use strict;
use CGI qw(:standard :html3 escape unescape);
use Apache::Constants qw(:common);
use Apache::File ();
use Apache::Util qw(ht_time escape_uri unescape_uri escape_html);
use Fcntl qw( :DEFAULT :flock );
use POSIX qw(strftime);
use DB_File;
use vars qw(@FIELDS %REQUIRED $GUESTBOOKFILE %HoA);
local *DBM;

@FIELDS = qw(First_Name Last_Name
             Email_Address1 Email_Address2 Website
             Home_Phone Work_Phone Cell_Phone Other_Phone
             Street_Address1 Street_Address2 City State Zip
             Country Birthday Gender);

sub write_guestbook {
    unless (TieLock($GUESTBOOKFILE, 1)) {
	print strong('Sorry, an error occurred: unable to open ' . $GUESTBOOKFILE),p();
	return;
        }

    my $i = param("HoAindex"); # check for an update
    unless ($i) {
      ## increment the sequencer.
      $HoA{sequence} = 0 unless exists $HoA{sequence};
      $i = ++$HoA{sequence};
      }

    my $date = strftime('%d-%b-%Y %R',localtime);
    $HoA{$i} = join(">", ($date), map {escape(param($_))} (@FIELDS));

    unTieLock($GUESTBOOKFILE);
    return( "Thank you <b>". param('First_Name')
                     ."</b>, for signing the guestbook.");
}

sub delete_guestbook {
    unless (TieLock($GUESTBOOKFILE, 1)) {
	print strong('Sorry, an error occurred: unable to open ' . $GUESTBOOKFILE),p();
	return;
        }

    my $i = param("HoAindex"); # get the delete index
    unless ($i) {
	print strong('Sorry, an error occurred: unable to get entry index ' . $GUESTBOOKFILE),p();
	return;
      }

    delete $HoA{$i};

    unTieLock($GUESTBOOKFILE);
    return( "Thank you <b>". param('First_Name')
                     ."</b>, your delete has been completed.");
}

sub load_address {
    my $fname = param('First_Name');
    my $lname = param('Last_Name');
    my $return_msg;

    unless (TieLock($GUESTBOOKFILE, 0)) {
	print strong('Sorry, an error occurred: unable to open ' . $GUESTBOOKFILE),p();
	return;
        }

    my @data;
    for my $addr (sort keys %HoA) {
	@data =  map {unescape($_)} split( ">", $HoA{$addr}, 18);
        $data[0] = $addr;              #overlay the date with the key.
        last if ($fname eq $data[1]) && ($lname eq $data[2]);
        if ($data[0] eq "sequence") {
          @data = ();
          $return_msg = "Sorry <b>". param('First_Name')
                     ."</b>, but your existing entry has not been found.";
          }
        }

    unTieLock($GUESTBOOKFILE);
    return ($return_msg, @data);
}

sub view_guestbook {
    my $guestbook;

    my @rows;
    unless (TieLock($GUESTBOOKFILE, 0)) {
	print strong('Sorry, an error occurred: unable to open ' . $GUESTBOOKFILE),p();
	return;
        }

    for my $addr (sort keys %HoA) {
        next if $addr eq "sequence";
	my @data =  map {unescape($_)."&nbsp;"} split( ">", $HoA{$addr}, 18);
	unshift @rows, td(\@data);
        }

    unshift @rows, th(['Entry Date',@FIELDS]);
    $guestbook .= p(
	    table({-border=>'1', -hspace=>'5',
                   -cellspacing=>'1', -cellpadding=>'4'},
		  TR(\@rows)));

    unTieLock($GUESTBOOKFILE);
    return ($guestbook);
}

sub TieLock { # tie and lock the dbm file.
   my $path = shift;
   my $for_writing = shift;
   my $lock_type;
    if ($for_writing) {
	$lock_type = LOCK_EX; 
    } 
    else {
	$lock_type = LOCK_SH; 
    }
   my $db = tie %HoA, 'DB_File', $path, O_RDWR | O_CREAT, 0666, $DB_HASH
       or die "[Error processing $path ] $!";

   my $fd = $db->fd;
   open DBM, "+<&=$fd" or die "Could not dup DBM for lock: $!";

# now try to lock it
   my $success;
   my $tries = 0;
   while ($tries++ < 10) {
	last if $success = flock (DBM, $lock_type|LOCK_NB);
	print p("Waiting for $lock_type lock on AddressBook file...");
	sleep(1);		# wait a second
        }

   undef $db;
   unless ($success) {
	warn("Couldn't get lock for $lock_type"); 
	return;
        }
   return 1;
   }

sub unTieLock { # untie the dbm file.
   untie %HoA;
   close DBM;
   }