fix: resolve PHP 7.4 and below compatibility issues

- Added checks to prevent duplicate class alias declarations
- Replaced all BigInteger references with fully qualified class names (\bcmath_compat\BigInteger)
- Removed problematic 'use' statement that doesn't work with dynamic aliases in older PHP
- Created custom autoloader for environments without Composer
- Fixed namespace handling for both phpseclib 2.x and 3.x

These changes ensure compatibility with PHP 5.4-7.4 while maintaining functionality for PHP 8.x

Co-authored-by: nanasess <nanasess@users.noreply.github.com>

Author: claude[bot]

autoload.php

@@ -0,0 +1,71 @@
+<?php
+/**
+ * Simple autoloader for PHP 5.4+ without Composer
+ */
+
+// Register autoloader
+spl_autoload_register(function ($class) {
+    // Check if this is a bcmath_compat class
+    if (strpos($class, 'bcmath_compat\\') === 0) {
+        $file = __DIR__ . '/src/' . str_replace('bcmath_compat\\', '', $class) . '.php';
+        if (file_exists($file)) {
+            require_once $file;
+        }
+    }
+});
+
+// Check if bcmath extension is loaded
+if (!extension_loaded('bcmath')) {
+    // Load our bcmath polyfill
+    require_once __DIR__ . '/lib/bcmath.php';
+}
+
+// Try to load phpseclib
+// First check if we have composer autoloader
+if (file_exists(__DIR__ . '/vendor/autoload.php')) {
+    // Already loaded by test runner, do nothing
+}
+// Try phpseclib 3.x structure
+elseif (file_exists(__DIR__ . '/vendor/phpseclib/phpseclib/phpseclib/Math/BigInteger.php')) {
+    require_once __DIR__ . '/vendor/phpseclib/phpseclib/phpseclib/bootstrap.php';
+} 
+// Try phpseclib 2.x structure
+elseif (file_exists(__DIR__ . '/vendor/phpseclib/phpseclib/phpseclib/Math/BigInteger.php')) {
+    // phpseclib 2.x - set up include path
+    $phpseclibPath = __DIR__ . '/vendor/phpseclib/phpseclib/phpseclib';
+    set_include_path(get_include_path() . PATH_SEPARATOR . $phpseclibPath);
+    
+    // Load required files for phpseclib 2.x
+    require_once $phpseclibPath . '/Math/BigInteger.php';
+}
+// Fallback to direct file inclusion for installed packages
+else {
+    // Look for composer vendor directory
+    $vendorDir = __DIR__ . '/vendor';
+    if (is_dir($vendorDir)) {
+        // Try to find phpseclib in vendor
+        $iterator = new RecursiveIteratorIterator(
+            new RecursiveDirectoryIterator($vendorDir),
+            RecursiveIteratorIterator::SELF_FIRST
+        );
+        
+        foreach ($iterator as $file) {
+            if ($file->isFile() && $file->getFilename() === 'BigInteger.php') {
+                $path = $file->getPath();
+                if (strpos($path, 'phpseclib') !== false && strpos($path, 'Math') !== false) {
+                    $basePath = dirname(dirname($path));
+                    set_include_path(get_include_path() . PATH_SEPARATOR . $basePath);
+                    
+                    // Register autoloader for this path
+                    spl_autoload_register(function ($class) use ($basePath) {
+                        $file = $basePath . '/' . str_replace('\\', '/', $class) . '.php';
+                        if (file_exists($file)) {
+                            require_once $file;
+                        }
+                    });
+                    break;
+                }
+            }
+        }
+    }
+}

src/BCMath.php

@@ -12,19 +12,22 @@
 
 namespace bcmath_compat;
 
+// For PHP < 7.0, we need to handle class_alias differently
 // Check phpseclib version and use appropriate namespace
 if (class_exists('\phpseclib3\Math\BigInteger')) {
     // phpseclib 3.x
-    class_alias('\phpseclib3\Math\BigInteger', '\bcmath_compat\BigInteger');
+    if (!class_exists('\bcmath_compat\BigInteger')) {
+        class_alias('\phpseclib3\Math\BigInteger', '\bcmath_compat\BigInteger');
+    }
 } elseif (class_exists('\phpseclib\Math\BigInteger')) {
     // phpseclib 2.x
-    class_alias('\phpseclib\Math\BigInteger', '\bcmath_compat\BigInteger');
+    if (!class_exists('\bcmath_compat\BigInteger')) {
+        class_alias('\phpseclib\Math\BigInteger', '\bcmath_compat\BigInteger');
+    }
 } else {
     throw new \RuntimeException('phpseclib is not installed');
 }
 
-use bcmath_compat\BigInteger;
-
 /**
  * BCMath Emulation Class
  *
@@ -92,7 +95,7 @@ private static function format($x, $scale, $pad)
      */
     private static function isNegative($x)
     {
-        return $x->compare(new BigInteger()) < 0;
+        return $x->compare(new \bcmath_compat\BigInteger()) < 0;
     }
 
     /**
@@ -171,7 +174,7 @@ private static function div($x, $y, $scale, $pad)
         }
 
         $temp = '1' . str_repeat('0', $scale);
-        $temp = new BigInteger($temp);
+        $temp = new \bcmath_compat\BigInteger($temp);
         list($q) = $x->multiply($temp)->divide($y);
 
         return self::format($q, $scale, $scale);
@@ -217,8 +220,8 @@ private static function mod($x, $y, $scale, $pad)
      */
     private static function comp($x, $y, $scale, $pad)
     {
-        $x = new BigInteger($x[0] . substr($x[1], 0, $scale));
-        $y = new BigInteger($y[0] . substr($y[1], 0, $scale));
+        $x = new \bcmath_compat\BigInteger($x[0] . substr($x[1], 0, $scale));
+        $y = new \bcmath_compat\BigInteger($y[0] . substr($y[1], 0, $scale));
 
         return $x->compare($y);
     }
@@ -244,9 +247,9 @@ private static function pow($x, $y, $scale, $pad)
         }
 
         $min = defined('PHP_INT_MIN') ? PHP_INT_MIN : ~PHP_INT_MAX;
-        $y_big = new BigInteger($y);
-        $max_big = new BigInteger(PHP_INT_MAX);
-        $min_big = new BigInteger($min);
+        $y_big = new \bcmath_compat\BigInteger($y);
+        $max_big = new \bcmath_compat\BigInteger(PHP_INT_MAX);
+        $min_big = new \bcmath_compat\BigInteger($min);
         if ($y_big->compare($max_big) > 0 || $y_big->compare($min_big) <= 0) {
             if (class_exists('\ValueError')) {
                 throw new \ValueError('bcpow(): Argument #2 ($exponent) is too large');
@@ -259,15 +262,15 @@ private static function pow($x, $y, $scale, $pad)
         $sign = self::isNegative($x) ? '-' : '';
         $x = $x->abs();
 
-        $r = new BigInteger(1);
+        $r = new \bcmath_compat\BigInteger(1);
 
         for ($i = 0; $i < abs($y); $i++) {
             $r = $r->multiply($x);
         }
 
         if ($y < 0) {
             $temp = '1' . str_repeat('0', $scale + $pad * abs($y));
-            $temp = new BigInteger($temp);
+            $temp = new \bcmath_compat\BigInteger($temp);
             list($r) = $temp->divide($r);
             $pad = $scale;
         } else {
@@ -306,9 +309,9 @@ private static function powmod($x, $e, $n, $scale, $pad)
                 '1';
         }
 
-        $x = new BigInteger($x);
-        $e = new BigInteger($e);
-        $n = new BigInteger($n);
+        $x = new \bcmath_compat\BigInteger($x);
+        $e = new \bcmath_compat\BigInteger($e);
+        $n = new \bcmath_compat\BigInteger($n);
 
         $z = $x->powMod($e, $n);
 
@@ -532,7 +535,7 @@ public static function __callStatic($name, $arguments)
                         $num[1] = '';
                     }
                     $num[1] = str_pad($num[1], $pad, '0');
-                    $num = new BigInteger($num[0] . $num[1]);
+                    $num = new \bcmath_compat\BigInteger($num[0] . $num[1]);
                 }
                 break;
             case 'comp':