fusonic / opengraph

namespace Fusonic\OpenGraph;

use DOMElement;

use Fusonic\Linq\Linq;

use Fusonic\OpenGraph\Objects\ObjectBase;

use Fusonic\OpenGraph\Objects\Website;

use LogicException;

use Psr\Http\Client\ClientExceptionInterface;

use Psr\Http\Client\ClientInterface;

use Psr\Http\Message\RequestFactoryInterface;

use Symfony\Component\DomCrawler\Crawler;

/**

 * Consumer that extracts Open Graph data from either a URL or a HTML string.

     * When enabled, crawler will read content of title and meta description if no

     * Open Graph data is provided by target page.

     */

    public bool $useFallbackMode = false;

    /**

     * When enabled, crawler will throw exceptions for some crawling errors like unexpected

     * Open Graph elements.

     */

    public bool $debug = false;

    /**

     * @param ClientInterface|null         $client         A PSR-18 ClientInterface implementation.

     * @param RequestFactoryInterface|null $requestFactory A PSR-17 RequestFactoryInterface implementation.

     */

    public function __construct(?ClientInterface $client = null, ?RequestFactoryInterface $requestFactory = null)

    {

        $this->client = $client;

        $this->requestFactory = $requestFactory;

    }

    /**

     * Fetches HTML content from the given URL and then crawls it for Open Graph data.

     *

     * @param string $url URL to be crawled.

     *

     * @return ObjectBase

     *

     * @throws ClientExceptionInterface

     */

    public function loadUrl(string $url): ObjectBase

    {

        if ($this->client === null) {

            throw new LogicException(

                "To use loadUrl() you must provide \$client and \$requestFactory when instantiating the consumer."

            );

        }

        $request = $this->requestFactory->createRequest("GET", $url);

        $response = $this->client->sendRequest($request);

        return $this->loadHtml($response->getBody()->getContents(), $url);

    }

    /**

     * Crawls the given HTML string for OpenGraph data.

     *

     * @param string $html        HTML string, usually whole content of crawled web resource.

     * @param string $fallbackUrl URL to use when fallback mode is enabled.

     *

     * @return  ObjectBase

     */

    public function loadHtml(string $html, string $fallbackUrl = null): ObjectBase

    {

        // Extract all data that can be found

        $page = $this->extractOpenGraphData($html);

        // Use the user's URL as fallback

        if ($this->useFallbackMode && $page->url === null) {

            $page->url = $fallbackUrl;

        }

        // Return result

        return $page;

    }

    private function extractOpenGraphData(string $content): ObjectBase

    {

        $crawler = new Crawler;

        $crawler->addHTMLContent($content, 'UTF-8');

        $properties = [];

        foreach(['name', 'property'] as $t)

        {

            // Get all meta-tags starting with "og:"

            $ogMetaTags = $crawler->filter("meta[{$t}^='og:']");

            // Create clean property array

            $props = Linq::from($ogMetaTags)

                ->select(

                    function (DOMElement $tag) use ($t) {

                        $name = strtolower(trim($tag->getAttribute($t)));

                        $value = trim($tag->getAttribute("content"));

                        return new Property($name, $value);

                    }

                )

                ->toArray();

            $properties = array_merge($properties, $props);

        }

        // Create new object of the correct type

        $typeProperty = Linq::from($properties)

            ->firstOrNull(

                function (Property $property) {

                    return $property->key === Property::TYPE;

                }

            );

        switch ($typeProperty !== null ? $typeProperty->value : null) {

            default:

                $object = new Website();

                break;

        }

        // Assign all properties to the object

        $object->assignProperties($properties, $this->debug);

        // Fallback for url

        if ($this->useFallbackMode && !$object->url) {

            $urlElement = $crawler->filter("link[rel='canonical']")->first();

            if ($urlElement->count() > 0) {

                $object->url = trim($urlElement->attr("href"));

            }

        }

        // Fallback for title

        if ($this->useFallbackMode && !$object->title) {

            $titleElement = $crawler->filter("title")->first();

            if ($titleElement->count() > 0) {

                $object->title = trim($titleElement->text());

            }

        }

        // Fallback for description

        if ($this->useFallbackMode && !$object->description) {

            $descriptionElement = $crawler->filter("meta[property='description']")->first();

            if ($descriptionElement->count() > 0) {

                $object->description = trim($descriptionElement->attr("content"));

            }

        }

        return $object;

    }

}