/*

 * 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

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package jdk.jfr.consumer;

import java.io.IOException;

import java.nio.file.DirectoryStream;

import java.nio.file.Files;

import java.nio.file.Path;

import java.security.AccessControlContext;

import java.time.Duration;

import java.time.Instant;

import java.util.ArrayList;

import java.util.Arrays;

import java.util.Collections;

import java.util.Comparator;

import java.util.HashMap;

import java.util.HashSet;

import java.util.List;

import java.util.Map;

import java.util.Objects;

import java.util.Set;

import java.util.SortedMap;

import java.util.TreeMap;

import java.util.function.Consumer;

import jdk.jfr.internal.LogLevel;

import jdk.jfr.internal.LogTag;

import jdk.jfr.internal.Logger;

import jdk.jfr.internal.Repository;

import jdk.jfr.internal.consumer.ChunkHeader;

import jdk.jfr.internal.consumer.EventConsumer;

import jdk.jfr.internal.consumer.RecordingInput;

final class EventDirectoryStream implements EventStream {

    private static final class RepositoryFiles {

        private final Path repostory;

        private final SortedMap<Long, Path> pathSet = new TreeMap<>();

        private final Map<Path, Long> pathLookup = new HashMap<>();

        private volatile boolean closed;

        public RepositoryFiles(Path repostory) {

            this.repostory = repostory;

        }

        long getTimestamp(Path p) {

            return  pathLookup.get(p);

        }

        Path nextPath(long startTimeNanos) {

            while (!closed) {

                SortedMap<Long, Path> after = pathSet.tailMap(startTimeNanos);

                if (!after.isEmpty()) {

                    Path path = after.get(after.firstKey());

                    Logger.log(LogTag.JFR_SYSTEM_STREAMING, LogLevel.TRACE, "Return path " + path + " for start time nanos " + startTimeNanos);

                    return path;

                }

                try {

                    if (updatePaths(repostory)) {

                        continue;

                    }

                } catch (IOException e) {

                    Logger.log(LogTag.JFR_SYSTEM_STREAMING, LogLevel.DEBUG, "IOException during repository file scan " + e.getMessage());

                    // This can happen if a chunk is being removed

                    // between the file was discovered and an instance

                    // of an EventSet was constructed. Just ignore,

                    // and retry later.

                }

                try {

                    synchronized (pathSet) {

                        pathSet.wait(1000);

                    }

                } catch (InterruptedException e) {

                    // ignore

                }

            }

            return null;

        }

        private boolean updatePaths(Path repo) throws IOException {

            if (repo == null) {

                repo = Repository.getRepository().getRepositoryPath().toPath();

            }

            boolean foundNew = false;

            List<Path> added = new ArrayList<>();

            Set<Path> current = new HashSet<>();

            if (!Files.exists(repo)) {

                // Repository removed, probably due to shutdown

                return true;

            }

            try (DirectoryStream<Path> dirStream = Files.newDirectoryStream(repo, "*.jfr")) {

                for (Path p : dirStream) {

                    if (!pathLookup.containsKey(p)) {

                        added.add(p);

                        Logger.log(LogTag.JFR_SYSTEM_STREAMING, LogLevel.DEBUG, "New file found: " + p.toAbsolutePath());

                    }

                    current.add(p);

                }

            }

            List<Path> removed = new ArrayList<>();

            for (Path p : pathLookup.keySet()) {

                if (!current.contains(p)) {

                    removed.add(p);

                }

            }

            for (Path remove : removed) {

                Long time = pathLookup.get(remove);

                pathSet.remove(time);

                pathLookup.remove(remove);

            }

            Collections.sort(added, (p1, p2) -> p1.compareTo(p2));

            for (Path p : added) {

                // Only add files that have a complete header

                // as the JVM may be in progress writing the file

                long size = Files.size(p);

                if (size >= ChunkHeader.HEADER_SIZE) {

                    long startNanos = readStartTime(p);

                    pathSet.put(startNanos, p);

                    pathLookup.put(p, startNanos);

                    foundNew = true;

                }

            }

            return foundNew;

        }

        private long readStartTime(Path p) throws IOException {

            try (RecordingInput in = new RecordingInput(p.toFile(), 100)) {

                ChunkHeader c = new ChunkHeader(in);

                return c.getStartNanos();

            }

        }

        public void close() {

            synchronized (pathSet) {

                this.closed = true;

                pathSet.notify();

            }

        }

    }

    static final class ParserConsumer extends EventConsumer {

        private static final Comparator<? super RecordedEvent> END_TIME = (e1, e2) -> Long.compare(e1.endTime, e2.endTime);

        private static final int DEFAULT_ARRAY_SIZE = 10_000;

        private final RepositoryFiles repositoryFiles;

        private ChunkParser chunkParser;

        private boolean reuse = true;

        private RecordedEvent[] sortedList;

        private boolean ordered = true;

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

            super(acc);

            repositoryFiles = new RepositoryFiles(p);

        }

        @Override

        public void process() throws IOException {

            Path path = repositoryFiles.nextPath(startNanos);

            startNanos = repositoryFiles.getTimestamp(path) + 1;

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

                while (!isClosed()) {

                    boolean awaitnewEvent = false;

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

                        chunkParser.setReuse(this.reuse);

                        chunkParser.setOrdered(this.ordered);

                        chunkParser.resetEventCache();

                        chunkParser.updateEventParsers();

                        if (ordered) {

                            awaitnewEvent = processOrdered(awaitnewEvent);

                        } else {

                            awaitnewEvent = processUnordered(awaitnewEvent);

                        }

                        runFlushActions();

                    }

                    path = repositoryFiles.nextPath(startNanos);

                    startNanos = repositoryFiles.getTimestamp(path) + 1;

                    input.setFile(path);

                }

            }

        }

        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;

        }

        public void setReuse(boolean reuse) {

            this.reuse = reuse;

        }

        public void setOrdered(boolean ordered) {

            this.ordered = ordered;

        }

        @Override

        public void close() {

            repositoryFiles.close();

        }

    }

    static final class SharedParserConsumer extends EventConsumer {

        private EventSetLocation location;

        private EventSet eventSet;

        private int eventSetIndex;

        private int eventArrayIndex;

        private RecordedEvent[] currentEventArray = new RecordedEvent[0];

        public SharedParserConsumer(AccessControlContext acc) throws IOException {

            super(acc);

        }

        public void process() throws IOException {

            this.location = EventSetLocation.current();

            this.eventSet = location.acquire(startNanos, null); // use timestamp

                                                                // from

            if (eventSet == null) {

                return;

            }

            while (!isClosed()) {

                processSegment();

                runFlushActions();

                do {

                    if (isClosed()) {

                        return;

                    }

                    currentEventArray = eventSet.readEvents(eventSetIndex);

                    if (currentEventArray == EventSet.END_OF_SET) {

                        eventSet = eventSet.next(eventFilter);

                        if (eventSet == null || isClosed()) {

                            return;

                        }

                        eventSetIndex = 0;

                        continue;

                    }

                    if (currentEventArray == null) {

                        return; // no more events

                    }

                    eventSetIndex++;

                } while (currentEventArray.length == 0);

                eventArrayIndex = 0;

            }

        }

        private void processSegment() {

            while (eventArrayIndex < currentEventArray.length) {

                RecordedEvent e = currentEventArray[eventArrayIndex++];

                if (e == null) {

                    return;

                }

                dispatch(e);

            }

        }

        public void close() {

            setClosed(true);

            // TODO: Data races here, must fix

            synchronized (this) {

                if (eventSet != null) {

                    eventSet.release(null);

                }

                if (location != null) {

                    location.release();

                }

            }

            runCloseActions();

        }

        public void setReuse(boolean reuse) {

            // ignore hint

        }

    }

    private final EventConsumer eventConsumer;

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

        eventConsumer = new ParserConsumer(acc, p);

    }

    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);

    }

}