wrt/Display.pm

#!/usr/bin/perl

=pod

=head1 NAME

Display - module to display fragments of text on the web and elsewhere

=head1 SYNOPSIS

    #!/usr/bin/perl

    use Display qw(%WalaConf %DISPLAY_CONF &handle);

    do 'conf.pl' if -e 'conf.pl'; # grab config

    $WalaConf{'ShowSearchlinks'} = 0;

    print handle(@ARGV);

=head1 DESCRIPTION

Display started life as a simple script to concatenate fragments of handwritten
HTML by date. It has since haphazardly accumulated several of the usual weblog
features (comments, lightweight markup, feed generation, embedded Perl, poetry
tools, ill-advised dependencies), but the basic idea hasn't changed much.

The module will work with FastCGI, via CGI::Fast, if called from the
appropriate wrapper script.

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

package Display;

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

BEGIN {
  use base qw(Exporter);
  our @EXPORT_OK = qw(%WalaConf %DISPLAY_CONF &handle);

  use XML::Atom::SimpleFeed;
  use Wala qw(%WalaConf %DISPLAY_CONF);

  use Display::HTML qw(:highlevel);
  use Display::Markup qw(line_parse);
  use Display::Image qw(image_size);
}
our @EXPORT_OK;

######################
#  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',
);

$WalaConf{'ShowSearchlinks'} = 0;

=head1 SUBROUTINES

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

=over

=item handle

Handle a given request, either in the form of a CGI query object
or a date/entry string.

=cut

sub handle {
    my (@options) = @_;
    my $output;

    # Get parameters from any CGI objects we've been given:
    @options = map { expand_query($_) } @options;

    # By default, we display the most recent month.
    $options[0] = 'new' unless $options[0];

    # Title for head/foot template:
    $DISPLAY_CONF{title} = join ' ', @options;

    # Maps 'all' and 'new' to appropriate entries:
    @options = map { expand_option($_) } @options;

    for my $o (@options) {
      return feed_print() if $o eq 'feed';
      $output .= output($o);
    }

    # Wrap entries in header/footer:
    $output = fragment_slurp($DISPLAY_CONF{HEADER})
            . $output
            . fragment_slurp($DISPLAY_CONF{FOOTER});

    return $output;
}

=item output

Returns appropriate output for a given option.

=cut

sub output {
  my ($option) = @_;

  if ( $option =~ m'^[0-9/]{5,11}[a-z_/]+$' ) {
    # nnnn/[nn/nn/]doc_name
    # It's a document within a date.
    return entry_markup(entry_print($option) . datestamp($option));
  }
  elsif ( $option =~ m'^[0-9]{4}/[0-9]{1,2}/[0-9]{1,2}$' ) {
    # nnnn/nn/nn - A specific date.  Print it in full.
    return 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.
    return month_print($option);
  }
  elsif ( $option =~ m'^[0-9]{4}$' ) {
    # nnnn - It's a year. Display a list of entries.
    return year_print($option);
  }
  elsif ($option eq 'portfolio') {
    return entry_print($option, 'all');
  }
  elsif ($option =~ m'^[a-z_]') {
    # Assume it's a document in the root directory.
    return entry_markup(entry_print($option, 'all'));
  }

}


=item expand_query

Expands a CGI query (for example, one passed in from CGI::Fast) to an
appropriate list of parameters.

=cut

sub expand_query {
    my ($option) = shift;
    if ( (ref($option) eq 'CGI::Fast') or (ref($option) eq 'CGI')) {
        return $option->param('keywords');
    } else {
        return $option;
    }
}


=item expand_option

Expands/converts 'all' and 'new' to appropriate values.

=cut

sub expand_option {
    my ($option) = shift;

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

    if ($option eq 'all') {
        return dir_list($DISPLAY_CONF{ROOT_DIR}, 'high_to_low',
                        qr/^[0-9]{1,4}$/); 
    } elsif ($option eq 'new') {
        return recent_month();
    } else {
        return $option;
    }

}


=item recent_month

Tries to find the most recent month in the archive.

If a year file is text, returns that instead.

=cut

sub recent_month {

    my ($dir) = $DISPLAY_CONF{ROOT_DIR};

    # Below replaces:
    # my ($sec, $min, $hour, $mday, $mon,
    #     $year, $wday, $yday, $isdst) = localtime(time);
    my ($mon, $year) = (localtime time)[4,5];

    $mon++;
    $year += 1900;

    if (-e "$dir/$year/$mon") {
        return "$year/$mon";
    }
    else {

        my @year_files = dir_list($dir, 'high_to_low', qr/^[0-9]{1,4}$/);

        if (-T "$dir/$year_files[0]") {
            return $year_files[0];
        }

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

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

}


=item month_before

Return the month before the given month in the archive.

Very naive; there has got to be a smarter way.

=cut

{ my %cache; # cheap memoization

  sub month_before {
    my ($this_month) = @_;

    if (exists $cache{$this_month}) {
      return $cache{$this_month};
    }

    my ($year, $month) = ( $this_month =~ m/^            # start of string
                        ([0-9]{4})   # 4 digit year
                        \/           #
                        ([0-9]{1,2}) # 2 digit month
                        /x );

    if ($month == 1) {
      $month = 12;
      $year  = $year - 1;
    } else {
      $month--;
    }

    until (-e "$DISPLAY_CONF{ROOT_DIR}/$year/$month") {

      if (! -d "$DISPLAY_CONF{ROOT_DIR}/$year") {
        # give up easily
        return 0;
      }

      # handle January:
      if ($month == 1) {
        $month = 12;
        $year--;
        next;
      }
      $month--;
    }

    return $cache{$this_month} = "$year/$month";

  }
}


=item dir_list

Return a $sort_order sorted list of files matching regex $pattern in a
directory.

Calls $sort_order, which can be one of:

         alpha - alphabetical 
 reverse_alpha - alphabetical, reversed
   high_to_low - numeric, high to low
   low_to_high - numeric, low to high

=cut

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

    opendir LIST_DIR, $dir
      or die "Couldn't open $dir: $!";

    my @files = sort $sort_order
                     grep { m/$file_pattern/ }
                     readdir LIST_DIR;

    closedir LIST_DIR;

    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.

=cut

sub year_print {
    my ($year) = @_;
    my ($year_file) = "$DISPLAY_CONF{ROOT_DIR}/$year";
    my ($year_url) = "$DISPLAY_CONF{URL_ROOT}$year";
    my $result;

    if (-d $year_file) {

        # Handle year directories with index files.
        $result .= entry_print($year) if -T "$year_file/index";
        
        # this is stupid:
        my $header_text = icon_markup($year, $year);
        $header_text = '' unless $header_text;

        $result .= heading("$header_text $year", 3);

        my @months = dir_list($year_file, 'high_to_low', qr/^[0-9]{1,2}$/);

        my $year_text;
        my $count = 0; # explicitly defined for later printing.

        foreach my $month (@months) {
            my @entries = dir_list("$year_file/$month", 'low_to_high',
                                   qr/^[0-9]{1,2}$/);

            # Add the count of files to $update_count:
            $count += @entries;
            
            my $month_text;
            foreach my $entry (@entries) {
                $month_text .= a("href: $year_url/$month/$entry", $entry) . "\n";
            }
            $month_text = small('(' . $month_text . ')');
          
            my $link = a("href: $year_url/$month", month_name($month));
            $year_text .= table_row(
                            table_cell('class: datelink', $link),
                            table_cell('class: datelink', $month_text)
                          ) . "\n\n";
        }

        $result .= "\n\n" . table($year_text) . "\n";

        if ($count > 1) {
            my ($average) = int($count / @months);
            $count = "$count entries, roughly $average an active month.";
        }
        elsif ($count == 0) { $count = $count . ' entries'; }
        elsif ($count == 1) { $count = $count . ' entry'; }

        $result .= p($count);

    } elsif (-T $year_file) {
        $result .= entry_print($year);
    } else {
        $result .= p('No such year.');
    }

    return entry_markup($result);
}

=item month_print

Prints the entries in a given month (nnnn/nn).

=cut

sub month_print {
    my ($month) = @_;
    my $month_file = "$DISPLAY_CONF{ROOT_DIR}/$month";
    my $result;

    # 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.
    if (-d $month_file) {
        if (-T "$month_file/index") {
            $result .= entry_print($month);
        }

        my @entry_files = dir_list ($month_file, 'high_to_low',
                                      qr/^[0-9]{1,2}$/);
    
        foreach my $entry_file (@entry_files) {
           $result .= entry_markup( entry_print("$month/$entry_file")
                                    . datestamp("$month/$entry_file") );
        }

    } elsif (-T $month_file) {
        $result .= entry_print($month);
    }

    $result .= p( 'class: centerpiece',
                  a("href: $DISPLAY_CONF{URL_ROOT}" . month_before($month), 'previous') ) . "\n\n";

    return $result;
}


=item entry_print

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

=cut

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

    # location of entry on local filesystem, and its URL:
    my $entry_loc = "$DISPLAY_CONF{ROOT_DIR}/$entry";
    my $entry_url = $DISPLAY_CONF{URL_ROOT} . $entry;
    
    my $result;

    # display an icon, if we have one:
    if ( my $ico_markup = icon_markup($entry) ) {
        $result .= heading($ico_markup, 2) . "\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");

        # followed by any sub-entries:

        my @sub_entries = get_sub_entries($entry_loc);

        if ( $level eq 'index' and @sub_entries >= 1 ) {
            # spit out icons or text links for extra files
            $result .= list_contents($entry, @sub_entries);
        } elsif ( $level eq 'all' and @sub_entries >= 1 ) {

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

            foreach my $se (@sub_entries) {
                next if ($se =~ m/[.](tgz|zip|tar[.]gz|gz|txt)$/);

                # print each of the other files, separated by little headers
                #my $url = "$DISPLAY_CONF{URL_ROOT}$entry/$se";
                #$result .= "\n\n" . p('{' . a("href: $url", $se) . '}') . "\n\n";

                $result .= p('class: centerpiece', '+');
                $result .= entry_print("$entry/$se");
            }

        } 

    }

    return $result;
}

sub get_sub_entries {
  my $entry_loc = shift;
  my $match = qr/^[a-z_]+(\.(tgz|zip|tar[.]gz|gz|txt))?$/;

  my %ignore = ('index' => 1);
  return grep { ! $ignore{$_} } dir_list ($entry_loc, 'alpha', $match);
}

sub list_contents {
  my ($entry) = shift;
  my (@entries) = @_;

  my $contents;
  foreach my $se (@entries) {
    my $linktext = icon_markup("$entry/$se", $se);
    $linktext = $se unless $linktext;

    $contents .= ' ' . a("href: $DISPLAY_CONF{URL_ROOT}$entry/$se",
        $linktext,
        "title: $se");
  }

  return p( em('more') . ": $contents" ) . "\n";

}

=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

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 gif 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.

=cut

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

    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 .= a("href: $WalaConf{ScriptName}?$wiki_date_name",
                            'read the margins',
                            'title: a page you can edit');
        } else {
            $wikistamp .= a("href: $WalaConf{ScriptName}?$wiki_date_name",
                            'write in the margins',
                            'title: a page you can edit');
        }
           
        # return a fancy datestamp.

        my $month_name = month_name($entry_month);
        my $year_url = "href: $DISPLAY_CONF{URL_ROOT}$entry_year";
        $stamp = "\n  "
               . a($year_url, $entry_year, "title: $entry_year") . "\n  "
               . a("$year_url/$entry_month", $month_name, "title: $entry_year/$entry_month") . "\n  "
               . a("$year_url/$entry_month/$entry_day", $entry_day, "title: $entry_year/$entry_month/$entry_day") . "\n  "
               . $wikistamp . "\n";
    } else {
        $stamp = "(failed to construct datestamp for $entry)";
    }

    return p('class: datelink', $stamp);
}


=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.

This might be the place to implement an in-memory cache for FastCGI or mod_perl
environments.  The trick is that the line_parse() results for certain files
shouldn't be cached because they contain embedded code.

=cut

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

    # if $file is text
    if (-T $file) {
        my $everything;
    
        open my $fh, '<', $file
            or die "Couldn't open $file: $!\n";

        {
            # line sep
            local $/ = undef;
            $everything = <$fh>;
        }

        close $fh or die "Couldn't close: $!";

        # eval embedded Perl and ${variables}:
        eval_perl($everything);

        # Take care of any special markup.
        # We pass along $file so it has some context to work with

        return line_parse ($everything, $file);

    } else {
        return q{};
    }
}


=item eval_perl

Evaluate embedded Perl in a string, replacing blocks enclosed with <perl> tags
with whatever they return (well, evaluated in a scalar context). Modifies
a string in-place, so be careful.

Also handles simple ${variables}, replacing them (for now) from %DISPLAY_CONF
values.

=cut

sub eval_perl {

    while ($_[0] =~ m/<perl>(.*?)<\/perl>/s) {
        my $block = $1;

        my $output = eval $block;

        if ($@) {
          # got an error
          $_[0] =~ s/<perl>\Q$block\E<\/perl>/$@/s;
        } else {
          # include anything returned from $block
          $_[0] =~ s/<perl>\Q$block\E<\/perl>/$output/s;
        }
    }

    # interpolate variables
    $_[0] =~ s/\${([a-zA-Z_]+)}/$DISPLAY_CONF{$1}/ge;

    return;
}


=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

Return an Atom feed of entries for a month. Defaults to the most
recent month in the archive.

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

=cut

sub feed_print {
    my $month = shift;
    $month = recent_month() unless defined $month;

    # 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},
        generator => "Display.pm / XML::Atom::SimpleFeed",
    );

    # 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',
                                   qr/^[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");

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

    }

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

}



=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;