feat(day 60): determine moon phase using 28-day lunar cycle and reference new moon date

Author: JohnSunny21

FreeCodeCamp/CodingQ/SpaceWeek/SpaceWeek6.py

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+"""
+Space Week Day 6: Moon Phase
+For day six of Space Week, you will be given a date in the format "YYYY-MM-DD" and need to determine the phase of the moon for that day using the following rules:
+
+Use a simplified lunar cycle of 28 days, divided into four equal phases:
+
+"New": days 1 - 7
+"Waxing": days 8 - 14
+"Full": days 15 - 21
+"Waning": days 22 - 28
+After day 28, the cycle repeats with day 1, a new moon.
+
+Use "2000-01-06" as a reference new moon (day 1 of the cycle) to determine the phase of the given day.
+You will not be given any dates before the reference date.
+Return the correct phase as a string.
+"""
+
+import unittest
+from datetime import datetime
+
+class SpaceWeek6Test(unittest.TestCase):
+
+    def test1(self):
+        self.assertEqual(moon_phase("2000-01-12"),"New")
+
+    def test2(self):
+        self.assertEqual(moon_phase("2000-01-13"),"Waxing")
+
+    def test3(self):
+        self.assertEqual(moon_phase("2014-10-15"),"Full")
+
+    def test4(self):
+        self.assertEqual(moon_phase("2012-10-21"),"Waning")
+
+    def test5(self):
+        self.assertEqual(moon_phase("2022-12-14"),"New")
+
+
+
+
+
+def moon_phase(date_string):
+    
+   reference_date = datetime(2000,1,6)
+   given_date = datetime.strptime(date_string,"%Y-%m-%d")
+   days_passed = (given_date - reference_date).days
+   cycle_day = (days_passed % 28) + 1 # Day 1 to 28
+
+
+   if 1<= cycle_day <= 7:
+       return "New"
+   elif 8 <= cycle_day <= 14:
+       return "Waxing"
+   elif 15 <= cycle_day <= 21:
+       return "Full"
+   else:
+       return "Waning"
+
+
+
+
+if __name__ == "__main__":
+    print(moon_phase("2000-01-06"))
+    print(moon_phase("2000-01-13"))
+    unittest.main()