#!/usr/bin/perl

# original skript: Shishir Gundavaram, shishir@ora.com
# z knihy CGI programovanie webovskych stranok a aplikacii
# vyslo u O'Reilly(tm)
# cesky preklad ComputerPress, ISBN80-7226-088-X
# slovensky kometar: Svatoslav Straka, straka@developer.sk

$webmaster = "straka\@developer\.sk";

$method = $ENV{'REQUEST_METHOD'};
$script = $ENV{'SCRIPT_NAME'};
$query  = $ENV{'QUERY_STRING'};
$document_root = $ENV{'DOCUMENT_ROOT'};

# $guest_file - relativna cesta k suboru s odkazmi
$guest_file = "/guestbook.html";
$full_path = $document_root . $guest_file;

# $exclusive_lock a $unlock maju vyznam len na systemoch na ktorych
# je implementovany prikaz flock, na Windows nie!
$exclusive_lock = 2;
$unlock = 8;


if ($method eq "GET") {
    if ($query eq "add") {
	$date_time = &get_date_time();
        
        # Tu si mozete zvolit nazov pre Vas guestbook
        &MIME_header ("text/html", "Developer Zone Guestbook");

# popis ku guestbooku a vytvorenie formulara pre pridavanie odkazov
        print <<End_Of_Guestbook_Form;

Guestbook CGI skript Vam umoznuje nechat nam odkaz. Prosim vypiste 
pozadovane informacie a kliknite na tlacitko "Pridaj odkaz".
<P>
Momentalne je: $date_time
<HR>

<FORM METHOD="POST">
<PRE>
<EM>Meno</EM>:       <INPUT TYPE="text" NAME="name" SIZE=40>
<EM>E-mail</EM>:     <INPUT TYPE="text" NAME="from" SIZE=40>
<EM>WWW Server</EM>: <INPUT TYPE="text" NAME="www"  SIZE=40>
</PRE>
<P>
<EM>Sem napiste Vas odkaz:</EM><BR>
<TEXTAREA ROWS=3 COLS=60 NAME="comments"></TEXTAREA><P>
<INPUT TYPE="submit" VALUE="Pridaj odkaz">
<INPUT TYPE="reset"  VALUE="Vymaz formular"><BR>
<P>
</FORM>
<HR>

End_Of_Guestbook_Form

    } else {

	if ( open(GUESTBOOK, "<" . $full_path) ) {
	            # pokym Vas system nepozna prikaz flock, odpoznamkujte
	            # nasledujuci riadok!
                flock (GUESTBOOK, $exclusive_lock);
        
        # Mozete si zvolit nadpis pre stranku, na ktorej budu
        # vypisane odkazy
		&MIME_header ("text/html", "Tu je guestbook!");
                print <<Pridanie_Odkazu;

<a href="$script?add">Pridaj odkaz</a>
<hr>
Pridanie_Odkazu
                
                while (<GUESTBOOK>) {
                    print;
                }
                # pokym Vas system nepozna prikaz flock, odpoznamkujte
	            # nasledujuci riadok!
                flock (GUESTBOOK, $unlock);
                close(GUESTBOOK);
		
	} else {
                &return_error (500, "Guestbook File Error",
			"Cannot read from the guestbook file [$full_path].");
        }
   }
} elsif ($method eq "POST") {
    
    if ( open (GUESTBOOK, ">>" . $full_path) ) {
        
        # pokym Vas system nepozna prikaz flock, odpoznamkujte
	    # nasledujuci riadok!
        flock (GUESTBOOK, $exclusive_lock);

	$date_time = &get_date_time();
	&parse_form_data (*FORM);
        
        # Ak uzivatel nezada svoje meno, doplni sa "Anonym"
        $FORM{'name'}  = "Anonym"               if !$FORM{'name'};
        $FORM{'from'}  = $ENV{'REMOTE_HOST'}    if !$FORM{'from'};
        
        $FORM{'comments'} =~ s/\n/<BR>/g;

        print GUESTBOOK <<End_Of_Write;

<P>
<B>$date_time:</B><BR>
Odkaz pridal <EM>$FORM{'name'}</EM>, <EM>$FORM{'from'}</EM>:
<P>
$FORM{'comments'}

End_Of_Write


        if ($FORM{'www'}) {
            print GUESTBOOK <<End_of_Web_Address;
			
<P>
$FORM{'name'} je dostupny aj cez: 
<A HREF="$FORM{'www'}">$FORM{'www'}</A>

End_of_Web_Address

        }
		
        print GUESTBOOK "<P><HR>";
        
        # pokym Vas system nepozna prikaz flock, odpoznamkujte
	    # nasledujuci riadok!
        flock (GUESTBOOK, $unlock);
        close(GUESTBOOK);

        # Nadpis pre stranku s podakovanim
        &MIME_header ("text/html", "Dakujeme!");

        # podakovanie za pridanie odkazu
        print <<End_of_Thanks;
        
Dakujeme za navstevu guestbooku. Ak si ho chcete prezriet,
kliknite <A HREF="$script">sem</A>.

End_of_Thanks

    } else {
        &return_error (500, "Guestbook File Error",
               "Cannot write to the guestbook file [$full_path].");
    }
		
} else {
    &return_error (500, "Server Error",
                        "Server uses unsupported method");
}

exit(0);

sub MIME_header
{
    local ($mime_type, $title_string, $header) = @_;

    if (!$header) {
        $header = $title_string;
    }

    print "Content-type: ", $mime_type, "\n\n";
    print "<HTML>", "\n";
    print "<HEAD><TITLE>", $title_string, "</TITLE></HEAD>", "\n";
    print "<BODY>", "\n";
    print "<H1>", $header, "</H1>";
    print "<HR>";
}

sub get_date_time 
{
    local ($months, $weekdays, $ampm, $time_string);

    $months = "januar/febraur/marec/april/maj/jun/jul/" . 
              "august/september/oktober/november/december";
    $weekdays = "Nedela/Pondelok/Utorok/Streda/Stvrtok/Piatok/Sobota";

    local ($sec, $min, $hour, $day, $nmonth, $year, $wday, $yday, $isdst) 
	          = localtime(time);

    if ($hour > 12) {
        $hour -= 12;
        $ampm = "pm";
    } else {
        $ampm = "am";
    }

    if ($hour == 0) {
	       $hour = 12;
    }

    $year += 1900;

    $week  = (split("/", $weekdays))[$wday];
    $month = (split("/", $months))[$nmonth];

    $time_string = sprintf("%s, %s. %s %s - %02d:%02d:%02d %s", 
                                $week, $day, $month, $year, 
                                $hour, $min, $sec, $ampm);

    return ($time_string);
}

sub parse_form_data
{
    local (*FORM_DATA) = @_;
	
    local ( $request_method, $post_info, @key_value_pairs,
		          $key_value, $key, $value);

    read (STDIN, $post_info, $ENV{'CONTENT_LENGTH'});

    @key_value_pairs = split (/&/, $post_info);

    foreach $key_value (@key_value_pairs) {
        ($key, $value) = split (/=/, $key_value);
        $value =~ tr/+/ /;
        $value =~ s/%([\dA-Fa-f][\dA-Fa-f])/pack ("C", hex ($1))/eg;

        if (defined($FORM_DATA{$key})) {
            $FORM_DATA{$key} = join ("\0", $FORM_DATA{$key}, $value);
        } else {
            $FORM_DATA{$key} = $value;
        }
    }
}

sub return_error
{
    local ($status, $keyword, $message) = @_;

    print "Content-type: text/html", "\n";
    print "Status: ", $status, " ", $keyword, "\n\n";

    print <<End_of_Error;

<title>CGI Program - Unexpected Error</title>
<h1>$keyword</h1>
<hr>$message</hr>
Please contact $webmaster for more information.

End_of_Error

    exit(1);
}