#!/usr/bin/perl

# Extracts users sessions from the sorted log files
# A user session defined as an hour or less.
# Author: Ian Hickman

use strict;

use Time::Local;

# read in first line and initialise some variables
my (@field, %table);
my ($time, $thistime, $lasttime, $lastuser);

my %months=( "Jan", "00", "Feb", "01", "Mar", "02", "Apr", "03", "May", "04", "Jun", "05", "Jul", "06", "Aug", "07", "Sep",
"08", "Oct", "09", "Nov", "10", "Dec", "11" );

$_=<STDIN>;
@field=split;

# remember last user
$lastuser=$field[0];

# reformat time
$_=$field[3];
my ($day, $monthtext, $year, $hour, $min, $sec)=/.(\d\d).(\w+).(\d{4}).(\d\d).(\d\d).(\d\d)/;
my $month=$months{$monthtext};
$lasttime=timelocal( $sec, $min, $hour, $day, $month, $year );

# loop through all lines
while( <STDIN> ){
  @field=split;

  # reformat time 
  $_=$field[3];
  my ($day, $monthtext, $year, $hour, $min, $sec)=/.(\d\d).(\w+).(\d{4}).(\d\d).(\d\d).(\d\d)/;
  my $month=$months{$monthtext};
  $thistime=timelocal( $sec, $min, $hour, $day, $month, $year );
  $time=$thistime-$lasttime;

  # if same user session
  if( $field[0] eq $lastuser ){

    # update lasttime
    if( $time>-1 ){
      $table{$time}++;
    }
    $lasttime=$thistime;

  } else {

    # else user has finished session
    $lastuser=$field[0];
    $lasttime=$thistime;
  }
}

my $times;

foreach $times ( keys ( %table )){
  print"$times\t$table{$times}\n";
}