<?php

/**
 * SCSSPHP
 *
 * @copyright 2012-2020 Leaf Corcoran
 *
 * @license http://opensource.org/licenses/MIT MIT
 *
 * @link http://scssphp.github.io/scssphp
 */

namespace Tangible\ScssPhp\Value;

use Tangible\ScssPhp\Visitor\ValueVisitor;

/**
 * A SassScript boolean value.
 */
final class SassBoolean extends Value
{
    /**
     * @var SassBoolean|null
     */
    private static $trueInstance;

    /**
     * @var SassBoolean|null
     */
    private static $falseInstance;

    /**
     * @var bool
     * @readonly
     */
    private $value;

    public static function create(bool $value): SassBoolean
    {
        if ($value) {
            if (self::$trueInstance === null) {
                self::$trueInstance = new self(true);
            }

            return self::$trueInstance;
        }

        if (self::$falseInstance === null) {
            self::$falseInstance = new self(false);
        }

        return self::$falseInstance;
    }

    private function __construct(bool $value)
    {
        $this->value = $value;
    }

    public function getValue(): bool
    {
        return $this->value;
    }

    public function isTruthy(): bool
    {
        return $this->value;
    }

    public function accept(ValueVisitor $visitor)
    {
        return $visitor->visitBoolean($this);
    }

    public function assertBoolean(?string $name = null): SassBoolean
    {
        return $this;
    }

    public function unaryNot(): Value
    {
        return self::create(!$this->value);
    }

    public function equals(object $other): bool
    {
        if (!$other instanceof SassBoolean) {
            return false;
        }

        return $this->value === $other->value;
    }
}
