/*

 * Copyright (c) 2019, Oracle and/or its affiliates. All rights reserved.

 * DO NOT ALTER OR REMOVE COPYRIGHT NOTICES OR THIS FILE HEADER.

 *

 * This code is free software; you can redistribute it and/or modify it

 * under the terms of the GNU General Public License version 2 only, as

 * published by the Free Software Foundation.

 *

 * This code is distributed in the hope that it will be useful, but WITHOUT

 * ANY WARRANTY; without even the implied warranty of MERCHANTABILITY or

 * FITNESS FOR A PARTICULAR PURPOSE.  See the GNU General Public License

 * version 2 for more details (a copy is included in the LICENSE file that

 * accompanied this code).

 *

 * You should have received a copy of the GNU General Public License version

 * 2 along with this work; if not, write to the Free Software Foundation,

 * Inc., 51 Franklin St, Fifth Floor, Boston, MA 02110-1301 USA.

 *

 * Please contact Oracle, 500 Oracle Parkway, Redwood Shores, CA 94065 USA

 * or visit www.oracle.com if you need additional information or have any

 * questions.

 */

import java.io.IOException;

import java.io.OutputStream;

import java.net.ServerSocket;

import java.nio.file.Paths;

import java.util.ArrayList;

import java.util.Arrays;

import java.util.HashMap;

import java.util.List;

import java.util.Map;

import java.util.Scanner;

import java.util.regex.MatchResult;

/*

 * An enhanced dummy LDAP server which can playback captured LDAP messages.

 *

 * Loads a sequence of LDAP messages from a capture file into its cache.

 * It listens for LDAP requests, finds a match in its cache and sends the

 * corresponding LDAP responses.

 *

 * The capture file contains an LDAP protocol exchange in the hexadecimal

 * dump format emitted by sun.misc.HexDumpEncoder:

 *

 * xxxx: 00 11 22 33 44 55 66 77   88 99 aa bb cc dd ee ff  ................

 *

 * Typically, LDAP protocol exchange is generated by running the LDAP client

 * application program against a real LDAP server and setting the JNDI/LDAP

 * environment property: com.sun.jndi.ldap.trace.ber to activate LDAP message

 * tracing.

 */

public class LdapPlaybackServer extends BaseLdapServer {

    /*

     * A cache of LDAP requests and responses.

     * Messages with the same ID are stored in a list.

     * The first element in the list is the LDAP request,

     * the remaining elements are the LDAP responses.

     */

    private final Map<Integer, List<byte[]>> cache = new HashMap<>();

    public LdapPlaybackServer(ServerSocket serverSocket, String fileName) {

        super(serverSocket);

        setDebugLevel(DebugLevel.CUSTOMIZE, this.getClass());

        setCommonRequestHandler(this::handleRequest);

    }

    /*

     * Load a capture file containing an LDAP protocol exchange in the

     * hexadecimal dump format emitted by sun.misc.HexDumpEncoder:

     *

     * xxxx: 00 11 22 33 44 55 66 77   88 99 aa bb cc dd ee ff  ................

     */

    private void loadCaptureFile(String filename) throws IOException {

        StringBuilder hexString = new StringBuilder();

        String pattern = "(....): (..) (..) (..) (..) (..) (..) (..) (..)   (..) (..) (..) (..) (..) (..) (..) (..).*";

        String preLineNum = "";

        try (Scanner fileScanner = new Scanner(Paths.get(filename))) {

            while (fileScanner.hasNextLine()) {

                try (Scanner lineScanner = new Scanner(

                        fileScanner.nextLine())) {

                    if (lineScanner.findInLine(pattern) == null) {

                        preLineNum = "";

                        continue;

                    }

                    MatchResult result = lineScanner.match();

                    for (int i = 1; i <= result.groupCount(); i++) {

                        String digits = result.group(i);

                        if (digits.length() == 4) {

                            if (digits.equals("0000") && !preLineNum

                                    .equalsIgnoreCase(

                                            "FFF0")) { // start-of-message

                                if (hexString.length() > 0) {

                                    addToCache(hexString.toString());

                                    hexString = new StringBuilder();

                                }

                            }

                            preLineNum = digits;

                            continue;

                        } else if (digits.equals("  ")) { // short message

                            continue;

                        }

                        hexString.append(digits);

                    }

                }

            }

        }

        if (!hexString.toString().isEmpty()) {

            addToCache(hexString.toString());

        }

    }

    /*

     * Add an LDAP encoding to the cache (by messageID key).

     */

    private void addToCache(String hexString) {

        LdapMessage message = new LdapMessage(hexString);

        byte[] encoding = message.getMessages();

        int messageID = message.getMessageID();

        List<byte[]> encodings = cache.get(messageID);

        if (encodings == null) {

            encodings = new ArrayList<>();

        }

        debug("    adding LDAP " + message.getOperation() + " with message ID "

                + messageID + " to the cache");

        encodings.add(encoding);

        cache.put(messageID, encodings);

    }

    @Override

    public void stopServer() {

        debug("force stopping server");

        super.stopServer();

    }

    private void handleRequest(LdapMessage request, OutputStream out)

            throws IOException {

        int messageID = request.getMessageID();

        debug("received LDAP " + request.getOperation() + "  [message ID "

                + messageID + "]");

        List<byte[]> encodings = cache.get(messageID);

        if (encodings == null || (!Arrays

                .equals(request.getMessages(), encodings.get(0)))) {

            throw new RuntimeException(

                    "LDAPServer: ERROR: received an LDAP " + request

                            .getOperation() + " (ID=" + messageID

                            + ") not present in cache");

        }

        for (int i = 1; i < encodings.size(); i++) {

            // skip the request (at index 0)

            byte[] response = encodings.get(i);

            out.write(response, 0, response.length);

            LdapMessage responseMsg = new LdapMessage(response);

            debug("Sent LDAP " + responseMsg.getOperation() + "  [message ID "

                    + responseMsg.getMessageID() + "]");

        }

    }

    @Override

    public void run() {

        try {

            debug("listening on port " + getPort());

            super.run();

        } catch (Exception e) {

            debug("ERROR: " + e);

            e.printStackTrace();

        }

    }

}