#!/usr/bin/perl -w
#web_search -- a program to simulate how site index the 'Net
#invocation: <web_search *.pl> to index all the *.pl files in the current directory

use strict;

my %words;

### Index the files

undef $/; #file slurp mode

for my $name (@ARGV)
{
    open F,"<$name" or die "couldn't open $name\n";

    map { push( @{$words{$_}}, $name) } split(/\s+/, <F>);

    #print "$_-> @{$words{$_}}\n" for keys %words; #pretty print
}

### Ask for search keywords

$/="\n"; #unslurp for user input

print "\nEnter you list of search words: ";

open I, "-";

while(<I>)
{
  chomp;
  my $search_words=$_;
  my @tmp = split;
  my $intersection=pop @tmp;
  my @intersection=@{$words{$intersection}} if defined($words{$intersection});

  for my $curr (@tmp)
  {
    @intersection=map {my $t=$_; $_ if grep { $t eq $_ } @{$words{$curr}}} @intersection;
  }

  @intersection=grep {$_} @intersection;

  print "\"".join(" AND ",split(/\s+/,$search_words))."\"";

  if (@intersection)
  {
      print " found in ";
      print join(", ",@intersection)."\n";
  }else
  {
      print " not found\n";
  }

}