package jalview.bin;

import java.io.File;
import java.lang.management.ManagementFactory;
import java.util.ArrayList;

public class Launcher
{

  private final static String startClass = "jalview.bin.Jalview";

  private final static int maxHeapSizePerCent = 95;

  private final static String maxMemArg = "-maxMem";

  public static void main(String[] args)
  {
    final String javaBin = System.getProperty("java.home") + File.separator
            + "bin" + File.separator + "java";

    ArrayList<String> command = new ArrayList<>();
    command.add(javaBin);

    for (String jvmArg : ManagementFactory.getRuntimeMXBean()
            .getInputArguments())
    {
      command.add(jvmArg);
    }
    command.add("-cp");
    command.add(ManagementFactory.getRuntimeMXBean().getClassPath());
    ArrayList<String> arguments = new ArrayList<>();
    boolean maxMem = false;
    for (String arg : args)
    {
      if (arg.equals(maxMemArg) && !maxMem)
      {
        maxMem = true;
        // remove any existing max heap size argument
        ARG: for (int i = 0; i < command.size(); i++)
        {
          if (command.get(i).startsWith("-Xmx"))
          {
            command.remove(i);
            break ARG; // assuming at most one -Xmx
          }
        }
        long maxMemLong = -1;
        long physicalMem = getPhysicalMemory();
        if (physicalMem > 0)
        {
          maxMemLong = physicalMem * maxHeapSizePerCent / 100;
        }
        if (maxMemLong > 0)
        {
          command.add("-Xmx" + Long.toString(maxMemLong));
        }
      }
      else
      {
        arguments.add(arg);
      }
    }
    command.add(startClass);
    command.addAll(arguments);

    final ProcessBuilder builder = new ProcessBuilder(command);

    System.out.println("COMMAND: " + builder.command().toString());

    try
    {
      builder.inheritIO();
      builder.start();
    } catch (Exception e)
    {
      e.printStackTrace();
    }
    System.exit(0);

  }

  public static long getPhysicalMemory()
  {
    final Object o = ManagementFactory.getOperatingSystemMXBean();

    try
    {
      if (o instanceof com.sun.management.OperatingSystemMXBean)
      {
        final com.sun.management.OperatingSystemMXBean osb = (com.sun.management.OperatingSystemMXBean) o;
        return osb.getTotalPhysicalMemorySize();
      }
    } catch (NoClassDefFoundError e)
    {
      // com.sun.management.OperatingSystemMXBean doesn't exist in this JVM
      System.out.println("No com.sun.management.OperatingSystemMXBean");
    }

    // We didn't get a com.sun.management.OperatingSystemMXBean.
    return -1;
  }

}