feature symfony#53060 [Uid] Add UuidV1::toV6(), UuidV1::toV7() and UuidV6::toV7() (fancyweb, nicolas-grekas)

This PR was merged into the 7.1 branch.

Discussion
----------

[Uid] Add `UuidV1::toV6()`, `UuidV1::toV7()` and `UuidV6::toV7()`

| Q             | A
| ------------- | ---
| Branch?       | 7.1
| Bug fix?      | no
| New feature?  | yes
| Deprecations? | false
| Issues        | -
| License       | MIT

The goal is to help working with new UUIDv6 & v7 versions when you receive legacy UUIDv1.

UUIDv6 and v1 are 100% compatible since v6 is just a "reordering" of v1.

UUIDv7 and v1 are not strictly compatible for several reasons: the timestamp precision is not the same. Also, there is no clock seq or variant or node in v7 but full randomness instead. And maybe others?
However, I believe we can still technically do the conversion (timestamp -> timestamp, clock seq + variant + node -> randomness) with at least one concession: the sub-milliseconds v1 timestamp precision is lost since v7 doesn't support it.

My proposed v1 to v7 implementation has 2 issues:
* sub-microsecond entropy is entirely lost
* monotonicity is lost?

I'm opening this PR so that `@nicolas`-grekas gets triggered by the inefficiency of my code and finds a better solution 😁
I'm kidding, I actually know he already has an idea because he explained it to me during the Brussels HackDay but I couldn't understand it well enough to be able to implement it 😅

Commits
-------

9ee1437 [Uid] Add `UuidV1::toV6()`, `UuidV1::toV7()` and `UuidV6::toV7()`
93f1812 [Uid] Add `UuidV6::fromV1()` and `UuidV7::fromV1()` methods

Author: nicolas-grekas

src/Symfony/Component/Uid/BinaryUtil.php

@@ -118,8 +118,10 @@ public static function add(string $a, string $b): string
 
     /**
      * @param string $time Count of 100-nanosecond intervals since the UUID epoch 1582-10-15 00:00:00 in hexadecimal
+     *
+     * @return string Count of 100-nanosecond intervals since the UUID epoch 1582-10-15 00:00:00 as a numeric string
      */
-    public static function hexToDateTime(string $time): \DateTimeImmutable
+    public static function hexToNumericString(string $time): string
     {
         if (\PHP_INT_SIZE >= 8) {
             $time = (string) (hexdec($time) - self::TIME_OFFSET_INT);
@@ -140,7 +142,17 @@ public static function hexToDateTime(string $time): \DateTimeImmutable
             $time = '-' === $time[0] ? '-'.str_pad(substr($time, 1), 8, '0', \STR_PAD_LEFT) : str_pad($time, 8, '0', \STR_PAD_LEFT);
         }
 
-        return \DateTimeImmutable::createFromFormat('U.u?', substr_replace($time, '.', -7, 0));
+        return $time;
+    }
+
+    /**
+     * Sub-microseconds are lost since they are not handled by \DateTimeImmutable.
+     *
+     * @param string $time Count of 100-nanosecond intervals since the UUID epoch 1582-10-15 00:00:00 in hexadecimal
+     */
+    public static function hexToDateTime(string $time): \DateTimeImmutable
+    {
+        return \DateTimeImmutable::createFromFormat('U.u?', substr_replace(self::hexToNumericString($time), '.', -7, 0));
     }
 
     /**

src/Symfony/Component/Uid/CHANGELOG.md

@@ -1,6 +1,11 @@
 CHANGELOG
 =========
 
+7.1
+---
+
+ * Add `UuidV1::toV6()`, `UuidV1::toV7()` and `UuidV6::toV7()`
+
 6.2
 ---
 

src/Symfony/Component/Uid/Tests/UuidTest.php

@@ -427,4 +427,48 @@ public function testFromStringBase58Padding()
     {
         $this->assertInstanceOf(Uuid::class, Uuid::fromString('111111111u9QRyVM94rdmZ'));
     }
+
+    public function testV1ToV6()
+    {
+        $uuidV1 = new UuidV1('8189d3de-9670-11ee-b9d1-0242ac120002');
+        $uuidV6 = $uuidV1->toV6();
+
+        $this->assertEquals($uuidV1->getDateTime(), $uuidV6->getDateTime());
+        $this->assertSame($uuidV1->getNode(), $uuidV6->getNode());
+        $this->assertEquals($uuidV6, $uuidV1->toV6());
+    }
+
+    public function testV1ToV7BeforeUnixEpochThrows()
+    {
+        $this->expectException(\InvalidArgumentException::class);
+        $this->expectExceptionMessage('Cannot convert UUID to v7: its timestamp is before the Unix epoch.');
+
+        (new UuidV1('9aba8000-ff00-11b0-b3db-3b3fc83afdfc'))->toV7(); // Timestamp is 1969-01-01 00:00:00.0000000
+    }
+
+    public function testV1ToV7()
+    {
+        $uuidV1 = new UuidV1('eb248d80-ea4f-11ec-9d2a-839425e6fb88');
+        $sameUuidV1100NanosecondsLater = new UuidV1('eb248d81-ea4f-11ec-9d2a-839425e6fb88');
+        $uuidV7 = $uuidV1->toV7();
+        $sameUuidV7100NanosecondsLater = $sameUuidV1100NanosecondsLater->toV7();
+
+        $this->assertSame($uuidV1->getDateTime()->format('Uv'), $uuidV7->getDateTime()->format('Uv'));
+        $this->assertEquals($uuidV7, $uuidV1->toV7());
+        $this->assertNotEquals($uuidV7, $sameUuidV7100NanosecondsLater);
+        $this->assertSame(hexdec('0'.substr($uuidV7, -2)) + 1, hexdec('0'.substr($sameUuidV7100NanosecondsLater, -2)));
+    }
+
+    public function testV1ToV7WhenExtraTimeEntropyOverflows()
+    {
+        $uuidV1 = new UuidV1('10e7718f-2d4f-11be-bfed-cdd35907e584');
+        $sameUuidV1100NanosecondsLater = new UuidV1('10e77190-2d4f-11be-bfed-cdd35907e584');
+        $uuidV7 = $uuidV1->toV7();
+        $sameUuidV7100NanosecondsLater = $sameUuidV1100NanosecondsLater->toV7();
+
+        $this->assertSame($uuidV1->getDateTime()->format('Uv'), $uuidV7->getDateTime()->format('Uv'));
+        $this->assertEquals($uuidV7, $uuidV1->toV7());
+        $this->assertNotEquals($uuidV7, $sameUuidV7100NanosecondsLater);
+        $this->assertSame(hexdec('0'.substr($uuidV7, -2)) + 1, hexdec('0'.substr($sameUuidV7100NanosecondsLater, -2)));
+    }
 }

src/Symfony/Component/Uid/UuidV1.php

@@ -41,6 +41,18 @@ public function getNode(): string
         return uuid_mac($this->uid);
     }
 
+    public function toV6(): UuidV6
+    {
+        $uuid = $this->uid;
+
+        return new UuidV6(substr($uuid, 15, 3).substr($uuid, 9, 4).$uuid[0].'-'.substr($uuid, 1, 4).'-6'.substr($uuid, 5, 3).substr($uuid, 18, 6).substr($uuid, 24));
+    }
+
+    public function toV7(): UuidV7
+    {
+        return $this->toV6()->toV7();
+    }
+
     public static function generate(\DateTimeInterface $time = null, Uuid $node = null): string
     {
         $uuid = !$time || !$node ? uuid_create(static::TYPE) : parent::NIL;

src/Symfony/Component/Uid/UuidV6.php

@@ -43,6 +43,33 @@ public function getNode(): string
         return substr($this->uid, 24);
     }
 
+    public function toV7(): UuidV7
+    {
+        $uuid = $this->uid;
+        $time = BinaryUtil::hexToNumericString('0'.substr($uuid, 0, 8).substr($uuid, 9, 4).substr($uuid, 15, 3));
+        if ('-' === $time[0]) {
+            throw new \InvalidArgumentException('Cannot convert UUID to v7: its timestamp is before the Unix epoch.');
+        }
+
+        $ms = \strlen($time) > 4 ? substr($time, 0, -4) : '0';
+        $time = dechex(10000 * hexdec(substr($uuid, 20, 3)) + substr($time, -4));
+
+        if (\strlen($time) > 6) {
+            $uuid[29] = dechex(hexdec($uuid[29]) ^ hexdec($time[0]));
+            $time = substr($time, 1);
+        }
+
+        return new UuidV7(substr_replace(sprintf(
+            '%012s-7%s-%s%s-%s%06s',
+            \PHP_INT_SIZE >= 8 ? dechex($ms) : bin2hex(BinaryUtil::fromBase($ms, BinaryUtil::BASE10)),
+            substr($uuid, -6, 3),
+            $uuid[19],
+            substr($uuid, -3),
+            substr($uuid, -12, 6),
+            $time
+        ), '-', 8, 0));
+    }
+
     public static function generate(\DateTimeInterface $time = null, Uuid $node = null): string
     {
         $uuidV1 = UuidV1::generate($time, $node);