param baseName the base file name.
     * @return a File.
     * @throws FileSystemException if a file system error occurs.
     */
    protected File createAndAddFile(final File parent, final String baseName) throws FileSystemException {
        final File file = createFile(tempDir, baseName);
        // Keep track to delete later
        addFile(file);
        return file;
    }

    /**
     * Create the temporary file.
     *
     * @param parent The file to use as the parent of the file being created.
     * @param name The name of the file to create.
     * @return The File that was created.
     * @throws FileSystemException if an error occurs creating the file.
     */
    protected File createFile(final File parent, final String name) throws FileSystemException {
        return new File(parent, UriParser.decode(name));
    }

    /**
     * Create the temporary file name.
     *
     * @param baseName The base to prepend to the file name being created.
     * @return the name of the File.
     */
    protected String createFilename(final String baseName) {
        // BUG29007
        // return baseName + "_" + getFilecount() + ".tmp";

        // imario@apache.org: BUG34976 get rid of maybe reserved and dangerous characters
        // e.g. to allow replication of http://hostname.org/fileservlet?file=abc.txt
        final String safeBaseName = UriParser.encode(baseName, TMP_RESERVED_CHARS).replace('%', '_');
        return "tmp_" + getFilecount() + "_" + safeBaseName;
    }

    /**
     * Physically deletes the file from the file system.
     *
     * @param file The File to delete.
     */
    protected void deleteFile(final File file) {
        try {
            final FileObject fileObject = getContext().toFileObject(file);
            fileObject.deleteAll();
        } catch (final FileSystemException e) {
            final String message = Messages.getString("vfs.impl/delete-temp.warn", file.getName());
            VfsLog.warn(getLogger(), log, message, e);
        }
    }

    /**
     * Gets the file count.
     *
     * @return the file count.
     */
    protected long getFilecount() {
        return fileCount;
    }

    /**
     * Initializes this component.
     *
     * @throws FileSystemException if an error occurs.
     */
    @Override
    public void init() throws FileSystemException {
        if (tempDir == null) {
            tempDir = new File(FileUtils.getTempDirectoryPath(), "vfs_cache").getAbsoluteFile();
        }

        fileCount = RANDOM.nextInt() & MASK;

        if (!tempDirMessageLogged) {
            final String message = Messages.getString("vfs.impl/temp-dir.debug", tempDir);
            VfsLog.debug(getLogger(), log, message);

            tempDirMessageLogged = true;
        }
    }

    /**
     * Removes a file from the copies list. Will be used for cleanup.
     * <p>
     * Notice: The system awaits that the returning object can be cast to a {@link File}.
     *
     * @return the File that was removed.
     */
    protected Object removeFile() {
        synchronized (copies) {
            return copies.remove(0);
        }
    }

    /**
     * Removes an instance from the list of copies.
     *
     * @param file The File to remove.
     */
    protected void removeFile(final Object file) {
        synchronized (copies) {
            copies.remove(file);
        }
    }

    /**
     * Creates a local copy of the file, and all its descendants.
     *
     * @param srcFile The file to copy.
     * @param selector The FileSelector.
     * @return the created File.
     * @throws FileSystemException if an error occurs copying the file.
     */
    @Override
    public File replicateFile(final FileObject srcFile, final FileSelector selector) throws FileSystemException {
        final String baseName = srcFile.getName().getBaseName();
        final File file = allocateFile(baseName);

        // Copy from the source file
        final FileObject destFile = getContext().toFileObject(file);
        destFile.copyFrom(srcFile, selector);

        return file;
    }
}