From fa4c151fc61412540881c05f54cd43fba45cf70e Mon Sep 17 00:00:00 2001
From: oittaa <8972248+oittaa@users.noreply.github.com>
Date: Fri, 13 Sep 2024 01:36:06 +0200
Subject: [PATCH] Add minimal UUID v7 implementation

---
 README.md | 30 +++++++++++++++++++++++++++++-
 1 file changed, 29 insertions(+), 1 deletion(-)

diff --git a/README.md b/README.md
index c4cfdc5..eb8bc4d 100644
--- a/README.md
+++ b/README.md
@@ -7,7 +7,7 @@ A small PHP class for generating [RFC 9562][RFC 9562] universally unique identif
 
 If all you want is a unique ID, you should call `uuid4()`.
 
-> Implementations SHOULD utilize UUID version 7 instead of UUID version 1 and 6 if possible.
+> Implementations SHOULD utilize UUIDv7 instead of UUIDv1 and UUIDv6 if possible.
 
 If you're regularly generating more than thousand UUIDs per second, you might want to use `uuid8()` instead of `uuid7()`. This implementation of `uuid8()` sacrifices some entropy compared to `uuid7()`, but offers 100 nanosecond granularity while being otherwise compatible.
 
@@ -27,6 +27,34 @@ function uuid4()
 echo uuid4();
 ```
 
+## Minimal UUID v7 implementation
+
+```php
+<?php
+function uuid7()
+{
+    static $last_timestamp = 0;
+    $unixts_ms = intval(microtime(true) * 1000);
+    if ($last_timestamp >= $unixts_ms) {
+        $unixts_ms = $last_timestamp + 1;
+    }
+    $last_timestamp = $unixts_ms;
+    $data = random_bytes(10);
+    $data[0] = chr((ord($data[0]) & 0x0f) | 0x70); // set version
+    $data[2] = chr((ord($data[2]) & 0x3f) | 0x80); // set variant
+    return vsprintf(
+        '%s%s-%s-%s-%s-%s%s%s',
+        str_split(
+            str_pad(dechex($unixts_ms), 12, '0', \STR_PAD_LEFT) .
+                bin2hex($data),
+            4
+        )
+    );
+}
+
+echo uuid7();
+```
+
 ## Installation
 
 If you need comparison tools or sortable identifiers like in versions 6, 7, and 8, you might find this small and fast package useful. It doesn't require any other dependencies.