/*
   Copyright The Narayana Authors
   SPDX short identifier: Apache-2.0
 */



package com.arjuna.ats.internal.arjuna.utils;

import java.io.ByteArrayOutputStream;
import java.io.File;
import java.io.FileOutputStream;
import java.io.IOException;
import java.io.InputStream;
import java.io.OutputStream;
import java.io.UnsupportedEncodingException;
import java.nio.charset.StandardCharsets;
import java.util.StringTokenizer;

import com.arjuna.ats.arjuna.exceptions.FatalError;
import com.arjuna.ats.arjuna.logging.tsLogger;

/**
 * Obtains a unique value to represent the process id via reflection.
 */

public class ExecProcessId implements com.arjuna.ats.arjuna.utils.Process
{

    /**
     * @return the process id. This had better be unique between processes on
     *         the same machine. If not we're in trouble!
     */

    public int getpid ()
    {
        synchronized (ExecProcessId._lock)
        {
            if (_pid == -1)
            {
                String cmd[] = null;
                File tempFile = null;

                if (System.getProperty("os.name").toLowerCase().indexOf(
                        "windows") == -1)
                    cmd = new String[]
                    { "/bin/sh", "-c", "echo $$ $PPID" };
                else
                {
                    try
                    {
                        // http://www.scheibli.com/projects/getpids/index.html (GPL)
                        tempFile = File.createTempFile("getpids", "ts");

                        byte[] bytes = new byte[1024];
                        int read;
                        InputStream in  = ExecProcessId.class.getResourceAsStream("getpids.exe");
                        OutputStream out = new FileOutputStream(tempFile);

                        try
                        {
                            while ((read = in.read(bytes)) != -1)
                                out.write(bytes, 0, read);
                        }
                        finally
                        {
                            in.close();
                            out.close();
                        }

                        cmd = new String[] { tempFile.getAbsolutePath() };
                    }
                    catch (final Exception ex)
                    {
                        throw new FatalError(
                                tsLogger.i18NLogger.get_utils_ExecProcessId_2() + " "+ex, ex);
                    }
                }

                if (cmd != null)
                {
                    Process p = null;

                    try
                    {
                        p = Runtime.getRuntime().exec(cmd);
                    }
                    catch (final IOException ex)
                    {
                        throw new FatalError(
                                tsLogger.i18NLogger.get_utils_ExecProcessId_3() + " "+ex, ex);
                    }

                    ByteArrayOutputStream bstream = new ByteArrayOutputStream();
                    byte[] bytes = new byte[1024];
                    int read;

                    try
                    {
                        while ((read = p.getInputStream().read(bytes)) != -1)
                            bstream.write(bytes, 0, read);
                    }
                    catch (final Exception ex)
                    {
                        throw new FatalError(
                                tsLogger.i18NLogger.get_utils_ExecProcessId_4() + " "+ex, ex);
                    }
                    finally
                    {
                        try
                        {
                            bstream.close();
                        }
                        catch (final Exception ex) {
                            tsLogger.i18NLogger.warn_utils_ExecProcessId_5(ex);
                        }
                    }

                    if (tempFile != null)
                        tempFile.delete();

                    StringTokenizer theTokenizer;
                    try {
                        theTokenizer = new StringTokenizer(bstream.toString(StandardCharsets.UTF_8.name()));
                    } catch (UnsupportedEncodingException e) {
                        tsLogger.i18NLogger.fatal_encoding_not_supported(StandardCharsets.UTF_8.name());
                        throw new IllegalStateException(
                            tsLogger.i18NLogger.get_encoding_not_supported(StandardCharsets.UTF_8.name()));
                    }
                    theTokenizer.nextToken();

                    String pid = theTokenizer.nextToken();

                    try
                    {
                        _pid = Integer.parseInt(pid);
                    }
                    catch (final Exception ex)
                    {

                    }
                }
            }
        }

        if (_pid == -1)
            throw new FatalError(
                    tsLogger.i18NLogger.get_utils_ExecProcessId_1());

        return _pid;
    }

    private static final Object _lock = new Object();

    private int _pid = -1;
}