#!/usr/bin/perl

=pod

=head1 NAME

display - script to display fragments of text on the web and elsewhere

=head1 DESCRIPTION

display started life as a way to concatenate fragments of handwritten HTML by
date. While the script has since haphazardly accumulated several of the usual
weblog features (comments, lightweight markup, feed generation, embedded Perl,
poetry tools, stupid dependencies), it hasn't changed much in six years. The
current version is intended to support FastCGI via CGI::Fast, if available, and
otherwise operate as a traditional CGI or commandline utility. It may have some
distance to go towards this goal.

Entries are stored in a simple directory tree under C<$DISPLAY_CONF{ROOT_DIR}>.

Like:

     archives/2001/1/1
     archives/2001/1/1/sub_entry

An entry may be either a plain text file, or a directory containing several
such files + whatever else you'd like to store.  If it's a directory, the file
called "index" will be treated as the text of the entry, and all other lower
case filenames without extensions will be treated as sub-entries or documents
within that entry, and displayed accordingly.

Directories may be nested to an arbitrary depth, though I don't promise that
this won't break on you.

A PNG or JPEG file with a name like

    2001/1/1.icon.png
    2001/1/1/index.icon.png
    2001/1/1/whatever.icon.png

will be treated as an icon for the appropriate entry file.

=head2 MARKUP

Entries may consist of hand-written HTML (to be passed along without further
interpretation), a supported form of lightweight markup, or some combination
thereof. Actually, an entry may consist of any darn thing you please, as long
as Perl will agree that it is text, but presumably you're going to be feeding
this to a browser.

Special markup is indicated by a variety of XML-style container tags.

B<Embedded Perl> - evaluated and replaced by whatever value you return
(evaluated in a scalar context):

     <perl>my $dog = "Ralph."; return $dog;</perl>

This code is evaluated before any other processing is done, so you can return
any other markup understood by the script and have it handled appropriately.

B<Interpolated variables> - actually keys to %TEMPLATE, for the moment:

     <perl>$TEMPLATE{dog} = "Ralph"; return '';</perl>
     <p>My dog is named ${dog}.</p>

Embedded code and variables are mostly intended for use in F<header> and
F<footer> files, where it's handy to drop in titles or conditionalize aspects
of a layout. You want to be careful with this sort of thing - it's useful in
small doses, but it's also a maintainability nightmare waiting to happen.
(WordPress, I am looking at you.)

B<Several forms of lightweight markup>:

     <wala>Wala::Markup, via Wala.pm - very basic wiki syntax</wala>

     <textile>Dean Allen's Textile, via Brad Choate's
     Text::Textile.</textile>

     <freeverse>An easy way to
     get properly broken lines
     -- en and em dashes ---
     for poetry and such.</freeverse>

B<And a couple of shortcuts>:

     <image>filename.ext
     alt text, if any</image>

     <list>
     one list item

     another list item
     </list>

As it stands, freeverse, image, and list are not particularly robust.

=cut

use strict;
use warnings;
no  warnings 'uninitialized';

use lib 'lib';
use lib 'wala';

use CGI::Fast;
use Image::Size;
use Text::Textile;
use XML::Atom::SimpleFeed;
use Wala qw (%WalaConf %DISPLAY_CONF);

# default options:
%DISPLAY_CONF = (
    ROOT_DIR       => 'archives',         # root dir for archived files
    URL_ROOT       => 'http://p1k3.com/', # root URL for building links
    IMAGE_URL_ROOT => 'http://p1k3.com/', # same for images
    HEADER         => 'header',
    FOOTER         => 'footer',
);

# Grab configuration:
if (-e 'conf.pl') {
    do 'conf.pl';
}

$WalaConf{'ShowSearchlinks'} = 0;

# Handle input from FastCGI:
while (my $query = new CGI::Fast) {
    handle($query);
}

# Fini.

=head1 SUBROUTINES

For no bigger than this thing is, it gets a little convoluted.

=over

=item handle()

Handle queries.

=cut

sub handle {
    my ($query) = @_;

    # Get the time, format the couple of variables I'll actually use.
    my ($sec, $min, $hour, $mday, $mon, $year, $wday, $yday,
        $isdst) = localtime(time);
    $mon++;
    $year += 1900;

    # grab the command line options, using "new" if none are provided
    #my @options = @ARGV;
    #unless ($options[0]) { $options[0] = $ENV{'QUERY_STRING'} };
    my @options = $query->param('keywords');
    unless ($options[0]) { $options[0] = 'new' };

    # now that we have some metadata,
    # set some variables to be used in fragment interpretation.
    # (these get inserted down in line_parse(); this is less than ideal)
    $DISPLAY_CONF{title} = join(' ', @options);

    # Unless this is already in an HTML document, spit out some default HTML.
    my $print_footer = 0;
    unless ($options[0] eq 'feed') {
      print fragment_slurp($DISPLAY_CONF{HEADER});
      $print_footer = 1;
    }

    # take care of "all" alias in options
    # get everything in the archive root directory
    my @old_options = @options;
    for (@old_options) {
      if ($_ eq 'all') {
        push (@options, dir_list ($DISPLAY_CONF{ROOT_DIR},
              "high_to_low",
              "^[0-9]{1,4}\$") );
      }
    }

    # do appropriate things:

    foreach my $option (@options) {

      # take care of trailing slashes
      chop ($option) if (substr($option, -1, 1) eq '/');

      # This just provides an alias for the most recent month.
      if ($option =~ m/^(feed|new)/) {
        my $special = $1;

        if (-e "$DISPLAY_CONF{ROOT_DIR}/$year/$mon") {
          $option = "$year/$mon";
        } else {
          $option = recent_month();
        }

        # Handle feed generation using XML::Atom::SimpleFeed.
        if ($special eq 'feed') {
          feed_print($option);
          exit;
        }
      }

      if ( $option =~ m'^[0-9/]{5,11}[a-z_/]+$' ) {
        # nnnn/[nn/nn/]doc_name
        # It's a document within a date.  entry_print it.
        print entry_markup(entry_print($option, 'index') . datestamp($option));
      }

      elsif ( $option =~ m'^[0-9]{4}/[0-9]{1,2}/[0-9]{1,2}$' ) {
        # nnnn/nn/nn
        # It's a specific date.  Print it in full.
        print entry_markup(entry_print($option, 'all') . datestamp($option));
      }

      elsif ( $option =~ m'^[0-9]{4}/[0-9]{1,2}$' ) {
        # nnnn/nn - It's a month.  Print it.
        month_print($option);
      }

      elsif ( $option =~ m'^[0-9]{4}$' ) {
        # nnnn - It's a year. Display a list of entries.
        year_print($option);
      }

      elsif ($option =~ m'^[a-z_]') {
        # assume it's a document in the root directory
        print entry_markup(entry_print($option, 'all'));
      }
    }

    # Finish up...
    # Print a footer.
    if ($print_footer) {
      print fragment_slurp($DISPLAY_CONF{FOOTER});
    }

}


sub recent_month {

  my (@year_files) = dir_list ("$DISPLAY_CONF{ROOT_DIR}",
      'high_to_low',
      '^[0-9]{1,4}$');

  my (@month_files) = dir_list ("$DISPLAY_CONF{ROOT_DIR}/$year_files[0]",
      'high_to_low',
      '^[0-9]{1,2}');

  return "$year_files[0]/$month_files[0]";

}

=item dir_list()

Return a $sort_order sorted list of files matching $pattern in a
directory.  Called by year_print(), month_print(), and entry_print().

calls $sort_order, which can be one of

 alpha - alphabetical 
 reverse_alpha - alphabetical, reversed (might not work yet)
 high_to_low - numeric, high to low
 low_to_high - numeric, low to high

=cut

sub dir_list {
    my ($dir, $sort_order, $file_pattern) = @_;
    my (@files);
    
    $file_pattern = "^[0-9]{1,2}\$" unless ($file_pattern);
    $sort_order = "high_to_low" unless ($sort_order);

    opendir LIST_DIR, $dir;
    @files = grep /$file_pattern/, readdir LIST_DIR;
    closedir LIST_DIR;

    @files = sort $sort_order @files;

    return @files;
}

# various named sorts for dir_list
sub alpha         { $a cmp $b; } # alphabetical
sub high_to_low   { $b <=> $a; } # numeric, high to low
sub low_to_high   { $a <=> $b; } # numberic, low to high
sub reverse_alpha { $b cmp $a; } # alphabetical, reversed


=item year_print()

List out the updates for a year. Calls dir_list(), entry_print().

=cut

sub year_print {
    my ($year) = @_;
    my (@update_files, $update_count, $ico_markup);

    if (-d "$DISPLAY_CONF{ROOT_DIR}/$year") {
        print '<div class="entry">' . "\n";

        if (-T "$DISPLAY_CONF{ROOT_DIR}/$year/index") {
            print entry_print($year, 'index');
        }
        
        if ( $ico_markup = icon_markup($year, $year) ) { 
            print "<h3>$ico_markup $year</h3>";
        } else {
            print "<h3>$year</h3>\n";
        }

        my @month_files = dir_list ("$DISPLAY_CONF{ROOT_DIR}/$year",
                                 "high_to_low",
                                 "^[0-9]{1,2}\$");

        print "\n<table>\n";
        $update_count = 0;
        foreach my $month_file (@month_files) {
            @update_files = dir_list ("$DISPLAY_CONF{ROOT_DIR}/$year/$month_file",
                "low_to_high", "^[0-9]{1,2}\$");

            # Add the count of files to $update_count.
            $update_count += @update_files;
           
            print '<tr> <td class="datelink">'
                . a("$DISPLAY_CONF{URL_ROOT}$year/$month_file", month_name($month_file))
                . "</td> <td class=\"datelink\">\n";

            print "( <small>";

            foreach my $update_file (@update_files) {
                print a("$DISPLAY_CONF{URL_ROOT}$year/$month_file/$update_file", $update_file)
                    . "\n";
            }
            print "</small> )</td> </tr>\n\n";
        }
        print "</table>\n";

        print "<p>$update_count ";
        if ($update_count > 1) {
            my ($monthly_average) = int($update_count / @month_files);
            print " entries, an arithmetic mean of $monthly_average a month.";
        } elsif ($update_count == 0) {
            print " entries";
        } elsif ($update_count == 1) {
            print " entry";
        }
        print '</p>';

    } elsif (-T "$DISPLAY_CONF{ROOT_DIR}/$year") {
        print entry_print($year, 'index');
    } else {
        print '<p>No such year.</p>';
    }
    print "</div>\n";

    return ($update_count);
}

=item month_print()

Prints the entries in a given month (nnnn/nn). Calls dir_list(), datestamp().

=cut

sub month_print {
    my ($year_digits, $month_digits, $calendar);
    # If a directory exists for $month, use dir_list to grab
    # the entry files it contains into @entry_files, sorted
    # numerically.  Then send each entry to entry_print.
    my ($month) = @_;

    if (-d "$DISPLAY_CONF{ROOT_DIR}/$month") {
        if (-T "$DISPLAY_CONF{ROOT_DIR}/$month/index") {
            print entry_print($month, "index");
        }

        my (@entry_files) = dir_list ("$DISPLAY_CONF{ROOT_DIR}/$month",
                                      "high_to_low",
                                      "^[0-9]{1,2}\$");
    
        foreach my $entry_file (@entry_files) {
           print entry_markup( entry_print("$month/$entry_file", 'index')
                               . datestamp("$month/$entry_file") );
        }
    } elsif (-T "$DISPLAY_CONF{ROOT_DIR}/$month") {
        print entry_print($month, 'index');
    }
}

=item entry_print()

Prints the contents of a given entry. Calls datestamp, fragment_print,
dir_list, and icon_markup. Recursively calls itself.

=cut

sub entry_print {
    my ($entry, $level) = @_;

    my ($result);

    my $entry_loc = "$DISPLAY_CONF{ROOT_DIR}/$entry"; # location of entry on local filesystem
    my $entry_url = $DISPLAY_CONF{URL_ROOT} . $entry; # and its URL
    
    # display an icon, if we have one.
    if ( my $ico_markup = icon_markup ($entry, "") ) {
            $result .= "<h2>$ico_markup</h2>\n\n";
    }

    if (-T $entry_loc) {
        # is text, slurp it and return
        return ($result . fragment_slurp($entry_loc));
    } elsif (-d $entry_loc) {

        # print index as head
        $result .= fragment_slurp ("$entry_loc/index");

        my @sub_entries = dir_list ($entry_loc, 'alpha',
                                 '^[a-z_]+(\.tgz|\.zip|\.tar\.gz)?$');
      
        # followed by any sub-entries
        if ( ($level eq 'index') and (@sub_entries > 1) ) {
            # if we're just supposed to print an index
            # spit out icons or text links for extra files
            my $contents;
            my %ignore_entries = ("index" => 1, "standing_bear" => 1);

            foreach my $sub_entry (@sub_entries) {
                next if ($ignore_entries{$sub_entry});

                if ( my $sub_ico_markup = icon_markup("$entry/$sub_entry",
                                                      $sub_entry) ) { 
                    $contents .= qq|<a href="$DISPLAY_CONF{URL_ROOT}$entry/$sub_entry" |
                               . qq|title="$sub_entry">$sub_ico_markup</a>\n |;
                } else {
                    $contents .= qq|<a href="$DISPLAY_CONF{URL_ROOT}$entry/$sub_entry "|
                               . qq|title="$sub_entry">$sub_entry</a> \n|;
                }
            }

            $result .= "<p><em><strong>more</strong></em>: $contents</p>\n";
        } elsif ( ($level eq 'all') and (@sub_entries > 1) ) {

            # but if we're supposed to print everything in the directory
            # and if there's more there than just the index file,

            foreach my $sub_entry (@sub_entries) {
                next if ($sub_entry eq 'index'); # skip index
            
                # print each of the other files, separated by little headers
                $result .= "\n\n<p class=\"centerpiece\">{"
                         . a("$DISPLAY_CONF{URL_ROOT}$entry/$sub_entry", $sub_entry)
                         . "}</p>\n\n";

                # skipping any archives
                next if ($sub_entry =~ m/(\.tgz|\.zip|\.tar\.gz)$/);

                $result .= entry_print("$entry/$sub_entry", 'index');
            }

        } 

    }

    return $result;
}

=item icon_markup()

Check if an icon exists for a given entry if so, return markup to include it.
Icons are PNG or JPEG image files following a specific naming convention:

  index.icon.[png|jp(e)g] for directories
  [filename].icon.[png|jp(e)g] for flat text files

Called by entry_print, calls image_size, uses filename to determine type.

=cut

sub icon_markup {
    my ($entry, $alt) = @_;
    my ($entry_loc) = "$DISPLAY_CONF{ROOT_DIR}/$entry";
    my ($entry_url) = "$DISPLAY_CONF{IMAGE_URL_ROOT}${entry}";

    my ($icon_loc, $icon_url);

    if (-T $entry_loc) {
        $icon_loc = "$entry_loc.icon";
        $icon_url = "$entry_url.icon";
    } elsif (-d $entry_loc) {
        $icon_loc = "$entry_loc/index.icon";
        $icon_url = "$entry_url/index.icon";
    }

    # put a list of icon image types to check for here
    # (first one found will be used)
    my (@suffixes) = qw(png jpg jpeg);
    my $suffix = "";
    for (@suffixes) {
        if (-e "$icon_loc.$_") {
            $suffix = $_;
            last;
        }
    }
    
    # fail unless there's a file with one of the above suffixes
    return 0 unless $suffix;
    
    # call image_size to slurp width & height from the image file
    my ($width, $height) = image_size("$icon_loc.$suffix");

    return qq|<img src="$icon_url.$suffix"\n width="$width" |
         . qq|height="$height"\n alt="$alt" />|;
}

=item datestamp()

Returns a nice html datestamp for a given entry, including a wikilink for
discussion and suchlike.  Called by entry_print.

=cut

sub datestamp {
    my ($entry, $markup_start, $markup_end) = @_;

    unless ($markup_start and $markup_end) {
        $markup_start = "\n<p class=\"datelink\">";
        $markup_end = "</p>\n\n";
    }

    my ($stamp);
    if ( $entry =~ m/(^[0-9]{4}\/[0-9]{1,2}\/[0-9]{1,2})/ ) {

        my ($entry_year, $entry_month, $entry_day) = split (/\//, $1);

        # this stuff conditionalizes the wikilink
        # so that if nothing exists, you wind up with an edit form
        my ($wiki_date_name) = month_name($entry_month) . "_${entry_day}_${entry_year}";
        my $wikistamp;
        if (-e "$WalaConf{PagesDir}/${wiki_date_name}") {
            $wikistamp = qq{:: <a title="a page you can edit"}
                    . qq{  href="$WalaConf{ScriptName}?$wiki_date_name">read the margins</a>};
        } else {
            $wikistamp = qq{:: <a title="a page you can edit"}
                    . qq{  href="$WalaConf{ScriptName}?$wiki_date_name">write in the margins</a>};
        }
           
        # return a fancy datestamp.

        my $month_name = month_name($entry_month);
        $stamp = <<STAMP;
$markup_start
  <a href="$DISPLAY_CONF{URL_ROOT}$entry_year" title="$entry_year">$entry_year</a>
  <a href="$DISPLAY_CONF{URL_ROOT}$entry_year/$entry_month" title="$entry_year/$entry_month">$month_name</a>
  <a href="$DISPLAY_CONF{URL_ROOT}$entry_year/$entry_month/$entry_day" title="$entry_year/$entry_month/$entry_day">$entry_day</a>
  $wikistamp
$markup_end
STAMP

    } else {
        $stamp = "$markup_start(failed to construct datestamp for $entry)$markup_end";
    }

    return ($stamp);
}

=item fragment_print()

Print a text fragment - a header, footer, update, etc.
Called by main routines, used to print headers and footers.
Calls fragment_slurp to get the fragment it's supposed to print.
Returns 1 on successful completion, 0 otherwise.

=cut

sub fragment_print {
    my ($file) = @_;

    my $lines = fragment_slurp($file);

    if (length($lines)) {
        print $lines;
    } else {
        return '';
    }
}

=item fragment_slurp()

Read a text fragment, call line_parse to take care of funky markup and
interpreting embedded code, and then return it as a string. Takes one
parameter, the name of the file, and returns '' if it's not an extant text
file.  Called by entry_print, at least

=cut

sub fragment_slurp {
    my ($file) = @_;

    # if $file is text
    if (-T $file) {
        my $everything;
    
        open (my $fh, '<', $file) or return '';
        {
            # line sep
            local $/ = undef;
            $everything = <$fh>;
        }
        close $fh;

        # take care of any special markup
        # we feed $file to line_parse so it has some context to work with
        $everything = line_parse ($file, $everything);

        return $everything;
    } else {
        return '';
    }
}

=item line_parse()

Performs substitutions on lines called by fragment_slurp, at least.  Calls
image_markup, Text::Textile, Wala::wiki_page_to_html, eval_perl.  Returns
string.

Parses some special markup, specifically:

    <perl>embedded perl</perl>
    ${variable} interpolation from %DISPLAY_CONF
    <textile></textile> - Text::Textile to HTML
    <wala></wala> - Wala::wikify();
    <image>filename.ext</image>
    <freeverse></freeverse>
    <retcon></retcon>
    <list></list>

=cut

sub line_parse {
    my ($file, $everything) = (@_);

    # eval embedded Perl
    $everything = eval_perl($everything, $file);

    # interpolate variables
    $everything =~ s/\${([a-zA-Z_]+)}/$DISPLAY_CONF{$1}/ge;

    # take care of wala markup
    $everything =~ s/<wala>(.*?)<\/wala>/Wala::wikify($1)/seg;

    # take care of textile markup, if we've got any
    # this is wrapped in a conditional to keep from
    # creating the object if we don't need it.
    if ($everything =~ m/<textile>/s) {
        # head_offset: use h1., h2. in Textile formatting.
        my $textile = Text::Textile->new( head_offset => 2 );

        $everything =~ s/<textile>(.*?)<\/textile>/$textile->process($1)/seg;
    }

    # evaluate <image> tags.
    $everything =~ s!<image>(.*?)</image>!image_markup($file, $1)!seg; 

    my %tags = ( retcon => 'div class="retcon"',
                 freeverse => 'p',
                 list => "ul>\n<li" );

    my %end_tags = ( retcon => 'div',
                     freeverse => 'p',
                     list => 'li></ul' );

    my %blank_lines = ( freeverse => "</p>\n\n<p>",
                        list => "</li>\n\n<li>" );

    my %newlines = ( freeverse => "<br />\n" );

    my %dashes = ( freeverse => ' &mdash; ' );

    foreach my $key (keys %tags) {
        # Set some replacements, unless they've been explicitly set already.
        $end_tags{$key}    = $tags{$key} unless $end_tags{$key};
        $blank_lines{$key} = "\n\n"      unless $blank_lines{$key};
        $newlines{$key}    = "\n"        unless $newlines{$key};
        $dashes{$key}      = " -- "      unless $dashes{$key};

        while ($everything =~ m/(<$key>.*?<\/$key>)/s) {
            my $block = $1;

            # save the bits between instances of the block --
            # the \Q and \E escape any regex chars in the block
            my (@interstice_array) = split (/\Q$block\E/s, $everything);

            # now, transform the contents of the block we've found:

            # tags that surround the block
            $block =~ s/\n?<$key>\n?/<$tags{$key}>/gs;
            $block =~ s!\n?</$key>\n?!</$end_tags{$key}>!gs;
            
            # dashes
            $block =~ s/(\s+)\-{2}(\s+)/$1$dashes{$key}$2/gs;
           
            # blank lines within the block
            $block =~ s/\n\n/$blank_lines{$key}/gs;

            # single newlines (i.e., line ends) within the block
            # except those preceded by a double-quote, which probably
            # indicates a still-open tag.
            $block =~ s/([^"\n])\n([^\n])/$1$newlines{$key}$2/gs;

            # and slap it all back together as $everything
            $everything = join $block, @interstice_array;

        }
    }

    return $everything;
}

=item eval_perl()

Evaluate embedded Perl, replacing blocks enclosed with <perl> tags
with whatever they return (well, evaluated in a scalar context).

=cut

sub eval_perl {
    my ($everything, $file) = @_;

    while ($everything =~ m/<perl>(.*?)<\/perl>/s) {
        my $block = $1;

        my $output = eval $block;
        if ($@) {
          # got an error
          $everything =~ s/<perl>\Q$block\E<\/perl>/$@ in $file/s;
        } else {
          # include anything returned from $block
          $everything =~ s/<perl>\Q$block\E<\/perl>/$output/s;
        }
    }

    return $everything;
}


=item image markup()

Parse out an image tag and return the appropriate html. Calls image_size.
Called by line_parse.

=cut

sub image_markup {
    my ($file, $block) = @_;
        
    # get a directory for the file we're working with
    $file =~ s'[^/]* # everything not a /
               $     # up to end of string
              ''x;

    # truncated file date that just includes date + sub docs
    my ($file_date) = $file =~ m'([0-9]{4}/[0-9]{1,2}/[0-9]{1,2}/([a-z]*/)*)$';

    my ($image_name, $alt_text) = split/\n/, $block;

    my $image_file;
    if (-e "$file/$image_name" ) {
        $image_file = "$file/$image_name";
        $image_name = "${file_date}${image_name}";
    } elsif (-e "$DISPLAY_CONF{ROOT_DIR}/$image_name") {
        $image_file = "$DISPLAY_CONF{ROOT_DIR}/$image_name";
    }

    # get width & height in pixels for known filetypes
    my ($width, $height) = image_size($image_file);

    # may need to change this if rewrites don't work
    return qq|<img src="$DISPLAY_CONF{IMAGE_URL_ROOT}$image_name"\n height="$height"|
         . qq|\n width="$width"\n alt="$alt_text" />|;
}


=item month_name()

Turn numeric dates into English.

=cut

sub month_name {
    my ($number) = @_;

    # "Null" is here so that $month_name[1] corresponds to January, etc.
    my @months = qw(Null January February March April May June
                    July August September October November December);

    return $months[$number];
}


=item feed_print()

Dump out an Atom feed of entries for a month.

Called from handle(), calls entry_print, requires XML::Atom::SimpleFeed.

=cut

sub feed_print {
    my $month = shift;

    # create a feed object
    my $feed = XML::Atom::SimpleFeed->new(
        title   => $DISPLAY_CONF{title},
        link    => $DISPLAY_CONF{URL_ROOT},
        link    => { rel => 'self', href => $DISPLAY_CONF{feed_url}, },
        icon    => $DISPLAY_CONF{favicon_url},
        author  => $DISPLAY_CONF{author},
        id      => $DISPLAY_CONF{URL_ROOT},
    );

    # If a directory exists for $month, use dir_list to grab
    # the entry files it contains into @entry_files, sorted
    # numerically.  Then send each entry to entry_print.

    my @entry_files;

    if (-d "$DISPLAY_CONF{ROOT_DIR}/$month") {
        (@entry_files) = dir_list ("$DISPLAY_CONF{ROOT_DIR}/$month", 'high_to_low',
                "^[0-9]{1,2}\$");
    } else {
        return 0;
    }

    foreach my $entry_file (@entry_files) {
        # Going to feed this to SimpleFeed.
        my $content = entry_print("$month/$entry_file", 'index');

        $feed->add_entry(
            title     => "$month/$entry_file",
            link      => $DISPLAY_CONF{URL_ROOT} . "$month/$entry_file",
            id        => $DISPLAY_CONF{URL_ROOT} . "$month/$entry_file",
            content   => $content,
        );     

    }

    print "Content-type: application/atom+xml\n\n";
    $feed->print;
    return 1;

}


=item entry_markup()

Return text wrapped in the appropriate markup for an entry.  Just a wrapper
around div() at the moment.

=cut

sub entry_markup {
    my ($text) = @_;
    return div($text, 'entry');
}


=item div()

Return text wrapped in a div of the specified class.

=cut

sub div {
    my ($text, $class) = @_;
    my ($top, $result);

    if ($class) {
        $top = "<div class=\"$class\">\n";
    } else {
        $top = "<div>\n";
    }

    return ( $top . $text . "\n</div>\n" );
}


=item a()

Returns an HTML link. Called all over the place.

=cut

sub a {
    my ($url, $text) = @_;
    return "<a href=\"$url\">$text</a>";
}


=item ornament()

Returns a type ornament.

=cut

sub ornament {
    return '<small>&sect;</small>';
}


=item image_size()

Returns (width, height) of a variety of image files.  Called by icon_markup and
line_parse. Uses Image::Size if available, otherwise uses a couple of built-in
routines munged together from pngsize and jpegsize in wwwis, by Alex Knowles
and Andrew Tong.

=cut

sub image_size {
    my ($image_file) = shift;

    # Use Image::Size - this needs to be actually conditionalized.

    my ($x, $y, $type);
    ($x, $y, $type) = imgsize($image_file);
    return ($x, $y);

    # Otherwise we want to use our built-in routines:

    my ($head);

    if ( !open(IMAGE, '<', $image_file) ) {
        print STDERR "can't open IMG $image_file"; 
        return (0, 0);
    } else {
        binmode IMAGE;
        if ($image_file =~ m/\.png$/) { # it's a PNG
            my ($a, $b, $c, $d, $e, $f, $g, $h) = 0;

            if (defined($image_file)
                && read(IMAGE, $head, 8) == 8
                && ($head eq "\x8a\x4d\x4e\x47\x0d\x0a\x1a\x0a" ||
                    $head eq "\x89\x50\x4e\x47\x0d\x0a\x1a\x0a")
                && read(IMAGE, $head, 4) == 4
                && read(IMAGE, $head, 4) == 4
                && ($head eq "MHDR" || $head eq "IHDR")
                && read(IMAGE, $head, 8) == 8) {
                    # ($x, $y) = unpack("I"x2, $head);
                    #   doesn't work on little-endian machines
                    # return ($x,$y);
                    ($a,$b,$c,$d,$e,$f,$g,$h) = unpack ("C"x8, $head);
                    return ($a<<24|$b<<16|$c<<8|$d, $e<<24|$f<<16|$g<<8|$h);
                }
        } elsif ($image_file =~ m/\.jpe?g$/) { # it's a JPEG
            my($done) = 0;
            my($c1,$c2,$ch,$s,$length, $dummy) = (0,0,0,0,0,0);
            my($a,$b,$c,$d);

            if (defined($image_file)
               && read(IMAGE, $c1, 1)
               && read(IMAGE, $c2, 1)
               && ord($c1) == 0xFF
               && ord($c2) == 0xD8) {
                    while (ord($ch) != 0xDA && !$done) {
                        # Find next marker (JPEG markers begin with 0xFF)
                        # This can hang the program!!
                        while (ord($ch) != 0xFF) {
                            return(0,0) unless read(IMAGE, $ch, 1);
                        }

                        # JPEG markers can be padded with unlimited 0xFF's
                        while (ord($ch) == 0xFF) {
                            return(0,0) unless read(IMAGE, $ch, 1);
                        }
                        
                        # Now, $ch contains the value of the marker.
                        if ((ord($ch) >= 0xC0) && (ord($ch) <= 0xC3)) {
                            return(0,0) unless read (IMAGE, $dummy, 3);
                            return(0,0) unless read(IMAGE, $s, 4);
                            ($a,$b,$c,$d)=unpack("C"x4,$s);
                            return ($c<<8|$d, $a<<8|$b );
                        } else {
                            # We **MUST** skip variables, since FF's within
                            # variable names are NOT valid JPEG markers
                            return(0,0) unless read (IMAGE, $s, 2);
                            ($c1, $c2) = unpack("C"x2,$s);
                            $length = $c1<<8|$c2;
                            last if (!defined($length) || $length < 2);
                            read(IMAGE, $dummy, $length-2);
                        }
                    }        
                }
            } 

        return (0,0);
    } 
}

=back

=head1 SEE ALSO

walawiki.org, Blosxom, rassmalog, Text::Textile, XML::Atom::SimpleFeed,
Image::Size, CGI::Fast.

=head1 AUTHOR

Copyright 2001-2007 Brennen Bearnes

Image sizing code (in image_size) derived from wwwis, by Alex Knowles and
Andrew Tong.

    display.pl is free software; you can redistribute it and/or modify
    it under the terms of the GNU General Public License as published by
    the Free Software Foundation; either version 2 of the License, or
    (at your option) any later version.

    This program is distributed in the hope that it will be useful,
    but WITHOUT ANY WARRANTY; without even the implied warranty of
    MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
    GNU General Public License for more details.

=cut

1;