/*
 * 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.net.ftp.parser;

import java.util.regex.Pattern;

import org.apache.commons.net.ftp.Configurable;
import org.apache.commons.net.ftp.FTPClientConfig;
import org.apache.commons.net.ftp.FTPFileEntryParser;

/**
 * This is the default implementation of the FTPFileEntryParserFactory interface. This is the implementation that will be used by
 * org.apache.commons.net.ftp.FTPClient.listFiles() if no other implementation has been specified.
 *
 * @see org.apache.commons.net.ftp.FTPClient#listFiles
 * @see org.apache.commons.net.ftp.FTPClient#setParserFactory
 */
public class DefaultFTPFileEntryParserFactory implements FTPFileEntryParserFactory {

    // Match a plain Java Identifier
    private static final String JAVA_IDENTIFIER = "\\p{javaJavaIdentifierStart}(\\p{javaJavaIdentifierPart})*";
    // Match a qualified name, e.g. a.b.c.Name - but don't allow the default package as that would allow "VMS"/"UNIX" etc.
    private static final String JAVA_QUALIFIED_NAME = "(" + JAVA_IDENTIFIER + "\\.)+" + JAVA_IDENTIFIER;
    // Create the pattern, as it will be reused many times
    private static final Pattern JAVA_QUALIFIED_NAME_PATTERN = Pattern.compile(JAVA_QUALIFIED_NAME);

    /**
     * <p>
     * Implementation extracts a key from the supplied {@link FTPClientConfig FTPClientConfig} parameter and creates an object implementing the interface
     * FTPFileEntryParser and uses the supplied configuration to configure it.
     * </p>
     * <p>
     * Note that this method will generally not be called in scenarios that call for autodetection of parser type but rather, for situations where the user
     * knows that the server uses a non-default configuration and knows what that configuration is.
     * </p>
     *
     * @param config A {@link FTPClientConfig FTPClientConfig} used to configure the parser created
     *
     * @return the @link FTPFileEntryParser FTPFileEntryParser} so created.
     * @throws ParserInitializationException Thrown on any exception in instantiation
     * @throws NullPointerException          if {@code config} is {@code null}
     * @since 1.4
     */
    @Override
    public FTPFileEntryParser createFileEntryParser(final FTPClientConfig config) throws ParserInitializationException {
        final String key = config.getServerSystemKey();
        return createFileEntryParser(key, config);
    }

    /**
     * This default implementation of the FTPFileEntryParserFactory interface works according to the following logic: First it attempts to interpret the
     * supplied key as a fully qualified classname (default package is not allowed) of a class implementing the FTPFileEntryParser interface. If that succeeds,
     * a parser object of this class is instantiated and is returned; otherwise it attempts to interpret the key as an identirier commonly used by the FTP SYST
     * command to identify systems.
     * <p>
     * If <code>key</code> is not recognized as a fully qualified classname known to the system, this method will then attempt to see whether it <b>contains</b>
     * a string identifying one of the known parsers. This comparison is <b>case-insensitive</b>. The intent here is where possible, to select as keys strings
     * which are returned by the SYST command on the systems which the corresponding parser successfully parses. This enables this factory to be used in the
     * auto-detection system.
     *
     * @param key should be a fully qualified classname corresponding to a class implementing the FTPFileEntryParser interface<br>
     *            OR<br>
     *            a string containing (case-insensitively) one of the following keywords:
     *            <ul>
     *            <li>{@link FTPClientConfig#SYST_UNIX UNIX}</li>
     *            <li>{@link FTPClientConfig#SYST_NT WINDOWS}</li>
     *            <li>{@link FTPClientConfig#SYST_OS2 OS/2}</li>
     *            <li>{@link FTPClientConfig#SYST_OS400 OS/400}</li>
     *            <li>{@link FTPClientConfig#SYST_AS400 AS/400}</li>
     *            <li>{@link FTPClientConfig#SYST_VMS VMS}</li>
     *            <li>{@link FTPClientConfig#SYST_MVS MVS}</li>
     *            <li>{@link FTPClientConfig#SYST_NETWARE NETWARE}</li>
     *            <li>{@link FTPClientConfig#SYST_L8 TYPE:L8}</li>
     *            </ul>
     * @return the FTPFileEntryParser corresponding to the supplied key.
     * @throws ParserInitializationException thrown if for any reason the factory cannot resolve the supplied key into an FTPFileEntryParser.
     * @see FTPFileEntryParser
     */
    @Override
    public FTPFileEntryParser createFileEntryParser(final String key) {
        if (key == null) {
            throw new ParserInitializationException("Parser key cannot be null");
        }
        return createFileEntryParser(key, null);
    }

    // Common method to process both key and config parameters.
    private FTPFileEntryParser createFileEntryParser(final String key, final FTPClientConfig config) {
        FTPFileEntryParser parser = null;

        // Is the key a possible class name?
        if (JAVA_QUALIFIED_NAME_PATTERN.matcher(key).matches()) {
            try {
                final Class<?> parserClass = Class.forName(key);
                try {
                    parser = (FTPFileEntryParser) parserClass.newInstance();
                } catch (final ClassCastException e) {
                    throw new ParserInitializationException(
                            parserClass.getName() + " does not implement the interface " + "org.apache.commons.net.ftp.FTPFileEntryParser.", e);
                } catch (final Exception | ExceptionInInitializerError e) {
                    throw new ParserInitializationException("Error initializing parser", e);
                }
            } catch (final ClassNotFoundException e) {
                // OK, assume it is an alias
            }
        }

        if (parser == null) { // Now try for aliases
            final String ukey = key.toUpperCase(java.util.Locale.ENGLISH);
            if (ukey.contains(FTPClientConfig.SYST_UNIX_TRIM_LEADING)) {
                parser = new UnixFTPEntryParser(config, true);
            }
            // must check this after SYST_UNIX_TRIM_LEADING as it is a substring of it
            else if (ukey.contains(FTPClientConfig.SYST_UNIX)) {
                parser = new UnixFTPEntryParser(config, false);
            } else if (ukey.contains(FTPClientConfig.SYST_VMS)) {
                parser = new VMSVersioningFTPEntryParser(config);
            } else if (ukey.contains(FTPClientConfig.SYST_NT)) {
                parser = createNTFTPEntryParser(config);
            } else if (ukey.contains(FTPClientConfig.SYST_OS2)) {
                parser = new OS2FTPEntryParser(config);
            } else if (ukey.contains(FTPClientConfig.SYST_OS400) || ukey.contains(FTPClientConfig.SYST_AS400)) {
                parser = createOS400FTPEntryParser(config);
            } else if (ukey.contains(FTPClientConfig.SYST_MVS)) {
                parser = new MVSFTPEntryParser(); // Does not currently support config parameter
            } else if (ukey.contains(FTPClientConfig.SYST_NETWARE)) {
                parser = new NetwareFTPEntryParser(config);
            } else if (ukey.contains(FTPClientConfig.SYST_MACOS_PETER)) {
                parser = new MacOsPeterFTPEntryParser(config);
            } else if (ukey.contains(FTPClientConfig.SYST_L8)) {
                // L8 normally means Unix, but move it to the end for some L8 systems that aren't.
                // This check should be last!
                parser = new UnixFTPEntryParser(config);
            } else {
                throw new ParserInitializationException("Unknown parser type: " + key);
            }
        }

        if (parser instanceof Configurable) {
            ((Configurable) parser).configure(config);
        }
        return parser;
    }

    public FTPFileEntryParser createMVSEntryParser() {
        return new MVSFTPEntryParser();
    }

    public FTPFileEntryParser createNetwareFTPEntryParser() {
        return new NetwareFTPEntryParser();
    }

    public FTPFileEntryParser createNTFTPEntryParser() {
        return createNTFTPEntryParser(null);
    }

    /**
     * Creates an NT FTP parser: if the config exists, and the system key equals {@link FTPClientConfig#SYST_NT} then a plain {@link NTFTPEntryParser} is used,
     * otherwise a composite of {@link NTFTPEntryParser} and {@link UnixFTPEntryParser} is used.
     *
     * @param config the config to use, may be {@code null}
     * @return the parser
     */
    private FTPFileEntryParser createNTFTPEntryParser(final FTPClientConfig config) {
        if (config != null && FTPClientConfig.SYST_NT.equals(config.getServerSystemKey())) {
            return new NTFTPEntryParser(config);
        }
        // clone the config as it may be changed by the parsers (NET-602)
        final FTPClientConfig config2 = config != null ? new FTPClientConfig(config) : null;
        return new CompositeFileEntryParser(new FTPFileEntryParser[] { new NTFTPEntryParser(config),
                new UnixFTPEntryParser(config2, config2 != null && FTPClientConfig.SYST_UNIX_TRIM_LEADING.equals(config2.getServerSystemKey())) });
    }

    public FTPFileEntryParser createOS2FTPEntryParser() {
        return new OS2FTPEntryParser();
    }

    public FTPFileEntryParser createOS400FTPEntryParser() {
        return createOS400FTPEntryParser(null);
    }

    /**
     * Creates an OS400 FTP parser: if the config exists, and the system key equals {@link FTPClientConfig#SYST_OS400} then a plain {@link OS400FTPEntryParser}
     * is used, otherwise a composite of {@link OS400FTPEntryParser} and {@link UnixFTPEntryParser} is used.
     *
     * @param config the config to use, may be {@code null}
     * @return the parser
     */
    private FTPFileEntryParser createOS400FTPEntryParser(final FTPClientConfig config) {
        if (config != null && FTPClientConfig.SYST_OS400.equals(config.getServerSystemKey())) {
            return new OS400FTPEntryParser(config);
        }
        // clone the config as it may be changed by the parsers (NET-602)
        final FTPClientConfig config2 = config != null ? new FTPClientConfig(config) : null;
        return new CompositeFileEntryParser(new FTPFileEntryParser[] { new OS400FTPEntryParser(config),
                new UnixFTPEntryParser(config2, config2 != null && FTPClientConfig.SYST_UNIX_TRIM_LEADING.equals(config2.getServerSystemKey())) });
    }

    public FTPFileEntryParser createUnixFTPEntryParser() {
        return new UnixFTPEntryParser();
    }

    public FTPFileEntryParser createVMSVersioningFTPEntryParser() {
        return new VMSVersioningFTPEntryParser();
    }

}
