Improved PreviewGenerator by composing an ImageBuilder that creates new Image objects fore each URL

config/autoload/phpwkhtmltopdf.global.php

@@ -2,7 +2,6 @@
 return [
 
     'phpwkhtmltopdf' => [
-        'files_location' => 'data/cache',
         'images' => [
             'binary' => 'bin/wkhtmltoimage',
             'type' => 'jpg',

config/autoload/preview-generation.global.php

@@ -0,0 +1,8 @@
+<?php
+return [
+
+    'preview_generation' => [
+        'files_location' => 'data/cache',
+    ],
+
+];

module/CLI/config/cli.config.php

@@ -10,6 +10,7 @@ return [
             Command\Shortcode\ResolveUrlCommand::class,
             Command\Shortcode\ListShortcodesCommand::class,
             Command\Shortcode\GetVisitsCommand::class,
+            Command\Shortcode\GeneratePreviewCommand::class,
             Command\Visit\ProcessVisitsCommand::class,
             Command\Config\GenerateCharsetCommand::class,
             Command\Config\GenerateSecretCommand::class,

module/CLI/config/dependencies.config.php

@@ -14,6 +14,7 @@ return [
             Command\Shortcode\ResolveUrlCommand::class => AnnotatedFactory::class,
             Command\Shortcode\ListShortcodesCommand::class => AnnotatedFactory::class,
             Command\Shortcode\GetVisitsCommand::class => AnnotatedFactory::class,
+            Command\Shortcode\GeneratePreviewCommand::class => AnnotatedFactory::class,
             Command\Visit\ProcessVisitsCommand::class => AnnotatedFactory::class,
             Command\Config\GenerateCharsetCommand::class => AnnotatedFactory::class,
             Command\Config\GenerateSecretCommand::class => AnnotatedFactory::class,

module/CLI/src/Command/Shortcode/GeneratePreviewCommand.php

@@ -0,0 +1,87 @@
+<?php
+namespace Shlinkio\Shlink\CLI\Command\Shortcode;
+
+use Acelaya\ZsmAnnotatedServices\Annotation\Inject;
+use Shlinkio\Shlink\Common\Exception\PreviewGenerationException;
+use Shlinkio\Shlink\Common\Service\PreviewGenerator;
+use Shlinkio\Shlink\Common\Service\PreviewGeneratorInterface;
+use Shlinkio\Shlink\Core\Service\ShortUrlService;
+use Shlinkio\Shlink\Core\Service\ShortUrlServiceInterface;
+use Symfony\Component\Console\Command\Command;
+use Symfony\Component\Console\Input\InputInterface;
+use Symfony\Component\Console\Output\OutputInterface;
+use Zend\I18n\Translator\TranslatorInterface;
+
+class GeneratePreviewCommand extends Command
+{
+    /**
+     * @var PreviewGeneratorInterface
+     */
+    private $previewGenerator;
+    /**
+     * @var TranslatorInterface
+     */
+    private $translator;
+    /**
+     * @var ShortUrlServiceInterface
+     */
+    private $shortUrlService;
+
+    /**
+     * GeneratePreviewCommand constructor.
+     * @param ShortUrlServiceInterface $shortUrlService
+     * @param PreviewGeneratorInterface $previewGenerator
+     * @param TranslatorInterface $translator
+     *
+     * @Inject({ShortUrlService::class, PreviewGenerator::class, "translator"})
+     */
+    public function __construct(
+        ShortUrlServiceInterface $shortUrlService,
+        PreviewGeneratorInterface $previewGenerator,
+        TranslatorInterface $translator
+    ) {
+        $this->previewGenerator = $previewGenerator;
+        $this->translator = $translator;
+        $this->shortUrlService = $shortUrlService;
+        parent::__construct(null);
+    }
+
+    public function configure()
+    {
+        $this->setName('shortcode:process-previews')
+             ->setDescription(
+                 $this->translator->translate(
+                     'Processes and generates the previews for every URL, improving performance for later web requests.'
+                 )
+             );
+    }
+
+    public function execute(InputInterface $input, OutputInterface $output)
+    {
+        $page = 1;
+        do {
+            $shortUrls = $this->shortUrlService->listShortUrls($page);
+            $page += 1;
+
+            foreach ($shortUrls as $shortUrl) {
+                $this->processUrl($shortUrl->getOriginalUrl(), $output);
+            }
+        } while ($page <= $shortUrls->count());
+
+        $output->writeln('<info>' . $this->translator->translate('Finished processing all URLs') . '</info>');
+    }
+
+    protected function processUrl($url, OutputInterface $output)
+    {
+        try {
+            $output->write(sprintf($this->translator->translate('Processing URL %s...'), $url));
+            $this->previewGenerator->generatePreview($url);
+            $output->writeln($this->translator->translate(' <info>Success!</info>'));
+        } catch (PreviewGenerationException $e) {
+            $output->writeln([
+                ' <error>' . $this->translator->translate('Error') . '</error>',
+                '<error>' . $e->__toString() . '</error>',
+            ]);
+        }
+    }
+}

module/Common/config/dependencies.config.php

@@ -2,14 +2,13 @@
 use Acelaya\ZsmAnnotatedServices\Factory\V3\AnnotatedFactory;
 use Doctrine\Common\Cache\Cache;
 use Doctrine\ORM\EntityManager;
-use mikehaertl\wkhtmlto\Image;
 use Monolog\Logger;
 use Psr\Log\LoggerInterface;
 use Shlinkio\Shlink\Common\Factory\CacheFactory;
 use Shlinkio\Shlink\Common\Factory\EntityManagerFactory;
 use Shlinkio\Shlink\Common\Factory\LoggerFactory;
 use Shlinkio\Shlink\Common\Factory\TranslatorFactory;
-use Shlinkio\Shlink\Common\Image\ImageFactory;
+use Shlinkio\Shlink\Common\Image;
 use Shlinkio\Shlink\Common\Middleware\LocaleMiddleware;
 use Shlinkio\Shlink\Common\Service;
 use Shlinkio\Shlink\Common\Twig\Extension\TranslatorExtension;
@@ -24,12 +23,13 @@ return [
             GuzzleHttp\Client::class => InvokableFactory::class,
             Cache::class => CacheFactory::class,
             'Logger_Shlink' => LoggerFactory::class,
-            Image::class => ImageFactory::class,
 
             Translator::class => TranslatorFactory::class,
             TranslatorExtension::class => AnnotatedFactory::class,
             LocaleMiddleware::class => AnnotatedFactory::class,
 
+            Image\ImageBuilder::class => Image\ImageBuilderFactory::class,
+
             Service\IpLocationResolver::class => AnnotatedFactory::class,
             Service\PreviewGenerator::class => AnnotatedFactory::class,
         ],

module/Common/src/Image/ImageBuilder.php

@@ -0,0 +1,10 @@
+<?php
+namespace Shlinkio\Shlink\Common\Image;
+
+use mikehaertl\wkhtmlto\Image;
+use Zend\ServiceManager\AbstractPluginManager;
+
+class ImageBuilder extends AbstractPluginManager implements ImageBuilderInterface
+{
+    protected $instanceOf = Image::class;
+}

module/Common/src/Image/ImageBuilderFactory.php

@@ -0,0 +1,31 @@
+<?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 ImageBuilderFactory 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 $options = null)
+    {
+        return new ImageBuilder($container, ['factories' => [
+            Image::class => ImageFactory::class,
+        ]]);
+    }
+}

module/Common/src/Image/ImageBuilderInterface.php

@@ -0,0 +1,8 @@
+<?php
+namespace Shlinkio\Shlink\Common\Image;
+
+use Zend\ServiceManager\ServiceLocatorInterface;
+
+interface ImageBuilderInterface extends ServiceLocatorInterface
+{
+}

module/Common/src/Image/ImageFactory.php

@@ -25,6 +25,12 @@ class ImageFactory implements FactoryInterface
     public function __invoke(ContainerInterface $container, $requestedName, array $options = null)
     {
         $config = $container->get('config')['phpwkhtmltopdf'];
-        return new Image(isset($config['images']) ? $config['images'] : null);
+        $image = new Image(isset($config['images']) ? $config['images'] : null);
+
+        if (isset($options['url'])) {
+            $image->setPage($options['url']);
+        }
+
+        return $image;
     }
 }

module/Common/src/Service/PreviewGenerator.php

@@ -5,13 +5,11 @@ use Acelaya\ZsmAnnotatedServices\Annotation\Inject;
 use Doctrine\Common\Cache\Cache;
 use mikehaertl\wkhtmlto\Image;
 use Shlinkio\Shlink\Common\Exception\PreviewGenerationException;
+use Shlinkio\Shlink\Common\Image\ImageBuilder;
+use Shlinkio\Shlink\Common\Image\ImageBuilderInterface;
 
 class PreviewGenerator implements PreviewGeneratorInterface
 {
-    /**
-     * @var Image
-     */
-    private $image;
     /**
      * @var Cache
      */
@@ -20,20 +18,24 @@ class PreviewGenerator implements PreviewGeneratorInterface
      * @var string
      */
     private $location;
+    /**
+     * @var ImageBuilderInterface
+     */
+    private $imageBuilder;
 
     /**
      * PreviewGenerator constructor.
-     * @param Image $image
+     * @param ImageBuilderInterface $imageBuilder
      * @param Cache $cache
      * @param string $location
      *
-     * @Inject({Image::class, Cache::class, "config.phpwkhtmltopdf.files_location"})
+     * @Inject({ImageBuilder::class, Cache::class, "config.preview_generation.files_location"})
      */
-    public function __construct(Image $image, Cache $cache, $location)
+    public function __construct(ImageBuilderInterface $imageBuilder, Cache $cache, $location)
     {
-        $this->image = $image;
         $this->cache = $cache;
         $this->location = $location;
+        $this->imageBuilder = $imageBuilder;
     }
 
     /**
@@ -45,17 +47,19 @@ class PreviewGenerator implements PreviewGeneratorInterface
      */
     public function generatePreview($url)
     {
-        $cacheId = sprintf('preview_%s.%s', urlencode($url), $this->image->type);
+        /** @var Image $image */
+        $image = $this->imageBuilder->build(Image::class, ['url' => $url]);
+
+        $cacheId = sprintf('preview_%s.%s', urlencode($url), $image->type);
         if ($this->cache->contains($cacheId)) {
             return $this->cache->fetch($cacheId);
         }
 
         $path = $this->location . '/' . $cacheId;
-        $this->image->setPage($url);
+        $image->saveAs($path);
-        $this->image->saveAs($path);
 
         // Check if an error occurred
-        $error = $this->image->getError();
+        $error = $image->getError();
         if (! empty($error)) {
             throw PreviewGenerationException::fromImageError($error);
         }

module/Common/test/Service/PreviewGeneratorTest.php

@@ -6,7 +6,9 @@ use mikehaertl\wkhtmlto\Image;
 use PHPUnit_Framework_TestCase as TestCase;
 use Prophecy\Argument;
 use Prophecy\Prophecy\ObjectProphecy;
+use Shlinkio\Shlink\Common\Image\ImageBuilder;
 use Shlinkio\Shlink\Common\Service\PreviewGenerator;
+use Zend\ServiceManager\ServiceManager;
 
 class PreviewGeneratorTest extends TestCase
 {
@@ -27,7 +29,13 @@ class PreviewGeneratorTest extends TestCase
     {
         $this->image = $this->prophesize(Image::class);
         $this->cache = new ArrayCache();
-        $this->generator = new PreviewGenerator($this->image->reveal(), $this->cache, 'dir');
+        $this->generator = new PreviewGenerator(new ImageBuilder(new ServiceManager(), [
+            'factories' => [
+                Image::class => function () {
+                    return $this->image->reveal();
+                },
+            ]
+        ]), $this->cache, 'dir');
     }
 
     /**
@@ -50,7 +58,6 @@ class PreviewGeneratorTest extends TestCase
         $cacheId = sprintf('preview_%s.png', urlencode($url));
         $expectedPath = 'dir/' . $cacheId;
 
-        $this->image->setPage($url)->shouldBeCalledTimes(1);
         $this->image->saveAs($expectedPath)->shouldBeCalledTimes(1);
         $this->image->getError()->willReturn('')->shouldBeCalledTimes(1);
 
@@ -69,7 +76,6 @@ class PreviewGeneratorTest extends TestCase
         $cacheId = sprintf('preview_%s.png', urlencode($url));
         $expectedPath = 'dir/' . $cacheId;
 
-        $this->image->setPage($url)->shouldBeCalledTimes(1);
         $this->image->saveAs($expectedPath)->shouldBeCalledTimes(1);
         $this->image->getError()->willReturn('Error!!')->shouldBeCalledTimes(1);