Added some logic + error page with redirect back

content/check-code.yaml

+---
+error_message: The invite code does not appear to be valid. Please go back and try again.

routes/code.rb

@@ -12,14 +12,13 @@ class SignupSite < Sinatra::Base
   end
 
   post '/check-code' do
-    if (!params.key? :input_invite) ||
-       params[:input_invite].empty? ||
-       params[:input_invite] !~ /^\w{8}-\w{4}-\w{4}-\w{4}-\w{12}$/
-
-      @header   = 'Insomnia 24/7 shells signup'
-      @body     = 'Invite code appears to be invalid. Please try again.'
-      @progress = 25
-      erb :index
+    if params[:input_invite] !~ /^\w{8}-\w{4}-\w{4}-\w{4}-\w{12}$/
+      cc                       = YAML.load_file('content/check-code.yaml')
+      session[:error_message]  = cc['error_message']
+      session[:error_location] = '/enter-code'
+      session[:error_progress] = 25
+      session[:error_data]     = Rack::Utils.escape_html(params[:input_invite])
+      redirect '/error', 302
     else
       session[:invite] = Rack::Utils.escape_html(params[:input_invite])
       redirect '/enter-details', 302

routes/details.rb

@@ -13,6 +13,6 @@ class SignupSite < Sinatra::Base
   end
 
   post '/check-details' do
-    # Some checking stuff
+    'Not yet implemented.'
   end
 end

routes/error.rb

+# frozen_string_literal: true
+
+# Invite code handling
+class SignupSite < Sinatra::Base
+  get '/error' do
+    @header                     = 'Oh no!'
+    @body                       = session[:error_message]
+    @form                       = erb :error
+    @progress                   = session[:error_progress]
+    session[:error_reload_form] = true
+    erb :index
+  end
+end

signup_site.rb

@@ -21,3 +21,4 @@ end
 
 require_relative 'routes/code'
 require_relative 'routes/details'
+require_relative 'routes/error'

views/enter_code.erb

@@ -3,7 +3,12 @@
     <div class="form-group">
       <label for="input_invite" class="col-lg-2 control-label">Invite code</label>
       <div class="col-lg-10">
+      <% if session[:error_reload_form] %>
+        <input type="text" class="form-control" id="input_invite" name="input_invite" value="<%= session[:error_data] %>">
+        <% session[:error_reload_form] = false %>
+      <% else %>
         <input type="text" class="form-control" id="input_invite" name="input_invite" placeholder="1234abcd-1234-5678-9abc-432abc987def">
+      <% end%>
       </div>
     </div>
     <div class="form-group">

views/enter_details.erb

-<form class="form-horizontal">
+<form class="form-horizontal" method="POST" action="/check-details">
   <fieldset>
     <div class="form-group">
       <label for="input_username" class="col-lg-2 control-label">User name</label>

views/error.erb

+<form class="form-horizontal" method="GET" action="<%= session[:error_location] %>">
+  <fieldset>
+    <div class="form-group">
+      <div class="col-lg-10 col-lg-offset-2">
+        <button type="submit" class="btn btn-info">Go back</button>
+      </div>
+    </div>
+  </fieldset>
+</form>