/*
 * 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.camel.component.file.remote;

import java.util.regex.Pattern;

import org.apache.camel.spi.ClassResolver;
import org.apache.commons.net.ftp.Configurable;
import org.apache.commons.net.ftp.FTPClientConfig;
import org.apache.commons.net.ftp.FTPFileEntryParser;
import org.apache.commons.net.ftp.parser.CompositeFileEntryParser;
import org.apache.commons.net.ftp.parser.DefaultFTPFileEntryParserFactory;
import org.apache.commons.net.ftp.parser.MVSFTPEntryParser;
import org.apache.commons.net.ftp.parser.MacOsPeterFTPEntryParser;
import org.apache.commons.net.ftp.parser.NTFTPEntryParser;
import org.apache.commons.net.ftp.parser.NetwareFTPEntryParser;
import org.apache.commons.net.ftp.parser.OS2FTPEntryParser;
import org.apache.commons.net.ftp.parser.OS400FTPEntryParser;
import org.apache.commons.net.ftp.parser.ParserInitializationException;
import org.apache.commons.net.ftp.parser.UnixFTPEntryParser;
import org.apache.commons.net.ftp.parser.VMSVersioningFTPEntryParser;

/**
 * commons-net DefaultFTPFileEntryParserFactory uses Class.forName, and fails to load custom ParserFactories in various
 * runtimes such as OSGi. This class is an alternative ParserFactory that uses Camels {@link ClassResolver} to load
 * classes.
 */
public class CamelFTPParserFactory extends DefaultFTPFileEntryParserFactory {
    // 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);

    private ClassResolver ocr;

    public CamelFTPParserFactory(ClassResolver ocr) {
        this.ocr = ocr;
    }

    /**
     * setClassResolver sets a class resolver which can be used instead of Class.forName for class resolution.
     *
     * @param ocr Class Resolver
     */
    public void setClassResolver(ClassResolver ocr) {
        this.ocr = ocr;
    }

    @Override
    public FTPFileEntryParser createFileEntryParser(String key) {
        if (key == null) {
            throw new ParserInitializationException("Parser key cannot be null");
        }
        return createFileEntryParser(key, null);
    }

    @Override
    public FTPFileEntryParser createFileEntryParser(FTPClientConfig config) throws ParserInitializationException {
        String key = config.getServerSystemKey();
        return createFileEntryParser(key, config);
    }

    private FTPFileEntryParser createFileEntryParser(String key, FTPClientConfig config) {
        FTPFileEntryParser parser = null;

        // Is the key a possible class name?
        if (JAVA_QUALIFIED_NAME_PATTERN.matcher(key).matches()) {
            Class<?> parserClass = ocr.resolveClass(key);
            try {
                parser = (FTPFileEntryParser) parserClass.newInstance();
            } catch (ClassCastException e) {
                throw new ParserInitializationException(
                        parserClass.getName() + " does not implement the interface "
                                                        + "org.apache.commons.net.ftp.FTPFileEntryParser.",
                        e);
            } catch (Exception | ExceptionInInitializerError e) {
                throw new ParserInitializationException("Error initializing parser", e);
            }
        }
        if (parser == null) {
            final String ukey = key.toUpperCase(java.util.Locale.ENGLISH);
            if (ukey.indexOf(FTPClientConfig.SYST_UNIX_TRIM_LEADING) >= 0) {
                parser = new UnixFTPEntryParser(config, true);
                // must check this after SYST_UNIX_TRIM_LEADING as it is a substring of it
            } else if (ukey.indexOf(FTPClientConfig.SYST_UNIX) >= 0 || ukey.indexOf("LINUX") >= 0) {
                parser = new UnixFTPEntryParser(config, false);
            } else if (ukey.indexOf(FTPClientConfig.SYST_VMS) >= 0) {
                parser = new VMSVersioningFTPEntryParser(config);
            } else if (ukey.indexOf(FTPClientConfig.SYST_NT) >= 0 || ukey.indexOf("WIN32") >= 0) {
                parser = createNTFTPEntryParser(config);
            } else if (ukey.indexOf(FTPClientConfig.SYST_OS2) >= 0) {
                parser = new OS2FTPEntryParser(config);
            } else if (ukey.indexOf(FTPClientConfig.SYST_OS400) >= 0 || ukey.indexOf(FTPClientConfig.SYST_AS400) >= 0) {
                parser = createOS400FTPEntryParser(config);
            } else if (ukey.indexOf(FTPClientConfig.SYST_MVS) >= 0) {
                parser = new MVSFTPEntryParser(); // Does not currently support config parameter
            } else if (ukey.indexOf(FTPClientConfig.SYST_NETWARE) >= 0) {
                parser = new NetwareFTPEntryParser(config);
            } else if (ukey.indexOf(FTPClientConfig.SYST_MACOS_PETER) >= 0) {
                parser = new MacOsPeterFTPEntryParser(config);
            } else if (ukey.indexOf(FTPClientConfig.SYST_L8) >= 0) {
                // 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) {
            configurable.configure(config);
        }

        return parser;
    }

    /**
     * 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()))
                });
    }

    /**
     * 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()))
                });
    }
}
