Allow passing relative timedeltas to from_datetime (#645)

Author: FasterSpeeding

CHANGELOG.md

@@ -6,6 +6,7 @@ and this project adheres to [Semantic Versioning](https://semver.org/spec/v2.0.0
 
 ## [Unreleased]
 ### Added
+- Support for passing relative timedeltas to [tanjun.conversion.from_datetime][].
 - Support for passing multiple callbacks to `add_check`, `add_client_callback`, `add_listener`,
   `add_on_close` and `add_on_open`.
 

tanjun/conversion.py

@@ -1364,7 +1364,17 @@ def to_datetime(value: str, /) -> datetime.datetime:
 _VALID_DATETIME_STYLES = frozenset(("t", "T", "d", "D", "f", "F", "R"))
 
 
+@typing.overload
+def from_datetime(value: datetime.timedelta, /) -> str:
+    ...
+
+
+@typing.overload
 def from_datetime(value: datetime.datetime, /, *, style: str = "f") -> str:
+    ...
+
+
+def from_datetime(value: typing.Union[datetime.datetime, datetime.timedelta], /, *, style: str = "f") -> str:
     """Format a datetime as Discord's datetime format.
 
     More information on this format can be found at
@@ -1374,12 +1384,17 @@ def from_datetime(value: datetime.datetime, /, *, style: str = "f") -> str:
     ----------
     value
         The datetime to format.
+
+        If a timedelta is passed here then this is treated as a date that's
+        relative to the current time.
     style
         The style to use.
 
         The valid styles can be found at
         <https://discord.com/developers/docs/reference#message-formatting-formats>.
 
+        This is always "R" when `value` is a [datetime.timedelta][].
+
     Returns
     -------
     str
@@ -1391,6 +1406,9 @@ def from_datetime(value: datetime.datetime, /, *, style: str = "f") -> str:
         If the provided datetime is timezone naive.
         If an invalid style is provided.
     """
+    if isinstance(value, datetime.timedelta):
+        return from_datetime(datetime.datetime.now(tz=datetime.timezone.utc) + value, style="R")
+
     if style not in _VALID_DATETIME_STYLES:
         raise ValueError(f"Invalid style: {style}")
 

tests/test_conversion.py

@@ -38,6 +38,7 @@
 import urllib.parse
 from unittest import mock
 
+import freezegun
 import hikari
 import pytest
 
@@ -1855,6 +1856,13 @@ def test_from_datetime_for_invalid_style():
         tanjun.conversion.from_datetime(date, style="granddad")
 
 
+def test_from_datetime_for_time_delta():
+    with freezegun.freeze_time(datetime.datetime(2022, 12, 30, 6, 33, 47, 52643, tzinfo=datetime.timezone.utc)):
+        result = tanjun.conversion.from_datetime(datetime.timedelta(days=21, hours=23, minutes=32, seconds=34))
+
+    assert result == "<t:1674281181:R>"
+
+
 @pytest.mark.parametrize(
     ("value", "expected"),
     [