#!/usr/bin/perl

# Do users look at a paper then look at the ones it references 
# all in one session?
# usage: followupcitations3 < ../db/all
# V3 not just in this session, but over all user usage
# Author: Ian Hickman

use strict;

my (@field, @sourcepapers, %citedto, %citedfrom, $source, %citesinsession);
my ($line, $dloads, $refs, $dloadsminussession, $dloadsession, $lastuser)=(0, 0, 0, 0, 0, 0);

# open the list of citations (whatciteswhat)
print STDERR "opening citation db\n";
open( FILE, "whatciteswhat" ) || die"Cant open: $!";
while( <FILE> ){
  @field=split;
  $citedto{$field[0]}.=$field[1]." ";
  $citedfrom{$field[1]}.=$field[0]." ";
}
close( FILE ) || die"Cant open: $!";

print STDERR "doing rest\n";
while( <STDIN> ){

  @field=split;
  if( $lastuser ne $field[0] ){
    # between sessions
    %citesinsession="";
    $dloadsession=0;
    $lastuser="0";
  }
  $lastuser=$field[0];
  # in a session
  $line++;
  if( $field[6]=~/html/ || $field[6]=~/ps/ || $field[6]=~/pdf/ || $field[6]=~/e-print/ || $field[6]=~/ftp/ || $field[6]=~/dvi/ ){

    if( $dloadsession eq "0" ){
      $dloadsminussession--;
      $dloadsession=1;
    }

    # if it is a paper they are downloading
    # get the unique paper id
    my ($paperfield, $papernum);
    ($papernum)=/(\d{7})/;
    if( $field[6]=~/papers/ ){
      ($paperfield)=/\/ftp\/([\w-]+)\.?.*\/papers/;
    } else {
      ($paperfield)=/\/.*\/([\w-]+)\.?.*\/\??\d{7}/;
    }
    # $paper is the unique id of the paper
    my ($paper)=$paperfield."/".$papernum;

    if( $paperfield=~/hep/ ){      
      $dloads++;
      $dloadsminussession++;
    }
      
    # check table to see if this paper has been cited
    if( exists ( $citesinsession{$paper} )){
      print"$line user: $field[0] sources: $citesinsession{$paper} target: $paper\n";
      $refs++;
    }
      
    # add all target citations to table
    $_=$citedto{$paper};
    @sourcepapers=split;
    for( my $i=1; $i<@sourcepapers; $i++ ){
      $citesinsession{$sourcepapers[$i]}.=$paper." ";
    } # end for
  } # end if
} # end while

print"Total Downloads: $dloads\n";
print"Downloads minus Sessions: $dloadsminussession\n";
print"Total References: $refs\n";