Added wkhtmltopdf stuff and created preview generator service

module/Common/src/Image/ImageFactory.php

@@ -0,0 +1,30 @@
+<?php
+namespace Shlinkio\Shlink\Common\Image;
+
+use Interop\Container\ContainerInterface;
+use Interop\Container\Exception\ContainerException;
+use mikehaertl\wkhtmlto\Image;
+use Zend\ServiceManager\Exception\ServiceNotCreatedException;
+use Zend\ServiceManager\Exception\ServiceNotFoundException;
+use Zend\ServiceManager\Factory\FactoryInterface;
+
+class ImageFactory implements FactoryInterface
+{
+    /**
+     * Create an object
+     *
+     * @param  ContainerInterface $container
+     * @param  string $requestedName
+     * @param  null|array $options
+     * @return object
+     * @throws ServiceNotFoundException if unable to resolve the service.
+     * @throws ServiceNotCreatedException if an exception is raised when
+     *     creating a service.
+     * @throws ContainerException if any other error occurs
+     */
+    public function __invoke(ContainerInterface $container, $requestedName, array $options = null)
+    {
+        $config = $container->get('config')['phpwkhtmltopdf'];
+        return new Image(isset($config['images']) ? $config['images'] : null);
+    }
+}

module/Common/src/Service/PreviewGenerator.php

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+<?php
+namespace Shlinkio\Shlink\Common\Service;
+
+use Acelaya\ZsmAnnotatedServices\Annotation\Inject;
+use Doctrine\Common\Cache\Cache;
+use mikehaertl\wkhtmlto\Image;
+
+class PreviewGenerator implements PreviewGeneratorInterface
+{
+    /**
+     * @var Image
+     */
+    private $image;
+    /**
+     * @var Cache
+     */
+    private $cache;
+    /**
+     * @var string
+     */
+    private $location;
+
+    /**
+     * PreviewGenerator constructor.
+     * @param Image $image
+     * @param Cache $cache
+     * @param string $location
+     *
+     * @Inject({Image::class, Cache::class, "config.phpwkhtmltopdf.images.files_location"})
+     */
+    public function __construct(Image $image, Cache $cache, $location)
+    {
+        $this->image = $image;
+        $this->cache = $cache;
+        $this->location = $location;
+    }
+
+    /**
+     * Generates and stores preview for provided website and returns the path to the image file
+     *
+     * @param string $url
+     * @return string
+     */
+    public function generatePreview($url)
+    {
+        $cacheId = sprintf('preview_%s.png', urlencode($url));
+        if ($this->cache->contains($cacheId)) {
+            return $this->cache->fetch($cacheId);
+        }
+
+        $path = $this->location . '/' . $cacheId;
+        $this->image->setPage($url);
+        $this->image->saveAs($path);
+        $this->cache->save($cacheId, $path);
+
+        return $path;
+    }
+}

module/Common/src/Service/PreviewGeneratorInterface.php

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+<?php
+namespace Shlinkio\Shlink\Common\Service;
+
+interface PreviewGeneratorInterface
+{
+    /**
+     * Generates and stores preview for provided website and returns the path to the image file
+     *
+     * @param string $url
+     * @return string
+     */
+    public function generatePreview($url);
+}