<?php

declare(strict_types = 1);

/**
 * @author Robert Strutts
 * @copyright (c) 2026, Robert Strutts
 * @license MIT
 */
namespace IOcornerstone\Framework;

use IOcornerstone\Framework\Common;

/**
 * random_engine - Provides a high-level API to the randomness 
 * provided by an Random\Engine OR uses the next Fall Back FN.
 *
 */

class RandomEngine
{
    private $engine = false;

    public function __construct() {
        $version = (float) phpversion();
        if ($version > 8.1) {
            $this->engine = new \Random\Randomizer();
        }
    }

    public function getBytes(int $bytes_length = 16): string {
        return ($this->engine) ? $this->engine->getBytes($bytes_length) :
            random_bytes($bytes_length);
    }
    
    public function getInt(int $min, int $max): int {
        if ($this->engine) {
            return $this->engine->getInt($min, $max);
        }
        if (function_exists('random_int')) {
            return random_int($min, $max); // secure fallback
        } elseif (function_exists('mt_rand')) {
            return mt_rand($min, $max); // fast
        }
        return rand($min, $max); // old    
    }
    
    // Took from source https://pageconfig.com/post/fixed-length-large-random-numbers-with-php
    private function bigRand(int $len = 18 ): int {
        $rand = '';
        while( !( isset( $rand[$len-1] ) ) ) {
            $rand   .= mt_rand( );
        }
        return (int) substr( $rand , 0 , $len );
    }
    
    public function getNextBigPostiveInt(): int {
        if ($this->engine) {
            return $this->engine->nextInt();
        }
        return $this->bigRand();
    }
    
    private function selectFromArray(array $a, int $num ): array {
      $array_count = Common::getCount($a) - 1;
      if ($array_count < 1) {
          return [];
      }
      $ret = [];
      for($i=0; $i<$num; $i++) {
        $ret[] = $a[$this->getInt(0, $array_count)];
      }
      return $ret;
    }
    
    /**
     * Pick random keys from an Array
     */
    public function getArrayKeys(array $a, int $num): array {
        if ($this->engine) {
            return $this->engine->pickArrayKeys($a, $num);
        }
        return $this->selectFromArray($a, $num);
    }
    
    public function getShuffledArray(array $a): array {
        if ($this->engine) {
            return $this->engine->shuffleArray($a);
        }
        shuffle($a);
        return $a;
    }
    
    public function getShuffledBytes(string $bytes): string {
        if ($this->engine) {
            return $this->engine->shuffleBytes($bytes);
        }
        $len = mb_strlen($bytes);
        $a = []; 
        while($len-- > 0) { 
            $a[] = mb_substr($bytes, $len, 1); 
        }
        shuffle($a);
        return join('', $a);
    }
}