Refactor: split code into several django apps (we call them modules).

dav_base/config/apps.py

@@ -0,0 +1,71 @@
+import importlib
+import logging
+import re
+from django.apps import AppConfig as _AppConfig
+from django.core.exceptions import ImproperlyConfigured
+
+logger = logging.getLogger(__name__)
+
+
+class DefaultSetting(object):
+    def __init__(self, name, value, key_name=None, validator=None):
+        self.name = name
+        self.value = value
+        if key_name is None:
+            self.key_name = self.name.upper()
+        else:
+            self.key_name = key_name
+        self.validator = validator
+
+    def validate(self, value):
+        if hasattr(self, 'validator') and self.validator is not None:
+            if callable(self.validator):
+                if not self.validator(value):
+                    raise ImproperlyConfigured("Validator callback {clb} returned False".format(clb=self.validator))
+            else:
+                if not re.search(self.validator, value):
+                    raise ImproperlyConfigured("Does not match /{re}/".format(re=self.validator))
+
+
+class AppSettings(object):
+    def __init__(self, app_name, defaults):
+        settings_name = 'main.settings-' + app_name
+
+        try:
+            settings_module = importlib.import_module(settings_name)
+        except ImportError:
+            settings_module = None
+
+        for default in defaults:
+            if hasattr(settings_module, default.key_name):
+                value = getattr(settings_module, default.key_name)
+                try:
+                    default.validate(value)
+                except ImproperlyConfigured as e:
+                    msg = 'Invalid value of {key} in {module}: {cause}'.format(key=default.key_name,
+                                                                               module=settings_name,
+                                                                               cause=e.message)
+                    raise ImproperlyConfigured(msg)
+                setattr(self, default.name, value)
+            elif isinstance(default.value, ImproperlyConfigured):
+                raise default.value
+            else:
+                try:
+                    is_impconf = issubclass(default.value, ImproperlyConfigured)
+                except TypeError:
+                    is_impconf = False
+
+                if is_impconf:
+                    msg = '{key} must be defined in {module}'.format(key=default.key_name,
+                                                                     module=settings_name)
+                    raise default.value(msg)
+                else:
+                    setattr(self, default.name, default.value)
+
+
+class AppConfig(_AppConfig):
+    default_settings = ()
+
+    def __init__(self, app_name, app_module):
+        super(AppConfig, self).__init__(app_name, app_module)
+        self.settings = AppSettings(app_name, self.default_settings)