Add footnotes.pl to repo.

footnotes.pl will convert footnotes in
MultiMarkDown format to footnotes for
the Wordpress plugin "footnotes" and back.

Signed-off-by: Thomas Hochstein <thh@inter.net>

footnotes/footnotes.pl

@@ -0,0 +1,107 @@
+#! /usr/bin/perl -W
+#
+# footnotes Version 0.1 by Thomas Hochstein
+#
+# This script will convert footnotes in WP-footnotes notation
+# to MultiMarkDown, i.e. replace "((Text for footnote))" with
+# "[^1]" and add "[^1]: Text for footnote" at the end of the
+# text, incrementing the counter each time, or the other way
+# round.
+# 
+# Copyright (c) 2014 Thomas Hochstein <thh@inter.net>
+#
+# It can be redistributed and/or modified under the same terms under 
+# which Perl itself is published.
+
+my $VERSION = "0.1";
+
+use strict;
+use Getopt::Long qw(GetOptions);
+
+# read commandline option(s)
+my ($OptTo,$OptFile);
+GetOptions ('t|to=s'     => \$OptTo,
+            'f|file=s'   => \$OptFile,
+            'h|help'     => \&ShowPOD,
+            'V|version'  => \&ShowVersion) or exit 1;
+
+# read whole article from STDIN or --file
+undef $/;
+my $article;
+if ($OptFile) {
+  open(FILE, "< $OptFile") or die "Can't open $OptFile: $!";
+  $article = <FILE>;
+  close(FILE);
+} else {
+  $article = <>;
+}
+$/ = "\n";
+
+# conversion and output
+my $output;
+
+if (lc($OptTo) eq 'mmd') {
+  $output = &ConvertToMMD($article);
+} elsif (lc($OptTo) eq 'wp') {
+  $output = &ConvertToWP($article);
+} else {
+	print "Please set '--to' to 'mmd' or 'wp'!\n";
+  exit(1);
+}
+
+print $output;
+exit(0);
+
+################################################################################
+
+sub ConvertToMMD {
+  my $article = shift;
+  my $footnotes;
+  my $counter = 1;
+  
+  # match and remove all ((...)),
+  # replacing them with [^n], incrementing n each time
+  while ( $article =~ s/\(\((.+?)\)\)/"[^$counter]"/seo ) {
+    $footnotes .= "[^$counter]: " . $1 . "\n";
+    $counter++;
+  }
+
+  return "$article\n\n$footnotes\n";
+}
+
+sub ConvertToWP {
+  my $article = shift;
+  my @footnotes;
+  my $counter = 1;
+
+  # read footnotes in [^n] format
+  while ( $article =~ s/^\[\^$counter\]: (.+)$//m ) {
+    $footnotes[$counter] = $1;
+    $counter++;
+  }
+
+  # replace footnote plcaeholders with footnote content
+  $counter = 0;
+  foreach my $footnote (@footnotes) {
+    $article =~ s/\[\^$counter\]/"(($footnote))"/eg;
+    $counter++;
+  }
+
+  # remove trailing whitespace
+  $article =~ s/\n+$//g;
+
+  return "$article\n";
+}
+
+sub ShowVersion {
+  print "MMD-FootNotes v$VERSION\n";
+  print "Copyright (c) 2014 Thomas Hochstein <thh\@inter.net>\n";
+  print "This program is free software; you may redistribute it ".
+        "and/or modify it under the same terms as Perl itself.\n";
+  exit(100);
+};
+
+sub ShowPOD {
+  exec('perldoc', $0);
+  exit(100);
+};