Correctly calculate the maximum UUIDv7 time value (#38)

Author: oittaa

src/UUID.php

@@ -269,8 +269,8 @@ public static function getTime(string $uuid): ?string
             $retval .= substr_replace(str_pad(strval($ts), 8, '0', \STR_PAD_LEFT), '.', -7, 0);
         } elseif ($version === 7) {
             $unixts = hexdec(substr($timehex, 0, 10));
-            $subsec = str_pad(strval(self::decodeSubsec(hexdec(substr($timehex, 10)))), 7, '0', \STR_PAD_LEFT);
-            $retval = $unixts . '.' . $subsec;
+            $subsec = self::decodeSubsec(hexdec(substr($timehex, 10)));
+            $retval = substr_replace(str_pad(strval($unixts * 10 ** 7 + $subsec), 8, '0', \STR_PAD_LEFT), '.', -7, 0);
         }
         return $retval;
     }

tests/UuidTest.php

@@ -224,4 +224,18 @@ public function testGetTimeNegativeNearEpoch()
         $uuid6_time = UUID::getTime('1b21dd21-3813-6fff-b678-1556dde9b80e');
         $this->assertSame($uuid6_time, '-0.0000001');
     }
+    public function testGetTimeZero()
+    {
+        $uuid6_time = UUID::getTime('00000000-0000-6000-8000-000000000000');
+        $this->assertSame($uuid6_time, '-12219292800.0000000');
+        $uuid7_time = UUID::getTime('00000000-0000-7000-8000-000000000000');
+        $this->assertSame($uuid7_time, '0.0000000');
+    }
+    public function testGetTimeMax()
+    {
+        $uuid6_time = UUID::getTime('ffffffff-ffff-6fff-bfff-ffffffffffff');
+        $this->assertSame($uuid6_time, '103072857660.6846975');
+        $uuid7_time = UUID::getTime('ffffffff-ffff-7fff-bfff-ffffffffffff');
+        $this->assertSame($uuid7_time, '68719476736.0000000');
+    }
 }