package jalview.bin;

public class MemorySetting
{
  public static final long leaveFreeMinMemory = 536870912; // 0.5 GB

  public static final long applicationMinMemory = 536870912; // 0.5 GB

  private final static int maxHeapSizePerCentDefault = 90;

  public final static String maxHeapSizePerCentProperty = "jvmmempc";

  private final static long maxHeapSizeDefault = 34359738368L; // 32GB

  private final static long noMemMaxHeapSizeDefault = 8589934592L; // 8GB

  public final static String maxHeapSizeProperty = "jvmmemmax";

  public static long getMemorySetting()
  {
    return getMemorySetting(null, null);
  }

  public static long getMemorySetting(String jvmmemmaxString,
          String jvmmempcString)
  {
    // actual Xmx value-to-be
    long maxMemLong = -1;

    // get (absolute) jvmmaxmem setting
    long memmax = maxHeapSizeDefault;
    String jvmmemmaxorig = jvmmemmaxString;
    if (jvmmemmaxorig == null)
    {
      jvmmemmaxorig = System.getProperty(maxHeapSizeProperty);
    }
    String jvmmemmax = jvmmemmaxorig;
    if (jvmmemmax != null && jvmmemmax.length() > 0)
    {
      long multiplier = 1;
      switch (jvmmemmax.toLowerCase().substring(jvmmemmax.length() - 1))
      {
      case "t":
        multiplier = 1099511627776L; // 2^40
        jvmmemmax = jvmmemmax.substring(0, jvmmemmax.length() - 1);
        break;
      case "g":
        multiplier = 1073741824; // 2^30
        jvmmemmax = jvmmemmax.substring(0, jvmmemmax.length() - 1);
        break;
      case "m":
        multiplier = 1048576; // 2^20
        jvmmemmax = jvmmemmax.substring(0, jvmmemmax.length() - 1);
        break;
      case "k":
        multiplier = 1024; // 2^10
        jvmmemmax = jvmmemmax.substring(0, jvmmemmax.length() - 1);
        break;
      case "b":
        multiplier = 1; // 2^0
        jvmmemmax = jvmmemmax.substring(0, jvmmemmax.length() - 1);
        break;
      default:
        break;
      }

      // parse the arg
      try
      {
        memmax = Long.parseLong(jvmmemmax);
      } catch (NumberFormatException e)
      {
        memmax = maxHeapSizeDefault;
        System.out.println("MemorySetting Property '" + maxHeapSizeProperty
                + "' ("
                + jvmmemmaxorig + "') badly formatted, using default ("
                + memmax + ").");
      }

      // apply multiplier if not too big (i.e. bigger than a long)
      if (Long.MAX_VALUE / memmax < multiplier)
      {
        memmax = maxHeapSizeDefault;
        System.out.println(
                "MemorySetting Property '" + maxHeapSizeProperty + "' ("
                        + jvmmemmaxorig
                        + ") too big, using default (" + memmax + ").");
      }
      else
      {
        memmax = multiplier * memmax;
      }

      // check at least minimum value (this accounts for negatives too)
      if (memmax < MemorySetting.applicationMinMemory)
      {
        memmax = MemorySetting.applicationMinMemory;
        System.out.println(
                "MemorySetting Property '" + maxHeapSizeProperty + "' ("
                        + jvmmemmaxorig
                        + ") too small, using minimum (" + memmax + ").");
      }

    }
    else
    {
      // no need to warn if no setting
      // System.out.println("MemorySetting Property '" + maxHeapSizeProperty + "' not
      // set.");
    }

    // get max percent of physical memory
    float percent = maxHeapSizePerCentDefault;
    String jvmmempc = jvmmempcString;
    if (jvmmempc == null)
    {
      jvmmempc = System.getProperty(maxHeapSizePerCentProperty);
    }
    long pcmem = -1;
    try
    {
      if (jvmmempc != null)
      {
        float trypercent = Float.parseFloat(jvmmempc);
        if (0 < trypercent && trypercent <= 100f)
        {
          percent = trypercent;
        }
        else
        {
          System.out.println(
                  "MemorySetting Property '" + maxHeapSizePerCentProperty
                  + "' should be in range 1..100");
        }
      }
    } catch (NumberFormatException e)
    {
      System.out.println(
              "MemorySetting property '" + maxHeapSizePerCentProperty
                      + "' (" + jvmmempc + ") badly formatted");
    }

    // catch everything in case of no com.sun.management.OperatingSystemMXBean
    boolean memoryPercentError = false;
    try
    {
      pcmem = MemoryPercent.memPercent(percent);
    } catch (Throwable t)
    {
      memoryPercentError = true;
      System.out.println("Problem calling MemoryPercent.memPercent("
              + percent
              + "). Likely to be problem with com.sun.management.OperatingSystemMXBean");
      t.printStackTrace();
    }
    // In the case of an error reading the percentage if physical memory, let's cap maxMemLong to 8GB
    if (memoryPercentError && jvmmempc != null && pcmem == -1
            && memmax > noMemMaxHeapSizeDefault)
    {
      System.out.println(
              "Capping maximum memory to 8GB due to failure to read physical memory size.");
      memmax = noMemMaxHeapSizeDefault;
    }

    if (pcmem == -1) // not set
    {
      maxMemLong = memmax;
    }
    else
    {
      maxMemLong = Math.min(pcmem, memmax);
    }

    return maxMemLong;
  }

}