From fa2e74eacab046f27fb26353f3c11114fe97c997 Mon Sep 17 00:00:00 2001
From: Deon George <deon@dege.au>
Date: Thu, 7 Dec 2023 12:07:11 +1100
Subject: [PATCH] Changes to timew() and wtime() to leverage last 2 bits for 4
 year timestamp, making msgid checking valid according to FTSC. Added a test
 suite for timew()/wtime().

---
 app/helpers.php          | 37 ++++++++++++++++++++-----
 tests/Unit/TimeWTest.php | 59 ++++++++++++++++++++++++++++++++++++++++
 2 files changed, 89 insertions(+), 7 deletions(-)
 create mode 100644 tests/Unit/TimeWTest.php

diff --git a/app/helpers.php b/app/helpers.php
index 00dc03a..55e92e3 100644
--- a/app/helpers.php
+++ b/app/helpers.php
@@ -103,17 +103,18 @@ if (! function_exists('timew')) {
 	 * are unique using 1/10th second precision.
 	 *
 	 * Time is:
-	 * + 02 bits unused
+	 * + 02 bits least significant bits of year - giving us a 4 year timestamp
 	 * + 04 bits Month
 	 * + 05 bits Day
 	 * + 05 bits Hour
 	 * + 06 bits Min
 	 * + 06 bits Sec
 	 * + 04 bits 10th Sec
-	 * = 32 (2 bits free)
+	 * = 32 bits
 	 *
 	 * @param Carbon|null $time
 	 * @return int
+	 * @todo Since this is used as part of our msgid, we need to use the first 2 bits to get our 3 year unique msgid, ie: year&0x03
 	 */
 	function timew(Carbon $time=NULL): int
 	{
@@ -130,19 +131,30 @@ if (! function_exists('timew')) {
 
 		$delay = $time->getPreciseTimestamp(1);
 
-		$t = ($time->month & 0xf) << 5;
+		$t = 0;
+		$t = ($t | $time->year & 0x3) << 4;
+		$t = ($t | ($time->month & 0xf)) << 5;
 		$t = ($t | ($time->day & 0x1f)) << 5;
 		$t = ($t | ($time->hour & 0x1f)) << 6;
 		$t = ($t | ($time->minute & 0x3f)) << 6;
-		$t = ($t | ($time->second & 0x3f));
+		$t = ($t | ($time->second & 0x3f)) << 4;
+		$t = ($t | ((int)($time->milli/100)) & 0xf);
 
-		return hexdec(sprintf('%07x%1x',$t,(round($time->milli/100) & 0x7f)));
+		return $t;
 	}
 }
 
 if (! function_exists('wtime')) {
 	/**
 	 * Convert a 40 bit integer into a time.
+	 * We need to filter out loose bits, ie:
+	 * + year all bits valid
+	 * + month 11xx and 0000 are invalid
+	 * + day all bits valid except 0000
+	 * + hour 11xxx are invalid
+	 * + min 1111xx are invalid
+	 * + sec 1111xx are invalid
+	 * + 1/2 11xx, 101x are invalid
 	 * @see timew()
 	 *
 	 * @param int $time
@@ -158,25 +170,36 @@ if (! function_exists('wtime')) {
 		if ($time > pow(2,26)-1) {
 			$milli = ($time & 0xf);
 			$time = $time >> 4;
+			if ($milli > 9)
+				$milli = 9;
 
 		} else {
 			$milli = 0;
 		}
 
 		$sec = ($time & 0x3f);
+		if ($sec > 59)
+			$sec = 59;
 		$time = $time >> 6;
 
 		$min = ($time & 0x3f);
+		if ($min > 59)
+			$min = 59;
 		$time = $time >> 6;
 
 		$hr = ($time & 0x1f);
+		if ($hr > 23)
+			$hr = 23;
 		$time = $time >> 5;
 
 		$day = ($time & 0x1f);
 		$time = $time >> 5;
 
-		$month = ($time & 0x1f);
+		$month = ($time & 0xf);
+		if ($month > 12)
+			$month = 12;
+		$time = $time >> 4;
 
-		return Carbon::create($year,$month,$day,$hr,$min,$sec+$milli/10);
+		return Carbon::create(($year & 0xffc)+$time,$month,$day,$hr,$min,$sec+$milli/10);
 	}
 }
\ No newline at end of file
diff --git a/tests/Unit/TimeWTest.php b/tests/Unit/TimeWTest.php
new file mode 100644
index 0000000..0ee9b48
--- /dev/null
+++ b/tests/Unit/TimeWTest.php
@@ -0,0 +1,59 @@
+<?php
+
+namespace Tests\Unit;
+
+use Carbon\Carbon;
+use PHPUnit\Framework\TestCase;
+
+class TimeWTest extends TestCase
+{
+    /**
+     * A basic unit test example.
+     */
+    public function test_timew(): void
+    {
+        $date = Carbon::createFromFormat('Y-m-d H:i:s.v','2023-12-07 12:13:14.567');
+
+		$this->assertEquals(4042011877,timew($date));
+
+		$date = Carbon::createFromFormat('Y-m-d H:i:s.v','2019-12-07 12:13:14.567');
+
+		$this->assertEquals(4042011877,timew($date));
+
+		$date = Carbon::createFromFormat('Y-m-d H:i:s.v','2022-12-07 01:28:50.400');
+
+		$this->assertEquals(2967565092,timew($date));
+    }
+
+	/**
+	 * A basic unit test example.
+	 */
+	public function test_wtime(): void
+	{
+		$date = Carbon::createFromFormat('Y-m-d H:i:s.v','2023-12-07 12:13:14.5');
+
+		$this->assertEquals($date,wtime(4042011877,2022));
+
+		$date = Carbon::createFromFormat('Y-m-d H:i:s.v','2019-12-07 12:13:14.5');
+
+		$this->assertEquals($date,wtime(4042011877,2018));
+
+		$date = Carbon::createFromFormat('Y-m-d H:i:s.v','2022-12-07 01:28:50.400');
+
+		$this->assertEquals($date,wtime(2967565092,2022));
+	}
+
+	public function test_random_time(): void
+	{
+		$times = [];
+		$now = Carbon::now()->milli(rand(0,9)*100);
+
+		for ($i=0;$i<1000;$i++) {
+			$ran = $now->clone()->addYears(rand(-50,50))->addDays(rand(-365,365))->addHours(rand(-24,24))->addMinutes(rand(-60,60))->addSeconds(rand(-60,60));
+			$times[timew($ran)] = $ran;
+		}
+
+		foreach ($times as $wtime => $time)
+			$this->assertEquals($time,wtime($wtime,$time->year));
+	}
+}