From 0fa0ac0d1bf26898cf17617d7f451dadc4ca051f Mon Sep 17 00:00:00 2001
From: flashwave <me@flash.moe>
Date: Mon, 28 Dec 2020 18:32:43 +0000
Subject: [PATCH] TimeSpan fixes.

---
 lib/FWIF/FWIF.php | 63 +++++++++++++++++++----------------------------
 1 file changed, 25 insertions(+), 38 deletions(-)

diff --git a/lib/FWIF/FWIF.php b/lib/FWIF/FWIF.php
index af39473..77a5659 100644
--- a/lib/FWIF/FWIF.php
+++ b/lib/FWIF/FWIF.php
@@ -23,7 +23,7 @@ class FWIF {
     public const TYPE_ARRAY     = 0x05; // List of values, terminated with TRAILER
     public const TYPE_OBJECT    = 0x06; // List of values with ASCII names, terminated with TRAILER
     public const TYPE_DATETIME  = 0x07; // A gregorian year, month and day as well as an hour, minute, seconds and millisecond component, variable ranging from 4 to 7 bytes
-    public const TYPE_TIMESPAN  = 0x08; // A period of time, follows the same format DATETIME but uses an additional flag to indicate negative periods
+    public const TYPE_TIMESPAN  = 0x08; // A period of time, containing days, hours, minutes, seconds and milliseconds, variable ranging from 4 to 6 bytes
     
     public const TRAILER = 0xFF; // Termination byte
 
@@ -409,8 +409,7 @@ class FWIF {
         return new DateTimeImmutable($dt . 'UTC');
     }
 
-    private const TIMESPAN_FLAG_YEAR = 0x10000000;
-    private const TIMESPAN_FLAG_DMY  = 0x20000000;
+    private const TIMESPAN_FLAG_DAYS = 0x20000000;
     private const TIMESPAN_FLAG_NEGA = 0x40000000;
 
     private const TIMESPAN_MILLI_SHIFT = 16; // <<
@@ -419,19 +418,16 @@ class FWIF {
     private const TIMESPAN_SECS_SHIFT = 11; // <<
     private const TIMESPAN_MINS_SHIFT = 5; // <<
 
-    private const TIMESPAN_DAYS_SHIFT  = 10; // <<
-    private const TIMESPAN_MONTH_SHIFT = 6; // <<
+    private const TIMESPAN_DAYS_MASK = 0x7FFF;
 
-    private const TIMESPAN_YEAR_HI_MASK  = 0x3F00;
-    private const TIMESPAN_YEAR_HI_SHIFT = 8; // >>
-    private const TIMESPAN_YEAR_LO_MASK  = 0x00FF;
+    private const TIMESPAN_YEAR_DAYS = 365.0;
+    private const TIMESPAN_MONTH_DAYS = 31.0;
 
-    /* +--------+--------+ w - unsigned 10-bit millisecs    y - Y enable flag
-     * |.ndy.www|wwwwwwwS| S - unsigned 6-bit seconds       D - unsigned 5-bit day
-     * |SSSSSmmm|mmmHHHHH| m - unsigned 6-bit minutes       M - unsigned 4-bit month
-     * |.DDDDDMM|MMYYYYYY| H - unsigned 5-bit hours         Y - unsigned 14-bit year
-     * |YYYYYYYY|        | n - Negative flag
-     * +--------+--------+ d - DMY enable flag
+    /* +--------+--------+ w - unsigned 10-bit millisecs    n - Negative flag
+     * |.nd..www|wwwwwwwS| S - unsigned 6-bit seconds       d - DMY enable flag
+     * |SSSSSmmm|mmmHHHHH| m - unsigned 6-bit minutes       D - unsigned 15-bit day
+     * |.DDDDDDD|DDDDDDDD| H - unsigned 5-bit hours
+     * +--------+--------+ 
      */
 
     private static function encodeTimeSpan(DateInterval $di, int $flags): string {
@@ -441,24 +437,18 @@ class FWIF {
         $wsmh |= (      $di->i         & self::DATETIME_MINS_MASK)  << self::TIMESPAN_MINS_SHIFT;
         $wsmh |= (      $di->h         & self::DATETIME_HOUR_MASK);
 
-        if($di->d > 0 || $di->m > 0 || $di->y > 0) {
-            $wsmh |=  self::TIMESPAN_FLAG_DMY;
-            $dmy   = ($di->d & self::DATETIME_DAY_MASK)   << self::TIMESPAN_DAYS_SHIFT;
-            $dmy  |= ($di->m & self::DATETIME_MONTH_MASK) << self::TIMESPAN_MONTH_SHIFT;
+        $days = $di->days;
+        if($days === false) // Best I can come up with on short notice, fuck it
+            $days = (int)($di->d + ($di->m * self::TIMESPAN_YEAR_DAYS) + ($di->y * self::TIMESPAN_MONTH_DAYS));
 
-            if($di->y > 0) {
-                $wsmh |= self::TIMESPAN_FLAG_YEAR;
-                $dmy |= ($di->y & self::TIMESPAN_YEAR_HI_MASK) >> self::TIMESPAN_YEAR_HI_SHIFT;
-                $y    = ($di->y & self::TIMESPAN_YEAR_LO_MASK);
-            }
+        if($days > 0) {
+            $wsmh |= self::TIMESPAN_FLAG_DAYS;
+            $days &= self::TIMESPAN_DAYS_MASK;
         }
 
         $packed = pack('N', $wsmh);
-        if($wsmh & self::TIMESPAN_FLAG_DMY) {
-            $packed .= pack('n', $dmy);
-            if($wsmh & self::TIMESPAN_FLAG_YEAR)
-                $packed .= chr($y);
-        }
+        if($wsmh & self::TIMESPAN_FLAG_DAYS)
+            $packed .= pack('n', $days);
 
         return $packed;
     }
@@ -472,16 +462,13 @@ class FWIF {
         $di->i      =  ($wsmh >> self::TIMESPAN_MINS_SHIFT)  & self::DATETIME_MINS_MASK;
         $di->h      =   $wsmh                                & self::DATETIME_HOUR_MASK;
 
-        if($wsmh & self::TIMESPAN_FLAG_DMY) {
-            $dmy = unpack('n', fread($data, 2))[1];
-            $di->d = ($dmy >> self::TIMESPAN_DAYS_SHIFT)  & self::DATETIME_DAY_MASK;
-
-            // OOPS! THESE WILL BE HORRIBLY INACCURATE!
-            // Perhaps go back to the drawing board and tack months and years onto days?
-            $di->m = ($dmy >> self::TIMESPAN_MONTH_SHIFT) & self::DATETIME_MONTH_MASK;
-            if($wsmh & self::TIMESPAN_FLAG_YEAR)
-                $di->y = ord(fgetc($data))
-                    | (($dmy << self::TIMESPAN_YEAR_HI_SHIFT) & self::TIMESPAN_YEAR_HI_MASK);
+        if($wsmh & self::TIMESPAN_FLAG_DAYS) {
+            $days = unpack('n', fread($data, 2))[1] & self::TIMESPAN_DAYS_MASK;
+            $di->days = $days;
+            $di->y = (int)floor($days / self::TIMESPAN_YEAR_DAYS);
+            $days -= $di->y * self::TIMESPAN_YEAR_DAYS;
+            $di->m = (int)ceil($days / self::TIMESPAN_MONTH_DAYS);
+            $di->d = max(0, $days - ($di->m * self::TIMESPAN_MONTH_DAYS));
         }
 
         return $di;