books edition by admin

app/controllers/authors_controller.rb

@@ -0,0 +1,5 @@
+class AuthorsController < ApplicationController
+  def index
+    @authors = Author.all
+  end
+end

app/controllers/books_controller.rb

@@ -1,5 +1,43 @@
 class BooksController < ApplicationController
+  before_action :set_book, only: [:show, :edit, :update]
+  before_action :ensure_admin, only: [:edit, :update]
+
   def index
-    @books = Book.published.map { |book| BooksPresenter.new(book) }
+    if current_user.admin?
+      books = Book.all
+    else
+      books = Book.published
+    end
+    @books = books.map { |book| BooksPresenter.new(book) }
+  end
+
+  def show
+  end
+
+  def edit
+  end
+
+  def update
+    if @book.update(book_params)
+      redirect_to '/books'
+    end
+  end
+
+  private
+
+  def ensure_admin
+    unless current_user&.admin?
+      redirect_to '/welcome', notice: 'You are not allowed to perform this action'
+    end
+  end
+
+  def set_book
+    @book = BooksPresenter.new(Book.find(params[:id]))
+  end
+
+  def book_params
+    result = params.require(:book).permit(:title, :price, :published)
+    result['price'] = result['price'].to_d * 100
+    result
   end
 end