Add config class to get settings

We will need to be able to alter settings based on e.g. the request, so
as a first step, I'm introducing a layer between Django settings and the
Adyen code.

We introduce the concept of a config class, that can be set from the
Django settings. It defaults to a supplied config class that just
fetches the needed values from the Django settings as before. But now we
have the possibility of switiching out the config class to fetch those
values from elsewhere.

adyen/config.py

@@ -0,0 +1,35 @@
+from django.conf import settings
+from django.utils.module_loading import import_string
+
+
+def get_config():
+    """
+    Returns an instance of the configured config class.
+    """
+
+    try:
+        config_class_string = settings.ADYEN_CONFIG_CLASS
+    except AttributeError:
+        config_class_string = 'adyen.settings_config.FromSettingsConfig'
+    return import_string(config_class_string)()
+
+
+class AbstractAdyenConfig:
+    """
+    The base implementation for a config class.
+    """
+
+    def get_identifier(self):
+        raise NotImplementedError
+
+    def get_action_url(self):
+        raise NotImplementedError
+
+    def get_skin_code(self):
+        raise NotImplementedError
+
+    def get_skin_secret(self):
+        raise NotImplementedError
+
+    def get_ip_address_header(self):
+        raise NotImplementedError

adyen/facade.py

@@ -3,11 +3,11 @@
 import iptools
 import logging
 
-from django.conf import settings
 from django.http import HttpResponse
 
 from .gateway import Constants, Gateway, PaymentNotification, PaymentRedirection
 from .models import AdyenTransaction
+from .config import get_config
 
 logger = logging.getLogger('adyen')
 
@@ -16,9 +16,9 @@ class Facade():
 
     def __init__(self, **kwargs):
         init_params = {
-            Constants.IDENTIFIER: settings.ADYEN_IDENTIFIER,
-            Constants.SECRET_KEY: settings.ADYEN_SECRET_KEY,
-            Constants.ACTION_URL: settings.ADYEN_ACTION_URL,
+            Constants.IDENTIFIER: get_config().get_identifier(),
+            Constants.SECRET_KEY: get_config().get_skin_secret(),
+            Constants.ACTION_URL: get_config().get_action_url(),
         }
         # Initialize the gateway.
         self.gateway = Gateway(init_params)
@@ -54,10 +54,7 @@ def _get_origin_ip_address(cls, request):
         Django setting. We fallback on the canonical `REMOTE_ADDR`, used for
         regular, unproxied requests.
         """
-        try:
-            ip_address_http_header = settings.ADYEN_IP_ADDRESS_HTTP_HEADER
-        except AttributeError:
-            ip_address_http_header = 'REMOTE_ADDR'
+        ip_address_http_header = get_config().get_ip_address_header()
 
         try:
             ip_address = request.META[ip_address_http_header]
@@ -209,7 +206,7 @@ def assess_notification_relevance(self, request):
         # - On the other hand we have the `live` POST parameter, which lets
         # us know which Adyen platform fired this request.
         current_platform = (Constants.LIVE
-                            if Constants.LIVE in settings.ADYEN_ACTION_URL
+                            if Constants.LIVE in get_config().get_action_url()
                             else Constants.TEST)
 
         origin_platform = (Constants.LIVE

adyen/scaffold.py

@@ -2,12 +2,11 @@
 
 import bleach
 
-from django.conf import settings
-from django.core.exceptions import ImproperlyConfigured
 from django.utils import timezone
 
 from .facade import Facade
 from .gateway import Constants, MissingFieldException
+from .config import get_config
 
 
 class Scaffold():
@@ -36,10 +35,7 @@ def __init__(self, order_data=None):
 
     def get_form_action(self):
         """ Return the URL where the payment form should be submitted. """
-        try:
-            return settings.ADYEN_ACTION_URL
-        except AttributeError:
-            raise ImproperlyConfigured("Please set ADYEN_ACTION_URL")
+        return get_config().get_action_url()
 
     def get_form_fields(self):
         """ Return the payment form fields, rendered into HTML. """
@@ -64,13 +60,13 @@ def get_form_fields_list(self):
         # Build common field specs
         try:
             field_specs = {
-                Constants.MERCHANT_ACCOUNT: settings.ADYEN_IDENTIFIER,
+                Constants.MERCHANT_ACCOUNT: get_config().get_identifier(),
                 Constants.MERCHANT_REFERENCE: str(self.order_number),
                 Constants.SHOPPER_REFERENCE: self.client_id,
                 Constants.SHOPPER_EMAIL: self.client_email,
                 Constants.CURRENCY_CODE: self.currency_code,
                 Constants.PAYMENT_AMOUNT: self.amount,
-                Constants.SKIN_CODE: settings.ADYEN_SKIN_CODE,
+                Constants.SKIN_CODE: get_config().get_skin_code(),
                 Constants.SESSION_VALIDITY: session_validity.strftime(session_validity_format),
                 Constants.SHIP_BEFORE_DATE: ship_before_date.strftime(ship_before_date_format),
                 Constants.SHOPPER_LOCALE: self.shopper_locale,

adyen/settings_config.py

@@ -0,0 +1,43 @@
+from django.conf import settings
+from django.core.exceptions import ImproperlyConfigured
+
+from .config import AbstractAdyenConfig
+
+
+class FromSettingsConfig(AbstractAdyenConfig):
+    """
+    This config class is enabled by default and useful in simple deployments.
+    One can just set all needed values in the Django settings. It also
+    exists for backwards-compatibility with previous deployments.
+    """
+
+    def __init__(self):
+        """
+        We complain as early as possible when Django settings are missing.
+        """
+        required_settings = [
+            'ADYEN_IDENTIFIER', 'ADYEN_ACTION_URL', 'ADYEN_SKIN_CODE', 'ADYEN_SECRET_KEY']
+        missing_settings = [
+            setting for setting in required_settings if not hasattr(settings, setting)]
+        if missing_settings:
+            raise ImproperlyConfigured(
+                "You are using the FromSettingsConfig config class, but haven't set the "
+                "the following required settings: %s" % missing_settings)
+
+    def get_identifier(self):
+        return settings.ADYEN_IDENTIFIER
+
+    def get_action_url(self):
+        return settings.ADYEN_ACTION_URL
+
+    def get_skin_code(self):
+        return settings.ADYEN_SKIN_CODE
+
+    def get_skin_secret(self):
+        return settings.ADYEN_SECRET_KEY
+
+    def get_ip_address_header(self):
+        try:
+            return settings.ADYEN_IP_ADDRESS_HTTP_HEADER
+        except AttributeError:
+            return 'REMOTE_ADDR'