Add sessions control for logging in

app/controllers/application_controller.rb

@@ -1,4 +1,24 @@
 class ApplicationController < ActionController::Base
+  before_action :require_login
+  helper_method :current_user
+  helper_method :user_signed_in?
+
+  def current_user
+    User.find_by(id: session[:user_id])
+  end
+
+  def user_signed_in?
+    !current_user.nil?
+  end
+
+  private
+
+  def require_login
+    return if user_signed_in?
+
+    flash[:error] = 'You must be logged in to access this section'
+    redirect_to root_path
+  end
 
   def user_params
     params.require(:user).permit(:name)

app/controllers/sessions_controller.rb

@@ -1,2 +1,21 @@
 class SessionsController < ApplicationController
+  skip_before_action :require_login, only: %i[new create]
+  def new
+  end
+
+  def create
+    @user = User.find_by(name: user_params[:name])
+    if @user
+      session[:user_id] = @user.id
+      redirect_to categories_path, notice: "Welcome #{@user.name}! "
+    else
+      flash.now.alert = 'Sorry, the user name is incorrect.'
+      render :new
+    end
+  end
+
+  def destroy
+    session.delete(:user_id)
+    redirect_to root_path, notice: "Goodbye! You're now logged out!"
+  end
 end

app/controllers/users_controller.rb

@@ -1,4 +1,5 @@
 class UsersController < ApplicationController
+  skip_before_action :require_login, only: %i[new create]
   def new
     @user = User.new
   end

app/helpers/application_helper.rb

@@ -1,2 +1,21 @@
 module ApplicationHelper
+  def show_logged_in
+    if user_signed_in?
+      render 'shared/logged_in_user'
+    else
+      render 'shared/sign_buttons'
+    end
+  end
+
+  def show_user_links
+    render 'shared/user_links' if user_signed_in?
+  end
+
+  def show_alert
+    render 'shared/alert' if flash[:error]
+  end
+
+  def show_notice
+    render 'shared/notice' if flash[:success]
+  end
 end