<?php

if (!is_callable('random_int')) {

    /**

     * 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.

     */

    /**

     * Fetch a random integer between $min and $max inclusive

     *

     * @param int $min

     * @param int $max

     *

     * @throws Exception

     *

     * @return int

     */

    function random_int($min, $max)

    {

        /**

         * Type and input logic checks

         *

         * If you pass it a float in the range (~PHP_INT_MAX, PHP_INT_MAX)

         * (non-inclusive), it will sanely cast it to an int. If you it's equal to

         * ~PHP_INT_MAX or PHP_INT_MAX, we let it fail as not an integer. Floats

         * lose precision, so the <= and => operators might accidentally let a float

         * through.

         */

        try {

            $min = RandomCompat_intval($min);

        } catch (TypeError $ex) {

            throw new TypeError(

                'random_int(): $min must be an integer'

            );

        }

        try {

            $max = RandomCompat_intval($max);

        } catch (TypeError $ex) {

            throw new TypeError(

                'random_int(): $max must be an integer'

            );

        }

        /**

         * Now that we've verified our weak typing system has given us an integer,

         * let's validate the logic then we can move forward with generating random

         * integers along a given range.

         */

        if ($min > $max) {

            throw new Error(

                'Minimum value must be less than or equal to the maximum value'

            );

        }

        if ($max === $min) {

            return (int) $min;

        }

        /**

         * Initialize variables to 0

         *

         * We want to store:

         * $bytes => the number of random bytes we need

         * $mask => an integer bitmask (for use with the &) operator

         *          so we can minimize the number of discards

         */

        $attempts = $bits = $bytes = $mask = $valueShift = 0;

        /**

         * At this point, $range is a positive number greater than 0. It might

         * overflow, however, if $max - $min > PHP_INT_MAX. PHP will cast it to

         * a float and we will lose some precision.

         */

        $range = $max - $min;

        /**

         * Test for integer overflow:

         */

        if (!is_int($range)) {

            /**

             * Still safely calculate wider ranges.

             * Provided by @CodesInChaos, @oittaa

             *

             * @ref https://gist.github.com/CodesInChaos/03f9ea0b58e8b2b8d435

             *

             * We use ~0 as a mask in this case because it generates all 1s

             *

             * @ref https://eval.in/400356 (32-bit)

             * @ref http://3v4l.org/XX9r5  (64-bit)

             */

            $bytes = PHP_INT_SIZE;

            $mask = ~0;

        } else {

            /**

             * $bits is effectively ceil(log($range, 2)) without dealing with

             * type juggling

             */

            while ($range > 0) {

                if ($bits % 8 === 0) {

                    ++$bytes;

                }

                ++$bits;

                $range >>= 1;

                $mask = $mask << 1 | 1;

            }

            $valueShift = $min;

        }

        $val = 0;

        /**

         * Now that we have our parameters set up, let's begin generating

         * random integers until one falls between $min and $max

         */

        do {

            /**

             * The rejection probability is at most 0.5, so this corresponds

             * to a failure probability of 2^-128 for a working RNG

             */

            if ($attempts > 128) {

                throw new Exception(

                    'random_int: RNG is broken - too many rejections'

                );

            }

            /**

             * Let's grab the necessary number of random bytes

             */

            $randomByteString = random_bytes($bytes);

            /**

             * Let's turn $randomByteString into an integer

             *

             * This uses bitwise operators (<< and |) to build an integer

             * out of the values extracted from ord()

             *

             * Example: [9F] | [6D] | [32] | [0C] =>

             *   159 + 27904 + 3276800 + 201326592 =>

             *   204631455

             */

            $val &= 0;

            for ($i = 0; $i < $bytes; ++$i) {

                $val |= ord($randomByteString[$i]) << ($i * 8);

            }

            /**

             * Apply mask

             */

            $val &= $mask;

            $val += $valueShift;

            ++$attempts;

            /**

             * If $val overflows to a floating point number,

             * ... or is larger than $max,

             * ... or smaller than $min,

             * then try again.

             */

        } while (!is_int($val) || $val > $max || $val < $min);

        return (int) $val;

    }

}