Improve Backend Error page

Mostly handle things properly when the front-end is missing

Signed-off-by: Thomas Citharel <tcit@tcit.fr>

lib/web/templates/error/500_page.html.eex

@@ -10,7 +10,6 @@
         font-family: BlinkMacSystemFont, Roboto, Oxygen, Ubuntu, Cantarell, Segoe UI, Fira Sans, Droid Sans, Helvetica Neue, Helvetica, Arial, sans-serif;
         background: #efeef4;
         position: absolute;
-        text-align: center;
         color: #3c376e;
         width: 100%;
         height: 100%;
@@ -18,6 +17,12 @@
         display: flex;
         justify-content: center;
         align-items: center;
+        flex-direction: column;
+        margin: 0;
+      }
+
+      body.error .dialog {
+        text-align: center;
       }
       
       body.error .dialog h1 {
@@ -43,8 +48,30 @@
       </div>
       <div class="error__message">
         <h1><%= gettext "We're sorry, but something went wrong on our end." %></h1>
-        <p><%= gettext "The Mobilizon server seems to be temporarily down." %></p>
+        <p>
+          <%= gettext("The Mobilizon server %{instance} seems to be temporarily down.", instance: "<b>#{@instance}</b>") |> raw  %><br />
+        
+          <%= if is_nil(@contact) do %>
+            <%= gettext("If the issue persists, you may try to contact the server administrator.") %>
+          <% else %>
+            <%= gettext("If the issue persists, you may contact the server administrator at %{contact}.", contact: cond do
+              String.contains?(@contact, "@") -> "<a href=\"mailto:#{@contact}\">#{@contact}</a>"
+              String.match?(@contact, ~r/^https?:\/\/.*/) -> "<a href=\"#{@contact}\">#{@contact}</a>"
+              true -> @contact
+            end) |> raw %>
+          <% end %>
+        </p>
       </div>
     </main>
+    <%= if length(@details) > 0 do %>
+      <details>
+        <summary style="font-size: 1.25rem;"><%= gettext("Technical details") %></summary>
+        <pre>
+        <%= for detail <- @details do %>
+          <%= detail %><br>
+        <% end %>
+        </pre>
+      </details>
+    <% end %>
   </body>
 </html>