Improve api oembed controller (#3450)

* Add StreamEntryFinder class to parse URLs

* Use StreamEntryFinder and clean up api/oembed controller

app/controllers/api/oembed_controller.rb

@@ -4,30 +4,22 @@ class Api::OEmbedController < ApiController
   respond_to :json
 
   def show
-    @stream_entry = stream_entry_from_url(params[:url])
-    @width        = params[:maxwidth].present?  ? params[:maxwidth].to_i  : 400
-    @height       = params[:maxheight].present? ? params[:maxheight].to_i : nil
+    @stream_entry = find_stream_entry.stream_entry
+    @width = maxwidth_or_default
+    @height = maxheight_or_default
   end
 
   private
 
-  def stream_entry_from_url(url)
-    params = Rails.application.routes.recognize_path(url)
-
-    raise ActiveRecord::RecordNotFound unless recognized_stream_entry_url?(params)
-
-    stream_entry(params)
+  def find_stream_entry
+    StreamEntryFinder.new(params[:url])
   end
 
-  def recognized_stream_entry_url?(params)
-    %w(stream_entries statuses).include?(params[:controller]) && params[:action] == 'show'
+  def maxwidth_or_default
+    (params[:maxwidth].presence || 400).to_i
   end
 
-  def stream_entry(params)
-    if params[:controller] == 'stream_entries'
-      StreamEntry.find(params[:id])
-    else
-      Status.find(params[:id]).stream_entry
-    end
+  def maxheight_or_default
+    params[:maxheight].present? ? params[:maxheight].to_i : nil
   end
 end

app/lib/stream_entry_finder.rb

@@ -0,0 +1,34 @@
+# frozen_string_literal: true
+
+class StreamEntryFinder
+  attr_reader :url
+
+  def initialize(url)
+    @url = url
+  end
+
+  def stream_entry
+    verify_action!
+
+    case recognized_params[:controller]
+    when 'stream_entries'
+      StreamEntry.find(recognized_params[:id])
+    when 'statuses'
+      Status.find(recognized_params[:id]).stream_entry
+    else
+      raise ActiveRecord::RecordNotFound
+    end
+  end
+
+  private
+
+  def recognized_params
+    Rails.application.routes.recognize_path(url)
+  end
+
+  def verify_action!
+    unless recognized_params[:action] == 'show'
+      raise ActiveRecord::RecordNotFound
+    end
+  end
+end