path: root/doc/tips/convert_mediawiki_to_ikiwiki/discussion.mdwn

The u32 page is excellent, but I wonder if documenting the procedure here
would be worthwhile. Who knows, the remote site might disappear. But also
there are some variations on the approach that might be useful:

 * using a python script and the dom library to extract the page names from
   Special:Allpages (such as
   <http://www.staff.ncl.ac.uk/jon.dowland/unix/docs/get_pagenames.py>)
 * Or, querying the mysql back-end to get the names
 * using WWW::MediaWiki for importing/exporting pages from the wiki, instead
   of Special::Export

Also, some detail on converting mediawiki transclusion to ikiwiki inlines...

-- [[users/Jon]]

> "Who knows, the remote site might disappear.". Right now, it appears to
> have done just that. -- [[users/Jon]]


The iki-fast-load ruby script from the u32 page is given below:

        #!/usr/bin/env ruby

        # This script is called on the final sorted, de-spammed revision
        # XML file.
        #
        # It doesn't currently check for no-op revisions...  I believe
        # that git-fast-load will dutifully load them even though nothing
        # happened.  I don't care to solve this by adding a file cache
        # to this script.  You can run iki-diff-next.rb to highlight any
        # empty revisions that need to be removed.
        #
        # This turns each node into an equivalent file.
        #    It does not convert spaces to underscores in file names.
        #       This would break wikilinks.
        #       I suppose you could fix this with mod_speling or mod_rewrite.
        #
        # It replaces nodes in the Image: namespace with the files themselves.


        require 'rubygems'
        require 'node-callback'
        require 'time'
        require 'ostruct'


        # pipe is the stream to receive the git-fast-import commands
        # putfrom is true if this branch has existing commits on it, false if not.
        def format_git_commit(pipe, f)
           # Need to escape backslashes and double-quotes for git?
           # No, git breaks when I do this. 
           # For the filename "path with \\", git sez: bad default revision 'HEAD'
           # filename = '"' + filename.gsub('\\', '\\\\\\\\').gsub('"', '\\"') + '"'

           # In the calls below, length must be the size in bytes!!
           # TODO: I haven't figured out how this works in the land of UTF8 and Ruby 1.9.
           pipe.puts "commit #{f.branch}"
           pipe.puts "committer #{f.username} <#{f.email}> #{f.timestamp.rfc2822}"
           pipe.puts "data #{f.message.length}\n#{f.message}\n"
           pipe.puts "from #{f.branch}^0" if f.putfrom
           pipe.puts "M 644 inline #{f.filename}"
           pipe.puts "data #{f.content.length}\n#{f.content}\n"
           pipe.puts
        end


Mediawiki.pm - A plugin which supports mediawiki format.

	#!/usr/bin/perl
	# By Scott Bronson.  Licensed under the GPLv2+ License.
	# Extends Ikiwiki to be able to handle Mediawiki markup.
	#
	# To use the Mediawiki Plugin:
	# - Install Text::MediawikiFormat
	# - Turn of prefix_directives in your setup file.
	#     (TODO: we probably don't need to do this anymore?)
	#        prefix_directives => 1,
	# - Add this plugin on Ikiwiki's path (perl -V, look for @INC)
	#       cp mediawiki.pm something/IkiWiki/Plugin
	# - And enable it in your setup file
	#        add_plugins => [qw{mediawiki}],
	# - Finally, turn off the link plugin in setup (this is important)
	#        disable_plugins => [qw{link}],
	# - Rebuild everything (actually, this should be automatic right?)
	# - Now all files with a .mediawiki extension should be rendered properly.
	
	
	package IkiWiki::Plugin::mediawiki;
	
	use warnings;
	use strict;
	use IkiWiki 2.00;
	use URI;
	
	
	# This is a gross hack...  We disable the link plugin so that our
	# linkify routine is always called.  Then we call the link plugin
	# directly for all non-mediawiki pages.  Ouch...  Hopefully Ikiwiki
	# will be updated soon to support multiple link plugins.
	require IkiWiki::Plugin::link;
	
	# Even if T:MwF is not installed, we can still handle all the linking.
	# The user will just see Mediawiki markup rather than formatted markup.
	eval q{use Text::MediawikiFormat ()};
	my $markup_disabled = $@;
	
	# Work around a UTF8 bug in Text::MediawikiFormat
	# http://rt.cpan.org/Public/Bug/Display.html?id=26880
	unless($markup_disabled) {
	   no strict 'refs';
	   no warnings;
	   *{'Text::MediawikiFormat::uri_escape'} = \&URI::Escape::uri_escape_utf8;
	}
	
	my %metaheaders;    # keeps track of redirects for pagetemplate.
	my %tags;      # keeps track of tags for pagetemplate.
	
	
	sub import { #{{{
	   hook(type => "checkconfig", id => "mediawiki", call => \&checkconfig);
	   hook(type => "scan", id => "mediawiki", call => \&scan);
	   hook(type => "linkify", id => "mediawiki", call => \&linkify);
	   hook(type => "htmlize", id => "mediawiki", call => \&htmlize);
	   hook(type => "pagetemplate", id => "mediawiki", call => \&pagetemplate);
	} # }}}
	
	
	sub checkconfig
	{
	   return IkiWiki::Plugin::link::checkconfig(@_);
	}
	
	
	my $link_regexp = qr{
	    \[\[(?=[^!])        # beginning of link
	    ([^\n\r\]#|<>]+)      # 1: page to link to
	    (?:
	        \#              # '#', beginning of anchor
	        ([^|\]]+)       # 2: anchor text
	    )?                  # optional
	
	    (?:
	        \|              # followed by '|'
	        ([^\]\|]*)      # 3: link text
	    )?                  # optional
	    \]\]                # end of link
	        ([a-zA-Z]*)   # optional trailing alphas
	}x;
	
	
	# Convert spaces in the passed-in string into underscores.
	# If passed in undef, returns undef without throwing errors.
	sub underscorize
	{
	   my $var = shift;
	   $var =~ tr{ }{_} if $var;
	   return $var;
	}
	
	
	# Underscorize, strip leading and trailing space, and scrunch
	# multiple runs of spaces into one underscore.
	sub scrunch
	{
	   my $var = shift;
	   if($var) {
	      $var =~ s/^\s+|\s+$//g;      # strip leading and trailing space
	      $var =~ s/\s+/ /g;      # squash multiple spaces to one
	   }
	   return $var;
	}
	
	
	# Translates Mediawiki paths into Ikiwiki paths.
	# It needs to be pretty careful because Mediawiki and Ikiwiki handle
	# relative vs. absolute exactly opposite from each other.
	sub translate_path
	{
	   my $page = shift;
	   my $path = scrunch(shift);
	
	   # always start from root unless we're doing relative shenanigans.
	   $page = "/" unless $path =~ /^(?:\/|\.\.)/;
	
	   my @result = ();
	   for(split(/\//, "$page/$path")) {
	      if($_ eq '..') {
	         pop @result;
	      } else {
	         push @result, $_ if $_ ne "";
	      }
	   }
	
	   # temporary hack working around http://ikiwiki.info/bugs/Can__39__t_create_root_page/index.html?updated
	   # put this back the way it was once this bug is fixed upstream.
	   # This is actually a major problem because now Mediawiki pages can't link from /Git/git-svn to /git-svn.  And upstream appears to be uninterested in fixing this bug.  :(
	   # return "/" . join("/", @result);
	   return join("/", @result);
	}
	
	
	# Figures out the human-readable text for a wikilink
	sub linktext
	{
	   my($page, $inlink, $anchor, $title, $trailing) = @_;
	   my $link = translate_path($page,$inlink);
	
	   # translate_path always produces an absolute link.
	   # get rid of the leading slash before we display this link.
	   $link =~ s#^/##;
	
	   my $out = "";
	   if($title) {
	       $out = IkiWiki::pagetitle($title);
	   } else {
	      $link = $inlink if $inlink =~ /^\s*\//;
	       $out = $anchor ? "$link#$anchor" : $link;
	      if(defined $title && $title eq "") {
	         # a bare pipe appeared in the link...
	         # user wants to strip namespace and trailing parens.
	         $out =~ s/^[A-Za-z0-9_-]*://;
	         $out =~ s/\s*\(.*\)\s*$//;
	      }
	      # A trailing slash suppresses the leading slash
	      $out =~ s#^/(.*)/$#$1#;
	   }
	   $out .= $trailing if defined $trailing;
	   return $out;
	}
	
	
	sub tagpage ($)
	{
	   my $tag=shift;
	
	   if (exists $config{tagbase} && defined $config{tagbase}) {
	      $tag=$config{tagbase}."/".$tag;
	   }
	
	   return $tag;
	}
	
	
	# Pass a URL and optional text associated with it.  This call turns
	# it into fully-formatted HTML the same way Mediawiki would.
	# Counter is used to number untitled links sequentially on the page.
	# It should be set to 1 when you start parsing a new page.  This call
	# increments it automatically.
	sub generate_external_link
	{
	   my $url = shift;
	   my $text = shift;
	   my $counter = shift;
	
	   # Mediawiki trims off trailing commas.
	   # And apparently it does entity substitution first.
	   # Since we can't, we'll fake it.
	
	   # trim any leading and trailing whitespace
	   $url =~ s/^\s+|\s+$//g;
	
	   # url properly terminates on > but must special-case &gt;
	   my $trailer = "";
	   $url =~ s{(\&(?:gt|lt)\;.*)$}{ $trailer = $1, ''; }eg;
	
	   # Trim some potential trailing chars, put them outside the link.
	   my $tmptrail = "";
	   $url =~ s{([,)]+)$}{ $tmptrail .= $1, ''; }eg;
	   $trailer = $tmptrail . $trailer;
	
	   my $title = $url;
	   if(defined $text) {
	      if($text eq "") {
	         $text = "[$$counter]";
	         $$counter += 1;
	      }
	      $text =~ s/^\s+|\s+$//g;
	      $text =~ s/^\|//;
	   } else {
	      $text = $url;
	   }
	
	   return "<a href='$url' title='$title'>$text</a>$trailer";
	}
	
	
	# Called to handle bookmarks like [[#heading]] or <span class="createlink"><a href="http://u32.net/cgi-bin/ikiwiki.cgi?page=%20text%20&amp;from=Mediawiki_Plugin%2Fmediawiki&amp;do=create" rel="nofollow">?</a>#a</span>
	sub generate_fragment_link
	{
	   my $url = shift;
	   my $text = shift;
	
	   my $inurl = $url;
	   my $intext = $text;
	   $url = scrunch($url);
	
	   if(defined($text) && $text ne "") {
	      $text = scrunch($text);
	   } else {
	      $text = $url;
	   }
	
	   $url = underscorize($url);
	
	   # For some reason Mediawiki puts blank titles on all its fragment links.
	   # I don't see why we would duplicate that behavior here.
	   return "<a href='$url'>$text</a>";
	}
	
	
	sub generate_internal_link
	{
	   my($page, $inlink, $anchor, $title, $trailing, $proc) = @_;
	
	   # Ikiwiki's link link plugin wrecks this line when displaying on the site.
	   # Until the code highlighter plugin can turn off link finding,
	   # always escape double brackets in double quotes: [[
	   if($inlink eq '..') {
	      # Mediawiki doesn't touch links like [[..#hi|ho]].
	      return "[[" . $inlink . ($anchor?"#$anchor":"") .
	         ($title?"|$title":"") . "]]" . $trailing;
	   }
	
	   my($linkpage, $linktext);
	   if($inlink =~ /^ (:?) \s* Category (\s* \: \s*) ([^\]]*) $/x) {
	      # Handle category links
	      my $sep = $2;
	      $inlink = $3;
	      $linkpage = IkiWiki::linkpage(translate_path($page, $inlink));
	      if($1) {
	         # Produce a link but don't add this page to the given category.
	         $linkpage = tagpage($linkpage);
	         $linktext = ($title ? '' : "Category$sep") .
	            linktext($page, $inlink, $anchor, $title, $trailing);
	         $tags{$page}{$linkpage} = 1;
	      } else {
	         # Add this page to the given category but don't produce a link.
	         $tags{$page}{$linkpage} = 1;
	         &$proc(tagpage($linkpage), $linktext, $anchor);
	         return "";
	      }
	   } else {
	      # It's just a regular link
	      $linkpage = IkiWiki::linkpage(translate_path($page, $inlink));
	      $linktext = linktext($page, $inlink, $anchor, $title, $trailing);
	   }
	
	   return &$proc($linkpage, $linktext, $anchor);
	}
	
	
	sub check_redirect
	{
	   my %params=@_;
	
	   my $page=$params{page};
	   my $destpage=$params{destpage};
	   my $content=$params{content};
	
	   return "" if $page ne $destpage;
	
	   if($content !~ /^ \s* \#REDIRECT \s* \[\[ ( [^\]]+ ) \]\]/x) {
	      # this page isn't a redirect, render it normally.
	      return undef;
	   }
	
	   # The rest of this function is copied from the redir clause
	   # in meta::preprocess and actually handles the redirect.
	
	   my $value = $1;
	   $value =~ s/^\s+|\s+$//g;
	
	   my $safe=0;
	   if ($value !~ /^\w+:\/\//) {
	      # it's a local link
	      my ($redir_page, $redir_anchor) = split /\#/, $value;
	
	      add_depends($page, $redir_page);
	      my $link=bestlink($page, underscorize(translate_path($page,$redir_page)));
	      if (! length $link) {
	         return "<b>Redirect Error:</b> <nowiki>[[$redir_page]] not found.</nowiki>";
	      }
	
	      $value=urlto($link, $page);
	      $value.='#'.$redir_anchor if defined $redir_anchor;
	      $safe=1;
	
	      # redir cycle detection
	      $pagestate{$page}{mediawiki}{redir}=$link;
	      my $at=$page;
	      my %seen;
	      while (exists $pagestate{$at}{mediawiki}{redir}) {
	         if ($seen{$at}) {
	            return "<b>Redirect Error:</b> cycle found on <nowiki>[[$at]]</nowiki>";
	         }
	         $seen{$at}=1;
	         $at=$pagestate{$at}{mediawiki}{redir};
	      }
	   } else {
	      # it's an external link
	      $value = encode_entities($value);
	   }
	
	   my $redir="<meta http-equiv=\"refresh\" content=\"0; URL=$value\" />";
	   $redir=scrub($redir) if !$safe;
	   push @{$metaheaders{$page}}, $redir;
	
	   return "Redirecting to $value ...";
	}
	
	
	# Feed this routine a string containing <nowiki>...</nowiki> sections,
	# this routine calls your callback for every section not within nowikis,
	# collecting its return values and returning the rewritten string.
	sub skip_nowiki
	{
	   my $content = shift;
	   my $proc = shift;
	
	   my $result = "";
	   my $state = 0;
	
	   for(split(/(<nowiki[^>]*>.*?<\/nowiki\s*>)/s, $content)) {
	      $result .= ($state ? $_ : &$proc($_));
	      $state = !$state;
	   }
	
	   return $result;
	}
	
	
	# Converts all links in the page, wiki and otherwise.
	sub linkify (@)
	{
	   my %params=@_;
	
	   my $page=$params{page};
	   my $destpage=$params{destpage};
	   my $content=$params{content};
	
	   my $file=$pagesources{$page};
	   my $type=pagetype($file);
	   my $counter = 1;
	
	   if($type ne 'mediawiki') {
	      return IkiWiki::Plugin::link::linkify(@_);
	   }
	
	   my $redir = check_redirect(%params);
	   return $redir if defined $redir;
	
	   # this code was copied from MediawikiFormat.pm.
	   # Heavily changed because MF.pm screws up escaping when it does
	   # this awful hack: $uricCheat =~ tr/://d;
	   my $schemas = [qw(http https ftp mailto gopher)];
	   my $re = join "|", map {qr/\Q$_\E/} @$schemas;
	   my $schemes = qr/(?:$re)/;
	   # And this is copied from URI:
	   my $reserved   = q(;/?@&=+$,);   # NOTE: no colon or [] !
	   my $uric       = quotemeta($reserved) . $URI::unreserved . "%#";
	
	   my $result = skip_nowiki($content, sub {
	      $_ = shift;
	
	      # Escape any anchors
	      #s/<(a[\s>\/])/&lt;$1/ig;
	      # Disabled because this appears to screw up the aggregate plugin.
	      # I guess we'll rely on Iki to post-sanitize this sort of stuff.
	
	      # Replace external links, http://blah or [http://blah]
	      s{\b($schemes:[$uric][:$uric]+)|\[($schemes:[$uric][:$uric]+)([^\]]*?)\]}{
	         generate_external_link($1||$2, $3, \$counter)
	      }eg;
	
	      # Handle links that only contain fragments.
	      s{ \[\[ \s* (\#[^|\]'"<>&;]+) (?:\| ([^\]'"<>&;]*))? \]\] }{
	         generate_fragment_link($1, $2)
	      }xeg;
	
	      # Match all internal links
	      s{$link_regexp}{
	         generate_internal_link($page, $1, $2, $3, $4, sub {
	            my($linkpage, $linktext, $anchor) = @_;
	            return htmllink($page, $destpage, $linkpage,
	               linktext => $linktext,
	               anchor => underscorize(scrunch($anchor)));
	         });
	      }eg;
	   
	      return $_;
	   });
	
	   return $result;
	}
	
	
	# Find all WikiLinks in the page.
	sub scan (@)
	{
	   my %params = @_;
	   my $page=$params{page};
	   my $content=$params{content};
	
	   my $file=$pagesources{$page};
	   my $type=pagetype($file);
	
	   if($type ne 'mediawiki') {
	      return IkiWiki::Plugin::link::scan(@_);
	   }
	
	   skip_nowiki($content, sub {
	      $_ = shift;
	      while(/$link_regexp/g) {
	         generate_internal_link($page, $1, '', '', '', sub {
	            my($linkpage, $linktext, $anchor) = @_;
	            push @{$links{$page}}, $linkpage;
	            return undef;
	         });
	      }
	      return '';
	   });
	}
	
	
	# Convert the page to HTML.
	sub htmlize (@)
	{
	   my %params=@_;
	   my $page = $params{page};
	   my $content = $params{content};
	
	
	   return $content if $markup_disabled;
	
	   # Do a little preprocessing to babysit Text::MediawikiFormat
	   # If a line begins with tabs, T:MwF won't convert it into preformatted blocks.
	   $content =~ s/^\t/    /mg;
	
	   my $ret = Text::MediawikiFormat::format($content, {
	
	       allowed_tags    => [#HTML
	                # MediawikiFormat default
	                qw(b big blockquote br caption center cite code dd
	                   div dl dt em font h1 h2 h3 h4 h5 h6 hr i li ol p
	                   pre rb rp rt ruby s samp small strike strong sub
	                   sup table td th tr tt u ul var),
	                 # Mediawiki Specific
	                 qw(nowiki),
	                 # Our additions
	                 qw(del ins),   # These should have been added all along.
	                 qw(span),   # Mediawiki allows span but that's rather scary...?
	                 qw(a),      # this is unfortunate; should handle links after rendering the page.
	               ],
	
	       allowed_attrs   => [
	                qw(title align lang dir width height bgcolor),
	                qw(clear), # BR
	                qw(noshade), # HR
	                qw(cite), # BLOCKQUOTE, Q
	                qw(size face color), # FONT
	                # For various lists, mostly deprecated but safe
	                qw(type start value compact),
	                # Tables
	                qw(summary width border frame rules cellspacing
	                   cellpadding valign char charoff colgroup col
	                   span abbr axis headers scope rowspan colspan),
	                qw(id class name style), # For CSS
	                # Our additions
	                qw(href),
	               ],
	
	      }, {
	      extended => 0,
	      absolute_links => 0,
	      implicit_links => 0
	      });
	
	   return $ret;
	}
	
	
	# This is only needed to support the check_redirect call.
	sub pagetemplate (@)
	{
	   my %params = @_;
	   my $page = $params{page};
	   my $destpage = $params{destpage};
	   my $template = $params{template};
	
	   # handle metaheaders for redirects
	   if (exists $metaheaders{$page} && $template->query(name => "meta")) {
	   # avoid duplicate meta lines
	      my %seen;
	      $template->param(meta => join("\n", grep { (! $seen{$_}) && ($seen{$_}=1) } @{$metaheaders{$page}}));
	   }
	
	   $template->param(tags => [
	      map {
	         link => htmllink($page, $destpage, tagpage($_), rel => "tag")
	      }, sort keys %{$tags{$page}}
	   ]) if exists $tags{$page} && %{$tags{$page}} && $template->query(name => "tags");
	
	   # It's an rss/atom template. Add any categories.
	   if ($template->query(name => "categories")) {
	      if (exists $tags{$page} && %{$tags{$page}}) {
	         $template->param(categories => [map { category => $_ },
	            sort keys %{$tags{$page}}]);
	      }
	   }
	}
	
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