add layercake

layercake/layercake/dateutils.py

@@ -0,0 +1,49 @@
+import os
+from datetime import datetime, timedelta
+
+import pytz
+
+
+TZ = os.getenv('TZ', 'UTC')
+
+
+def now(tz: str = TZ) -> datetime:
+    """Returns the current datetime in the specified timezone.
+
+    If no timezone is provided, returns the current datetime in the local timezone.
+    """
+    return datetime.now(pytz.timezone(tz))
+
+
+def ttl(
+    *,
+    start_dt: datetime | None = None,
+    tz: str = TZ,
+    **kwargs,
+) -> int:
+    """Calculates the timestamp for a datetime in the future.
+    If start_dt is not provided, it uses the current datetime.
+    Additional keyword arguments specify the timedelta to add.
+    """
+    if not start_dt:
+        start_dt = now(tz)
+
+    dt = start_dt + timedelta(**kwargs)
+    return int(dt.timestamp())
+
+
+def timestamp(dt: datetime) -> int:
+    """Converts a datetime object to a Unix timestamp."""
+    return int(dt.timestamp())
+
+
+def fromisoformat(dt: str) -> datetime | None:
+    """Parses a datetime string in ISO 8601 format and returns a datetime object.
+    Returns None if the string is not in a valid ISO 8601 format.
+    """
+    try:
+        date = datetime.fromisoformat(dt)
+    except ValueError:
+        return None
+    else:
+        return date