Add basic version of Comments component

app/controllers/comments_controller.rb

@@ -1,11 +1,36 @@
 class CommentsController < ApplicationController
+  before_action :authenticate_user!, only: [:create]
+  
   def index
     comments = Comment
       .where(post_id: params[:post_id])
       .left_outer_joins(:user)
-      .select('comments.body, comments.updated_at, users.full_name')
+      .select('comments.id, comments.body, comments.updated_at, users.full_name as user_full_name')
       .order(updated_at: :desc)
+      .page(params[:page])
 
     render json: comments
   end
+
+  def create
+    comment = Comment.new(comment_params)
+
+    if comment.save
+      render json: comment, status: :no_content
+    else
+      render json: I18n.t('errors.unauthorized'), status: :unauthorized
+    end
+  end
+
+  private
+
+    def comment_params
+      params
+        .require(:comment)
+        .permit(:body)
+        .merge(
+          user_id: current_user.id,
+          post_id: params[:post_id]
+        )
+    end
 end