class Scale

class Scale extends Resize {
    
    /**
     * {@inheritdoc}
     */
    protected function arguments() {
        return [
            'width' => [
                'description' => 'The target width, in pixels. This value is omitted then the scaling will based only on the height value',
                'required' => FALSE,
                'default' => NULL,
            ],
            'height' => [
                'description' => 'The target height, in pixels. This value is omitted then the scaling will based only on the width value',
                'required' => FALSE,
                'default' => NULL,
            ],
            'upscale' => [
                'description' => 'Boolean indicating that files smaller than the dimensions will be scaled up. This generally results in a low quality image',
                'required' => FALSE,
                'default' => FALSE,
            ],
        ];
    }
    
    /**
     * {@inheritdoc}
     */
    protected function validateArguments(array $arguments) {
        // Assure at least one dimension.
        if (empty($arguments['width']) && empty($arguments['height'])) {
            throw new \InvalidArgumentException("At least one dimension ('width' or 'height') must be provided to the image 'scale' operation");
        }
        // Calculate one of the dimensions from the other target dimension,
        // ensuring the same aspect ratio as the source dimensions. If one of the
        // target dimensions is missing, that is the one that is calculated. If both
        // are specified then the dimension calculated is the one that would not be
        // calculated to be bigger than its target.
        $aspect = $this->getToolkit()
            ->getHeight() / $this->getToolkit()
            ->getWidth();
        if ($arguments['width'] && !$arguments['height'] || $arguments['width'] && $arguments['height'] && $aspect < $arguments['height'] / $arguments['width']) {
            $arguments['height'] = (int) round($arguments['width'] * $aspect);
        }
        else {
            $arguments['width'] = (int) round($arguments['height'] / $aspect);
        }
        // Assure integers for all arguments.
        $arguments['width'] = (int) round($arguments['width']);
        $arguments['height'] = (int) round($arguments['height']);
        // Fail when width or height are 0 or negative.
        if ($arguments['width'] <= 0) {
            throw new \InvalidArgumentException("Invalid width ('{$arguments['width']}') specified for the image 'scale' operation");
        }
        if ($arguments['height'] <= 0) {
            throw new \InvalidArgumentException("Invalid height ('{$arguments['height']}') specified for the image 'scale' operation");
        }
        return $arguments;
    }
    
    /**
     * {@inheritdoc}
     */
    protected function execute(array $arguments = []) {
        // Don't scale if we don't change the dimensions at all.
        if ($arguments['width'] !== $this->getToolkit()
            ->getWidth() || $arguments['height'] !== $this->getToolkit()
            ->getHeight()) {
            // Don't upscale if the option isn't enabled.
            if ($arguments['upscale'] || $arguments['width'] <= $this->getToolkit()
                ->getWidth() && $arguments['height'] <= $this->getToolkit()
                ->getHeight()) {
                return parent::execute($arguments);
            }
        }
        return TRUE;
    }

}