<?php

    interface Geometry {
         public  function getValue ();
         public  function getMass ();
    }

    class Paral  implements   Geometry {
        protected $a;
        protected $b;
        protected $c;
        protected $density;

        public function __construct($a, $b, $c, $density){
            $this->a = $a;
            $this->b = $b;
            $this->c = $c;
            $this->density = $density;
        }

        public  function getValue (){
            return $this->a*$this->b*$this->c;
        }

        public  function getMass (){
            return $this->getValue() * $this->density;
        }

        public function __toString(){
            return (string)($this->getMass());
        }
    }

    class Cube extends Paral implements Geometry  {
        public function __construct($a, $density){
            $this->a = $a;
            $this->b = $a;
            $this->c = $a;
            $this->density = $density;
        }
        public function __toString(){
            return (string) parent::__toString();
        }
    }

    class Sfera  implements Geometry {
        private $r;
        private $density;

        public function __construct($r, $density){
            $this->r = $r;
            $this->density = $density;
        }

        public  function getValue (){
            return 4/3*(3.14*$this->r*$this->r*$this->r);
        }

        public  function getMass (){
            return $this->getValue() * $this->density;

        }

        public function __toString(){
            return (string)($this->getMass());
        }

    }

    class Pyramid  implements Geometry {
        private $a;
        private $b;
        private $c;
        private $h;
        private $density;

        public function __construct($a, $b, $c, $h, $density){
            $this->a = $a;
            $this->b = $b;
            $this->c = $c;
            $this->h = $h;
            $this->density = $density;
        }

        public  function getValue (){
            $a = $this->a;
            $b = $this->b;
            $c = $this->c;
            $h = $this->h;
            $p = ($a+$b+$c)/2;
            $s = sqrt($p * ($p - $a) * ($p - $b)*($p - $c));
            return ($s*$h)/3;
        }

        public  function getMass (){
            return $this->getValue() * $this->density;
        }

        public function __toString(){
            return (string)($this->getMass());
        }
    }


$paral = new Paral(5,6,7,0.1);
print "Обем и масса паралелепипеда:" . "\n";
print $paral->getValue() . "\n";
print $paral->getMass() . "\n";
//print $paral;

$cube = new Cube(5,0.1);
print "Обем и масса куба:" . "\n";
print $cube->getValue() . "\n";
print $cube->getMass() . "\n";
//print $cube;

$sfera = new Sfera(3,0.1);
print "Обем и масса сферы:" . "\n";
print $sfera->getValue() . "\n";
print $sfera->getMass() . "\n";

$pyramid = new Pyramid(2, 3, 4, 7, 0.1);
print "Обем и масса пирамиды:" . "\n";
print $pyramid->getValue() . "\n";
print $pyramid->getMass() . "\n";

print "_______________________" . "\n" ;
print "Рандомный выбор фигуры: \n";

$figures = array();                                         //Рандомный выбор фигуры
$figuresMass = array();
for ($i = 0; $i < 4; $i++){
    $figures[$i]=rand(0, 3);
    switch ($figures[$i]) {
        case 0:
            $figures[$i]=new Paral(5,6,7,0.1);
            $figuresMass[$i] = $figures[$i]->getMass();
            break;
        case 1:
            $figures[$i]=new Cube(5,0.1);
            $figuresMass[$i] = $figures[$i]->getMass();
            break;
        case 2:
            $figures[$i]=new Sfera(3,0.1);
            $figuresMass[$i] = $figures[$i]->getMass();
            break;
        case 3:
            $figures[$i]=new Pyramid(2, 3, 4, 7, 0.1);
            $figuresMass[$i] = $figures[$i]->getMass();
            break;
    };
    print $i . " => ";
    print ($figuresMass[$i]);
    print "\n" ;
}

print "_______________________" . "\n" ;
print "Сортированный массив: \n";

sort($figuresMass);

foreach ($figuresMass as $key => $value) {
    echo $key." => ".$value ."\n";
}

?>