<?php

namespace Symfony\Component\Security\Tests\Core\Util;

use Symfony\Component\Security\Core\Util\NullSeedProvider;
use Symfony\Component\Security\Core\Util\PrngSchema;
use Symfony\Component\Security\Core\Util\Prng;

class PrngTest extends \PHPUnit_Framework_TestCase
{
    /**
     * T1: Monobit test
     *
     * @dataProvider getPrngs
     */
    public function testMonobit($prng)
    {
        $nbOnBits = substr_count($this->getBitSequence($prng, 20000), '1');
        $this->assertTrue($nbOnBits > 9654 && $nbOnBits < 10346, 'Monobit test failed, number of turned on bits: '.$nbOnBits);
    }

    /**
     * T2: Chi-square test with 15 degrees of freedom (chi-Quadrat-Anpassungstest)
     *
     * @dataProvider getPrngs
     */
    public function testPoker($prng)
    {
        $b = $this->getBitSequence($prng, 20000);
        $c = array();
        for ($i=0;$i<=15;$i++) {
            $c[$i] = 0;
        }

        for ($j=1; $j<=5000; $j++) {
            $k = 4 * $j - 1;
            $c[8 * $b[$k - 3] + 4 * $b[$k - 2] + 2 * $b[$k - 1] + $b[$k]] += 1;
        }

        $f = 0;
        for ($i=0; $i<= 15; $i++) {
            $f += $c[$i] * $c[$i];
        }

        $Y = 16/5000 * $f - 5000;

        $this->assertTrue($Y > 1.03 && $Y < 57.4, 'Poker test failed, Y = '.$Y);
    }

    /**
     * Run test
     *
     * @dataProvider getPrngs
     */
    public function testRun($prng)
    {
        $b = $this->getBitSequence($prng, 20000);

        $runs = array();
        for ($i=1; $i<=6; $i++) {
            $runs[$i] = 0;
        }

        $addRun = function($run) use (&$runs) {
            if ($run > 6) {
                $run = 6;
            }

            $runs[$run] += 1;
        };

        $currentRun = 0;
        $lastBit = null;
        for ($i=0; $i<20000; $i++) {
            if ($lastBit === $b[$i]) {
                $currentRun += 1;
            } else {
                if ($currentRun > 0) {
                    $addRun($currentRun);
                }

                $lastBit = $b[$i];
                $currentRun = 0;
            }
        }
        if ($currentRun > 0) {
            $addRun($currentRun);
        }

        $this->assertTrue($runs[1] > 2267 && $runs[1] < 2733, 'Runs of length 1 outside of defined interval: '.$runs[1]);
        $this->assertTrue($runs[2] > 1079 && $runs[2] < 1421, 'Runs of length 2 outside of defined interval: '.$runs[2]);
        $this->assertTrue($runs[3] > 502 && $runs[3] < 748, 'Runs of length 3 outside of defined interval: '.$runs[3]);
        $this->assertTrue($runs[4] > 233 && $runs[4] < 402, 'Runs of length 4 outside of defined interval: '.$runs[4]);
        $this->assertTrue($runs[5] > 90 && $runs[5] < 223, 'Runs of length 5 outside of defined interval: '.$runs[5]);
        $this->assertTrue($runs[6] > 90 && $runs[6] < 233, 'Runs of length 6 outside of defined interval: '.$runs[6]);
    }

    /**
     * Long-run test
     *
     * @dataProvider getPrngs
     */
    public function testLongRun($prng)
    {
        $b = $this->getBitSequence($prng, 20000);

        $longestRun = 0;
        $currentRun = $lastBit = null;
        for ($i=0;$i<20000;$i++) {
            if ($lastBit === $b[$i]) {
                $currentRun += 1;
            } else {
                if ($currentRun > $longestRun) {
                    $longestRun = $currentRun;
                }
                $lastBit = $b[$i];
                $currentRun = 0;
            }
        }
        if ($currentRun > $longestRun) {
            $longestRun = $currentRun;
        }

        $this->assertTrue($longestRun < 34, 'Failed longest run test: '.$longestRun);
    }

    /**
     * Serial Correlation (Autokorrelationstest)
     *
     * @dataProvider getPrngs
     */
    public function testSerialCorrelation($prng)
    {
        $shift = rand(1, 5000);
        $b = $this->getBitSequence($prng, 20000);

        $Z = 0;
        for ($i=0; $i<5000; $i++) {
            $Z += $b[$i] === $b[$i+$shift] ? 1 : 0;
        }

        $this->assertTrue($Z > 2326 && $Z < 2674, 'Failed serial correlation test: '.$Z);
    }

    public function getPrngs()
    {
        $prngs = array();

        // openssl with fallback
        $prng = new Prng();
        $prngs[] = array($prng);

        // no-openssl with custom seed provider
        $prng = new Prng(sys_get_temp_dir().'/_sf2.seed');
        $this->disableOpenSsl($prng);
        $prngs[] = array($prng);

        return $prngs;
    }

    protected function disableOpenSsl($prng)
    {
        $ref = new \ReflectionProperty($prng, 'useOpenSsl');
        $ref->setAccessible(true);
        $ref->setValue($prng, false);
    }

    private function getBitSequence($prng, $length)
    {
        $bitSequence = '';
        for ($i=0;$i<$length; $i+=40) {
            $value = unpack('H*', $prng->nextBytes(5));
            $value = str_pad(base_convert($value[1], 16, 2), 40, '0', STR_PAD_LEFT);
            $bitSequence .= $value;
        }

        return substr($bitSequence, 0, $length);
    }
}