From dcfaac392679c3ad031fc9b5806878b76bb4bf09 Mon Sep 17 00:00:00 2001
From: =?UTF-8?q?Francisco=20Javier=20L=C3=B3pez?= <fjlopez@gitlab.com>
Date: Thu, 11 Mar 2021 18:38:59 +0100
Subject: [PATCH] Add redirections file to wiki

---
 app/controllers/concerns/wiki_actions.rb |  2 ++
 app/models/wiki.rb                       | 31 ++++++++++++++++++++++++
 2 files changed, 33 insertions(+)

diff --git a/app/controllers/concerns/wiki_actions.rb b/app/controllers/concerns/wiki_actions.rb
index 60ff0a12d0ccb6..df1392527ef989 100644
--- a/app/controllers/concerns/wiki_actions.rb
+++ b/app/controllers/concerns/wiki_actions.rb
@@ -81,6 +81,8 @@ def show
       render 'shared/wikis/show'
     elsif file_blob
       send_blob(wiki.repository, file_blob)
+    elsif redirected_page = wiki.find_redirection(params[:id])
+      redirect_to wiki_page_path(wiki, redirected_page)
     elsif show_create_form?
       # Assign a title to the WikiPage unless `id` is a randomly generated slug from #new
       title = params[:id] unless params[:random_title].present?
diff --git a/app/models/wiki.rb b/app/models/wiki.rb
index 45747c0b03c484..0bea51d017a003 100644
--- a/app/models/wiki.rb
+++ b/app/models/wiki.rb
@@ -18,6 +18,8 @@ class Wiki
 
   HOMEPAGE = 'home'
   SIDEBAR = '_sidebar'
+  REDIRECTIONS = '_redirections'
+  SPECIAL_FILES = [SIDEBAR, REDIRECTIONS].freeze
 
   TITLE_ORDER = 'title'
   CREATED_AT_ORDER = 'created_at'
@@ -159,6 +161,10 @@ def find_sidebar(version = nil)
     find_page(SIDEBAR, version)
   end
 
+  def find_redirection(path)
+    redirections[path]
+  end
+
   def find_file(name, version = nil)
     wiki.file(name, version)
   end
@@ -281,6 +287,31 @@ def commit_details(action, message = nil, title = nil)
   def default_message(action, title)
     "#{user.username} #{action} page: #{title}"
   end
+
+  def redirections
+    strong_memoize(:redirections) do
+      redirection_file = find_redirections_file
+
+      {}.tap do |route_table|
+        next route_table unless redirection_file
+
+        redirection_file.content.each_line do |line|
+          route_mapping = line.tr(' ', '').match(/^(.+)->(.+)$/)
+
+          next unless route_mapping
+          next if route_mapping[1] == route_mapping[2]
+          # Avoid create redirections for special files
+          next if (Wiki::SPECIAL_FILES & [route_mapping[1], route_mapping[2]]).present?
+
+          route_table[route_mapping[1]] = route_mapping[2]
+        end
+      end
+    end
+  end
+
+  def find_redirections_file(version = nil)
+    find_page(REDIRECTIONS, version)
+  end
 end
 
 Wiki.prepend_if_ee('EE::Wiki')
-- 
GitLab