DEV: Allow plugins to register Onebox handlers (#16870)

This targets only the local Oneboxes and allows plugins to customize
regular or inline Oneboxes for routes inside the site.

lib/inline_oneboxer.rb

@@ -21,6 +21,14 @@ class InlineOneboxer
     Discourse.cache.read(cache_key(url))
   end
 
+  def self.local_handlers
+    @local_handlers ||= {}
+  end
+
+  def self.register_local_handler(controller, &handler)
+    local_handlers[controller] = handler
+  end
+
   def self.lookup(url, opts = nil)
     opts ||= {}
     opts = opts.with_indifferent_access
@@ -46,6 +54,8 @@ class InlineOneboxer
           # not permitted to see topic
           return nil
         end
+      elsif handler = local_handlers[route[:controller]]
+        return handler.call(url, route)
       end
     end
 

lib/oneboxer.rb

@@ -48,6 +48,14 @@ module Oneboxer
     @allowed_post_types ||= [Post.types[:regular], Post.types[:moderator_action]]
   end
 
+  def self.local_handlers
+    @local_handlers ||= {}
+  end
+
+  def self.register_local_handler(controller, &handler)
+    local_handlers[controller] = handler
+  end
+
   def self.preview(url, options = nil)
     options ||= {}
     invalidate(url) if options[:invalidate_oneboxes]
@@ -248,6 +256,10 @@ module Oneboxer
       when "topics"  then local_topic_html(url, route, opts)
       when "users"   then local_user_html(url, route)
       when "list"    then local_category_html(url, route)
+      else
+        if handler = local_handlers[route[:controller]]
+          handler.call(url, route)
+        end
       end
 
     html = html.presence || "<a href='#{URI(url).to_s}'>#{URI(url).to_s}</a>"

spec/lib/inline_oneboxer_spec.rb

@@ -314,4 +314,18 @@ describe InlineOneboxer do
       end
     end
   end
+
+  context "register_local_handler" do
+    it "calls registered local handler" do
+      InlineOneboxer.register_local_handler('wizard') do |url, route|
+        { url: url, title: 'Custom Onebox for Wizard' }
+      end
+
+      url = "#{Discourse.base_url}/wizard"
+      results = InlineOneboxer.new([url], skip_cache: true).process
+      expect(results).to be_present
+      expect(results[0][:url]).to eq(url)
+      expect(results[0][:title]).to eq('Custom Onebox for Wizard')
+    end
+  end
 end

spec/lib/oneboxer_spec.rb

@@ -641,4 +641,14 @@ describe Oneboxer do
     end
   end
 
+  context "register_local_handler" do
+    it "calls registered local handler" do
+      Oneboxer.register_local_handler('wizard') do |url, route|
+        'Custom Onebox for Wizard'
+      end
+
+      url = "#{Discourse.base_url}/wizard"
+      expect(Oneboxer.preview(url)).to eq('Custom Onebox for Wizard')
+    end
+  end
 end