Show warning on push to etherpad

If the protocol is not on the same day, show a warning before pushing
the template to the etherpad. #44

server.py

@@ -475,7 +475,10 @@ def show_protocol(protocol):
     documents_table = DocumentsTable(visible_documents)
     document_upload_form = DocumentUploadForm()
     source_upload_form = KnownProtocolSourceUploadForm()
-    return render_template("protocol-show.html", protocol=protocol, errors_table=errors_table, documents_table=documents_table, document_upload_form=document_upload_form, source_upload_form=source_upload_form)
+    time_diff = protocol.date - datetime.now().date()
+    print(time_diff)
+    large_time_diff = not protocol.is_done() and time_diff.days > 0
+    return render_template("protocol-show.html", protocol=protocol, errors_table=errors_table, documents_table=documents_table, document_upload_form=document_upload_form, source_upload_form=source_upload_form, time_diff=time_diff, large_time_diff=large_time_diff)
 
 @app.route("/protocol/delete/<int:protocol_id>")
 @login_required

templates/protocol-show.html

@@ -23,7 +23,7 @@
                 {% endif %} 
                 <a class="btn {% if protocol.is_done() %}btn-success{% else %}btn-default{% endif %}" href="{{url_for("update_protocol", protocol_id=protocol.id)}}">Editieren</a>
                 {% if config.ETHERPAD_ACTIVE %}
-                <a class="btn btn-primary" href="{{url_for("etherpush_protocol", protocol_id=protocol.id)}}">Etherpad</a>
+                <a class="btn btn-primary" href="{{url_for("etherpush_protocol", protocol_id=protocol.id)}}"{% if large_time_diff %} onclick="return confirm('Bist du dir sicher, dass du das Template bereits in das Etherpad kopieren willst? Die Sitzung ist erst in {{time_diff.days}} Tagen.');"{% endif %}>Etherpad</a>
                 {% endif %}
                 {% if not protocol.is_done() %}
                     <a class="btn btn-default" href="{{url_for("get_protocol_template", protocol_id=protocol.id)}}">Vorlage</a>