From 28266d9d610123d20333c6b05fcf83d1fb3e336a Mon Sep 17 00:00:00 2001
From: Gabriel Mazetto <gabriel@gitlab.com>
Date: Fri, 1 Apr 2016 00:17:37 -0300
Subject: [PATCH] Added WikiLinkFilter

---
 lib/banzai/filter/wiki_link_filter.rb | 52 +++++++++++++++++++++++++++
 lib/banzai/pipeline/wiki_pipeline.rb  |  6 ++--
 2 files changed, 56 insertions(+), 2 deletions(-)
 create mode 100644 lib/banzai/filter/wiki_link_filter.rb

diff --git a/lib/banzai/filter/wiki_link_filter.rb b/lib/banzai/filter/wiki_link_filter.rb
new file mode 100644
index 00000000000..7a585eff653
--- /dev/null
+++ b/lib/banzai/filter/wiki_link_filter.rb
@@ -0,0 +1,52 @@
+require 'uri'
+
+module Banzai
+  module Filter
+    # HTML filter that "fixes" relative links to files in a repository.
+    #
+    # Context options:
+    #   :project_wiki
+    class WikiLinkFilter < HTML::Pipeline::Filter
+
+      def call
+        return doc unless project_wiki?
+
+        doc.search('a:not(.gfm)').each do |el|
+          process_link_attr el.attribute('href')
+        end
+
+        doc
+      end
+
+      protected
+
+      def project_wiki?
+        !context[:project_wiki].nil?
+      end
+
+      def process_link_attr(html_attr)
+        return if html_attr.blank?
+
+        uri = URI(html_attr.value)
+        if uri.relative? && uri.path.present? && uri.path
+          html_attr.value = rebuild_wiki_uri(uri).to_s
+        end
+      rescue URI::Error
+        # noop
+      end
+
+      def rebuild_wiki_uri(uri)
+        uri.path = ::File.join(project_wiki_base_path, uri.path)
+        uri
+      end
+
+      def project_wiki
+        context[:project_wiki]
+      end
+
+      def project_wiki_base_path
+        project_wiki && project_wiki.wiki_base_path
+      end
+    end
+  end
+end
diff --git a/lib/banzai/pipeline/wiki_pipeline.rb b/lib/banzai/pipeline/wiki_pipeline.rb
index 0b5a9e0b2b8..1cdb3808961 100644
--- a/lib/banzai/pipeline/wiki_pipeline.rb
+++ b/lib/banzai/pipeline/wiki_pipeline.rb
@@ -2,8 +2,10 @@ module Banzai
   module Pipeline
     class WikiPipeline < FullPipeline
       def self.filters
-        @filters ||= super.insert_after(Filter::TableOfContentsFilter,
-                                        Filter::GollumTagsFilter)
+        @filters ||= begin
+          super.insert_after(Filter::TableOfContentsFilter, Filter::GollumTagsFilter)
+               .insert_after(Filter::GollumTagsFilter, Filter::WikiLinkFilter)
+        end
       end
     end
   end