Added Bas32.php

src/Socialbox/Classes/Base32.php

@@ -0,0 +1,86 @@
+<?php
+
+namespace Socialbox\Classes;
+
+use InvalidArgumentException;
+
+class Base32
+{
+    /**
+     * Array with all 32 characters for decoding from/encoding to base32.
+     */
+    private const LOOKUP_TABLE = [
+        'A', 'B', 'C', 'D', 'E', 'F', 'G', 'H', //  7
+        'I', 'J', 'K', 'L', 'M', 'N', 'O', 'P', // 15
+        'Q', 'R', 'S', 'T', 'U', 'V', 'W', 'X', // 23
+        'Y', 'Z', '2', '3', '4', '5', '6', '7', // 31
+        '='  // padding char
+    ];
+
+    /**
+     * Allowed padding lengths for base32 data.
+     */
+    private const ALLOWED_PADDING = [6, 4, 3, 1, 0];
+
+    /**
+     * Decodes base32 data.
+     *
+     * @param string $data
+     * @return string
+     * @throws InvalidArgumentException
+     */
+    public static function decode(string $data): string
+    {
+        if (empty($data))
+        {
+            throw new InvalidArgumentException('No data provided to decode');
+        }
+
+        $chars = self::LOOKUP_TABLE;
+        $chars_flipped = array_flip($chars);
+        $char_count = substr_count($data, $chars[32]);
+
+        if (!in_array($char_count, self::ALLOWED_PADDING, true))
+        {
+            throw new InvalidArgumentException(sprintf('Invalid padding in the base32 data: %s', $data));
+        }
+
+        for ($i = 0; $i < 4; ++$i)
+        {
+            if ($char_count === self::ALLOWED_PADDING[$i] &&
+                substr($data, -self::ALLOWED_PADDING[$i]) !== str_repeat($chars[32], self::ALLOWED_PADDING[$i]))
+            {
+                throw new InvalidArgumentException(sprintf('Invalid padding in the base32 data: %s', $data));
+            }
+        }
+
+        // Remove padding characters
+        $data = str_replace('=', (string)null, $data);
+        $data = str_split($data);
+        $binary_string = (string)null;
+
+        for ($i = 0, $data_count = count($data); $i < $data_count; $i += 8)
+        {
+            $x = (string)null;
+            for ($j = 0; $j < 8; ++$j)
+            {
+                $char = $data[$i + $j] ?? null;
+                if ($char === null || !isset($chars_flipped[$char]))
+                {
+                    throw new InvalidArgumentException(sprintf('Invalid character in the base32 data: %s', $char));
+                }
+
+                $x .= str_pad(base_convert((string)$chars_flipped[$char], 10, 2), 5, '0', STR_PAD_LEFT);
+            }
+
+            $eight_bits = str_split($x, 8);
+
+            foreach ($eight_bits as $bits)
+            {
+                $binary_string .= ($y = chr((int)base_convert($bits, 2, 10))) !== false ? $y : (string)null;
+            }
+        }
+
+        return $binary_string;
+    }
+}