<?php
namespace FluidTYPO3\Vhs\ViewHelpers\Media;

/*
 * This file is part of the FluidTYPO3/Vhs project under GPLv2 or later.
 *
 * For the full copyright and license information, please read the
 * LICENSE.md file that was distributed with this source code.
 */

use FluidTYPO3\Vhs\Traits\SourceSetViewHelperTrait;
use FluidTYPO3\Vhs\ViewHelpers\Media\Image\AbstractImageViewHelper;
use TYPO3Fluid\Fluid\Core\ViewHelper\Exception;

/**
 * Renders an image tag for the given resource including all valid
 * HTML5 attributes. Derivates of the original image are rendered
 * if the provided (optional) dimensions differ.
 *
 * ## rendering responsive Images variants
 *
 * You can use the srcset argument to generate several differently sized
 * versions of this image that will be added as a srcset argument to the img tag.
 * enter a list of widths in the srcset to genereate copies of the same crop +
 * ratio but in the specified widths. Put the width at the start that you want
 * to use as a fallback to be shown when no srcset functionality is supported.
 *
 * ### Example
 *
 * ```
 * <v:media.image src="fileadmin/some-image.png" srcset="480,768,992,1200" />
 * ```
 *
 * ### Browser Support
 *
 * To have the widest Browser-Support you should consider using a polyfill like:
 * http://scottjehl.github.io/picturefill/
 */
class ImageViewHelper extends AbstractImageViewHelper
{
    use SourceSetViewHelperTrait;

    /**
     * name of the tag to be created by this view helper
     *
     * @var string
     * @api
     */
    protected $tagName = 'img';

    public function initializeArguments(): void
    {
        parent::initializeArguments();
        $this->registerUniversalTagAttributes();
        $this->registerTagAttribute(
            'usemap',
            'string',
            'A hash-name reference to a map element with which to associate the image.'
        );
        $this->registerTagAttribute(
            'ismap',
            'string',
            'Specifies that its img element provides access to a server-side image map.',
            false,
            ''
        );
        $this->registerTagAttribute(
            'alt',
            'string',
            'Equivalent content for those who cannot process images or who have image loading disabled.',
            true
        );
        $this->registerArgument(
            'srcset',
            'mixed',
            'List of width used for the srcset variants (either CSV, array or implementing Traversable)'
        );
        $this->registerArgument(
            'srcsetDefault',
            'integer',
            'Default width to use as a fallback for browsers that don\'t support srcset'
        );
    }

    /**
     * Render method
     *
     * @return string
     * @throws Exception
     */
    public function render()
    {
        $this->preprocessImage();
        return $this->renderTag();
    }

    public function renderTag(): string
    {
        if (!empty($this->arguments['srcset'])) {
            $srcSetVariants = $this->addSourceSet($this->tag, $this->mediaSource);
        }

        if ($this->hasArgument('canvasWidth') || $this->hasArgument('canvasHeight')) {
            $width = $this->arguments['canvasWidth'];
            $height = $this->arguments['canvasHeight'];
            $src = $this->mediaSource;
        } elseif (!empty($srcSetVariants) && !empty($this->arguments['srcsetDefault'])) {
            $srcSetVariantDefault = $srcSetVariants[$this->arguments['srcsetDefault']];
            $src = $srcSetVariantDefault['src'];
            $width = $srcSetVariantDefault['width'];
            $height = $srcSetVariantDefault['height'];
        } else {
            $src = static::preprocessSourceUri($this->mediaSource, $this->arguments);
            $width = $this->imageInfo[0] ?? '';
            $height = $this->imageInfo[1] ?? '';
        }

        $this->tag->addAttribute('width', $width);
        $this->tag->addAttribute('height', $height);
        $this->tag->addAttribute('src', $src);

        /** @var string|null $alt */
        $alt = $this->arguments['alt'];
        // The alt-attribute is mandatory to have valid html-code, therefore add it even if it is empty
        $this->tag->addAttribute('alt', (string) $alt);

        if (empty($this->arguments['title'])) {
            $this->tag->addAttribute('title', $alt);
        }
        return $this->tag->render();
    }
}