#!/usr/bin/perl
#
# DeathClock 0.1 written 021307:1105 by BJP
#
# DeathClock attempts to predict how much time remains until a given filesystem runs out of storage.
#
# Usage: deathclock.pl <filesystem> <number_of_samples> <sleep_interval> <cycles> <panic_threshold> <email_address>
#
# 
#
$version=0.1;

use Mail::Sendmail;

startupRoutine();
mainRoutine();

sub mainRoutine()
{
  while(true)
  {
    collectStatusInfo();
    determineTimeRemaining();
    $counter++;

    if ($samples==$counter-1)
    {
      print"\n";
    }
         
    if ($samples<=$counter-1)
    {
      print "DeathClock: $spaceRemaining MB remaining in $filesystem. Estimated time of death: $timeRemaining.\n";
    }
         
    else
    {   
      print ".";
    }
         
    if ($counter-$samples>=$duration && $duration!=0)
    {
      print"\n";
      exit();   
    }
         
    sleep($sleep);
  }
}


sub collectStatusInfo()
{
   @dfStuff=`df -m | grep " $filesystem\$"`;
   @filesystemState=split /\s+/,@dfStuff[0];
   $filesystemSize=$filesystemState[1];
   $spaceRemaining=$filesystemState[2];
   unshift(@history,$spaceRemaining);
   if ($counter>$samples)
   {
     pop(@history);
   }
}
sub determineTimeRemaining()
{
 $timeRemaining=$spaceRemaining/((($history[$samples]-$history[0])/($samples*$sleep))+0.0001);

 ## 1) ^^^^ A really, REALLY long way of saying y=mx+b and solving for x :)
 ## 2) The +0.0001 there is to prevent div-by-zero errors when the delta stays flat for the entire sample set.


  if($timeRemaining<5270400 && $timeRemaining>0) # 2 months
  {
    panicCheck();

    $wks=int($timeRemaining/604800);
    $timeRemaining=int($timeRemaining%604800);
    $day=int($timeRemaining/86400);
    $timeRemaining=int($timeRemaining%86400);
    $hrs=int($timeRemaining/3600);
    $timeRemaining=int($timeRemaining%3600);
    $min=int($timeRemaining/60);
    $sec=int($timeRemaining%60);
 
    $timeRemaining="".$wks."w ".$day."d ".$hrs."h ".$min."m ".$sec."s";
  }

  else
  {
    $timeRemaining="Immortal (>2 months)";
  }
}


sub panicCheck()
{

  if ($timeRemaining<3600 && $timeRemaining>=0)
  {
    $panicStateDuration++;
  }
 
  else
  {
    $panicStateDuration=0;
  }
 
  if ($panicStateDuration>=$panicThreshold && $panicThreshold!=0)
  {
    print "DeathClock: Panic threshold exceeded!\n";
    notifyRecipients();
  }
}


sub notifyRecipients()
{
 
 if ($counter>=$lastPanic+$silencerWaitTime || $firstPass==1) # If we've waited long enough between sending emails..
 {
   print "DeathClock: Sending panic notification to $mailRecipients.\n";
 
   %mail=( To => $mailRecipients,
   From => $mailSender,
   Subject => "DeathClock Panic Notification",
   Message => "DeathClock strongly believes less than 1 hour remains until $filesystem on $whereAmI runs out of space." );
 
   sendmail(%mail) or die("Send failed: $Mail::Sendmail::error\n");
   $lastPanic=$counter;
   $firstPass=0;
 }
 
  else
  {
   print "DeathClock: Supressing email notification. Recipient(s) were notified less than 10 minutes ago.\n";
  } 
}
 

sub startupRoutine()
{
 
  if ($#ARGV!=5)
  {
    if ($#ARGV<5)
    {
      print"\n\nToo few arguments specified. See below.";
    }
 
 else
 {
   print"\n\nToo many arguments specified. See below.";
 }
 
 print "\n\nDeathClock v$version written 021307:1105 by BJP";
 print "\n\n    Usage:  $0 <filesystem> <number_of_samples> <sleep_interval> <cycles> <panic_threshold> <email_address>";
 print "\n  Example:  $0 /tmp 10 2 34 18 foo@bar.com";
 print "\n  English:  Monitor /tmp, based on 10 readings, checking every 2 seconds, and do so 34 times. If DeathClock sees less than an hour";
 print "\n            remains for 18 cycles in a row, it will notify foo@bar.com\n";
 print "\nSpecifying 0 for the cycles parameter will run DeathClock indefinitely. Specifying 0 for panic_threshold will disable panic reporting.";
 print "\nMultiple email recipients can be specified using a comma delimiter, and no spaces between the addresses.";
 print "\n\n\n";
 
 exit();
 }
 
 else
 {
        # Usage: deathclock.pl <filesystem> <number_of_samples> <sleep_interval> <cycles> <panic_threshold> <email_address>
 
 print "\n\nDeathClock: Starting up..\n";
        $whereAmI=`hostname`;
 $mailSender=$ENV{"USER"}."\@"."$whereAmI.yourcompanyname.com";
 $filesystem=$ARGV[0];
 $samples=$ARGV[1];
 $sleep=$ARGV[2];
 $duration=$ARGV[3];
 $panicThreshold=$ARGV[4];
 $mailRecipients=$ARGV[5];
 @history=();
 $queueLength=scalar(@history)+0;
 $silencerWaitTime=600/$sleep; # hardcoding this at 10 minutes..
 $firstPass=1;
 chomp($whereAmI);
 $wait=($sleep*$samples)+0;
 print "DeathClock: Collecting $wait seconds of growth information for $filesystem. Please wait.";
 
  }
 
}