#!/usr/bin/perl
# our needed packages
use strict "vars";
use Getopt::Std;

# Global Variables

# command line options
my $opt_string = "hd:c:i:t:o:";
getopts( "$opt_string", \my %opt ) or usage() and exit(1);
# system("clear");
if ( $opt{'h'} ) {
        usage();
        exit 0;
    }

my $DEVICE = $opt{'d'};
my $COMMAND = $opt{'c'};
my $INTERVAL = $opt{'i'};
my $TOTALTIME = $opt{'t'};
my $OUTFILE = $opt{'o'};

( usage() and die "Please supply a device name\n" ) unless $DEVICE;

if ($COMMAND and $TOTALTIME) {
    usage() and die "-c and -t options can not be used at the same time! \n";
}

if (not $TOTALTIME and not $COMMAND) {
    ( usage() and die "Please supply at least on of this parameters,  command to run or duration time!\n" );
}

( usage() and die "Please supply an interval time\n" ) unless $INTERVAL;
( usage() and die "Please supply a file name\n" ) unless $OUTFILE;

if ($TOTALTIME and $INTERVAL > $TOTALTIME) {
    (usage() and die "INTERVAL cannot be greater than TOTAL TIME!! \n");
}

#################### Main part ########################

chomp($DEVICE);
print "selected device to investigate is: " . $DEVICE . "\n";
my $FILE = "/proc/diskstats";

my $T=1;
my $start = time;
my $devicecount=0;

#### checking if the entered device is exist or not!
open (STATS, "cat $FILE |") or die "Error creating file  $!\n";
while (my $line = <STATS>) {
    if ($line =~ /($DEVICE)\s(\d+)\s(\d+)\s(\d+)\s(\d+)\s(\d+)\s(\d+)\s(\d+)\s(\d+)\s(\d+)\s(\d+)\s(\d+)/ ) {
	$devicecount++;
    }
}
if ($devicecount == 0 ){
    (die "Specified device,(" .$DEVICE. ") could not be found on this machine! \n"); 
}


### Doing the script by considering TOTALTIME mode
if ($TOTALTIME){
    while ($T=1) {
	if (time >= $start+$TOTALTIME){
	    $T = 0;
	    exit
	}
	open (STATS, "cat $FILE |") or die "Error creating file  $!\n";
	while (my $line = <STATS>) {
	    if ($line =~ /($DEVICE)\s(\d+)\s(\d+)\s(\d+)\s(\d+)\s(\d+)\s(\d+)\s(\d+)\s(\d+)\s(\d+)\s(\d+)\s(\d+)/ ) {
		print $line;
	    }
	}
	sleep($INTERVAL);
    }
}


### Doing the script by considering COMMAND mode
if ($COMMAND){
    my $USER = qx("whoami");
    chomp $USER;
   # system("$COMMAND&");
    sleep 1;
    my $goon = 1;
    while( $goon ){
	open(PSAUX,"ps aux |") or die  "Error creating PSAUX file  $!\n";
	my $found = 0; 
	while ( my $targetline = <PSAUX> ) {
	    if ($targetline =~ /^$USER\s+(\d+)\s.*\d:\d\d\s$COMMAND.*$/) {
		open (STATS, "cat $FILE |") or die "Error creating file  $!\n";
		while (my $line = <STATS>) {
		    if ($line =~ /($DEVICE)\s(\d+)\s(\d+)\s(\d+)\s(\d+)\s(\d+)\s(\d+)\s(\d+)\s(\d+)\s(\d+)\s(\d+)\s(\d+)/ ) {
			print "$1,$2,$3,$4,$5,$6,$7,$8,$9,$10,$11,$12\n";
			# print $line;
		    }
		}	
		sleep($INTERVAL);
		$found = 1;
	    } 
	}
	close (PSAUX);
	if ( not $found ){
	    $goon = 0;
	}
    }
}



# *********************************************************************

sub usage {
        print "-h help\n";
        print "-d <device> Device name for investigate (e.g.: vda1) \n";
        print "-c <'command'> a command to run and track (This cannot be used by the -t option at the same time!)  \n";
        print "-i <interval> interval time in seconds \n";
        print "-t <total time> total time of running the script in seconds (duration) \n";
        print "-o <output file> Output file name \n\n";
    }