Use form_for, stub login logic

app/controllers/authentication_controller.rb

   end
 
   def login
-    flash[:danger] = "Not yet implemented."
+    if params[:session][:email].blank? || params[:session][:password].blank?
+      flash[:warning] = "You forgot to add value"
+    else
+      u = User.find_by(email: params[:session][:email])
+
+      if u && u.authenticate(params[:session][:password])
+        # TODO Login logic here
+        flash[:success] = "Hello, #{u.person.full_name}!"
+      else
+        flash[:danger] = "Invalid username/password combination!"
+      end
+    end
+
     redirect_to action: 'login_form'
   end
 

app/views/authentication/create_password_form.html.haml

 
 .container
   = render 'shared/alerts'
-  = form_tag '/register', method: 'post', class: 'central-form' do
+  = form_for :user, url: '/register', html: {class: 'central-form'} do |f|
     %h2.central-form-header.text-center
       Create password
     %p
       Creating an account requires that you have been registered beforehand by an administrator. Contact someone if your email address is not recognized.
 
-    = email_field_tag :email, '', placeholder: 'Email address', class: 'form-control input-only'
-    = submit_tag "Send email", class: 'btn btn-primary btn-lg btn-block'
+    = f.email_field :email, placeholder: 'Email address', class: 'form-control input-only'
+    = f.submit "Send email", class: 'btn btn-primary btn-lg btn-block'
 
   .central-form
     %ul.hdis

app/views/authentication/forgotten_password_form.html.haml

   Forgot password
 .container
   = render 'shared/alerts'
-  = form_tag '/forgot', method: 'post', class:'central-form' do
+  = form_for :password_reset, url: '/forgot', html: {class:'central-form'} do |f|
     %h2.central-form-header.text-center
       Forgot password
 
-    = email_field_tag :email, '', placeholder: "Email address", class: 'form-control input-only'
-    = submit_tag "Send email", class: 'btn btn-primary btn-lg btn-block'
+    = f.email_field :email, placeholder: "Email address", class: 'form-control input-only'
+    = f.submit "Send email", class: 'btn btn-primary btn-lg btn-block'
 
   .central-form
     %ul.hdis

app/views/authentication/login_form.html.haml

 
 .container
   = render 'shared/alerts'
-  = form_tag("/login", method: "post", class: "central-form") do
+  = form_for :session, url: "/login", html: { class: "central-form"} do |f|
     %h2.central-form-header.text-center
       Please sign in
 
-    = email_field_tag(:email, '', placeholder: 'Email address', class: 'form-control input-top')
-    = password_field_tag(:password, '', placeholder: 'Password', class: 'form-control input-bottom')
+    = f.email_field(:email, placeholder: 'Email address', class: 'form-control input-top')
+    = f.password_field(:password, placeholder: 'Password', class: 'form-control input-bottom')
 
     .checkbox
       %label
-        = check_box_tag(:remember_me)
+        = f.check_box(:remember_me)
         Remember me
 
-    = submit_tag("Sign in", class: "btn btn-primary btn-lg btn-block")
+    = f.submit("Sign in", class: "btn btn-primary btn-lg btn-block")
 
   .central-form
     %ul.hdis