Add Nailsea market days

Closes: #37

agenda/__init__.py

@@ -404,6 +404,37 @@ def tobacco_factory_market_days(start_date: date) -> list[Event]:
     return events
 
 
+def nailsea_farmers_market_days(start_date: date) -> list[Event]:
+    """Nailsea Farmers Market days for the next 12 months from a given date."""
+    events: list[Event] = []
+    current_date = start_date
+    count = 0
+
+    tz = pytz.timezone("Europe/London")
+    t = time(9, 0)  # The market starts at 9am
+
+    while count < 12:
+        # Calculate the 3rd Saturday of the current month
+        third_saturday = current_date + relativedelta(day=1, weekday=SA(+3))
+
+        # Include it in the list only if it's on or after the start_date
+        if third_saturday >= start_date:
+            events.append(
+                Event(
+                    name="market",
+                    title="Nailsea Farmers Market",
+                    date=tz.localize(datetime.combine(third_saturday, t)),
+                )
+            )
+            count += 1
+
+        # Move to the next month
+        current_date += relativedelta(months=1)
+        current_date = date(current_date.year, current_date.month, 1)
+
+    return events
+
+
 # Test the function
 if __name__ == "__main__":
     start_date = date(2023, 10, 29)
@@ -583,7 +614,11 @@ def get_data(now: datetime) -> typing.Mapping[str, str | object]:
         "xmas_last_posting_dates": xmas_last_posting_dates,
         "gwr_advance_tickets": find_gwr_advance_ticket_date(),
         "critical_mass": critical_mass(today),
-        "market": windmill_hill_market_days(today) + tobacco_factory_market_days(today),
+        "market": (
+            windmill_hill_market_days(today)
+            + tobacco_factory_market_days(today)
+            + nailsea_farmers_market_days(today)
+        ),
         "rockets": thespacedevs.get_launches(rocket_dir, limit=40),
     }