package MusicBrainz::Server::Plugin::Diff; use strict; use warnings; use feature 'switch'; use base 'Template::Plugin'; use Algorithm::Diff qw( sdiff traverse_sequences ); use Digest::MD5 qw( md5_hex ); use Encode; use HTML::Tiny; use HTML::TreeBuilder; use Scalar::Util qw( blessed ); use MusicBrainz::Server::Translation qw( l ); use MusicBrainz::Server::Validation qw( trim_in_place ); no if $] >= 5.018, warnings => "experimental::smartmatch"; sub html_filter { my $text = shift; return unless defined $text; for ($text) { s/&/&/g; s//>/g; s/"/"/g; } return $text; } sub new { my ($class, $context) = @_; return bless { c => $context }, $class; } sub uri_for_action { my $self = shift; return $self->{c}{STASH}{c}->uri_for_action(@_)->as_string; } my $TOKEN_NEW_PARA = chr(10); my %class_map = ( '+' => 'diff-only-b', '-' => 'diff-only-a' ); my $h = HTML::Tiny->new; sub diff_side { my ($self, $old, $new, $filter, $split) = @_; $split //= ''; my @diffs = sdiff([ _split_text($old // '', $split) ], [ _split_text($new // '', $split) ]); return $self->_render_side_diff($filter, @diffs); } sub diff_html_side { my ($self, $old, $new, $filter) = @_; my $old_root = HTML::TreeBuilder->new_from_content(''.($old // '').''); my @old_tokens = map { _html_token($_) } $old_root->content_array_ref->[1]->content_list; my $new_root = HTML::TreeBuilder->new_from_content(''.($new // '').''); my @new_tokens = map { _html_token($_) } $new_root->content_array_ref->[1]->content_list; my @diffs = sdiff(\@old_tokens, \@new_tokens); return $self->_render_side_diff($filter, @diffs); } sub _html_token { my ($item) = @_; return blessed($item) ? $item->as_HTML : _split_text($item, '\s+'); } sub _split_text { my ($text, $split) = @_; my $hex = md5_hex(encode('utf-8', $text)); $text =~ s/($split)/$hex$1/g; return split($hex,$text); } sub _render_side_diff { my ($self, $filter, @diffs) = @_; my @stack; for my $diff (@diffs) { my ($change_type, $old, $new) = @$diff; next unless $change_type eq 'c' || $change_type eq 'u' || $change_type eq $filter; unless ($stack[-1] && $stack[-1]->{type} eq $change_type) { push @stack, { str => '', type => $change_type }; } if ($change_type eq 'c') { $stack[-1]->{str} .= $filter eq '+' ? "$new" : "$old"; } else { $stack[-1]->{str} .= $change_type eq '+' ? $new : $old; } } return join( '', map { my $class = $_->{type} eq 'u' ? '' : $_->{type} eq 'c' ? $class_map{$filter} : $class_map{$_->{type}}; my $text = $_->{str}; $h->span({ class => $class }, $text) } @stack ) } sub _link_artist_credit_name { my ($self, $acn, $name) = @_; my $comment; if ($acn->artist->comment) { $comment = ' (' . $acn->artist->comment . ')'; } else { $comment = ''; } if ($acn->artist->gid) { return $h->a({ href => $self->uri_for_action('/artist/show', [ $acn->artist->gid ]), title => $acn->artist->sort_name . $comment }, $name || html_filter($acn->name)); } else { return $h->span({ class => 'deleted tooltip', title => l('This entity has been removed, and cannot be displayed correctly.') }, $name || html_filter($acn->name)); } } sub _link_joined { my ($self, $acn) = @_; return $self->_link_artist_credit_name($acn) . (html_filter($acn->join_phrase) || ''); } sub diff_artist_credits { my ($self, $old, $new) = @_; my @diffs = sdiff( $old->names, $new->names, sub { my $name = shift; join( '', $name->artist->id || 'deleted', $name->name, $name->join_phrase || '' ); } ); my %sides = map { $_ => '' } qw( old new ); for my $diff (@diffs) { my ($change_type, $old_name, $new_name) = @$diff; given ($change_type) { when ('u') { my $html = $self->_link_joined($old_name); $sides{old} .= $html; $sides{new} .= $html; }; when ('c') { # Diff the credited names $sides{old} .= $self->_link_artist_credit_name( $old_name, $self->diff_side($old_name->name, $new_name->name, '-','\s+') ); $sides{new} .= $self->_link_artist_credit_name( $new_name, $self->diff_side($old_name->name, $new_name->name, '+', '\s+') ); # Diff the join phrases $sides{old} .= $self->diff_side($old_name->join_phrase, $new_name->join_phrase, '-', '\s+'); $sides{new} .= $self->diff_side($old_name->join_phrase, $new_name->join_phrase, '+', '\s+'); } when ('-') { $sides{old} .= $h->span( { class => $class_map{'-'} }, $self->_link_joined($old_name) ); } when ('+') { $sides{new} .= $h->span( { class => $class_map{'+'} }, $self->_link_joined($new_name) ); } } } return \%sides; } sub diff { my ($self, $old, $new) = @_; my $h = HTML::Tiny->new; my @spans; my @a = parse_paragraphs($old); my @b = parse_paragraphs($new); my %buffers = ( MATCH => '', DISCARD_A => '', DISCARD_B => '' ); my %classes = ( MATCH => 'diff-match', DISCARD_A => 'diff-only-a', DISCARD_B => 'diff-only-b', ); my $flush = sub { my $exclude = shift; while (my ($key, $class) = each %classes) { next if $exclude eq $key || !$buffers{$key}; push @spans, $h->span({ class => $class }, $buffers{$key}); $buffers{$key} = ''; } }; my @compact = traverse_sequences( \@a, \@b, { MATCH => sub { $flush->('MATCH'); $buffers{MATCH} .= $a[shift]; }, DISCARD_A => sub { $flush->('DISCARD_A'); $buffers{DISCARD_A} .= $a[shift]; }, DISCARD_B => sub { $flush->('DISCARD_B'); shift; $buffers{DISCARD_B} .= $b[shift]; }, } ); $flush->(''); return $h->div({ class => 'diff' }, \@spans); } sub parse_text { my ($text) = @_; $text =~ s/\s+/ /g; $text =~ s/\A //g; $text =~ s/ \z//g; # The spaces between words are included as part of the word tokens to make # the "diff" output more intuitive; for example if you diff "a big red # ball" to "a small green ball", the obvious diff is s/big red/small # green/. If spaces were their own tokens, the diff would be s/big/small/ # and s/red/green/. return split /(?= )/, $text; } sub parse_paragraphs { my $text = shift; $text =~ s/(\015\012|\012\015|\012|\015)\1+/\n\n/g; trim_in_place($text); my @paras = split /\n\n+/, $text; my @out; for my $p (@paras) { # push @out, $TOKEN_NEW_PARA if @out; push @out, parse_text($p); } return @out; } 1;