<?php
class Qs_Math
{
    public static function round($value, $precision = 0)
    {
        $roundedResult = 0;
        $value = (string)$value;
        $sign = '';
        if (substr($value, 0, 1) == ' - ') {
            $value = substr($value, 1);
            $sign = ' - ';
        }
        $precision = (int)$precision;
        $valueParts = explode('.', $value);
        $beforPoint = $valueParts[0];
        $afterPoint = (!empty($valueParts[1]))?$valueParts[1]:'';
        if ($precision >= 0) {
            $afterPoint = str_pad($afterPoint, $precision + 1, '0', STR_PAD_RIGHT);
            if ($precision > 0) {
                $lastChar = substr($afterPoint, $precision - 1, 1);
                $afterPointNew = ''; 
                $beforPointNew = '';
                if ((int)substr($afterPoint, $precision, 1) >= 5) {
                    $step = 0;
                    while ($lastChar == 9) {
                        if ($step < $precision) {
                            $afterPointNew = '0' . $afterPointNew;
                            $step++;
                            if ($step <= $precision - 1) {
                                $lastChar = (int)substr($afterPoint, $precision - $step - 1, 1);
                            } else {
                                $lastChar = (int)substr($beforPoint, $precision - $step - 1, 1);
                            }
                        } else {
                            $beforPointNew = '0' . $beforPointNew;
                            $step++;
                            $lastChar = (int)substr($beforPoint, $precision - $step - 1, 1); 
                        }
                    }
                    $lastChar = (int)$lastChar + 1;
                    if ($step < $precision) {
                        $afterPointNew = substr($afterPoint, 0, $precision - $step - 1) . $lastChar . $afterPointNew;
                        $beforPointNew = $beforPoint;
                    } else {
                        $beforPointNew = substr($beforPoint, 0, $precision - $step - 1) . $lastChar . $beforPointNew;
                    }
                    $roundedResult = $beforPointNew . '.' . $afterPointNew;
                } else {
                    $afterPoint = substr($afterPoint, 0, $precision);
                    $roundedResult = $beforPoint . '.' . str_pad($afterPoint, $precision, '0', STR_PAD_LEFT);
                } 
            } else {
                $beforPoint = (int)$beforPoint + (((int)substr($afterPoint, $precision, 1) >= 5)?1:0);
                $roundedResult = $beforPoint;
            }
        } else {
            $beforPointLength = strlen($beforPoint);
            if ($beforPointLength <= abs($precision)) {
                $roundedResult = 0;
            } else {
                $lastChar = substr($beforPoint, $precision - 1, 1);
                if ((int)substr($beforPoint, $precision, 1) >= 5) {
                    $step = 0;
                    while ($lastChar == 9) {
                        if ($step < $beforPointLength - abs($precision)) {
                            $beforPointNew = '0' . $beforPointNew;
                            $step++;
                            $lastChar = (int)substr($beforPoint, $precision - $step - 1, 1);
                        }
                    }
                    $lastChar = (int)$lastChar + 1;
                    $beforPointNew = $lastChar . $beforPointNew;
                    if ($beforPointLength > abs($precision) + $step + 1) {
                        $symbolsCount = $beforPointLength - abs($precision) - $step - 1;
                        $beforPointNew = substr($beforPoint, 0, $symbolsCount) . $beforPointNew;
                    } else {
                        $beforPointLength++;
                    }
                    $beforPointNew = str_pad($beforPointNew, $beforPointLength, '0', STR_PAD_RIGHT);
                    $roundedResult = $beforPointNew;
                } else {
                    $beforPoint = substr($beforPoint, 0, $precision);
                    $roundedResult = str_pad($beforPoint, $beforPointLength, '0', STR_PAD_RIGHT);
                }
            }
        }
        $roundedResult = $sign . $roundedResult;
        return (float)$roundedResult;
    }
    
    public static function myBaseConvert($number, $alphabet)
    {
        $base = strlen($alphabet);
        $number = intval($number);
        if ($number != 0) {
            $result = '';
            while ($number > 0) {
                $digit = $number % $base;
                $result = $alphabet[$digit] . $result;
                $number = (int)($number / $base);
    
            }
        } else {
            $result = $alphabet[0];
        }
        return $result;
    }
    
    public static function myMakeAlphabet($alphabet)
    {
        $result = array();
        $n = strlen($alphabet);
        for ($i = 0; $i < $n; ++$i) {
            if (!isset($result[$alphabet[$i]])) {
                $result[$alphabet[$i]] = $i;
            }
        }
        return $result;
    }
    
    
    public static function myBaseDeconvert($string, $alphabetArray)
    {
        if (!is_array($alphabetArray)) {
            //passed non-array, so try to make one
            $alphabetArray = Qs_Math::myMakeAlphabet($alphabetArray);
        }
        $base = count($alphabetArray);
        $n = strlen($string);
        $result = 0;
    
        for ($i = 0; $i < $n; ++$i) {
            $result *= $base;
            $result += $alphabetArray[$string[$i]];
        }
        return $result;
    }
    
    public static function sizeToByteString($size)
    {
        $sizes = array('B', 'kB', 'MB', 'GB', 'TB', 'PB', 'EB', 'ZB', 'YB');
        for ($i=0; $size >= 1024 && $i < 9; $i++) {
            $size /= 1024;
        }
        return round($size, 2) . ' ' . $sizes[$i];
    }
}