#!/usr/bin/perl -W
use strict;

#
#  This script implements last-mile communication with the storage RM.
#  It is called when Moab is initiating a data staging operation.  The
#  commands currently specified are:
#
# command: stage <SrcURL> <DstURL>
#          remove <URL>
# returns: <StageTime>[,<DstFileSize>]
#    exit: 0=success,1=syntax error,2=unrecognized command,3=system error
#   notes: The stage time should be reported in seconds until completion.
#          The destination file size is reported in bytes.  Returning zero
#          for the stage time means the staging operation is complete, and
#          a negative one indicates an indefinite stage time.  If an error
#          occurs, nothing is returned and the exit value is set.  The 
#          actual data stage operation should be executed in the background 
#          if the operation is expected to take more than one second.
#

my $transferrate = 0.0;                             # set transfer rate to value > 0 to allow stage time estimates
my $filesize     = 0.0;
my $stagetime    = 0.0;

my $stagecmd     = "/bin/cp";
my $removecmd    = "/bin/rm";

exit 1 if scalar(@ARGV) < 1;                        # verify existence of command parameter
my $command = $ARGV[0];                             # get command from arguments

if ('stage' eq $command)
  {
  exit 1 if scalar(@ARGV) < 3;                      # verify existence of src and dst parameters

  # NOTE: These will have to be parsed later (NYI)
  my $SrcFile = $ARGV[1];                           # extract SrcFile name from URL
  my $DstFile = $ARGV[2];                           # extract DstFile name from URL

  if (($filesize > 0.0) && ($transferrate > 0.0))
    {
    $stagetime = $filesize / $transferrate;
    }
  else
    {
    $stagetime = -1.0;
    }

  if (($stagetime < 0.0) || ($stagetime > 1.0))
    {
    system("$stagecmd $SrcFile $DstFile &");        # unknown or long stage time, so stage file in the background
    }
  else
    {
    system("$stagecmd $SrcFile $DstFile");          # short stage time, so block until staging is complete

    $stagetime = 0;
    }

  print "$stagetime";                               # output remaining stage time

  exit 0;                                           # assume success and exit with error code set to success
  }
elsif ('remove' eq $command)
  {
  exit 1 if scalar(@ARGV) < 2;                      # verify existence of file parameters

  # NOTE: This will have to be parsed later (NYI)
  my $File = $ARGV[1];                              # extract File name from URL

  system("$removecmd $File");                       # always block until file remove is complete

  exit 0;                                           # assume success and exit with error code set to success
  }
else
  {
  exit 2;                                           # exit with error code set to unrecognized command
  }