Merge branch 'impersonate' into 'master'

refactor login as to be impersonation with better login/logout

Modifies the existing "login as" feature to be called impersonation.

This also adds:

* Application keep track of who is impersonating the user so they can revert back to the original user without having to log out.
* Stores the user profile via `HTTP_REFERER` so you get redirected back to the person you have impersonated once you stop.

## Screenshots:

![](http://sindacio.us/i/2015-10-28_17-52-41.png)
![](http://sindacio.us/i/2015-10-28_17-53-08.png)

See merge request !1702

3 files changed, 38 insertions, 6 deletions

diff --git a/app/controllers/admin/application_controller.rb b/app/controllers/admin/application_controller.rb
index 56e24386463..9083bfb41cf 100644
--- a/app/controllers/admin/application_controller.rb
+++ b/app/controllers/admin/application_controller.rb
@@ -8,4 +8,10 @@ class Admin::ApplicationController < ApplicationController
   def authenticate_admin!
     return render_404 unless current_user.is_admin?
   end
+
+  def authorize_impersonator!
+    if session[:impersonator_id]
+      User.find_by!(username: session[:impersonator_id]).admin?
+    end
+  end
 end
diff --git a/app/controllers/admin/impersonation_controller.rb b/app/controllers/admin/impersonation_controller.rb
new file mode 100644
index 00000000000..0382402afa6
--- /dev/null
+++ b/app/controllers/admin/impersonation_controller.rb
@@ -0,0 +1,32 @@
+class Admin::ImpersonationController < Admin::ApplicationController
+  skip_before_action :authenticate_admin!, only: :destroy
+
+  before_action :user
+  before_action :authorize_impersonator!
+
+  def create
+    session[:impersonator_id] = current_user.username
+    session[:impersonator_return_to] = request.env['HTTP_REFERER']
+
+    warden.set_user(user, scope: 'user')
+
+    flash[:alert] = "You are impersonating #{user.username}."
+
+    redirect_to root_path
+  end
+
+  def destroy
+    redirect = session[:impersonator_return_to]
+
+    warden.set_user(user, scope: 'user')
+
+    session[:impersonator_return_to] = nil
+    session[:impersonator_id] = nil
+
+    redirect_to redirect || root_path
+  end
+
+  def user
+    @user ||= User.find_by!(username: params[:id] || session[:impersonator_id])
+  end
+end
diff --git a/app/controllers/admin/users_controller.rb b/app/controllers/admin/users_controller.rb
index c63d0793e31..d7c927d444c 100644
--- a/app/controllers/admin/users_controller.rb
+++ b/app/controllers/admin/users_controller.rb
@@ -63,12 +63,6 @@ class Admin::UsersController < Admin::ApplicationController
     end
   end
 
-  def login_as
-    sign_in(user)
-    flash[:alert] = "Logged in as #{user.username}"
-    redirect_to root_path
-  end
-
   def disable_two_factor
     user.disable_two_factor!
     redirect_to admin_user_path(user),