Let registrar users change registrar account

app/controllers/registrar/account_controller.rb

@@ -2,16 +2,23 @@ class Registrar
   class AccountController < BaseController
     skip_authorization_check
 
-    helper_method :linked_users
+    def show; end
 
-    def show
-      @user = current_registrar_user
+    def edit
+      @registrar = current_registrar_user.registrar
+    end
+
+    def update
+      @registrar = current_registrar_user.registrar
+      @registrar.update!(registrar_params)
+
+      redirect_to registrar_account_path, notice: t('.saved')
     end
 
     private
 
-    def linked_users
-      current_registrar_user.linked_users
+    def registrar_params
+      params.require(:registrar).permit(:billing_email)
     end
   end
-end
+end

app/views/registrar/account/_details.html.erb

@@ -0,0 +1,16 @@
+<div class="panel panel-default">
+    <div class="panel-heading">
+        <%= t '.header' %>
+    </div>
+
+    <div class="panel-body">
+        <dl class="dl-horizontal">
+            <dt><%= Registrar.human_attribute_name :billing_email %></dt>
+            <dd><%= registrar.billing_email %></dd>
+        </dl>
+    </div>
+
+    <div class="panel-footer text-right">
+        <%= link_to t('.edit_btn'), edit_registrar_account_path, class: 'btn btn-default btn-sm' %>
+    </div>
+</div>

app/views/registrar/account/_form.html.erb

@@ -0,0 +1,21 @@
+<%= form_for @registrar, url: registrar_account_path, method: :patch, html: { class: 'form-horizontal' } do |f| %>
+    <%= render 'form_errors', target: @registrar %>
+
+    <div class="form-group">
+        <div class="col-sm-2 control-label">
+            <%= f.label :billing_email %>
+        </div>
+
+        <div class="col-sm-4">
+            <%= f.email_field :billing_email, autofocus: true, class: 'form-control' %>
+        </div>
+    </div>
+
+    <hr>
+
+    <div class="row">
+        <div class="col-sm-6 text-right">
+            <%= f.submit t('.submit_btn'), class: 'btn btn-success' %>
+        </div>
+    </div>
+<% end %>

app/views/registrar/account/edit.html.erb

@@ -0,0 +1,10 @@
+<ol class="breadcrumb">
+    <li><%= link_to t('registrar.account.show.header'), registrar_account_path %></li>
+    <li><%= t '.header' %></li>
+</ol>
+
+<div class="page-header">
+    <h1><%= t '.header' %></h1>
+</div>
+
+<%= render 'form' %>

app/views/registrar/account/show.html.erb

@@ -3,7 +3,13 @@
 </div>
 
 <div class="row">
-    <div class="col-sm-4">
-        <%= render 'linked_users', linked_users: linked_users %>
+    <div class="col-sm-5">
+        <%= render 'details', registrar: current_registrar_user.registrar %>
     </div>
 </div>
+
+<div class="row">
+    <div class="col-sm-5">
+        <%= render 'linked_users', linked_users: current_registrar_user.linked_users %>
+    </div>
+</div>