Adjust to the in-house style

- Use jbuilder instead of hashes
- Use resource instead of direct HTTP verbs
    Verbs only make sense if you have one or two routes, if there are
    multiple that emulate what resource does then it's better to use resource.
- Paginate using link headers
- Cache responses

app/controllers/messages/by_bots_controller.rb

@@ -1,73 +1,57 @@
 class Messages::ByBotsController < MessagesController
+  include RawRequestBody
+
   allow_bot_access only: %i[ index create ]
 
+  before_action :set_room
+  before_action :ensure_body_or_attachment_present, only: :create
+
   def index
-    set_room
     @messages = find_paged_messages
-    render json: messages_as_json(@messages)
-  rescue ActiveRecord::RecordNotFound
-    head :not_found
+    set_pagination_headers
   end
 
   def create
-    set_room
-    @message = @room.messages.create_with_attachment!(message_params)
-    @message.broadcast_create
-    deliver_webhooks_to_bots
+    super
     head :created, location: message_url(@message)
-  rescue ActiveRecord::RecordNotFound
-    head :not_found
   end
 
   private
-    def messages_as_json(messages)
-      {
-        room: {
-          id: @room.id,
-          name: @room.name
-        },
-        messages: messages.map { |m| message_as_json(m) },
-        pagination: pagination_info(messages)
-      }
+    def set_room
+      @room = Current.user.rooms.find_by(id: params[:room_id])
+
+      head :not_found unless @room
     end
 
-    def message_as_json(message)
-      {
-        id: message.id,
-        body: {
-          plain: message.plain_text_body,
-          html: message.body&.body&.to_s
-        },
-        created_at: message.created_at.iso8601,
-        creator: {
-          id: message.creator.id,
-          name: message.creator.name,
-          is_bot: message.creator.bot?
-        }
-      }
+    def ensure_body_or_attachment_present
+      if params[:attachment].blank? && raw_request_body.blank?
+        head :unprocessable_content
+      end
     end
 
-    def pagination_info(messages)
-      return {} if messages.empty?
-      {
-        oldest_id: messages.last.id,
-        newest_id: messages.first.id,
-        has_more: messages.size == Message::PAGE_SIZE
-      }
+    def set_pagination_headers
+      headers["X-Total-Count"] = @room.messages.count.to_s
+
+      if next_page = next_page_params
+        headers["Link"] = %(<#{room_bot_messages_url(@room, params[:bot_key], **next_page)}>; rel="next")
+      end
+    end
+
+    def next_page_params
+      if @messages.any?
+        if params[:after].present?
+          { after: @messages.last.id } if @room.messages.after(@messages.last).exists?
+        else
+          { before: @messages.first.id } if @room.messages.before(@messages.first).exists?
+        end
+      end
     end
 
     def message_params
       if params[:attachment]
         params.permit(:attachment)
       else
-        reading(request.body) { |body| { body: body } }
+        { body: raw_request_body }
       end
     end
-
-    def reading(io)
-      io.rewind
-      yield io.read.force_encoding("UTF-8")
-    ensure
-      io.rewind
-    end
 end