add parse_datetime_to_timestamp() function

jc/utils.py

@@ -1,6 +1,8 @@
 """jc - JSON CLI output utility utils"""
 import textwrap
 import sys
+import locale
+from datetime import datetime, timezone
 
 
 def warning_message(message):
@@ -83,3 +85,107 @@ def has_data(data):
         Boolean      True if input string (data) contains non-whitespace characters, otherwise False
     """
     return True if data and not data.isspace() else False
+
+
+def parse_datetime_to_timestamp(data):
+    """
+    Input a date-time text string of several formats and convert to a naive or timezone-aware epoch timestamp in UTC
+
+    Parameters:
+
+        data:        (string) a string representation of a date-time in several supported formats
+
+    Returns:
+
+        Dict/None    A Dictionary of the following format:
+
+                     {
+                         "format":               integer,
+                         "timestamp_naive":      integer,
+                         "timestamp_utc":        integer      # aware timestamp only if UTC timezone detected
+                     }
+
+                     The format integer denotes which date_time format conversion succeeded.
+                     The timestamp_naive integer is the converted date-time string to a naive epoch timestamp.
+                     The timestamp_utc integer is the converted date-time string to an aware epoch timestamp
+                         in the UTC timezone. If an aware conversion cannot be performed (e.g. the UTC timezone
+                         is not found in the date-time string), then this field will be None.
+
+                     If the conversion completely fails, None is returned instead of a Dictionary
+    """
+    found = False
+    utc_tz = False
+    epoch_dt = None
+    epoch_dt_utc = None
+    timestamp_naive = None
+    timestamp_utc = None
+    timestamp_obj = {}
+    utc_tz = True if 'UTC' in data else False
+
+    # Format: 1 try C locale format conversion
+    # Tue Mar 23 16:12:11 2021
+    if not found:
+        try:
+            locale.setlocale(locale.LC_TIME, None)
+            epoch_dt = datetime.strptime(data, '%c')
+            timestamp_naive = int(epoch_dt.replace(tzinfo=None).timestamp())
+            timestamp_obj['format'] = 1
+            found = True
+        except Exception:
+            pass
+
+    # Format: 2 try en_US.UTF-8 local format (found in upower cli output)
+    # Tue 23 Mar 2021 04:12:11 PM UTC
+    if not found:
+        try:
+            epoch_dt = datetime.strptime(data, '%a %d %b %Y %I:%M:%S %p %Z')
+            timestamp_naive = int(epoch_dt.replace(tzinfo=None).timestamp())
+            timestamp_obj['format'] = 2
+            found = True
+        except Exception:
+            pass
+
+    # Format: 3 try date cli command in en_US.UTF-8 format
+    # Wed Mar 24 06:16:19 PM UTC 2021
+    if not found:
+        try:
+            epoch_dt = datetime.strptime(data, '%a %b %d %I:%M:%S %p %Z %Y')
+            timestamp_naive = int(epoch_dt.replace(tzinfo=None).timestamp())
+            timestamp_obj['format'] = 3
+            found = True
+        except Exception:
+            pass
+
+    # Format: 4 try date cli command in C locale format
+    # Wed Mar 24 11:11:30 PDT 2021
+    if not found:
+        try:
+            epoch_dt = datetime.strptime(data, '%a %b %d %H:%M:%S %Z %Y')
+            timestamp_naive = int(epoch_dt.replace(tzinfo=None).timestamp())
+            timestamp_obj['format'] = 4
+            found = True
+        except Exception:
+            pass
+
+    # Format: 5 try locally configured locale format conversion
+    # Could be anything :) this is a last-gasp attempt
+    if not found:
+        try:
+            locale.setlocale(locale.LC_TIME, '')
+            epoch_dt = datetime.strptime(data, '%c')
+            timestamp_naive = int(epoch_dt.replace(tzinfo=None).timestamp())
+            locale.setlocale(locale.LC_TIME, None)
+            timestamp_obj['format'] = 5
+            found = True
+        except Exception:
+            pass
+
+    if epoch_dt and utc_tz:
+        epoch_dt_utc = epoch_dt.replace(tzinfo=timezone.utc)
+        timestamp_utc = int(epoch_dt_utc.timestamp())
+
+    if timestamp_naive:
+        timestamp_obj['timestamp_naive'] = timestamp_naive
+        timestamp_obj['timestamp_utc'] = timestamp_utc if timestamp_utc else None
+
+    return timestamp_obj if timestamp_obj else None