Number.php

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<?php

namespace Rsi;

/**
 *  Helpers for numbers of all sorts.
 */
class Number{

  /**
   * Add a value to a non-decimal number.
   * @param string $value  Base value in base $base.
   * @param int $add  Decimal value to add to $value.
   * @param int $base  The base the $value is in (defaults to 10).
   * @param bool $upper  Convert the return value to uppercase (only for $base > 10). Auto-detect on null (defaults to true).
   * @return string  Value $value with $add added, in base $base.
   */
  public static function add($value,$add = 1,$base = null,$upper = null){
    if($upper === null) $upper = ($base > 10) && (strtoupper($value) == $value);
    if($base) $value = base_convert($value,$base,10);
    $value += $add;
    if($base) $value = base_convert($value,10,$base);
    if($upper) $value = strtoupper($value);
    return $value;
  }
  /**
   * Returns the size in bytes for shorthand notations (e.g. 1k -> 1024).
   * @see http://php.net/manual/en/faq.using.php#faq.using.shorthandbytes
   * @param string $size  Size in shorthand format.
   * @return int  Size in bytes.
   */
  public static function shorthandBytes($size){
    $factor = 1;
    switch(strtolower(substr($size,-1))){
      case 'e': $factor <<= 10;
      case 'p': $factor <<= 10;
      case 't': $factor <<= 10;
      case 'g': $factor <<= 10;
      case 'm': $factor <<= 10;
      case 'k': $factor <<= 10;
    }
    return $factor * (int)$size;
  }
  /**
   * Formats a size in bytes to its shorthand format.
   * @param int $size  Size in bytes.
   * @param int $decimals  Number of decimals.
   * @param string $dec_point  Separator for the decimal point.
   * @param string  $thousands_sep  Thousands separator.
   * @param string  $unit_sep  Separator between number and unit.
   * @return string
   */
  public static function formatBytes($size,$decimals = 1,$dec_point = '.',$thousands_sep = ',',$unit_sep = ' '){
    $unit = 'b';
    $units = ['kb','Mb','Gb','Tb'];
    if($size < 1024) $decimals = 0;
    else while(($size >= 1024) && $units){
      $size = $size / 1024;
      $unit = array_shift($units);
    }
    return number_format($size,$decimals,$dec_point,$thousands_sep) . $unit_sep . $unit;
  }
  /**
   * Format a number as a Roman number.
   * @param int $value  Decimal value.
   * @return string  Roman representation.
   */
  public static function toRoman($value){
    $result = '';
    $numbers = ['M' => 1000,'CM' => 900,'D' => 500,'CD' => 400,'C' => 100,'XC' => 90,'L' => 50,'XL' => 40,'X' => 10,'IX' => 9,'V' => 5,'IV' => 4,'I' => 1];
    while($value > 0) foreach($numbers as $roman => $number) if($value >= $number){
      $value -= $number;
      $result .= $roman;
      break;
    }
    return $result;
  }

  public static function celsiusToFahrenheit($value){
    return $value * 1.8 + 32;
  }

  public static function fahrenheitToCelsius($value){
    return ($value - 32) / 1.8;
  }
  /**
   * Split a value into different units.
   * @param float $value  Number to split.
   * @param array $units  Units to split into (key = name, value = count/unit).
   * @param float $tolerance  Stop splitting if the remainder is smaller than this amount.
   * @return array  Units (key = name, value = count), same sequence as units.
   */
  public static function units($value,$units,$tolerance = 0){
    $result = $counts = [];
    foreach(array_reverse(array_keys(\Rsi\Record::sort($units))) as $unit){
      $count = $value / $units[$unit];
      if($unit) $count = floor($count);
      if($count || $counts) $counts[$unit] = $count;
      if(($value -= $count * $units[$unit]) < $tolerance) break;
    }
    foreach($units as $unit => $count) if(array_key_exists($unit,$counts)) $result[$unit] = $counts[$unit];
    return $result;
  }
  /**
   * Turn a decimal number into a fraction.
   * @param float $value
   * @param float $tolerance  Tolerance for result.
   * @return array  Array with numerator and denominator.
   */
  public static function fraction($value,$tolerance = 0.000001){
    $num = $prev_den = 1;
    $den = $prev_num = 0;
    $sign = $value < 0 ? -1 : 1;
    $frac = 1 / ($value = abs($value));
    do{
        $frac = 1 / $frac;
        $rest = floor($frac);
        $prev = $num; $num = $rest * $num + $prev_num; $prev_num = $prev;
        $prev = $den; $den = $rest * $den + $prev_den; $prev_den = $prev;
        $frac = $frac - $rest;
    }
    while(abs($value - $num / $den) > $value * $tolerance);
    return [$sign * $num,$den];
  }
  /**
   * Evaluate a mathamatical expression.
   * @param string $expr  Mathamatical expression.
   * @return float  Answer (throws Exception on error).
   */
  public static function evaluate($expr){
    $number = '-?\\d+(?:\\.\\d+)?';
    $operators = ['^','*','/','%','+','-','>','>=','<','<=','==','!='];
    $functions = [
      'decbin','dechex','decoct','deg2rad','rad2deg',
      'abs','floor','ceil','sqrt','exp','ln','log','pi',
      'sin','sinh','arcsin','asin','arcsinh','asinh',
      'cos','cosh','arccos','acos','arccosh','acosh',
      'tan','tanh','arctan','atan','arctanh','atanh'
    ];
    $array_functions = [
      'min','max','count','sum','unique','filter','product'
    ];
    //separate minus operator from number
    $expr = substr(preg_replace('/(?<![\\(' . preg_quote(implode($operators),'/') . '])\\-/','- ','^' . $expr),1);

    //fix dates
    if(preg_match_all('/\'(\\d{4})- (\\d{1,2})- (\\d{1,2})/',$expr,$matches,PREG_SET_ORDER))
      foreach($matches as list($full,$year,$month,$day))
        $expr = str_replace($full,"'$year-" . Str::pad($month,2) . '-' . Str::pad($day,2),$expr);

    //evaluate groups and functions
    $expr = str_replace('π','pi()',$expr);
    while(preg_match('/(\\w*)\\(([^\\(\\)]*)\\)/',$expr,$match)){
      list($full,$func_name,$params) = $match;
      if($func_name){
        $params = explode(',',$params);
        $value = null;
        if(in_array($func_name,$functions)) $value = call_user_func($func_name,$params[0] === '' ? null : self::evaluate($params[0]));
        elseif(in_array($func_name,$array_functions)){
          if(is_array($value = call_user_func(function_exists($array_name = 'array_' . $func_name) ? $array_name : $func_name,array_map(['self','evaluate'],$params))))
            $value = implode(',',$value);
        }
        else switch($func_name){
          case 'time':
            if(($value = $params[0]) === '') $value = time();
            elseif(substr($value = $params[0],0,1) == "'") $value = strtotime(substr($value,1,-1));
            if($modifier = $params[1] ?? null) $value = strtotime($modifier,$value);
            break;
          case 'date':
            if(!is_numeric($value = date($params[1] ?? 'Y-m-d',self::evaluate($params[0])))) return $value;
            break;
          case 'frac': $value = fmod(self::evaluate($params[0]),1); break;
          case 'fracnum': $value = self::fraction(self::evaluate($params[0]),$params[1] ?? 0.000001)[0]; break;
          case 'fracden': $value = self::fraction(self::evaluate($params[0]),$params[1] ?? 0.000001)[1]; break;
          case 'round': $value = round(self::evaluate($params[0]),$params[1] ?? 0); break;
          case 'rand': $value = rand(self::evaluate($params[0]),self::evaluate($params[1] ?? 0)); break;
          case 'degc2f': $value = self::celsiusToFahrenheit(self::evaluate($params[0])); break;
          case 'degf2c': $value = self::fahrenheitToCelsius(self::evaluate($params[0])); break;
          case 'avg': return ($array = array_map(['self','evaluate'],$params)) ? array_sum($array) / count($array) : 0; break;
          case 'first': $value = self::evaluate(array_shift($params)); break;
          case 'last': $value = self::evaluate(array_pop($params)); break;
          case 'exists': $value = array_search(self::evaluate(array_shift($params)),array_map(['self','evaluate'],$params)) === false ? 0 : 1; break;
          case 'if': $value = self::evaluate($params[0]) ? self::evaluate($params[1] ?? 1) : self::evaluate($params[2] ?? 0); break;
          default: throw new \Exception("Unknown function '$func_name'");
        }
        $expr = str_replace($full,$value,$expr);
      }
      else $expr = str_replace($full,self::evaluate($params),$expr); //group
    }

    //evaluate operators
    foreach($operators as $operator) while(preg_match('/(' . $number . ')\\s*' . preg_quote($operator,'/') . '\\s*(' . $number . ')/',$expr,$match)){
      list($full,$a,$b) = $match;
      $value = null;
      switch($operator){
        case '^': $value = pow($a,$b); break;
        case '*': $value = $a * $b; break;
        case '/': $value = $a / $b; break;
        case '%': $value = $a % $b; break;
        case '+': $value = $a + $b; break;
        case '-': $value = $a - $b; break;
        case '>': $value = intval($a > $b); break;
        case '>=': $value = intval($a >= $b); break;
        case '<': $value = intval($a < $b); break;
        case '<=': $value = intval($a <= $b); break;
        case '==': $value = intval($a == $b); break;
        case '!=': $value = intval($a != $b); break;
        default: throw new \Exception("Unknown operator '$operator'");
      }
      $expr = str_replace($full,$value,$expr);
    }

    return $expr;
  }

}