From 2a9f043039dc60fc25bc14bab724419bedf746bb Mon Sep 17 00:00:00 2001
From: "J. Nick Koston" <nick@koston.org>
Date: Sun, 1 May 2022 23:44:54 -0500
Subject: [PATCH] Use ULID short format for context ids (#71119)

---
 homeassistant/core.py      |  2 +-
 homeassistant/util/ulid.py | 63 +++++++++++++++++++++++++++++++++-----
 tests/util/test_ulid.py    |  7 ++++-
 3 files changed, 63 insertions(+), 9 deletions(-)

diff --git a/homeassistant/core.py b/homeassistant/core.py
index 7245dad7864..d6b1ac85d8b 100644
--- a/homeassistant/core.py
+++ b/homeassistant/core.py
@@ -695,7 +695,7 @@ class Context:
 
     user_id: str | None = attr.ib(default=None)
     parent_id: str | None = attr.ib(default=None)
-    id: str = attr.ib(factory=ulid_util.ulid_hex)
+    id: str = attr.ib(factory=ulid_util.ulid)
 
     def as_dict(self) -> dict[str, str | None]:
         """Return a dictionary representation of the context."""
diff --git a/homeassistant/util/ulid.py b/homeassistant/util/ulid.py
index 888b5b2074b..c38d95bd169 100644
--- a/homeassistant/util/ulid.py
+++ b/homeassistant/util/ulid.py
@@ -4,11 +4,21 @@ from random import getrandbits
 import time
 
 
-# In the future once we require python 3.10 and above, we can
-# create a new function that uses base64.b32encodehex to shorten
-# these to 26 characters.
 def ulid_hex() -> str:
-    """Generate a ULID in hex that will work for a UUID.
+    """Generate a ULID in lowercase hex that will work for a UUID.
+
+    This ulid should not be used for cryptographically secure
+    operations.
+
+    This string can be converted with https://github.com/ahawker/ulid
+
+    ulid.from_uuid(uuid.UUID(ulid_hex))
+    """
+    return f"{int(time.time()*1000):012x}{getrandbits(80):020x}"
+
+
+def ulid() -> str:
+    """Generate a ULID.
 
     This ulid should not be used for cryptographically secure
     operations.
@@ -18,8 +28,47 @@ def ulid_hex() -> str:
      Timestamp          Randomness
        48bits             80bits
 
-    This string can be converted with https://github.com/ahawker/ulid
+    This string can be loaded directly with https://github.com/ahawker/ulid
 
-    ulid.from_uuid(uuid.UUID(value))
+    import homeassistant.util.ulid as ulid_util
+    import ulid
+    ulid.parse(ulid_util.ulid())
     """
-    return f"{int(time.time()*1000):012x}{getrandbits(80):020x}"
+    ulid_bytes = int(time.time() * 1000).to_bytes(6, byteorder="big") + int(
+        getrandbits(80)
+    ).to_bytes(10, byteorder="big")
+
+    # This is base32 crockford encoding with the loop unrolled for performance
+    #
+    # This code is adapted from:
+    # https://github.com/ahawker/ulid/blob/06289583e9de4286b4d80b4ad000d137816502ca/ulid/base32.py#L102
+    #
+    enc = "0123456789ABCDEFGHJKMNPQRSTVWXYZ"
+    return (
+        enc[(ulid_bytes[0] & 224) >> 5]
+        + enc[ulid_bytes[0] & 31]
+        + enc[(ulid_bytes[1] & 248) >> 3]
+        + enc[((ulid_bytes[1] & 7) << 2) | ((ulid_bytes[2] & 192) >> 6)]
+        + enc[((ulid_bytes[2] & 62) >> 1)]
+        + enc[((ulid_bytes[2] & 1) << 4) | ((ulid_bytes[3] & 240) >> 4)]
+        + enc[((ulid_bytes[3] & 15) << 1) | ((ulid_bytes[4] & 128) >> 7)]
+        + enc[(ulid_bytes[4] & 124) >> 2]
+        + enc[((ulid_bytes[4] & 3) << 3) | ((ulid_bytes[5] & 224) >> 5)]
+        + enc[ulid_bytes[5] & 31]
+        + enc[(ulid_bytes[6] & 248) >> 3]
+        + enc[((ulid_bytes[6] & 7) << 2) | ((ulid_bytes[7] & 192) >> 6)]
+        + enc[(ulid_bytes[7] & 62) >> 1]
+        + enc[((ulid_bytes[7] & 1) << 4) | ((ulid_bytes[8] & 240) >> 4)]
+        + enc[((ulid_bytes[8] & 15) << 1) | ((ulid_bytes[9] & 128) >> 7)]
+        + enc[(ulid_bytes[9] & 124) >> 2]
+        + enc[((ulid_bytes[9] & 3) << 3) | ((ulid_bytes[10] & 224) >> 5)]
+        + enc[ulid_bytes[10] & 31]
+        + enc[(ulid_bytes[11] & 248) >> 3]
+        + enc[((ulid_bytes[11] & 7) << 2) | ((ulid_bytes[12] & 192) >> 6)]
+        + enc[(ulid_bytes[12] & 62) >> 1]
+        + enc[((ulid_bytes[12] & 1) << 4) | ((ulid_bytes[13] & 240) >> 4)]
+        + enc[((ulid_bytes[13] & 15) << 1) | ((ulid_bytes[14] & 128) >> 7)]
+        + enc[(ulid_bytes[14] & 124) >> 2]
+        + enc[((ulid_bytes[14] & 3) << 3) | ((ulid_bytes[15] & 224) >> 5)]
+        + enc[ulid_bytes[15] & 31]
+    )
diff --git a/tests/util/test_ulid.py b/tests/util/test_ulid.py
index fc5d2af8c87..9f297bf373e 100644
--- a/tests/util/test_ulid.py
+++ b/tests/util/test_ulid.py
@@ -6,6 +6,11 @@ import homeassistant.util.ulid as ulid_util
 
 
 async def test_ulid_util_uuid_hex():
-    """Verify we can generate a ulid."""
+    """Verify we can generate a ulid in hex."""
     assert len(ulid_util.ulid_hex()) == 32
     assert uuid.UUID(ulid_util.ulid_hex())
+
+
+async def test_ulid_util_uuid():
+    """Verify we can generate a ulid."""
+    assert len(ulid_util.ulid()) == 26