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

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);

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
    $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.

  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.

    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.

    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 header and
    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.)

    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>

    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.

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

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

    output
        Returns appropriate output for a given option.

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

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

    recent_month
        Tries to find the most recent month in the archive.

        If a year file is text, returns that instead.

    month_before
        Return the month before the given month in the archive.

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

    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

    year_print
        List out the updates for a year.

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

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

    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.

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

    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.

    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.

    month_name
        Turn numeric dates into English.

    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.

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

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.