Replace hardcoded time units with named constants (#867)

* Replace hardcoded time units with named constants

- Replaced hardcoded time-related values with named constants.
- Facilitates easier adjustments of these values and reduces potential for errors.

* refactor: extract function-level constants to module-level

- Ensures better adherence to PEP 8 naming conventions and improves code readability.

* Add endline after pre-commit black

---------

Co-authored-by: Bartosz Sokorski <[email protected]>

Author: Minku-Koo

src/pendulum/formatting/difference_formatter.py

@@ -8,6 +8,23 @@
 if t.TYPE_CHECKING:
     from pendulum import Duration
 
+DAYS_THRESHOLD_FOR_HALF_WEEK = 3
+DAYS_THRESHOLD_FOR_HALF_MONTH = 15
+MONTHS_THRESHOLD_FOR_HALF_YEAR = 6
+
+HOURS_IN_NEARLY_A_DAY = 22
+DAYS_IN_NEARLY_A_MONTH = 27
+MONTHS_IN_NEARLY_A_YEAR = 11
+
+DAYS_OF_WEEK = 7
+SECONDS_OF_MINUTE = 60
+FEW_SECONDS_MAX = 10
+
+KEY_FUTURE = ".future"
+KEY_PAST = ".past"
+KEY_AFTER = ".after"
+KEY_BEFORE = ".before"
+
 
 class DifferenceFormatter:
     """
@@ -38,36 +55,41 @@ def format(
             unit = "year"
             count = diff.years
 
-            if diff.months > 6:
+            if diff.months > MONTHS_THRESHOLD_FOR_HALF_YEAR:
                 count += 1
-        elif diff.months == 11 and (diff.weeks * 7 + diff.remaining_days) > 15:
+        elif (diff.months == MONTHS_IN_NEARLY_A_YEAR) and (
+            (diff.weeks * DAYS_OF_WEEK + diff.remaining_days)
+            > DAYS_THRESHOLD_FOR_HALF_MONTH
+        ):
             unit = "year"
             count = 1
         elif diff.months > 0:
             unit = "month"
             count = diff.months
 
-            if (diff.weeks * 7 + diff.remaining_days) >= 27:
+            if (
+                diff.weeks * DAYS_OF_WEEK + diff.remaining_days
+            ) >= DAYS_IN_NEARLY_A_MONTH:
                 count += 1
         elif diff.weeks > 0:
             unit = "week"
             count = diff.weeks
 
-            if diff.remaining_days > 3:
+            if diff.remaining_days > DAYS_THRESHOLD_FOR_HALF_WEEK:
                 count += 1
         elif diff.remaining_days > 0:
             unit = "day"
             count = diff.remaining_days
 
-            if diff.hours >= 22:
+            if diff.hours >= HOURS_IN_NEARLY_A_DAY:
                 count += 1
         elif diff.hours > 0:
             unit = "hour"
             count = diff.hours
         elif diff.minutes > 0:
             unit = "minute"
             count = diff.minutes
-        elif 10 < diff.remaining_seconds <= 59:
+        elif FEW_SECONDS_MAX < diff.remaining_seconds < SECONDS_OF_MINUTE:
             unit = "second"
             count = diff.remaining_seconds
         else:
@@ -86,42 +108,39 @@ def format(
                         key += ".ago"
                 else:
                     if is_future:
-                        key += ".after"
+                        key += KEY_AFTER
                     else:
-                        key += ".before"
+                        key += KEY_BEFORE
 
                 return t.cast("str", locale.get(key).format(time))
             else:
                 unit = "second"
                 count = diff.remaining_seconds
-
         if count == 0:
             count = 1
-
         if absolute:
             key = f"translations.units.{unit}"
         else:
             is_future = diff.invert
-
             if is_now:
                 # Relative to now, so we can use
                 # the CLDR data
                 key = f"translations.relative.{unit}"
 
                 if is_future:
-                    key += ".future"
+                    key += KEY_FUTURE
                 else:
-                    key += ".past"
+                    key += KEY_PAST
             else:
                 # Absolute comparison
                 # So we have to use the custom locale data
 
                 # Checking for special pluralization rules
                 key = "custom.units_relative"
                 if is_future:
-                    key += f".{unit}.future"
+                    key += f".{unit}{KEY_FUTURE}"
                 else:
-                    key += f".{unit}.past"
+                    key += f".{unit}{KEY_PAST}"
 
                 trans = locale.get(key)
                 if not trans:
@@ -133,9 +152,9 @@ def format(
 
                 key = "custom"
                 if is_future:
-                    key += ".after"
+                    key += KEY_AFTER
                 else:
-                    key += ".before"
+                    key += KEY_BEFORE
 
                 return t.cast("str", locale.get(key).format(time))