Make the membership fee reminders configurable

Instead of hardcoded values.

Fix #139

README.md

@@ -342,6 +342,20 @@ List of available settings in your `settings_local.py` file.
 - `EXTRA_TEMPLATE_DIRS`: See *Customizing templates*
 - `LDAP_ACTIVATE`: See *LDAP*
 - `MEMBER_MEMBERSHIP_INFO_URL`: Link to a page with information on how to become a member or pay the membership fee
+
+- `MEMBERSHIP_FEE_REMINDER_DATES`: how long before/after the membership fee
+  anniversary date we want to send a reminder email to the member. It defaults
+  to the following:
+
+```
+MEMBERSHIP_FEE_REMINDER_DATES = [
+    {'months': -3},  # 3 months before
+    {'months': -2},  # 2 months before
+    {'months': -1},  # 1 month before
+    {'days': 0},     # the day of anniversary
+    {'months': +1},  # 1 month after
+]
+```
 - `SUBSCRIPTION_REFERENCE`: Pattern used to display a unique reference for any subscription. Helpful for bank wire transfer identification
 - `REGISTRATION_OPEN` : Allow visitor to join the association by register on COIN
 - `ACCOUNT_ACTIVATION_DAYS` : All account with unvalidated email will be deleted after X days

coin/members/management/commands/call_for_membership_fees.py

@@ -30,11 +30,10 @@ class Command(BaseCommand):
             raise CommandError(
                 'Please enter a valid date : YYYY-mm-dd (ex: 2011-07-04)')
 
-        end_dates = [date + relativedelta(months=-3),
-                     date + relativedelta(months=-2),
-                     date + relativedelta(months=-1),
-                     date,
-                     date + relativedelta(months=+1)]
+        end_dates = [
+            date + relativedelta(**params)
+            for params in settings.MEMBERSHIP_FEE_REMINDER_DATES
+        ]
 
         if verbosity >= 2:
             self.stdout.write("Selecting members whose membership fee end at "

coin/settings_base.py

@@ -265,6 +265,18 @@ DEFAULT_MEMBERSHIP_FEE = 20
 # membership fee
 MEMBER_MEMBERSHIP_INFO_URL = ''
 
+
+# When should we remind a member about its membership ?  List of deltas from
+# the anniversary date, can be a combination of positive (after anniversary)
+# and negative (before aniversary) af months, days and weeks.
+MEMBERSHIP_FEE_REMINDER_DATES = [
+    {'months': -3},  # 3 months before
+    {'months': -2},  # 2 months before
+    {'months': -1},  # 1 month before
+    {'days': 0},     # the day of anniversary
+    {'months': +1},  # 1 month after
+]
+
 # Pattern used to display a unique reference for any subscription
 # Helpful for bank wire transfer identification
 SUBSCRIPTION_REFERENCE = 'REF-{subscription.offer.reference}-{subscription.pk}'