From c95cb24ca74013d01390f4559687e91301a2e9ef Mon Sep 17 00:00:00 2001
From: Bernard Siebens <bernard@siebens.org>
Date: Sun, 26 Apr 2026 22:01:32 +0200
Subject: [PATCH] Extend `Season` model: add `generate_default` method for
 creating seasons with configurable defaults, and `_add_months` utility for
 date calculations.

---
 teams/models.py | 40 ++++++++++++++++++++++++++++++++++++++++
 1 file changed, 40 insertions(+)

diff --git a/teams/models.py b/teams/models.py
index 8819133..e6a96ca 100644
--- a/teams/models.py
+++ b/teams/models.py
@@ -1,5 +1,8 @@
+import calendar
 import datetime
+import re
 
+from constance import config
 from django.db import models
 from django.utils import timezone
 from django.utils.translation import gettext_lazy as _
@@ -42,3 +45,40 @@ class Season(RulesModel):
         if values_only:
             return season.date_range
         return season
+
+    @classmethod
+    def generate_default(cls, day: int | None = None, month: int | None = None, duration: str | None = None) -> "Season":
+        if day is None:
+            day = config.TF_DEFAULT_SEASON_DAY
+        if month is None:
+            month = config.TF_DEFAULT_SEASON_MONTH
+        if duration is None:
+            duration = config.TF_DEFAULT_SEASON_DURATION
+
+        current_year = timezone.now().date().year
+        start_date = datetime.date(current_year, month, day)
+
+        match = re.fullmatch(r"(\d+)([ym])", duration.strip().lower())
+        if match is None:
+            raise ValueError('Duration must be specified as "<number>y" or "<number>m", for example "1y", "1m", or "3m".')
+
+        duration_value = int(match.group(1))
+        duration_unit = match.group(2)
+
+        if duration_unit == "y":
+            end_date = cls._add_months(start_date, duration_value * 12) - datetime.timedelta(days=1)
+        elif duration_unit == "m":
+            end_date = cls._add_months(start_date, duration_value) - datetime.timedelta(days=1)
+        else:
+            raise ValueError('Duration unit must be "y" or "m".')
+
+        return cls.objects.create(start_date=start_date, end_date=end_date)
+
+    @staticmethod
+    def _add_months(date_value: datetime.date, months: int) -> datetime.date:
+        month_index = date_value.month - 1 + months
+        year = date_value.year + month_index // 12
+        month = month_index % 12 + 1
+        day = min(date_value.day, calendar.monthrange(year, month)[1])
+
+        return date_value.replace(year=year, month=month, day=day)