/*

 * 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.  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

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

 * questions.

 */

package jdk.jfr.consumer;

import java.io.IOException;

import java.nio.file.Path;

import java.security.AccessControlContext;

import java.time.Duration;

import java.time.Instant;

import java.util.Arrays;

import java.util.Comparator;

import java.util.Objects;

import java.util.function.Consumer;

import jdk.jfr.internal.consumer.RecordingInput;

import jdk.jfr.internal.consumer.RepositoryFiles;

/**

 * Implementation of an {@code EventStream}} that operates against a directory

 * with chunk files.

 *

 */

final class EventDirectoryStream implements EventStream {

    static final class DirectoryConsumer extends EventConsumer {

        private static final int DEFAULT_ARRAY_SIZE = 10_000;

        private final RepositoryFiles repositoryFiles;

        private ChunkParser chunkParser;

        private RecordedEvent[] sortedList;

        protected long chunkStartNanos;

        public DirectoryConsumer(AccessControlContext acc, Path p) throws IOException {

            super(acc);

            repositoryFiles = new RepositoryFiles(p);

        }

        @Override

        public void process() throws IOException {

            chunkStartNanos = startNanos;

            Path path;

            if (startTime == EventConsumer.NEXT_EVENT) {

                // TODO: Need to skip forward to the next event

                // For now, use the last chunk.

                path = repositoryFiles.lastPath();

            } else {

                path = repositoryFiles.nextPath(chunkStartNanos);

            }

            chunkStartNanos = repositoryFiles.getTimestamp(path) + 1;

            try (RecordingInput input = new RecordingInput(path.toFile())) {

                chunkParser = new ChunkParser(input, this.reuse);

                while (!isClosed()) {

                    boolean awaitnewEvent = false;

                    while (!isClosed() && !chunkParser.isChunkFinished()) {

                        chunkParser.setReuse(this.reuse);

                        chunkParser.setOrdered(this.ordered);

                        chunkParser.resetEventCache();

                        chunkParser.setParserFilter(this.eventFilter);

                        chunkParser.updateEventParsers();

                        if (ordered) {

                            awaitnewEvent = processOrdered(awaitnewEvent);

                        } else {

                            awaitnewEvent = processUnordered(awaitnewEvent);

                        }

                        runFlushActions();

                    }

                    path = repositoryFiles.nextPath(chunkStartNanos);

                    if (path == null) {

                        return; // stream closed

                    }

                    chunkStartNanos = repositoryFiles.getTimestamp(path) + 1;

                    input.setFile(path);

                    chunkParser = chunkParser.newChunkParser();

                }

            }

        }

        private boolean processOrdered(boolean awaitNewEvents) throws IOException {

            if (sortedList == null) {

                sortedList = new RecordedEvent[DEFAULT_ARRAY_SIZE];

            }

            int index = 0;

            while (true) {

                RecordedEvent e = chunkParser.readStreamingEvent(awaitNewEvents);

                if (e == null) {

                    // wait for new event with next call to

                    // readStreamingEvent()

                    awaitNewEvents = true;

                    break;

                }

                awaitNewEvents = false;

                if (index == sortedList.length) {

                    sortedList = Arrays.copyOf(sortedList, sortedList.length * 2);

                }

                sortedList[index++] = e;

            }

            // no events found

            if (index == 0 && chunkParser.isChunkFinished()) {

                return awaitNewEvents;

            }

            // at least 2 events, sort them

            if (index > 1) {

                Arrays.sort(sortedList, 0, index, END_TIME);

            }

            for (int i = 0; i < index; i++) {

                dispatch(sortedList[i]);

            }

            return awaitNewEvents;

        }

        private boolean processUnordered(boolean awaitNewEvents) throws IOException {

            while (true) {

                RecordedEvent e = chunkParser.readStreamingEvent(awaitNewEvents);

                if (e == null) {

                    awaitNewEvents = true;

                    break;

                } else {

                    dispatch(e);

                }

            }

            return awaitNewEvents;

        }

        @Override

        public void close() {

            repositoryFiles.close();

        }

    }

    private final EventConsumer eventConsumer;

    public EventDirectoryStream(AccessControlContext acc, Path p, Instant startTime) throws IOException {

        eventConsumer = new DirectoryConsumer(acc, p);

        eventConsumer.startTime = startTime;

    }

    public void close() {

        eventConsumer.close();

    }

    public void onFlush(Runnable action) {

        Objects.requireNonNull(action);

        eventConsumer.onFlush(action);

    }

    void start(long startNanos) {

        eventConsumer.start(startNanos);

    }

    @Override

    public void start() {

        start(Instant.now().toEpochMilli() * 1000 * 1000L);

    }

    @Override

    public void startAsync() {

        startAsync(Instant.now().toEpochMilli() * 1000 * 1000L);

    }

    void startAsync(long startNanos) {

        eventConsumer.startAsync(startNanos);

    }

    @Override

    public void onEvent(Consumer<RecordedEvent> action) {

        Objects.requireNonNull(action);

        eventConsumer.onEvent(action);

    }

    @Override

    public void onEvent(String eventName, Consumer<RecordedEvent> action) {

        Objects.requireNonNull(eventName);

        Objects.requireNonNull(action);

        eventConsumer.onEvent(eventName, action);

    }

    @Override

    public void onClose(Runnable action) {

        Objects.requireNonNull(action);

        eventConsumer.addCloseAction(action);

    }

    @Override

    public boolean remove(Object action) {

        Objects.requireNonNull(action);

        return eventConsumer.remove(action);

    }

    @Override

    public void awaitTermination(Duration timeout) {

        Objects.requireNonNull(timeout);

        eventConsumer.awaitTermination(timeout);

    }

    @Override

    public void awaitTermination() {

        eventConsumer.awaitTermination(Duration.ofMillis(0));

    }

    @Override

    public void setReuse(boolean reuse) {

        eventConsumer.setReuse(reuse);

    }

    @Override

    public void setOrdered(boolean ordered) {

        eventConsumer.setOrdered(ordered);

    }

    @Override

    public void setStartTime(Instant startTime) {

        eventConsumer.setStartTime(startTime);

    }

}