/*

 * Copyright (c) 2016, 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.  Oracle designates this

 * particular file as subject to the "Classpath" exception as provided

 * by Oracle in the LICENSE file that accompanied this code.

 *

 * 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

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package jdk.jfr.internal.consumer;

import java.io.IOException;

import jdk.jfr.internal.LogLevel;

import jdk.jfr.internal.LogTag;

import jdk.jfr.internal.Logger;

import jdk.jfr.internal.MetadataDescriptor;

import jdk.jfr.internal.Utils;

public final class ChunkHeader {

    private static final long HEADER_SIZE = 68;

    private static final byte UPDATING_CHUNK_HEADER = (byte) 255;

    private static final long CHUNK_SIZE_POSITION = 8;

    private static final long DURATION_NANOS_POSITION = 40;

    private static final long FILE_STATE_POSITION = 64;

    private static final long METADATA_TYPE_ID = 0;

    private static final byte[] FILE_MAGIC = { 'F', 'L', 'R', '\0' };

    private final short major;

    private final short minor;

    private final long chunkStartTicks;

    private final long ticksPerSecond;

    private final long chunkStartNanos;

    private final long absoluteChunkStart;

    private final RecordingInput input;

    private final long id;

    private long absoluteEventStart;

    private long chunkSize = 0;

    private long constantPoolPosition = 0;

    private long metadataPosition = 0;

    private long durationNanos;

    private long absoluteChunkEnd;

    private boolean isFinished;

    private boolean finished;

    public ChunkHeader(RecordingInput input) throws IOException {

        this(input, 0, 0);

    }

    private ChunkHeader(RecordingInput input, long absoluteChunkStart, long id) throws IOException {

        this.absoluteChunkStart = absoluteChunkStart;

        this.absoluteEventStart = absoluteChunkStart + HEADER_SIZE;

        if (input.getFileSize() < HEADER_SIZE) {

            throw new IOException("Not a complete Chunk header");

        }

        input.setValidSize(absoluteChunkStart + HEADER_SIZE);

        input.position(absoluteChunkStart);

        if (input.position() >= input.size()) {

           throw new IOException("Chunk contains no data");

        }

        verifyMagic(input);

        this.input = input;

        this.id = id;

        Logger.log(LogTag.JFR_SYSTEM_PARSER, LogLevel.INFO, "Chunk: " + id);

        Logger.log(LogTag.JFR_SYSTEM_PARSER, LogLevel.INFO, "Chunk: file=" + input.getFilename());

        Logger.log(LogTag.JFR_SYSTEM_PARSER, LogLevel.INFO, "Chunk: startPosition=" + absoluteChunkStart);

        major = input.readRawShort();

        Logger.log(LogTag.JFR_SYSTEM_PARSER, LogLevel.INFO, "Chunk: major=" + major);

        minor = input.readRawShort();

        Logger.log(LogTag.JFR_SYSTEM_PARSER, LogLevel.INFO, "Chunk: minor=" + minor);

        if (major != 1 && major != 2) {

            throw new IOException("File version " + major + "." + minor + ". Only Flight Recorder files of version 1.x and 2.x can be read by this JDK.");

        }

        input.readRawLong(); // chunk size

        Logger.log(LogTag.JFR_SYSTEM_PARSER, LogLevel.INFO, "Chunk: chunkSize=" + chunkSize);

        input.readRawLong(); // constant pool position

        Logger.log(LogTag.JFR_SYSTEM_PARSER, LogLevel.INFO, "Chunk: constantPoolPosition=" + constantPoolPosition);

        input.readRawLong(); // metadata position

        Logger.log(LogTag.JFR_SYSTEM_PARSER, LogLevel.INFO, "Chunk: metadataPosition=" + metadataPosition);

        chunkStartNanos = input.readRawLong(); // nanos since epoch

        Logger.log(LogTag.JFR_SYSTEM_PARSER, LogLevel.INFO, "Chunk: startNanos=" + chunkStartNanos);

        durationNanos = input.readRawLong(); // duration nanos, not used

        Logger.log(LogTag.JFR_SYSTEM_PARSER, LogLevel.INFO, "Chunk: durationNanos=" + durationNanos);

        chunkStartTicks = input.readRawLong();

        Logger.log(LogTag.JFR_SYSTEM_PARSER, LogLevel.INFO, "Chunk: startTicks=" + chunkStartTicks);

        ticksPerSecond = input.readRawLong();

        Logger.log(LogTag.JFR_SYSTEM_PARSER, LogLevel.INFO, "Chunk: ticksPerSecond=" + ticksPerSecond);

        refresh();

        input.position(absoluteEventStart);

    }

    void refresh() throws IOException {

        while (true) {

            byte fileState1;

            input.positionPhysical(absoluteChunkStart + FILE_STATE_POSITION);

            while ((fileState1 = input.readPhysicalByte()) == UPDATING_CHUNK_HEADER) {

                Utils.takeNap(1);

                input.positionPhysical(absoluteChunkStart + FILE_STATE_POSITION);

            }

            input.positionPhysical(absoluteChunkStart + CHUNK_SIZE_POSITION);

            long chunkSize = input.readPhysicalLong();

            long constantPoolPosition = input.readPhysicalLong();

            long metadataPosition = input.readPhysicalLong();

            input.positionPhysical(absoluteChunkStart + DURATION_NANOS_POSITION);

            long durationNanos = input.readPhysicalLong();

            input.positionPhysical(absoluteChunkStart + FILE_STATE_POSITION);

            byte fileState2 =  input.readPhysicalByte();

            if (fileState1 == fileState2) { // valid header

                finished = fileState1 == 0;

                if (metadataPosition != 0) {

                    Logger.log(LogTag.JFR_SYSTEM_PARSER, LogLevel.INFO, "Setting input size to " + (absoluteChunkStart + chunkSize));

                    if (finished) {

                        // This assumes that the whole recording

                        // is finished if the first chunk is.

                        // This is a limitation we may want to

                        // remove, but greatly improves performance as

                        // data can be read across chunk boundaries

                        // of multi-chunk files and only once.

                        input.setValidSize(input.getFileSize());

                    } else {

                        input.setValidSize(absoluteChunkStart + chunkSize);

                    }

                    this.chunkSize = chunkSize;

                    Logger.log(LogTag.JFR_SYSTEM_PARSER, LogLevel.INFO, "Chunk: chunkSize=" + chunkSize);

                    this.constantPoolPosition = constantPoolPosition;

                    Logger.log(LogTag.JFR_SYSTEM_PARSER, LogLevel.INFO, "Chunk: constantPoolPosition=" + constantPoolPosition);

                    this.metadataPosition = metadataPosition;

                    Logger.log(LogTag.JFR_SYSTEM_PARSER, LogLevel.INFO, "Chunk: metadataPosition=" + metadataPosition);

                    this.durationNanos = durationNanos;

                    Logger.log(LogTag.JFR_SYSTEM_PARSER, LogLevel.INFO, "Chunk: durationNanos =" + durationNanos);

                    isFinished = fileState2 == 0;

                    Logger.log(LogTag.JFR_SYSTEM_PARSER, LogLevel.INFO, "Chunk: generation=" + fileState2);

                    Logger.log(LogTag.JFR_SYSTEM_PARSER, LogLevel.INFO, "Chunk: finished=" + isFinished);

                    Logger.log(LogTag.JFR_SYSTEM_PARSER, LogLevel.INFO, "Chunk: fileSize=" + input.size());

                    absoluteChunkEnd = absoluteChunkStart + chunkSize;

                    return;

                }

            }

        }

    }

    public void awaitFinished() throws IOException {

        if (finished) {

            return;

        }

        long pos = input.position();

        try {

            input.positionPhysical(absoluteChunkStart + FILE_STATE_POSITION);

            while (true) {

                byte filestate = input.readPhysicalByte();

                if (filestate == 0) {

                    finished = true;

                    return;

                }

                Utils.takeNap(1);

            }

        } finally {

            input.position(pos);

        }

    }

    public boolean isLastChunk() throws IOException {

        awaitFinished();

        // streaming files only have one chunk

        return input.getFileSize() == absoluteChunkEnd;

   }

    public boolean isFinished() throws IOException {

        return isFinished;

    }

    public ChunkHeader nextHeader() throws IOException {

        return new ChunkHeader(input, absoluteChunkEnd, id + 1);

    }

    public MetadataDescriptor readMetadata() throws IOException {

        return readMetadata(null);

    }

    public MetadataDescriptor readMetadata(MetadataDescriptor previous) throws IOException {

        input.position(absoluteChunkStart + metadataPosition);

        input.readInt(); // size

        long id = input.readLong(); // event type id

        if (id != METADATA_TYPE_ID) {

            throw new IOException("Expected metadata event. Type id=" + id + ", should have been " + METADATA_TYPE_ID);

        }

        input.readLong(); // start time

        input.readLong(); // duration

        long metadataId = input.readLong();

        if (previous != null && metadataId == previous.metadataId) {

            return previous;

        }

        Logger.log(LogTag.JFR_SYSTEM_PARSER, LogLevel.TRACE, "New metadata id = " + metadataId);

        MetadataDescriptor m =  MetadataDescriptor.read(input);

        m.metadataId = metadataId;

        return m;

    }

    public short getMajor() {

        return major;

    }

    public short getMinor() {

        return minor;

    }

    public long getAbsoluteChunkStart() {

        return absoluteChunkStart;

    }

    public long getAbsoluteEventStart() {

        return absoluteEventStart;

    }

    public long getConstantPoolPosition() {

        return constantPoolPosition;

    }

    public long getMetataPosition() {

        return metadataPosition;

    }

    public long getStartTicks() {

        return chunkStartTicks;

    }

    public long getChunkSize() {

        return chunkSize;

    }

    public double getTicksPerSecond() {

        return ticksPerSecond;

    }

    public long getStartNanos() {

        return chunkStartNanos;

    }

    public long getEnd() {

        return absoluteChunkEnd;

    }

    public long getSize() {

        return chunkSize;

    }

    public long getDurationNanos() {

        return durationNanos;

    }

    public RecordingInput getInput() {

        return input;

    }

    private static void verifyMagic(RecordingInput input) throws IOException {

        for (byte c : FILE_MAGIC) {

            if (input.readByte() != c) {

                throw new IOException("Not a Flight Recorder file");

            }

        }

    }

    public long getEventStart() {

        return absoluteEventStart;

    }

    static long headerSize() {

        return HEADER_SIZE;

    }

}