From 85aec531f5fc91fd05d4caed2f1f75cb3627abf1 Mon Sep 17 00:00:00 2001
From: kinegratii <kinegratii@gmail.com>
Date: Tue, 2 Apr 2024 22:43:18 +0800
Subject: [PATCH] :sparkles: New LunarDate for last day in a year or a month

---
 borax/calendars/festivals2.py |  2 +-
 borax/calendars/lunardate.py  | 18 +++++++++++++++---
 docs/changelog.md             |  2 +-
 tests/test_lunardate.py       | 11 +++++++++++
 4 files changed, 28 insertions(+), 5 deletions(-)

diff --git a/borax/calendars/festivals2.py b/borax/calendars/festivals2.py
index de999a4..6ef87eb 100644
--- a/borax/calendars/festivals2.py
+++ b/borax/calendars/festivals2.py
@@ -181,7 +181,7 @@ def solar_month(year: int, month: int) -> Tuple[date, date]:
     @staticmethod
     def lunar_year(year: int, end_year: int = 0) -> Tuple[LunarDate, LunarDate]:
         end_year = end_year or year
-        return LunarDate(year, 1, 1), LunarDate.last_day_of_year(end_year)
+        return LunarDate(year, 1, 1), LunarDate.last_day(end_year)
 
     @staticmethod
     def lunar_month(year: int, month: int, leap: int = _IGNORE_LEAP_MONTH) -> Tuple[LunarDate, LunarDate]:
diff --git a/borax/calendars/lunardate.py b/borax/calendars/lunardate.py
index 8250037..aa87b03 100644
--- a/borax/calendars/lunardate.py
+++ b/borax/calendars/lunardate.py
@@ -659,9 +659,21 @@ def tomorrow(cls) -> 'LunarDate':
         return cls.from_solar_date(sd.year, sd.month, sd.day)
 
     @classmethod
-    def last_day_of_year(cls, year: int) -> 'LunarDate':
-        """return the last day in a lunar year."""
-        month, day, leap = list(LCalendars.iter_year_month(year))[-1]
+    def last_day(cls, year: int, month: int = 0, leap: int = 0) -> 'LunarDate':
+        """return the last day in a lunar year or a lunar month."""
+        mdls = list(LCalendars.iter_year_month(year))
+        if month == 0:
+            index = -1
+        else:
+            leap_month_of_year = LCalendars.leap_month(year)
+            if leap:
+                if month == leap_month_of_year:
+                    index = month
+                else:
+                    raise InvalidLunarDateError(f'{year=}, {month=},leap=1 does not exist.')
+            else:
+                index = month - 1 + int(leap_month_of_year and month > leap_month_of_year)
+        month, day, leap = mdls[index]
         return cls(year, month, day, leap)
 
     @classmethod
diff --git a/docs/changelog.md b/docs/changelog.md
index 8da96ea..1be80c8 100644
--- a/docs/changelog.md
+++ b/docs/changelog.md
@@ -2,7 +2,7 @@
 
 ## v4.1.1
 
-- 新增创建农历年最后一天的方法 `LunarDate.last_day_of_year`
+- 新增创建农历年或农历月最后一天的方法 `LunarDate.last_day`
 - `SolarFestival` 和`LunarFestival` 初始化函数 `freq` 参数支持字符串设置（ [ #56](https://github.com/kinegratii/borax/issues/56) ）
 - `Period.solar_year` 和 `Period.lunar_year` 新增 `end_year` 参数，支持跨年份计算
 - 废弃模块：`borax.choices`
diff --git a/tests/test_lunardate.py b/tests/test_lunardate.py
index 1ae8465..6005949 100644
--- a/tests/test_lunardate.py
+++ b/tests/test_lunardate.py
@@ -39,6 +39,17 @@ def test_create_specific_dates(self):
 
         self.assertEqual(LunarDate(2023, 12, 30), LunarDate.last_day_of_year(2023))
 
+    def test_last_day(self):
+        self.assertEqual(LunarDate(2023, 12, 30), LunarDate.last_day(2023))
+        self.assertEqual(LunarDate(2023, 1, 29), LunarDate.last_day(2023, 1))
+        self.assertEqual(LunarDate(2023, 2, 30), LunarDate.last_day(2023, 2))
+        self.assertEqual(LunarDate(2023, 2, 29, 1), LunarDate.last_day(2023, 2, leap=1))
+        self.assertEqual(LunarDate(2023, 3, 29), LunarDate.last_day(2023, 3))
+
+        self.assertEqual(LunarDate(2024, 12, 29), LunarDate.last_day(2024))
+        with self.assertRaises(Exception):
+            LunarDate.last_day(2024, 2, 1)
+
     def test_convert_datetime(self):
         dt = LunarDate(1976, 8, 8, 1).to_solar_date()
         self.assertEqual(date(1976, 10, 1), dt)