#!/usr/bin/perl -w
#
# Copyright (C) 2007  Alex Schroeder <alex@gnu.org>
#
# This program 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 3 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.
#
# You should have received a copy of the GNU General Public License
# along with this program.  If not, see <http://www.gnu.org/licenses/>.

require LWP;
use Getopt::Std;

our ($opt_v, $opt_w, $opt_f);

# We make our own specialization of LWP::UserAgent that asks for
# user/password if document is protected.
{
  package RequestAgent;
  @ISA = qw(LWP::UserAgent);

  sub new {
    my $self = LWP::UserAgent::new(@_);
    $self;
  }

  sub get_basic_credentials {
    my($self, $realm, $uri) = @_;
    return split(':', $main::opt_w, 2);
  }
}

my $usage = qq{$0 [-i URL] [-t SECONDS]
\t[-u USERNAME] [-p PASSWORD] [-w USERNAME:PASSWORD]
\t[-f FORMAT] [-a TAG] [-d TAG] [TARGET]

TARGET is the base URL for the wiki. Visiting this URL should show you
its homepage.

You add a TAG using -a and delete it using -d. Multiple tags can be
separated by a space or a comma.

FORMAT defaults to [[tag:TheTag]]. If you use just words, specify -f1.

Provide the page names to retag on STDIN or use -i to point to a page.
You can use the index action with the raw parameter. See example
below.

The list of page names should use the MIME type text/plain.

By default, retag will tag a page every five seconds. Use -t to
override this. SECONDS is the number of seconds to wait between
requests.

The edits will show up on the list of changes as anonymous edits. If
you want to provide a USERNAME, you can use -u to do so.

If you want to tag pages on a locked wiki, you need to provide a
PASSWORD using -p.

On the other hand, if your wiki is protected by so-called "basic
authentication" -- that is, if you need to provide a username and
password before you can even view the site -- then you can pass those
along using the -w option. Separate username and password using a
colon.

Example:

retag -i 'http://www.emacswiki.org/cgi-bin/alex?search=tag%3Akitsunemori+2006+2007;context=0;raw=1' \\
      -u AlexSchroeder -a MondayGroup http://www.emacswiki.org/cgi-bin/alex
};

sub UrlEncode {
  my $str = shift;
  return '' unless $str;
  my @letters = split(//, $str);
  my @safe = ('a' .. 'z', 'A' .. 'Z', '0' .. '9', '-', '_', '.', '!', '~', '*', "'", '(', ')', '#');
  foreach my $letter (@letters) {
    my $pattern = quotemeta($letter);
    if (not grep(/$pattern/, @safe)) {
      $letter = sprintf("%%%02x", ord($letter));
    }
  }
  return join('', @letters);
}

sub GetRaw {
  my ($uri) = @_;
  my $ua = RequestAgent->new;
  my $response = $ua->get($uri);
  print "no response\n" unless $response->code;
  print "GET ", $response->code, " ", $response->message, "\n" if $opt_v;
  return $response->content if $response->is_success;
}

my $FreeLinkPattern = "([-,.()' _0-9A-Za-z\x80-\xff]+)";

sub PostRaw {
  my ($uri, $id, $data, $username, $password) = @_;
  my $ua = RequestAgent->new;
  my $response = $ua->post($uri, {title=>$id, text=>$data, raw=>1,
				  question=>1, recent_edit=>'on',
				  username=>$username, pwd=>$password});
  my $status = $response->code . ' ' . $response->message;
  warn "POST $id failed: $status.\n" unless $response->is_success;
}

sub tag {
  my ($target, $interval, $username, $password,
      $pageref, $addref, $delref) = @_;
  foreach my $id (@$pageref) {
    print "$id\n";
    my $page = UrlEncode ($id);
    my $data = GetRaw("$target?action=browse;id=$page;raw=1");
    # Every page starts with a new copy.
    my %tags = map { $_ => 1 } @$addref;
    # The current code does not remove tags sprinkled all over the
    # page. The code will in fact add those tags to the final tagline.
    if ($data =~ /\n\nTags: (.*)/) {
      my $tags = $1;
      if ($opt_f) {
	foreach my $tag (split /,\s*/, $1) {
	  $tags{$tag} = 1;
	}
      } else {
	while ($tags =~ /\[\[tag:$FreeLinkPattern(\|[^]|]+)?\]\]/ogi) {
	  $tags{$1} = 1;
	}
      }
      foreach my $tag (@$delref) {
	delete $tags{$tag};
      }
    }
    my $newtags;
    if ($opt_f) {
      $newtags = join(', ', sort keys %tags);
    } else {
      $newtags = join(' ', map { "\[\[tag:$_\]\]" } sort keys %tags);
    }
    # The code will not remove the tagline if the last tag is removed.
    # It will add a tagline if there is none.
    $data =~ s/\n\nTags: .*/\n\nTags: $newtags/ or $data .= "\n\nTags: $newtags";
    PostRaw($target, $id, $data, $username, $password);
    sleep($interval);
  }
}

sub main {
  our($opt_h, $opt_i, $opt_t, $opt_d, $opt_u, $opt_p);
  getopts('hvi:t:u:p:w:a:d:f:');
  die $usage if $opt_h;
  die "Missing tags to add or delete. Use -a TAG or -d TAG.\n"
    unless $opt_a or $opt_d;
  my $interval = $opt_t ? $opt_t : 5;
  my (@add, @delete);
  @add = split(/[ ,]+/, $opt_a) if $opt_a;
  @delete = split(/[ ,]+/, $opt_d) if $opt_d;
  my $username = $opt_u;
  my $password = $opt_p;
  my $target = shift(@ARGV);
  die "You need to provide exactly one target URL. Use -h for more help.\n"
    unless $target and not @ARGV;
  my @pages = ();
  if ($opt_i) {
    my $data = GetRaw($opt_i);
    @pages = split(/\n/, $data);
  } else {
    print "List of pages:\n";
    while (<STDIN>) {
      chomp;
      push(@pages, $_);
    }
  }
  die "The list of pages is missing.  Use -i.\n" unless @pages;
  tag($target, $interval, $username, $password, \@pages, \@add, \@delete);
}

main();