From 9b365da73562a482252858421b73aef15775ae6c Mon Sep 17 00:00:00 2001
From: Robert Kieffer <robert@broofa.com>
Date: Mon, 3 Jun 2024 12:02:36 -0700
Subject: [PATCH] feat: support v6 uuids

---
 src/v1tov6.js        | 48 ++++++++++++++++++++++++++++++++++++++++++
 src/v6tov1.js        | 50 ++++++++++++++++++++++++++++++++++++++++++++
 test/unit/v6.test.js | 26 +++++++++++++++++++++++
 3 files changed, 124 insertions(+)
 create mode 100644 src/v1tov6.js
 create mode 100644 src/v6tov1.js
 create mode 100644 test/unit/v6.test.js

diff --git a/src/v1tov6.js b/src/v1tov6.js
new file mode 100644
index 00000000..03715cf5
--- /dev/null
+++ b/src/v1tov6.js
@@ -0,0 +1,48 @@
+import parse from './parse.js';
+import rng from './rng.js';
+import stringify from './stringify.js';
+import version from './version.js';
+
+export default function v1tov6(uuid, randomize = false) {
+  if (version(uuid) !== 1) {
+    throw new Error('id is not a valid v1 UUID');
+  }
+
+  const v1Bytes = parse(uuid);
+
+  if (randomize) {
+    const rnds = rng();
+    v1Bytes[8] = (rnds[0] & 0x3f) | 0x80;
+    v1Bytes[9] = rnds[1];
+    v1Bytes[10] = rnds[2];
+    v1Bytes[11] = rnds[3];
+    v1Bytes[12] = rnds[4];
+    v1Bytes[13] = rnds[5];
+    v1Bytes[14] = rnds[6];
+    v1Bytes[15] = rnds[7];
+  }
+
+  const v6Bytes = Uint8Array.from([
+    ((v1Bytes[6] & 0x0f) << 4) | ((v1Bytes[7] >> 4) & 0x0f),
+    ((v1Bytes[7] & 0x0f) << 4) | ((v1Bytes[4] & 0xf0) >> 4),
+    ((v1Bytes[4] & 0x0f) << 4) | ((v1Bytes[5] & 0xf0) >> 4),
+    ((v1Bytes[5] & 0x0f) << 4) | ((v1Bytes[0] & 0xf0) >> 4),
+
+    ((v1Bytes[0] & 0x0f) << 4) | ((v1Bytes[1] & 0xf0) >> 4),
+    ((v1Bytes[1] & 0x0f) << 4) | ((v1Bytes[2] & 0xf0) >> 4),
+
+    0x60 | (v1Bytes[2] & 0x0f),
+    v1Bytes[3],
+
+    v1Bytes[8],
+    v1Bytes[9],
+    v1Bytes[10],
+    v1Bytes[11],
+    v1Bytes[12],
+    v1Bytes[13],
+    v1Bytes[14],
+    v1Bytes[15],
+  ]);
+
+  return stringify(v6Bytes);
+}
diff --git a/src/v6tov1.js b/src/v6tov1.js
new file mode 100644
index 00000000..3a76cba4
--- /dev/null
+++ b/src/v6tov1.js
@@ -0,0 +1,50 @@
+import parse from './parse.js';
+import stringify from './stringify.js';
+import version from './version.js';
+
+/**
+ * Convert a v1 UUID to a v6 UUID.
+ *
+ * Note: Per https://www.rfc-editor.org/rfc/rfc9562.html#section-5.6-4, the
+ * clock_seq and node fields SHOULD be randomized to aid in collision resistance
+ * and security.  However. this behavior is not enabled by default for two reasons:
+ *
+ * 1. Doing so makes the conversion non-reversible.  I.e. `v6tov1(v1tov6(uuid))
+ *    !== uuid`.
+ * 2. Doing so makes the conversion non-deterministic.  I.e. `v1tov6(uuid) !==
+ *    v1tov6(uuid)`
+ *
+ * Callers wishing to enable the RFC-recommended randomization can do so by
+ * passing `true` for the second parameter.
+ */
+export default function v6tov1(uuid, randomize = false) {
+  if (version(uuid) !== 6) {
+    throw new Error('id is not a valid v6 UUID');
+  }
+
+  const v1Bytes = parse(uuid);
+
+  const v6Bytes = Uint8Array.from([
+    ((v1Bytes[3] & 0x0f) << 4) | ((v1Bytes[4] >> 4) & 0x0f),
+    ((v1Bytes[4] & 0x0f) << 4) | ((v1Bytes[5] & 0xf0) >> 4),
+    ((v1Bytes[5] & 0x0f) << 4) | (v1Bytes[6] & 0x0f),
+    v1Bytes[7],
+
+    ((v1Bytes[1] & 0x0f) << 4) | ((v1Bytes[2] & 0xf0) >> 4),
+    ((v1Bytes[2] & 0x0f) << 4) | ((v1Bytes[3] & 0xf0) >> 4),
+
+    0x10 | ((v1Bytes[0] & 0xf0) >> 4),
+    ((v1Bytes[0] & 0x0f) << 4) | ((v1Bytes[1] & 0xf0) >> 4),
+
+    v1Bytes[8],
+    v1Bytes[9],
+    v1Bytes[10],
+    v1Bytes[11],
+    v1Bytes[12],
+    v1Bytes[13],
+    v1Bytes[14],
+    v1Bytes[15],
+  ]);
+
+  return stringify(v6Bytes);
+}
diff --git a/test/unit/v6.test.js b/test/unit/v6.test.js
new file mode 100644
index 00000000..d7ef639a
--- /dev/null
+++ b/test/unit/v6.test.js
@@ -0,0 +1,26 @@
+import assert from 'assert';
+import v1tov6 from '../../src/v1tov6.js';
+import v6tov1 from '../../src/v6tov1.js';
+
+describe('v1 <-> v6 conversion', () => {
+  const v1Fixture = 'f1207660-21d2-11ef-8c4f-419efbd44d48';
+  const v6Fixture = '1ef21d2f-1207-6660-8c4f-419efbd44d48';
+
+  test('v1 -> v6 conversion', () => {
+    const id = v1tov6(v1Fixture);
+    assert.equal(id, v6Fixture);
+  });
+
+  test('v1 -> v6 conversion (w', () => {
+    const id = v1tov6(v1Fixture, true);
+
+    //
+    assert.notEqual(id, v6Fixture);
+    assert.equal(id.slice(0, 24), v6Fixture.slice(0, 24));
+  });
+
+  test('v6 -> v1 conversion', () => {
+    const id = v6tov1(v6Fixture);
+    assert.equal(id, v1Fixture);
+  });
+});