/*

 * Copyright (c) 2016, 2018, 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.consumer;

import java.io.Closeable;

import java.io.EOFException;

import java.io.File;

import java.io.IOException;

import java.nio.file.NoSuchFileException;

import java.nio.file.Path;

import java.util.ArrayList;

import java.util.HashSet;

import java.util.List;

import jdk.jfr.EventType;

import jdk.jfr.internal.MetadataDescriptor;

import jdk.jfr.internal.consumer.ChunkHeader;

import jdk.jfr.internal.consumer.RecordingInput;

/**

 * A recording file.

 * <p>

 * The following example shows how read and print all events in a recording file.

 *

 * <pre>

 * <code>

 * try (RecordingFile recordingFile = new RecordingFile(Paths.get("recording.jfr"))) {

 *   while (recordingFile.hasMoreEvents()) {

 *     RecordedEvent event = recordingFile.readEvent();

 *     System.out.println(event);

 *   }

 * }

 * </code>

 * </pre>

 *

 * @since 9

 */

public final class RecordingFile implements Closeable {

    private final File file;

    private RecordingInput input;

    private ChunkParser chunkParser;

    private RecordedEvent nextEvent;

    private boolean eof;

    /**

     * Creates a recording file.

     *

     * @param file the path of the file to open, not {@code null}

     * @throws IOException if it's not a valid recording file, or an I/O error

     *         occurred

     * @throws NoSuchFileException if the {@code file} can't be located

     *

     * @throws SecurityException if a security manager exists and its

     *         {@code checkRead} method denies read access to the file.

     */

    public RecordingFile(Path file) throws IOException {

        this.file = file.toFile();

        this.input = new RecordingInput(this.file);

        findNext();

    }

    /**

     * Reads the next event in the recording.

     *

     * @return the next event, not {@code null}

     *

     * @throws EOFException if no more events exist in the recording file

     * @throws IOException if an I/O error occurs.

     *

     * @see #hasMoreEvents()

     */

    public RecordedEvent readEvent() throws IOException {

        if (eof) {

            ensureOpen();

            throw new EOFException();

        }

        RecordedEvent event = nextEvent;

        nextEvent = chunkParser.readEvent();

        if (nextEvent == null) {

            findNext();

        }

        return event;

    }

    /**

     * Returns {@code true} if unread events exist in the recording file,

     * {@code false} otherwise.

     *

     * @return {@code true} if unread events exist in the recording, {@code false}

     *         otherwise.

     */

    public boolean hasMoreEvents() {

        return !eof;

    }

    /**

     * Returns a list of all event types in this recording.

     *

     * @return a list of event types, not {@code null}

     * @throws IOException if an I/O error occurred while reading from the file

     *

     * @see #hasMoreEvents()

     */

    public List<EventType> readEventTypes() throws IOException {

        ensureOpen();

        List<EventType> types = new ArrayList<>();

        HashSet<Long> foundIds = new HashSet<>();

        try (RecordingInput ri = new RecordingInput(file)) {

            ChunkHeader ch = new ChunkHeader(ri);

            aggregateTypeForChunk(ch, types, foundIds);

            while (!ch.isLastChunk()) {

                ch = ch.nextHeader();

                aggregateTypeForChunk(ch, types, foundIds);

            }

        }

        return types;

    }

    private static void aggregateTypeForChunk(ChunkHeader ch, List<EventType> types, HashSet<Long> foundIds) throws IOException {

        MetadataDescriptor m = ch.readMetadata();

        for (EventType t : m.getEventTypes()) {

            if (!foundIds.contains(t.getId())) {

                types.add(t);

                foundIds.add(t.getId());

            }

        }

    }

    /**

     * Closes this recording file and releases any system resources that are

     * associated with it.

     *

     * @throws IOException if an I/O error occurred

     */

    public void close() throws IOException {

        if (input != null) {

            eof = true;

            input.close();

            chunkParser = null;

            input = null;

            nextEvent = null;

        }

    }

    /**

     * Returns a list of all events in a file.

     * <p>

     * This method is intended for simple cases where it's convenient to read all

     * events in a single operation. It isn't intended for reading large files.

     *

     * @param path the path to the file, not {@code null}

     *

     * @return the events from the file as a {@code List} object; whether the

     *         {@code List} is modifiable or not is implementation dependent and

     *         therefore not specified, not {@code null}

     *

     * @throws IOException if an I/O error occurred, it's not a Flight Recorder

     *         file or a version of a JFR file that can't be parsed

     *

     * @throws SecurityException if a security manager exists and its

     *         {@code checkRead} method denies read access to the file.

     */

    public static List<RecordedEvent> readAllEvents(Path path) throws IOException {

        try (RecordingFile r = new RecordingFile(path)) {

            List<RecordedEvent> list = new ArrayList<>();

            while (r.hasMoreEvents()) {

                list.add(r.readEvent());

            }

            return list;

        }

    }

    // either sets next to an event or sets eof to true

    private void findNext() throws IOException {

        while (nextEvent == null) {

            if (chunkParser == null) {

                chunkParser = new ChunkParser(input);

            } else if (!chunkParser.isLastChunk()) {

                chunkParser = chunkParser.nextChunkParser();

            } else {

                eof = true;

                return;

            }

            nextEvent = chunkParser.readEvent();

        }

    }

    private void ensureOpen() throws IOException {

        if (input == null) {

            throw new IOException("Stream Closed");

        }

    }

}