From 33ae14c6ca3731520d433b2cfb29bf33b02688b8 Mon Sep 17 00:00:00 2001
From: ltbringer <amresh.venugopal@gmail.com>
Date: Fri, 4 Feb 2022 00:20:25 +0530
Subject: [PATCH] add: datetime utility functions.

---
 dialogy/utils/datetime.py | 53 +++++++++++++++++++++++++++++++++++++++
 1 file changed, 53 insertions(+)
 create mode 100644 dialogy/utils/datetime.py

diff --git a/dialogy/utils/datetime.py b/dialogy/utils/datetime.py
new file mode 100644
index 00000000..f0e2630b
--- /dev/null
+++ b/dialogy/utils/datetime.py
@@ -0,0 +1,53 @@
+import math
+from datetime import datetime
+from typing import Callable
+
+import pytz
+
+
+def make_unix_ts(tz: str = "UTC") -> Callable[[str], int]:
+    """
+    Convert date in ISO 8601 format to unix ms timestamp.
+
+    :param tz: A timezone string, defaults to "UTC"
+    :type tz: Optional[str], optional
+    :return: A callable that converts a date in ISO 8601 format to unix ms timestamp.
+    :rtype: Callable[[str], int]
+    """
+
+    def make_tz_aware(date_string: str) -> int:
+        """
+        Convert date in ISO 8601 format to unix ms timestamp.
+
+        :param date_string: A date in ISO 8601 format.
+        :type date_string: str
+        :return: A unix timestamp (13 digit).
+        :rtype: int
+        """
+        if isinstance(date_string, int):
+            return date_string
+        dt = datetime.fromisoformat(date_string)
+        if dt.tzinfo is None and tz not in pytz.all_timezones:
+            raise ValueError(f"Invalid timezone {tz} pick from:\n{pytz.all_timezones}")
+
+        if dt.tzinfo is None:
+            dt = dt.replace(tzinfo=pytz.timezone(tz))
+        return int(dt.timestamp() * 1000)
+
+    return make_tz_aware
+
+
+def is_unix_ts(ts: int) -> bool:
+    """
+    Check if the input is a unix timestamp.
+
+    :param ts: A unix timestamp (13-digit).
+    :type ts: int
+    :return: True if :code:`ts` is a unix timestamp, else False.
+    :rtype: bool
+    """
+    try:
+        datetime.fromtimestamp(ts / 1000)
+        return True
+    except ValueError:
+        return False