From 004156712b7669a228d6d9bc688f53c4cc69fa13 Mon Sep 17 00:00:00 2001
From: flashwave <me@flash.moe>
Date: Sun, 22 Dec 2024 02:02:53 +0000
Subject: [PATCH] Rewrote Base62 algorithm to avoid errors with very big
 numbers.

---
 VERSION                      |  2 +-
 src/IntegerBaseConverter.php | 48 ++++++++++--------------------------
 tests/Base62Test.php         |  6 +++--
 3 files changed, 18 insertions(+), 38 deletions(-)

diff --git a/VERSION b/VERSION
index 231699d..8617fda 100644
--- a/VERSION
+++ b/VERSION
@@ -1 +1 @@
-0.2410.630140
+0.2410.830201
diff --git a/src/IntegerBaseConverter.php b/src/IntegerBaseConverter.php
index a15528c..cc06c0d 100644
--- a/src/IntegerBaseConverter.php
+++ b/src/IntegerBaseConverter.php
@@ -1,7 +1,7 @@
 <?php
 // IntegerBaseConverter.php
 // Created: 2024-07-31
-// Updated: 2024-08-04
+// Updated: 2024-12-22
 
 namespace Index;
 
@@ -11,7 +11,7 @@ use InvalidArgumentException;
  * Provides methods for encoding integers in different bases.
  */
 class IntegerBaseConverter {
-    private int $maxBase;
+    private int $base;
 
     /**
      * @param string $characterSet Specifies the provided character set, must be a string consisting out of at least two unique characters.
@@ -27,38 +27,27 @@ class IntegerBaseConverter {
         if(XString::countUnique($characterSet) !== $length)
             throw new InvalidArgumentException('$characterSet must contain a set of entirely unique characters');
 
-        $this->maxBase = $length;
+        $this->base = $length;
     }
 
     /**
      * Converts a positive base10 integer to another base.
      *
      * @param int $integer The integer to encode.
-     * @param int $toBase Target base, 0 for the base of the provided character set.
      * @return string The encoded data, as a string.
      */
-    public function encode(int $integer, int $toBase = 0): string {
+    public function encode(int $integer): string {
         if($integer < 0)
             throw new InvalidArgumentException('$integer contains a negative value, which cannot be represented');
-        if($toBase === 0)
-            $toBase = $this->maxBase;
-        else {
-            if($toBase < 2)
-                throw new InvalidArgumentException('lowest supported value for $toBase is 2');
-            if($toBase > $this->maxBase)
-                throw new InvalidArgumentException('specified $toBase value is greater than the amount of characters in the provided character set');
-        }
-
         if($integer === 0)
-            return '';
+            return $this->characterSet[0];
 
         $output = '';
 
-        for($i = floor(log10($integer) / log10($toBase)); $i >= 0; --$i) {
-            $exp = $toBase ** $i;
-            $index = (int)floor($integer / $exp);
-            $output .= $this->characterSet[$index];
-            $integer -= $index * $exp;
+        while($integer > 0) {
+            $remainder = $integer % $this->base;
+            $output = $this->characterSet[$remainder] . $output;
+            $integer = intdiv($integer, $this->base);
         }
 
         return $output;
@@ -68,33 +57,22 @@ class IntegerBaseConverter {
      * Converts another base encoded integer to a base10 integer.
      *
      * @param string $string The encoded integer.
-     * @param int $fromBase Source base, 0 for the base of the provided character set.
      * @return int|false Returns the decoded integer or false on failure.
      */
-    public function decode(string $string, int $fromBase = 0): int|false {
-        if($fromBase === 0)
-            $fromBase = $this->maxBase;
-        else {
-            if($fromBase < 2)
-                throw new InvalidArgumentException('lowest supported value for $fromBase is 2');
-            if($fromBase > $this->maxBase)
-                throw new InvalidArgumentException('specified $fromBase value is greater than the amount of characters in the provided character set');
-        }
-
+    public function decode(string $string): int|false {
         if($string === '')
             return 0;
 
         $output = 0;
-        $length = strlen($string) - 1;
 
-        for($i = 0; $i <= $length; ++$i) {
+        for($i = 0; $i < strlen($string); ++$i) {
             $pos = strpos($this->characterSet, $string[$i]);
             if($pos === false)
                 return false;
 
-            $output += $pos * ($fromBase ** ($length - $i));
+            $output = $output * $this->base + $pos;
         }
 
-        return (int)$output;
+        return $output;
     }
 }
diff --git a/tests/Base62Test.php b/tests/Base62Test.php
index 1b83576..bd9037c 100644
--- a/tests/Base62Test.php
+++ b/tests/Base62Test.php
@@ -1,7 +1,7 @@
 <?php
 // Base62Test.php
 // Created: 2022-01-28
-// Updated: 2024-07-31
+// Updated: 2024-12-22
 
 declare(strict_types=1);
 
@@ -14,16 +14,18 @@ final class Base62Test extends TestCase {
     public const TESTS = [
         ['aaaaaa', 9311514030],
         ['Soap', 12962613],
-        ['', 0],
+        ['0', 0],
         ['1', 1],
         ['kPH', 80085],
         ['UC', 3510],
         ['p', 25],
         ['6zi', 25252],
         ['1ly7vk', 1234567890],
+        ['15vjOLmUu1', 14739082838046309],
     ];
 
     public function testDecode(): void {
+        $this->assertEquals(0, XNumber::fromBase62(''));
         foreach(self::TESTS as $test)
             $this->assertEquals($test[1], XNumber::fromBase62($test[0]));
     }