<?php
/**
 * Random_* Compatibility Library
 * for using the new PHP 7 random_* API in PHP 5 projects
 *
 * The MIT License (MIT)
 *
 * Copyright (c) 2015 - 2017 Paragon Initiative Enterprises
 *
 * Permission is hereby granted, free of charge, to any person obtaining a copy
 * of this software and associated documentation files (the "Software"), to deal
 * in the Software without restriction, including without limitation the rights
 * to use, copy, modify, merge, publish, distribute, sublicense, and/or sell
 * copies of the Software, and to permit persons to whom the Software is
 * furnished to do so, subject to the following conditions:
 *
 * The above copyright notice and this permission notice shall be included in
 * all copies or substantial portions of the Software.
 *
 * THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS OR
 * IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY,
 * FITNESS FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT. IN NO EVENT SHALL THE
 * AUTHORS OR COPYRIGHT HOLDERS BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER
 * LIABILITY, WHETHER IN AN ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING FROM,
 * OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS IN THE
 * SOFTWARE.
 */
defined('BASEPATH') OR exit('No direct script access allowed');

if (!is_callable('RandomCompat_strlen'))
{
	if (defined('MB_OVERLOAD_STRING') && ini_get('mbstring.func_overload') & MB_OVERLOAD_STRING)
	{
		/**
		 * strlen() implementation that isn't brittle to mbstring.func_overload
		 *
		 * This version uses mb_strlen() in '8bit' mode to treat strings as raw
		 * binary rather than UTF-8, ISO-8859-1, etc
		 *
		 * @param string $binary_string
		 *
		 * @throws TypeError
		 *
		 * @return int
		 */
		function RandomCompat_strlen($binary_string)
		{
			if (!is_string($binary_string))
			{
				throw new TypeError('RandomCompat_strlen() expects a string');
			}
			
			return (int) mb_strlen($binary_string, '8bit');
		}
		
	}
	else
	{
		/**
		 * strlen() implementation that isn't brittle to mbstring.func_overload
		 *
		 * This version just used the default strlen()
		 *
		 * @param string $binary_string
		 *
		 * @throws TypeError
		 *
		 * @return int
		 */
		function RandomCompat_strlen($binary_string)
		{
			if (!is_string($binary_string))
			{
				throw new TypeError('RandomCompat_strlen() expects a string');
			}
			return (int) strlen($binary_string);
		}
	}
}

if (!is_callable('RandomCompat_substr'))
{
	
	if (defined('MB_OVERLOAD_STRING') && ini_get('mbstring.func_overload') & MB_OVERLOAD_STRING)
	{
		/**
		 * substr() implementation that isn't brittle to mbstring.func_overload
		 *
		 * This version uses mb_substr() in '8bit' mode to treat strings as raw
		 * binary rather than UTF-8, ISO-8859-1, etc
		 *
		 * @param string $binary_string
		 * @param int $start
		 * @param int $length (optional)
		 *
		 * @throws TypeError
		 *
		 * @return string
		 */
		function RandomCompat_substr($binary_string, $start, $length = null)
		{
			if (!is_string($binary_string))
			{
				throw new TypeError('RandomCompat_substr(): First argument should be a string');
			}
			
			if (!is_int($start))
			{
				throw new TypeError('RandomCompat_substr(): Second argument should be an integer');
			}
			
			if ($length === null)
			{
				/**
				 * mb_substr($str, 0, NULL, '8bit') returns an empty string on
				 * PHP 5.3, so we have to find the length ourselves.
				 */
				$length = RandomCompat_strlen($binary_string) - $start;
			}
			elseif (!is_int($length))
			{
				throw new TypeError('RandomCompat_substr(): Third argument should be an integer, or omitted');
			}
			
			// Consistency with PHP's behavior
			if ($start === RandomCompat_strlen($binary_string) && $length === 0)
			{
				return '';
			}
			if ($start > RandomCompat_strlen($binary_string))
			{
				return '';
			}
			
			return (string) mb_substr($binary_string, $start, $length, '8bit');
		}
		
	}
	else
	{
		
		/**
		 * substr() implementation that isn't brittle to mbstring.func_overload
		 *
		 * This version just uses the default substr()
		 *
		 * @param string $binary_string
		 * @param int $start
		 * @param int $length (optional)
		 *
		 * @throws TypeError
		 *
		 * @return string
		 */
		function RandomCompat_substr($binary_string, $start, $length = null)
		{
			if (!is_string($binary_string))
			{
				throw new TypeError('RandomCompat_substr(): First argument should be a string');
			}
			
			if (!is_int($start))
			{
				throw new TypeError('RandomCompat_substr(): Second argument should be an integer');
			}
			
			if ($length !== null)
			{
				if (!is_int($length))
				{
					throw new TypeError('RandomCompat_substr(): Third argument should be an integer, or omitted');
				}
				
				return (string) substr($binary_string, $start, $length);
			}
			
			return (string) substr($binary_string, $start);
		}
	}
}
