Авторизация через Facebook, Google, Twitter и Github используя Omniauth

class ServicesController < ApplicationController
 before_filter :authenticate_user!, :except => [:create]

def index
 # get all authentication services assigned to the current user
 @services = current_user.services.all
end

def destroy
 # remove an authentication service linked to the current user
 @service = current_user.services.find(params[:id])
 @service.destroy
 
 redirect_to services_path
end

def create
 # get the service parameter from the Rails router
 params[:service] ? service_route = params[:service] : service_route = 'no service (invalid callback)'

 # get the full hash from omniauth
 omniauth = request.env['omniauth.auth']

 # continue only if hash and parameter exist
 if omniauth and params[:service]
   
   # map the returned hashes to our variables first - the hashes differ for every service
   if service_route == 'facebook'
     omniauth['extra']['user_hash']['email'] ? email =  omniauth['extra']['user_hash']['email'] : email = ''
     omniauth['extra']['user_hash']['name'] ? name =  omniauth['extra']['user_hash']['name'] : name = ''
     omniauth['extra']['user_hash']['id'] ?  uid =  omniauth['extra']['user_hash']['id'] : uid = ''
     omniauth['provider'] ? provider =  omniauth['provider'] : provider = ''
   elsif service_route == 'github'
     omniauth['user_info']['email'] ? email =  omniauth['user_info']['email'] : email = ''
     omniauth['user_info']['name'] ? name =  omniauth['user_info']['name'] : name = ''
     omniauth['extra']['user_hash']['id'] ?  uid =  omniauth['extra']['user_hash']['id'] : uid = ''
     omniauth['provider'] ? provider =  omniauth['provider'] : provider = ''
   elsif service_route == 'twitter'
     email = ''    # Twitter API never returns the email address
     omniauth['user_info']['name'] ? name =  omniauth['user_info']['name'] : name = ''
     omniauth['uid'] ?  uid =  omniauth['uid'] : uid = ''
     omniauth['provider'] ? provider =  omniauth['provider'] : provider = ''
   else
     # we have an unrecognized service, just output the hash that has been returned
     render :text => omniauth.to_yaml
     #render :text => uid.to_s + " - " + name + " - " + email + " - " + provider
     return
   end
 
   # continue only if provider and uid exist
   if uid != '' and provider != ''
       
     # nobody can sign in twice, nobody can sign up while being signed in (this saves a lot of trouble)
     if !user_signed_in?
       
       # check if user has already signed in using this service provider and continue with sign in process if yes
       auth = Service.find_by_provider_and_uid(provider, uid)
       if auth
         flash[:notice] = 'Signed in successfully via ' + provider.capitalize + '.'
         sign_in_and_redirect(:user, auth.user)
       else
         # check if this user is already registered with this email address; get out if no email has been provided
         if email != ''
           # search for a user with this email address
           existinguser = User.find_by_email(email)
           if existinguser
             # map this new login method via a service provider to an existing account if the email address is the same
             existinguser.services.create(:provider => provider, :uid => uid, :uname => name, :uemail => email)
             flash[:notice] = 'Sign in via ' + provider.capitalize + ' has been added to your account ' + existinguser.email + '. Signed in successfully!'
             sign_in_and_redirect(:user, existinguser)
           else
             # let's create a new user: register this user and add this authentication method for this user
             name = name[0, 39] if name.length > 39             # otherwise our user validation will hit us

             # new user, set email, a random password and take the name from the authentication service
             user = User.new :email => email, :password => SecureRandom.hex(10), :fullname => name

             # add this authentication service to our new user
             user.services.build(:provider => provider, :uid => uid, :uname => name, :uemail => email)

             # do not send confirmation email, we directly save and confirm the new record
             user.skip_confirmation!
             user.save!
             user.confirm!

             # flash and sign in
             flash[:myinfo] = 'Your account on CommunityGuides has been created via ' + provider.capitalize + '. In your profile you can change your personal information and add a local password.'
             sign_in_and_redirect(:user, user)
           end
         else
           flash[:error] =  service_route.capitalize + ' can not be used to sign-up on CommunityGuides as no valid email address has been provided. Please use another authentication provider or use local sign-up. If you already have an account, please sign-in and add ' + service_route.capitalize + ' from your profile.'
           redirect_to new_user_session_path
         end
       end
     else
       # the user is currently signed in
       
       # check if this service is already linked to his/her account, if not, add it
       auth = Service.find_by_provider_and_uid(provider, uid)
       if !auth
         current_user.services.create(:provider => provider, :uid => uid, :uname => name, :uemail => email)
         flash[:notice] = 'Sign in via ' + provider.capitalize + ' has been added to your account.'
         redirect_to services_path
       else
         flash[:notice] = service_route.capitalize + ' is already linked to your account.'
         redirect_to services_path
       end  
     end  
   else
     flash[:error] =  service_route.capitalize + ' returned invalid data for the user id.'
     redirect_to new_user_session_path
   end
 else
   flash[:error] = 'Error while authenticating via ' + service_route.capitalize + '.'
   redirect_to new_user_session_path
 end
end

<section id="deviseauth">
   <h2>Sign in</h2>

   <h3>Sign in with your CommunityGuides account -- OR -- use an authentication service</h3>

   <div id="local" class="box">    
       <%= form_for(resource, :as => resource_name, :url => session_path(resource_name)) do |f| %>
         <p><%= f.label :email %><br />
         <%= f.text_field :email %></p>

         <p><%= f.label :password %><br />
         <%= f.password_field :password %></p>

         <% if devise_mapping.rememberable? %>
           <p><%= f.check_box :remember_me %> <%= f.label :remember_me %></p>
         <% end %>

         <p><%= f.submit "Sign in" %></p>
       <% end %>
   </div>

   <div id="remote">
       <div id="terms" class="box">
           <%= link_to "Terms of Service", "#" %>
       </div>  
       <div id="services" class="box">
           <a href="/auth/facebook" class="services"><%= image_tag "facebook_64.png", :size => "64x64",  :alt => "Facebook" %>Facebook</a>
           <a href="/auth/google" class="services"><%= image_tag "google_64.png", :size => "64x64",  :alt => "Google" %>Google</a>
           <a href="/auth/github" class="services"><%= image_tag "github_64.png", :size => "64x64",  :alt => "Github" %>Github</a>
           <a href="/auth/twitter" class="services"><%= image_tag "twitter_64.png", :size => "64x64",  :alt => "Twitter" %>Twitter</a>
       </div>
   </div>

   <div id="devise_links">
       <%= render :partial => "devise/shared/links" %>
   </div>
</section>

<section id="deviseauth">
   <h2>Sign up</h2>

   <h3>Sign up on CommunityGuides manually -- OR -- or use one of your existing accounts</h3>

   <div id="local2" class="box">
       <%= form_for(resource, :as => resource_name, :url => registration_path(resource_name)) do |f| %>
         <%= devise_error_messages! %>

         <p><%= f.label :email %><br />
         <%= f.text_field :email %></p>

         <p><%= f.label :password %><br />
         <%= f.password_field :password %></p>

         <p><%= f.label :password_confirmation %><br />
         <%= f.password_field :password_confirmation %></p>

         <p><%= recaptcha_tags %></p>

         <p><%= f.submit "Sign up" %></p>
       <% end %>
   </div>

   <div id="remote2">
       <div id="terms" class="box">
           <%= link_to "Terms of Service", "#" %>
       </div>  
       <div id="services" class="box">
           <a href="/auth/facebook" class="services2"><%= image_tag "facebook_64.png", :size => "64x64",  :alt => "Facebook" %>Facebook</a>
           <a href="/auth/google" class="services2"><%= image_tag "google_64.png", :size => "64x64",  :alt => "Google" %>Google</a>
           <a href="/auth/github" class="services2"><%= image_tag "github_64.png", :size => "64x64",  :alt => "Github" %>Github*</a>
           <div id="footnote_signup">* You can use Github only if you set a public email address</div>
       </div>  
   </div>

   <div id="devise_links">
       <%= render :partial => "devise/shared/links" %>
   </div>
</section>

<section id="deviseauth">
   <h2>Authentication Services - Setting</h2>

   <div id="currservices">
       <h3>The following <%= @services.count == 1 ? 'account is' : 'accounts are' %> connected with your local account at CommunityGuides:</h3>
   
       <% @services.each do |service| %>  
         <div class="services_used">  
             <%= image_tag "#{service.provider}_64.png", :size => "64x64" %>
             <div class = "user">
               <div class="line1">Name: <%= service.uname %> (ID: <%= service.uid %>)</div>  
               <div class="line2">Email: <%= service.uemail != '' ? service.uemail : 'not set' %></div>
               <div class="line3">
                   <% @services.count == 1 ? @msg = 'Removing the last account linked might lock you out of your account if you do not know the email/password sign-in of your local account!' : @msg = '' %>
                   <%= link_to "Remove this service", service, :confirm => 'Are you sure you want to remove this authentication service? ' + @msg, :method => :delete, :class => "remove" %>
               </div>
             </div>
         </div>  
       <% end %>
   </div>

   <div id="availableservices">
       <h3>You can connect more services to your account:</h3>
       <div id="services">
           <a href="/auth/facebook" class="services"><%= image_tag "facebook_64.png", :size => "64x64",  :alt => "Facebook" %>Facebook</a>
           <a href="/auth/google" class="services"><%= image_tag "google_64.png", :size => "64x64",  :alt => "Google" %>Google</a>
           <a href="/auth/github" class="services"><%= image_tag "github_64.png", :size => "64x64",  :alt => "Github" %>Github</a>
           <a href="/auth/twitter" class="services"><%= image_tag "twitter_64.png", :size => "64x64",  :alt => "Twitter" %>Twitter</a>
       </div>
       <h4>If you signed-up for CommunityGuides via an authentication service a random password has been set for the local password. You can request a new password using the "Forgot your Password?" link on the sign-in page.</h4>
   </div>  
</section>

...
def update
 # no mass assignment for country_id, we do it manually
 # check for existence of the country in case a malicious user manipulates the params (fails silently)
 if params[resource_name][:country_id]          
   resource.country_id = params[resource_name][:country_id] if Country.find_by_id(params[resource_name][:country_id])
 end

 if current_user.haslocalpw
   super
 else
   # this account has been created with a random pw / the user is signed in via an omniauth service
   # if the user does not want to set a password we remove the params to prevent a validation error
   if params[resource_name][:password].blank?
     params[resource_name].delete(:password)
     params[resource_name].delete(:password_confirmation) if params[resource_name][:password_confirmation].blank?
   else
     # if the user wants to set a password we set haslocalpw for the future
     params[resource_name][:haslocalpw] = true
   end
   
   # this is copied over from the original devise controller, instead of update_with_password we use update_attributes
   if resource.update_attributes(params[resource_name])
      set_flash_message :notice, :updated
      sign_in resource_name, resource
      redirect_to after_update_path_for(resource)
    else
      clean_up_passwords(resource)
      render_with_scope :edit
    end
 end
end
...