Implement advanced login

Author: mhartl

app/assets/stylesheets/custom.scss

@@ -194,6 +194,19 @@ input {
     color: $state-danger-text;
   }
 }
+.checkbox {
+  margin-top: -10px;
+  margin-bottom: 10px;
+  span {
+    margin-left: 20px;
+    font-weight: normal;
+  }
+}
+
+#session_remember_me {
+  width: auto;
+  margin-left: 0;
+}
 
 /* Dropdown menu */
 

app/controllers/sessions_controller.rb

@@ -7,6 +7,7 @@ def create
     user = User.find_by(email: params[:session][:email].downcase)
     if user && user.authenticate(params[:session][:password])
       reset_session
+      params[:session][:remember_me] == '1' ? remember(user) : forget(user)
       log_in user
       redirect_to user
     else
@@ -16,7 +17,7 @@ def create
   end
 
   def destroy
-    log_out
+    log_out if logged_in?
     redirect_to root_url, status: :see_other
   end
 end

app/helpers/sessions_helper.rb

@@ -5,10 +5,23 @@ def log_in(user)
     session[:user_id] = user.id
   end
 
-  # Returns the current logged-in user (if any).
+  # Remembers a user in a persistent session.
+  def remember(user)
+    user.remember
+    cookies.permanent.encrypted[:user_id] = user.id
+    cookies.permanent[:remember_token] = user.remember_token
+  end
+
+  # Returns the user corresponding to the remember token cookie.
   def current_user
-    if session[:user_id]
-      @current_user ||= User.find_by(id: session[:user_id])
+    if (user_id = session[:user_id])
+      @current_user ||= User.find_by(id: user_id)
+    elsif (user_id = cookies.encrypted[:user_id])
+      user = User.find_by(id: user_id)
+      if user && user.authenticated?(cookies[:remember_token])
+        log_in user
+        @current_user = user
+      end
     end
   end
 
@@ -17,8 +30,16 @@ def logged_in?
     !current_user.nil?
   end
 
+  # Forgets a persistent session.
+  def forget(user)
+    user.forget
+    cookies.delete(:user_id)
+    cookies.delete(:remember_token)
+  end
+
   # Logs out the current user.
   def log_out
+    forget(current_user)
     reset_session
     @current_user = nil
   end

app/models/user.rb

@@ -1,4 +1,5 @@
 class User < ApplicationRecord
+  attr_accessor :remember_token
   before_save { self.email = email.downcase }
   validates :name,  presence: true, length: { maximum: 50 }
   VALID_EMAIL_REGEX = /\A[\w+\-.]+@[a-z\d\-.]+\.[a-z]+\z/i
@@ -14,4 +15,26 @@ def User.digest(string)
                                                   BCrypt::Engine.cost
     BCrypt::Password.create(string, cost: cost)
   end
+
+  # Returns a random token.
+  def User.new_token
+    SecureRandom.urlsafe_base64
+  end
+
+  # Remembers a user in the database for use in persistent sessions.
+  def remember
+    self.remember_token = User.new_token
+    update_attribute(:remember_digest, User.digest(remember_token))
+  end
+
+  # Returns true if the given token matches the digest.
+  def authenticated?(remember_token)
+    return false if remember_digest.nil?
+    BCrypt::Password.new(remember_digest).is_password?(remember_token)
+  end
+
+  # Forgets a user.
+  def forget
+    update_attribute(:remember_digest, nil)
+  end
 end

app/views/sessions/new.html.erb

@@ -11,6 +11,11 @@
       <%= f.label :password %>
       <%= f.password_field :password, class: 'form-control' %>
 
+      <%= f.label :remember_me, class: "checkbox inline" do %>
+        <%= f.check_box :remember_me %>
+        <span>Remember me on this computer</span>
+      <% end %>
+
       <%= f.submit "Log in", class: "btn btn-primary" %>
     <% end %>
 

db/migrate/20220408205520_add_remember_digest_to_users.rb

@@ -0,0 +1,5 @@
+class AddRememberDigestToUsers < ActiveRecord::Migration[7.0]
+  def change
+    add_column :users, :remember_digest, :string
+  end
+end

db/schema.rb

@@ -0,0 +1,19 @@
+require "test_helper"
+
+class SessionsHelperTest < ActionView::TestCase
+
+  def setup
+    @user = users(:michael)
+    remember(@user)
+  end
+
+  test "current_user returns right user when session is nil" do
+    assert_equal @user, current_user
+    assert is_logged_in?
+  end
+
+  test "current_user returns nil when remember digest is wrong" do
+    @user.update_attribute(:remember_digest, User.digest(User.new_token))
+    assert_nil current_user
+  end
+end

test/helpers/sessions_helper_test.rb

@@ -33,9 +33,24 @@ def setup
     assert_not is_logged_in?
     assert_response :see_other
     assert_redirected_to root_url
+    # Simulate a user clicking logout in a second window.
+    delete logout_path
     follow_redirect!
     assert_select "a[href=?]", login_path
     assert_select "a[href=?]", logout_path,      count: 0
     assert_select "a[href=?]", user_path(@user), count: 0
   end
+
+  test "login with remembering" do
+    log_in_as(@user, remember_me: '1')
+    assert_not cookies[:remember_token].blank?
+  end
+
+  test "login without remembering" do
+    # Log in to set the cookie.
+    log_in_as(@user, remember_me: '1')
+    # Log in again and verify that the cookie is deleted.
+    log_in_as(@user, remember_me: '0')
+    assert cookies[:remember_token].blank?
+  end
 end

test/integration/users_login_test.rb

@@ -6,7 +6,7 @@ def setup
     @user = User.new(name: "Example User", email: "[email protected]",
                      password: "foobar", password_confirmation: "foobar")
   end
-  
+
   test "should be valid" do
     assert @user.valid?
   end
@@ -64,4 +64,8 @@ def setup
     @user.password = @user.password_confirmation = "a" * 5
     assert_not @user.valid?
   end
+
+  test "authenticated? should return false for a user with nil digest" do
+    assert_not @user.authenticated?('')
+  end
 end