/*
 * Copyright (c) 2016, 2026, Oracle and/or its affiliates.
 *
 * This program is free software; you can redistribute it and/or modify it under the terms of the GNU General Public License, version 2.0, as published by
 * the Free Software Foundation.
 *
 * This program is designed to work with certain software that is licensed under separate terms, as designated in a particular file or component or in
 * included license documentation. The authors of MySQL hereby grant you an additional permission to link the program and your derivative works with the
 * separately licensed software that they have either included with the program or referenced in the documentation.
 *
 * Without limiting anything contained in the foregoing, this file, which is part of MySQL Connector/J, is also subject to the Universal FOSS Exception,
 * version 1.0, a copy of which can be found at http://oss.oracle.com/licenses/universal-foss-exception.
 *
 * This program 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 2.0, for more details.
 *
 * You should have received a copy of the GNU General Public License along with this program; if not, write to the Free Software Foundation, Inc.,
 * 51 Franklin St, Fifth Floor, Boston, MA 02110-1301 USA
 */

package com.mysql.cj.protocol.a;

import java.io.IOException;
import java.util.Optional;

import com.mysql.cj.Messages;
import com.mysql.cj.log.Log;
import com.mysql.cj.protocol.MessageReader;
import com.mysql.cj.util.StringUtils;

/**
 * A decorating {@link MessageReader} which traces all received packets to the provided logger.
 */
public class TracingPacketReader implements MessageReader<NativePacketHeader, NativePacketPayload> {

    /** Max number of bytes to dump when tracing the protocol */
    private final static int MAX_PACKET_DUMP_LENGTH = 1024;

    private MessageReader<NativePacketHeader, NativePacketPayload> packetReader;
    private Log log;

    public TracingPacketReader(MessageReader<NativePacketHeader, NativePacketPayload> packetReader, Log log) {
        this.packetReader = packetReader;
        this.log = log;
    }

    @Override
    public NativePacketHeader readHeader() throws IOException {
        return traceHeader(this.packetReader.readHeader());
    }

    @Override
    public NativePacketHeader probeHeader() throws IOException {
        return traceHeader(this.packetReader.probeHeader());
    }

    private NativePacketHeader traceHeader(NativePacketHeader hdr) throws IOException {
        StringBuilder traceMessageBuf = new StringBuilder();

        traceMessageBuf.append(Messages.getString("PacketReader.3"));
        traceMessageBuf.append(hdr.getMessageSize());
        traceMessageBuf.append(Messages.getString("PacketReader.4"));
        traceMessageBuf.append(StringUtils.dumpAsHex(hdr.getBuffer().array(), NativeConstants.HEADER_LENGTH));

        this.log.logTrace(traceMessageBuf.toString());

        return hdr;
    }

    @Override
    public NativePacketPayload readMessage(Optional<NativePacketPayload> reuse, NativePacketHeader header) throws IOException {
        return traceMessage(this.packetReader.readMessage(reuse, header), header.getMessageSize(), reuse.isPresent());
    }

    @Override
    public NativePacketPayload probeMessage(Optional<NativePacketPayload> reuse, NativePacketHeader header) throws IOException {
        return traceMessage(this.packetReader.probeMessage(reuse, header), header.getMessageSize(), reuse.isPresent());
    }

    private NativePacketPayload traceMessage(NativePacketPayload buf, int packetLength, boolean reuse) throws IOException {
        StringBuilder traceMessageBuf = new StringBuilder();

        traceMessageBuf.append(Messages.getString(reuse ? "PacketReader.5" : "PacketReader.6"));
        traceMessageBuf.append(StringUtils.dumpAsHex(buf.getByteBuffer(), packetLength < MAX_PACKET_DUMP_LENGTH ? packetLength : MAX_PACKET_DUMP_LENGTH));

        if (packetLength > MAX_PACKET_DUMP_LENGTH) {
            traceMessageBuf.append(Messages.getString("PacketReader.7"));
            traceMessageBuf.append(MAX_PACKET_DUMP_LENGTH);
            traceMessageBuf.append(Messages.getString("PacketReader.8"));
        }

        this.log.logTrace(traceMessageBuf.toString());

        return buf;
    }

    @Override
    public byte getMessageSequence() {
        return this.packetReader.getMessageSequence();
    }

    @Override
    public void resetMessageSequence() {
        this.packetReader.resetMessageSequence();
    }

    @Override
    public MessageReader<NativePacketHeader, NativePacketPayload> undecorateAll() {
        return this.packetReader.undecorateAll();
    }

    @Override
    public MessageReader<NativePacketHeader, NativePacketPayload> undecorate() {
        return this.packetReader;
    }

}
