#!/usr/bin/env perl

=head1 Perl web application framework - sessions and hidden fields

=head2 Introduction to general code

This is a demonstration program showing which provides the shell
framework for a web based CGI application written in Perl.

This example if the second of three - known as "sweeter". The other
two examples, also downloadable from http://www.wellho.net, are
known as sweet and sweetest. You can learn / study sweet and
sweeter to help you understand the principles involved. We suggest
you work with sweetest if you're going to write an application
yourself that's based on the principles illustrated here.

=item 1. read any incoming form

=item 2. Use the value read to pick up the session

=item 3. Do any work to analyse inputs and validate them

=item 4. Do work to prepare for next page

=item 5. Save the session

=item 6. Send out the response page

=cut

$fill{"now"} = localtime();
$fill{"title"} = "Application Template";

$sessdir = "../../../sessions";

print "Content-type: text/html\n\n";

# item 1. read any incoming form
#-------------------------------

collect_form();

# item 2. Use the value read to pick up the session
#--------------------------------------------------

if ($form{plsess}) {
        $sessname = $form{plsess};
        open (FHS,"$sessdir/$sessname.ses");
        while (<FHS>) {
                chop;
                ($name,$val) = split;
                $val =~ tr/+/ /;
                $val =~ s/%(..)/pack("C",hex($1))/eg;
                $session{$name} = $val;
        }
} else {
        $sessname = $$.time();
        # Take the opportunity of a new session to clean up stale ones
        opendir (DH,$sessdir);
        while ($fname = readdir DH) {
                next if ($fname =~ /^\./);
                if (-M "$sessdir/$fname" > 0.5) {
                        unlink "$sessdir/$fname";
                }
        }
}
$fill{plsess} = $sessname;
$stepnumber = $session{step};

# Inputs in %session and %form translate to %session and %fill

# item 3. Do any work to analyse inputs and validate them
#--------------------------------------------------------

$aok = 1;
$errstr = "";
if ($stepnumber == 0) { # Initialisation
        # Move on to next step - prepare for page 1
        $stepnumber = 1;
} elsif ($stepnumber == 1) {
        if ($form{yourname} !~ /\w/) {
                $aok = 0;
                $errstr .= "name must include a word character<br>";
        } else {
                $session{name} = $form{yourname};
        }
        if ($form{youremail} !~ /@/) {
                $aok = 0;
                $errstr .= "email must include an @ character<br>";
        } else {
                $session{email} = $form{youremail};
        }
        $stepnumber++ if ($aok);
} elsif ($stepnumber == 2) {
        if ($form{yourtown} !~ /\w/) {
                $aok = 0;
                $errstr .= "Town must include a letter<br>";
        } else {
                $session{town} = $form{yourtown};
        }
        if ($form{yourpostcode} !~ /^[A-Z]{1,2}[1-9]/) {
                $aok = 0;
                $errstr .= "Postcode invalid<br>";
        } else {
                $session{postcode} = $form{yourpostcode};
        }
        $stepnumber++ if ($aok);
} else {
}

# item 4. Do work to prepare for next page
#-----------------------------------------

$fill{status} = "You are at page $stepnumber of 3";
$fill{stuff} = "Results will appear here";
$fill{errstr} = $errstr;

if ($stepnumber == 1) {
        $fill{"form"} = "name: <input name=yourname value=\"".webify($form{yourname})."\"><br>";
        $fill{"form"} .= "email: <input name=youremail value=\"".webify($form{youremail})."\"><br>";
} elsif ($stepnumber == 2) {
        $fill{"form"} = "town: <input name=yourtown value=\"".webify($form{yourtown})."\"><br>";
        $fill{"form"} .= "postcode: <input name=yourpostcode value=\"".webify($form{yourpostcode})."\"><br>";
} elsif ($stepnumber == 3) {
        $fill{stuff} = "<b>Hello ".webify($session{name})." from ".webify($session{town})."<br>";
        $fill{stuff} .= "email ".webify($session{email})." pc ".webify($session{postcode})."</b><br>";
        $stepnumber = 0;
} else {
}

# item 5. Save the session
#-------------------------

$session{step} = $stepnumber;
open (FHS,">$sessdir/$sessname.ses");
foreach $name (keys %session) {
        $val = $session{$name};
        $val =~ s/%/%25/g;
        $val =~ s/\+/%2b/g;
        $val =~ s/\n/%0a/g;
        print FHS "$name $val\n";
        }
close FHS;

# item 6. Send out the response page
#-----------------------------------
# Complete the output template and send it to the user

$fill{step} = $stepnumber;

while (<DATA>) {
        s/%(\w+)%/$fill{$1}/g;
        print;
        }

################## Standard functions

=head2 Standard functions

Note that the following standard functions would be placed into a
separate file (a module) for a live application. For the purpose of
this demo, we've put everyting into the one file

=cut

sub webify {
        $_ = $_[0];
        s/&/&amp;/g;
        s/</&lt;/g;
        s/>/&gt;/g;
        s/"/&quot;/g;
        return $_;
        }

sub collect_form {

if ($ENV{"REQUEST_METHOD"} eq "POST") {
        read(STDIN,$buffer,$ENV{"CONTENT_LENGTH"});
        $form{"method"} = "POST";
} else {
        $buffer = $ENV{QUERY_STRING};
        $form{"method"} = "GET";
}

@fof = split(/&/,$buffer);
foreach $field(@fof) {
        ($name,$value) = split(/=/,$field);
        $value =~ tr/+/ /;
        $value =~ s/%([a-fA-F0-9]{2})/pack("C",hex($1))/eg;
        if ($form{$name}) {
                $form{$name} .= "\n$value";
        } else {
                $form{$name} = $value;
                }
        }
}
##################################################################

# After the __END__ we'll place the template for all response pages

__END__
<html><head>
<title>%title% - Well House Consultants demo</title>
</head>
<body bgcolor=#CCFFFF>
<h1>Demonstration - %title%</h1>
This is the introductory piece of text about this application.<hr>
This is the current status:<br><br>%status%<hr>
<font color=red>%errstr%</font>
<form method=POST>This is the next form
<input name=plsess type=hidden value=%plsess%><br>
%form%
<input type=submit></form><hr>
Here are your results:<br><br>%stuff%<hr>
Copyright statement, etc .. %now% ...<br>
debug info: page no. %step%, session %plsess%
</body></html>