/*

 * 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.internal.consumer;

import java.io.IOException;

import java.nio.file.DirectoryStream;

import java.nio.file.Files;

import java.nio.file.Path;

import java.util.ArrayList;

import java.util.Collections;

import java.util.HashMap;

import java.util.HashSet;

import java.util.List;

import java.util.Map;

import java.util.NavigableMap;

import java.util.Set;

import java.util.SortedMap;

import java.util.TreeMap;

import jdk.jfr.internal.LogLevel;

import jdk.jfr.internal.LogTag;

import jdk.jfr.internal.Logger;

import jdk.jfr.internal.Repository;

import jdk.jfr.internal.SecuritySupport.SafePath;

public final class RepositoryFiles {

    private final Path repository;

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

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

    private volatile boolean closed;

    public RepositoryFiles(SafePath repository) {

        this.repository = repository == null ? null : repository.toPath();

    }

    public long getTimestamp(Path p) {

        return pathLookup.get(p);

    }

    public Path lastPath() {

    }

    public Path nextPath(long startTimeNanos) {

        while (!closed) {

            }

                if (!after.isEmpty()) {

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

                    return path;

                }

            }

            try {

                if (updatePaths(repository)) {

                    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<>();

        try (DirectoryStream<Path> dirStream = Files.newDirectoryStream(repo)) {

            for (Path p : dirStream) {

                if (!pathLookup.containsKey(p)) {

                    String s = p.toString();

                    if (s.endsWith(".jfr")) {

                        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();

        }

    }

}