/*
 * 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.provider.ftp;

import java.io.IOException;
import java.io.InputStream;
import java.io.OutputStream;
import java.time.Instant;

import org.apache.commons.logging.Log;
import org.apache.commons.logging.LogFactory;
import org.apache.commons.net.ftp.FTPClient;
import org.apache.commons.net.ftp.FTPConnectionClosedException;
import org.apache.commons.net.ftp.FTPFile;
import org.apache.commons.net.ftp.FTPReply;
import org.apache.commons.vfs2.FileSystemException;
import org.apache.commons.vfs2.FileSystemOptions;
import org.apache.commons.vfs2.UserAuthenticationData;
import org.apache.commons.vfs2.provider.GenericFileName;
import org.apache.commons.vfs2.util.UserAuthenticatorUtils;

/**
 * A wrapper to the FTPClient to allow automatic reconnect on connection loss.
 * <p>
 * I decided to not to use eg. noop() to determine the state of the connection to avoid unnecessary server round-trips.
 * </p>
 */
public class FTPClientWrapper implements FtpClient {

    private static final Log LOG = LogFactory.getLog(FTPClientWrapper.class);

    /**
     * Authentication options.
     */
    protected final FileSystemOptions fileSystemOptions;
    private FTPClient ftpClient;
    private final GenericFileName rootFileName;

    /**
     * Constructs a new instance.
     *
     * @param rootFileName the root file name.
     * @param fileSystemOptions the file system options.
     * @throws FileSystemException if a file system error occurs.
     */
    protected FTPClientWrapper(final GenericFileName rootFileName, final FileSystemOptions fileSystemOptions)
        throws FileSystemException {
        this.rootFileName = rootFileName;
        this.fileSystemOptions = fileSystemOptions;
        getFtpClient(); // fail-fast
    }

    @Override
    public boolean abort() throws IOException {
        try {
            // imario@apache.org: 2005-02-14
            // it should be better to really "abort" the transfer, but
            // currently I didn't manage to make it work - so lets "abort" the hard way.
            // return getFtpClient().abort();
            disconnect();
            return true;
        } catch (final IOException e) {
            disconnect();
        }
        return true;
    }

    @Override
    public OutputStream appendFileStream(final String relPath) throws IOException {
        try {
            return getFtpClient().appendFileStream(relPath);
        } catch (final IOException e) {
            disconnect();
            return getFtpClient().appendFileStream(relPath);
        }
    }

    @Override
    public boolean completePendingCommand() throws IOException {
        if (ftpClient != null) {
            return getFtpClient().completePendingCommand();
        }
        return true;
    }

    /**
     * Creates an FTP client.
     *
     * @return a new FTP client.
     * @throws FileSystemException if an error occurs while establishing a connection.
     */
    private FTPClient createClient() throws FileSystemException {
        final GenericFileName rootName = getRoot();
        UserAuthenticationData authData = null;
        try {
            authData = UserAuthenticatorUtils.authenticate(fileSystemOptions, FtpFileProvider.AUTHENTICATOR_TYPES);
            return createClient(rootName, authData);
        } finally {
            UserAuthenticatorUtils.cleanup(authData);
        }
    }

    /**
     * Creates an FTPClient.
     *
     * @param rootFileName the root file name.
     * @param authData authentication data.
     * @return an FTPClient.
     * @throws FileSystemException if an error occurs while establishing a connection.
     */
    protected FTPClient createClient(final GenericFileName rootFileName, final UserAuthenticationData authData)
        throws FileSystemException {
        return FtpClientFactory.createConnection(rootFileName.getHostName(), rootFileName.getPort(),
            UserAuthenticatorUtils.getData(authData, UserAuthenticationData.USERNAME,
                UserAuthenticatorUtils.toChar(rootFileName.getUserName())),
            UserAuthenticatorUtils.getData(authData, UserAuthenticationData.PASSWORD,
                UserAuthenticatorUtils.toChar(rootFileName.getPassword())),
            rootFileName.getPath(), getFileSystemOptions());
    }

    @Override
    public boolean deleteFile(final String relPath) throws IOException {
        try {
            return getFtpClient().deleteFile(relPath);
        } catch (final IOException e) {
            disconnect();
            return getFtpClient().deleteFile(relPath);
        }
    }

    @Override
    public void disconnect() throws IOException {
        if (ftpClient != null) {
            try {
                ftpClient.quit();
            } catch (final IOException e) {
                LOG.debug("I/O exception while trying to quit, connection likely timed out, ignoring.", e);
            } finally {
                try {
                    getFtpClient().disconnect();
                } catch (final IOException e) {
                    LOG.warn("I/O exception while trying to disconnect, connection likely closed, ignoring.", e);
                } finally {
                    ftpClient = null;
                }
            }
        }
    }

    /**
     * Gets the FileSystemOptions.
     *
     * @return the FileSystemOptions.
     */
    public FileSystemOptions getFileSystemOptions() {
        return fileSystemOptions;
    }

    /**
     * Package-private for debugging only, consider private.
     *
     * @return the actual FTP client.
     * @throws FileSystemException if an error occurs while establishing a connection.
     */
    FTPClient getFtpClient() throws FileSystemException {
        if (ftpClient == null) {
            ftpClient = createClient();
        }
        return ftpClient;
    }

    @Override
    public int getReplyCode() throws IOException {
        return getFtpClient().getReplyCode();
    }

    @Override
    public String getReplyString() throws IOException {
        return getFtpClient().getReplyString();
    }

    /**
     * Gets the root file name.
     *
     * @return  the root file name.
     */
    public GenericFileName getRoot() {
        return rootFileName;
    }

    /**
     * {@inheritDoc}
     */
    @Override
    public boolean hasFeature(final String feature) throws IOException {
        try {
            return getFtpClient().hasFeature(feature);
        } catch (final IOException ex) {
            disconnect();
            return getFtpClient().hasFeature(feature);
        }
    }

    @Override
    public boolean isConnected() throws FileSystemException {
        return ftpClient != null && ftpClient.isConnected();
    }

    @Override
    public FTPFile[] listFiles(final String relPath) throws IOException {
        try {
            // VFS-210: return getFtpClient().listFiles(relPath);
            return listFilesInDirectory(relPath);
        } catch (final IOException e) {
            disconnect();
            return listFilesInDirectory(relPath);
        }
    }

    private FTPFile[] listFilesInDirectory(final String relPath) throws IOException {
        // VFS-307: no check if we can simply list the files, this might fail if there are spaces in the path
        FTPFile[] ftpFiles = getFtpClient().listFiles(relPath);
        if (FTPReply.isPositiveCompletion(getFtpClient().getReplyCode())) {
            return ftpFiles;
        }

        // VFS-307: now try the hard way by cd'ing into the directory, list and cd back
        // if VFS is required to fallback here the user might experience a real bad FTP performance
        // as then every list requires 4 FTP commands.
        String workingDirectory = null;
        if (relPath != null) {
            workingDirectory = getFtpClient().printWorkingDirectory();
            if (!getFtpClient().changeWorkingDirectory(relPath)) {
                return null;
            }
        }

        ftpFiles = getFtpClient().listFiles();

        if (relPath != null && !getFtpClient().changeWorkingDirectory(workingDirectory)) {
            throw new FileSystemException("vfs.provider.ftp.wrapper/change-work-directory-back.error",
                workingDirectory);
        }
        return ftpFiles;
    }

    @Override
    public boolean makeDirectory(final String relPath) throws IOException {
        try {
            return getFtpClient().makeDirectory(relPath);
        } catch (final IOException e) {
            disconnect();
            return getFtpClient().makeDirectory(relPath);
        }
    }

    /**
     * {@inheritDoc}
     */
    @Override
    public Instant mdtmInstant(final String relPath) throws IOException {
        try {
            return getFtpClient().mdtmCalendar(relPath).toInstant();
        } catch (final IOException ex) {
            disconnect();
            return getFtpClient().mdtmCalendar(relPath).toInstant();
        }
    }

    @Override
    public boolean removeDirectory(final String relPath) throws IOException {
        try {
            return getFtpClient().removeDirectory(relPath);
        } catch (final IOException e) {
            disconnect();
            return getFtpClient().removeDirectory(relPath);
        }
    }

    @Override
    public boolean rename(final String oldName, final String newName) throws IOException {
        try {
            return getFtpClient().rename(oldName, newName);
        } catch (final IOException e) {
            disconnect();
            return getFtpClient().rename(oldName, newName);
        }
    }

    @Override
    public InputStream retrieveFileStream(final String relPath) throws IOException {
        try {
            return getFtpClient().retrieveFileStream(relPath);
        } catch (final IOException e) {
            disconnect();
            return getFtpClient().retrieveFileStream(relPath);
        }
    }

    @Override
    public InputStream retrieveFileStream(final String relPath, final int bufferSize) throws IOException {
        try {
            final FTPClient client = getFtpClient();
            client.setBufferSize(bufferSize);
            return client.retrieveFileStream(relPath);
        } catch (final IOException e) {
            disconnect();
            final FTPClient client = getFtpClient();
            client.setBufferSize(bufferSize);
            return client.retrieveFileStream(relPath);
        }
    }

    @Override
    public InputStream retrieveFileStream(final String relPath, final long restartOffset) throws IOException {
        try {
            final FTPClient client = getFtpClient();
            client.setRestartOffset(restartOffset);
            return client.retrieveFileStream(relPath);
        } catch (final IOException e) {
            disconnect();
            final FTPClient client = getFtpClient();
            client.setRestartOffset(restartOffset);
            return client.retrieveFileStream(relPath);
        }
    }

    /**
     * A convenience method to send the FTP OPTS command to the server, receive the reply, and return the reply code.
     * <p>
     * FTP request Syntax:
     * </p>
     * <pre>{@code
     * opts             = opts-cmd SP command-name
     *                         [ SP command-options ] CRLF
     * opts-cmd         = "opts"
     * command-name     = <any FTP command which allows option setting>
     * command-options  = <format specified by individual FTP command>
     * }</pre>
     * @param commandName The OPTS command name.
     * @param commandOptions The OPTS command options.
     * @return The reply code received from the server.
     * @throws FTPConnectionClosedException If the FTP server prematurely closes the connection as a result of the client being idle or some other reason
     *                                      causing the server to send FTP reply code 421. This exception may be caught either as an IOException or
     *                                      independently as itself.
     * @throws IOException                  If an I/O error occurs while either sending the command or receiving the server reply.
     * @since 2.11.0
     */
    public int sendOptions(final String commandName, String commandOptions) throws IOException {
        // Commons Net 3.12.0
        // return getFtpClient().opts(commandName, commandOptions);
        return getFtpClient().sendCommand("OPTS", commandName + ' ' + commandOptions);
    }

    @Override
    public void setBufferSize(final int bufferSize) throws FileSystemException {
        getFtpClient().setBufferSize(bufferSize);
    }

    @Override
    public OutputStream storeFileStream(final String relPath) throws IOException {
        try {
            return getFtpClient().storeFileStream(relPath);
        } catch (final IOException e) {
            disconnect();
            return getFtpClient().storeFileStream(relPath);
        }
    }
}