/*

 * Copyright (c) 2014, 2015, 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 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.options.OptionKey;

import org.graalvm.compiler.options.OptionValues;

import org.graalvm.compiler.serviceprovider.GraalServices;

import jdk.vm.ci.hotspot.HotSpotJVMCIRuntime;

/**

 * 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

 */

public class PrintStreamOptionKey extends OptionKey<String> {

    public PrintStreamOptionKey() {

        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();

                    }

                }

            }

            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 = System.getProperty("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());

        }

    }

}