Add new ProblemReportEmail base class, for simpler email previews

just so some of the template context can be provided automatically.  although,
this *is* a bit heavy currently - should let caller pass in email handler etc.

rattail/emails.py

@@ -2,7 +2,7 @@
 ################################################################################
 #
 #  Rattail -- Retail Software Framework
-#  Copyright © 2010-2019 Lance Edgar
+#  Copyright © 2010-2020 Lance Edgar
 #
 #  This file is part of Rattail.
 #
@@ -36,6 +36,37 @@ from rattail.mail import Email
 from rattail.util import load_object
 from rattail.core import Object
 from rattail.time import make_utc, localtime
+from rattail.problems import ProblemReport, get_problem_report_handler
+
+
+class ProblemReportEmail(Email):
+    """
+    Base class for all "problem report" emails
+    """
+    abstract = True
+
+    def obtain_sample_data(self, request):
+        data = self.sample_data(request)
+        handler = get_problem_report_handler(self.config)
+
+        if 'report' not in data:
+            reports = handler.get_all_problem_reports()
+            email_key = self.__class__.__name__
+            for report in reports:
+                if report.email_key == email_key:
+                    data['report'] = report(self.config)
+                    break
+
+            if 'report' not in data:
+                report = ProblemReport(self.config)
+                report.problem_title = "Generic Title (problem report not found)"
+                data['report'] = report
+
+        if 'system_title' not in data:
+            system_key = data['report'].system_key or 'rattail'
+            data['system_title'] = handler.get_system_title(system_key)
+
+        return data
 
 
 class datasync_error_watcher_get_changes(Email):

rattail/mail.py

@@ -2,7 +2,7 @@
 ################################################################################
 #
 #  Rattail -- Retail Software Framework
-#  Copyright © 2010-2018 Lance Edgar
+#  Copyright © 2010-2020 Lance Edgar
 #
 #  This file is part of Rattail.
 #
@@ -309,7 +309,22 @@ class Email(object):
             templates = [resource_path(p) for p in templates]
         self.templates = TemplateLookup(directories=templates)
 
+    def obtain_sample_data(self, request):
+        """
+        This method is responsible for obtaining the full set of sample data,
+        to be used as context when generating a preview for the email.
+
+        Note, you normally should not override this method!  Please see also
+        the :meth:`sample_data()` method.
+        """
+        return self.sample_data(request)
+
     def sample_data(self, request):
+        """
+        This method can return a dict of sample data, to be used as context
+        when generating a preview for the email.  Subclasses are welcome to
+        override this method.
+        """
         return {}
 
     def get_enabled(self):