#!/usr/bin/perl -w

use strict;

# Type: CGI
# Usually I use CGI.pm, but sometimes when I just want to    validate data from users I use these two functions :
#      get_param()
#      validate_form()
#
# Tested on textfields and password_fields

print "Content-type: text/html; charset=iso-8859-1\n\n";

my %data = get_param();
validate_form(\%data);

# I added this line of code to display results
print $_." ----- ".$data{$_}."<br/>" foreach keys %data;



###############################
#  function: validate_form()  #
###############################
#  ERROR when:
#
#     - some field's are empty. User didn't fill them        #       (for example password or login)
#     - password and re-password are not the same

sub validate_form {
  my $data = shift;
  foreach (keys %$data) {
	print "EMPTY FIELD !<br/>" if (!$data->{$_});
  }
  # simply check values that are important for us
  print "WRONG PASSWORD !<br/>"if ($data->{'password'} !~   /^$data->{'re-password'}$/);
}



###########################
#  function: get_param()  #
###########################
# function get all parameters (name - value) from form
# It returns hash  ('name' => 'value')
#
# When user enter ' ' [space] function changes it to '_'. 
# For example:
# Nick: This is my nick
#       (function change it to This_is_my_nick)
# It also change %40 to @
#
# ERROR when:
#
#      - user enter different thing than [a-zA-Z0-9-_]

sub get_param {
  my $params = <>;
  my $err = "WARNING: You can use only numbers and letters  a-z A-Z<br/>";

  $params =~ s/\+/_/g;
  $params =~ s/%40/@/g; # you can use chr() to change hex                                 
  print $err if $params =~ /%/g;
  return split /&|=/, $params;
}