/*
 * Copyright (c) 2015, 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.
 *
 * 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 org.graalvm.compiler.hotspot;

import static org.graalvm.compiler.hotspot.HotSpotGraalOptionValues.GRAAL_OPTION_PROPERTY_PREFIX;
import static org.graalvm.compiler.hotspot.HotSpotGraalOptionValues.defaultOptions;

import java.io.FileNotFoundException;
import java.io.FileOutputStream;
import java.io.IOException;
import java.io.OutputStream;
import java.io.PrintStream;
import java.util.List;

import org.graalvm.compiler.core.common.SuppressFBWarnings;
import org.graalvm.compiler.debug.TTYStreamProvider;
import org.graalvm.compiler.options.Option;
import org.graalvm.compiler.options.OptionKey;
import org.graalvm.compiler.options.OptionType;
import org.graalvm.compiler.options.OptionValues;
import org.graalvm.compiler.serviceprovider.GraalServices;
import org.graalvm.compiler.serviceprovider.ServiceProvider;

import jdk.vm.ci.hotspot.HotSpotJVMCIRuntime;
import jdk.vm.ci.services.Services;

@ServiceProvider(TTYStreamProvider.class)
public class HotSpotTTYStreamProvider implements TTYStreamProvider {

    public static class Options {

        // @formatter:off
        @Option(help = "File to which logging is sent.  A %p in the name will be replaced with a string identifying " +
                       "the process, usually the process id and %t will be replaced by System.currentTimeMillis().", type = OptionType.Expert)
        public static final LogStreamOptionKey LogFile = new LogStreamOptionKey();
        // @formatter:on
    }

    @Override
    public PrintStream getStream() {
        return Options.LogFile.getStream(defaultOptions());
    }

    /**
     * An option for a configurable file name that can also open a {@link PrintStream} on the file.
     * If no value is given for the option, the stream will output to HotSpot's
     * {@link HotSpotJVMCIRuntime#getLogStream() log} stream
     */
    private static class LogStreamOptionKey extends OptionKey<String> {

        LogStreamOptionKey() {
            super(null);
        }

        /**
         * @return {@code nameTemplate} with all instances of %p replaced by
         *         {@link GraalServices#getExecutionID()} and %t by
         *         {@link System#currentTimeMillis()}
         */
        private static String makeFilename(String nameTemplate) {
            String name = nameTemplate;
            if (name.contains("%p")) {
                name = name.replaceAll("%p", GraalServices.getExecutionID());
            }
            if (name.contains("%t")) {
                name = name.replaceAll("%t", String.valueOf(System.currentTimeMillis()));
            }
            return name;
        }

        /**
         * An output stream that redirects to {@link HotSpotJVMCIRuntime#getLogStream()}. The
         * {@link HotSpotJVMCIRuntime#getLogStream()} value is only accessed the first time an IO
         * operation is performed on the stream. This is required to break a deadlock in early JVMCI
         * initialization.
         */
        static class DelayedOutputStream extends OutputStream {
            private volatile OutputStream lazy;

            private OutputStream lazy() {
                if (lazy == null) {
                    synchronized (this) {
                        if (lazy == null) {
                            lazy = HotSpotJVMCIRuntime.runtime().getLogStream();
                            PrintStream ps = new PrintStream(lazy);
                            ps.printf("[Use -D%sLogFile=<path> to redirect Graal log output to a file.]%n", GRAAL_OPTION_PROPERTY_PREFIX);
                        }
                    }
                }
                return lazy;
            }

            @Override
            public void write(byte[] b, int off, int len) throws IOException {
                lazy().write(b, off, len);
            }

            @Override
            public void write(int b) throws IOException {
                lazy().write(b);
            }

            @Override
            public void flush() throws IOException {
                lazy().flush();
            }

            @Override
            public void close() throws IOException {
                lazy().close();
            }
        }

        /**
         * Gets the print stream configured by this option. If no file is configured, the print
         * stream will output to HotSpot's {@link HotSpotJVMCIRuntime#getLogStream() log} stream.
         */
        @SuppressFBWarnings(value = "DLS_DEAD_LOCAL_STORE", justification = "false positive on dead store to `ps`")
        public PrintStream getStream(OptionValues options) {
            String nameTemplate = getValue(options);
            if (nameTemplate != null) {
                String name = makeFilename(nameTemplate);
                try {
                    final boolean enableAutoflush = true;
                    PrintStream ps = new PrintStream(new FileOutputStream(name), enableAutoflush);
                    /*
                     * Add the JVM and Java arguments to the log file to help identity it.
                     */
                    List<String> inputArguments = GraalServices.getInputArguments();
                    if (inputArguments != null) {
                        ps.println("VM Arguments: " + String.join(" ", inputArguments));
                    }
                    String cmd = Services.getSavedProperties().get("sun.java.command");
                    if (cmd != null) {
                        ps.println("sun.java.command=" + cmd);
                    }
                    return ps;
                } catch (FileNotFoundException e) {
                    throw new RuntimeException("couldn't open file: " + name, e);
                }
            } else {
                return new PrintStream(new DelayedOutputStream());
            }
        }
    }

}