From c4d4d0a218cc2889a8ef0e2932e8e5368208d53b Mon Sep 17 00:00:00 2001
From: MosheEichler <meichler@paloaltonetworks.com>
Date: Sun, 6 Aug 2023 15:56:25 +0300
Subject: [PATCH] add support for Elasticsearch datetime format

---
 arrow/__init__.py       | 2 ++
 arrow/formatter.py      | 9 +++++----
 tests/test_formatter.py | 7 +++++++
 3 files changed, 14 insertions(+), 4 deletions(-)

diff --git a/arrow/__init__.py b/arrow/__init__.py
index bc5970970..e167ef72b 100644
--- a/arrow/__init__.py
+++ b/arrow/__init__.py
@@ -13,6 +13,7 @@
     FORMAT_RFC3339,
     FORMAT_RSS,
     FORMAT_W3C,
+    FORMAT_ES,
 )
 from .parser import ParserError
 
@@ -35,5 +36,6 @@
     "FORMAT_RFC3339",
     "FORMAT_RSS",
     "FORMAT_W3C",
+    "FORMAT_ES",
     "ParserError",
 ]
diff --git a/arrow/formatter.py b/arrow/formatter.py
index 728bea1aa..9e44f9ea8 100644
--- a/arrow/formatter.py
+++ b/arrow/formatter.py
@@ -26,6 +26,7 @@
 FORMAT_RFC3339: Final[str] = "YYYY-MM-DD HH:mm:ssZZ"
 FORMAT_RSS: Final[str] = "ddd, DD MMM YYYY HH:mm:ss Z"
 FORMAT_W3C: Final[str] = "YYYY-MM-DD HH:mm:ssZZ"
+FORMAT_ES: Final[str] = "yyyy-MM-dd HH:mm:ss.SSSZ"
 
 
 class DateTimeFormatter:
@@ -35,7 +36,7 @@ class DateTimeFormatter:
     # emulated in Python's re library, see https://stackoverflow.com/a/13577411/2701578
 
     _FORMAT_RE: Final[Pattern[str]] = re.compile(
-        r"(\[(?:(?=(?P<literal>[^]]))(?P=literal))*\]|YYY?Y?|MM?M?M?|Do|DD?D?D?|d?dd?d?|HH?|hh?|mm?|ss?|SS?S?S?S?S?|ZZ?Z?|a|A|X|x|W)"
+        r"(\[(?:(?=(?P<literal>[^]]))(?P=literal))*\]|YYY?Y?|yyy?y?|MM?M?M?|Do|DD?D?D?|d?dd?d?|HH?|hh?|mm?|ss?|SS?S?S?S?S?|ZZ?Z?|a|A|X|x|W)"
     )
 
     locale: locales.Locale
@@ -56,9 +57,9 @@ def _format_token(self, dt: datetime, token: Optional[str]) -> Optional[str]:
         if token and token.startswith("[") and token.endswith("]"):
             return token[1:-1]
 
-        if token == "YYYY":
+        if token in ("YYYY", "yyyy"):
             return self.locale.year_full(dt.year)
-        if token == "YY":
+        if token in ("YY", "yy"):
             return self.locale.year_abbreviation(dt.year)
 
         if token == "MMMM":
@@ -74,7 +75,7 @@ def _format_token(self, dt: datetime, token: Optional[str]) -> Optional[str]:
             return f"{dt.timetuple().tm_yday:03d}"
         if token == "DDD":
             return f"{dt.timetuple().tm_yday}"
-        if token == "DD":
+        if token in ("DD", "dd"):
             return f"{dt.day:02d}"
         if token == "D":
             return f"{dt.day}"
diff --git a/tests/test_formatter.py b/tests/test_formatter.py
index 06831f1e0..b2a8297b4 100644
--- a/tests/test_formatter.py
+++ b/tests/test_formatter.py
@@ -15,6 +15,7 @@
     FORMAT_RFC3339,
     FORMAT_RSS,
     FORMAT_W3C,
+    FORMAT_ES,
 )
 
 from .utils import make_full_tz_list
@@ -278,3 +279,9 @@ def test_w3c(self):
             self.formatter.format(self.datetime, FORMAT_W3C)
             == "1975-12-25 14:15:16-05:00"
         )
+
+    def test_elasticsearch(self):
+        assert (
+            self.formatter.format(self.datetime, FORMAT_ES)
+            == "1975-12-25 14:15:16.000-0500"
+        )