Merge pull request #86 from unarist/feat/activitypub

ActivityPubResolverを追加

app/MetadataResolver/ActivityPubResolver.php

@@ -0,0 +1,80 @@
+<?php
+
+namespace App\MetadataResolver;
+
+use Psr\Http\Message\ResponseInterface;
+use GuzzleHttp\Exception\TransferException;
+use Illuminate\Support\Facades\Log;
+
+class ActivityPubResolver implements Resolver, Parser
+{
+    /**
+     * @var \GuzzleHttp\Client
+     */
+    private $activityClient;
+
+    public function __construct()
+    {
+        $this->activityClient = new \GuzzleHttp\Client([
+            'headers' => [
+                'Accept' => 'application/activity+json, application/ld+json; profile="https://www.w3.org/ns/activitystreams"'
+            ]
+        ]);
+    }
+
+    public function resolve(string $url): Metadata
+    {
+        $res = $this->activityClient->get($url);
+        if ($res->getStatusCode() === 200) {
+            return $this->parse($res->getBody());
+        } else {
+            throw new \RuntimeException("{$res->getStatusCode()}: $url");
+        }
+    }
+
+    public function parse(string $json): Metadata
+    {
+        $activityOrObject = json_decode($json, true);
+        $object = $activityOrObject['object'] ?? $activityOrObject;
+
+        $metadata = new Metadata();
+
+        $metadata->title = isset($object['attributedTo']) ? $this->getTitleFromActor($object['attributedTo']) : '';
+        $metadata->description .= isset($object['summary']) ? $object['summary'] . " | " : '';
+        $metadata->description .= isset($object['content']) ? $this->html2text($object['content']) : '';
+        $metadata->image = $object['attachment'][0]['url'] ?? '';
+
+        return $metadata;
+    }
+
+    private function getTitleFromActor(string $url): string
+    {
+        try {
+            $res = $this->activityClient->get($url);
+            if ($res->getStatusCode() !== 200) {
+                Log::info(self::class . ': Actorの取得に失敗 URL=' . $url);
+                return '';
+            }
+
+            $actor = json_decode($res->getBody(), true);
+            $title = $actor['name'] ?? '';
+            if (isset($actor['preferredUsername'])) {
+                $title .= ' (@' . $actor['preferredUsername'] . '@' . parse_url($actor['id'], PHP_URL_HOST) . ')';
+            }
+
+            return $title;
+        } catch (TransferException $e) {
+            Log::info(self::class . ': Actorの取得に失敗 URL=' . $url);
+            return '';
+        }
+    }
+
+    private function html2text(string $html): string
+    {
+        $html = mb_convert_encoding($html, 'HTML-ENTITIES', 'UTF-8');
+        $html = preg_replace('~<br\s*/?\s*>|</p>\s*<p[^>]*>~i', "\n", $html);
+        $dom = new \DOMDocument();
+        $dom->loadHTML($html, LIBXML_HTML_NOIMPLIED | LIBXML_HTML_NODEFDTD);
+        return $dom->textContent;
+    }
+}

app/MetadataResolver/MetadataResolver.php

@@ -2,6 +2,9 @@
 
 namespace App\MetadataResolver;
 
+use GuzzleHttp\Exception\ClientException;
+use GuzzleHttp\Exception\ServerException;
+
 class MetadataResolver implements Resolver
 {
     public $rules = [
@@ -18,9 +21,17 @@ class MetadataResolver implements Resolver
         '~www\.patreon\.com/~' => PatreonResolver::class,
         '~www\.deviantart\.com/.*/art/.*~' => DeviantArtResolver::class,
         '~\.syosetu\.com/n\d+[a-z]{2,}~' => NarouResolver::class,
-        '/.*/' => OGPResolver::class
     ];
 
+    public $mimeTypes = [
+        'application/activity+json' => ActivityPubResolver::class,
+        'application/ld+json' => ActivityPubResolver::class,
+        'text/html' => OGPResolver::class,
+        '*/*' => OGPResolver::class
+    ];
+
+    public $defaultResolver = OGPResolver::class;
+
     public function resolve(string $url): Metadata
     {
         foreach ($this->rules as $pattern => $class) {
@@ -31,6 +42,64 @@ class MetadataResolver implements Resolver
             }
         }
 
+        $result = $this->resolveWithAcceptHeader($url);
+        if ($result !== null) {
+            return $result;
+        }
+
+        if (isset($this->defaultResolver)) {
+            $resolver = new $this->defaultResolver();
+            return $resolver->resolve($url);
+        }
+
         throw new \UnexpectedValueException('URL not matched.');
     }
+    
+    public function resolveWithAcceptHeader(string $url): ?Metadata
+    {
+        try {
+            // Rails等はAcceptに */* が入っていると、ブラウザの適当なAcceptヘッダだと判断して全部無視してしまう。
+            // c.f. https://github.com/rails/rails/issues/9940
+            // そこでここでは */* を「Acceptヘッダを無視してきたレスポンス（よくある）」のハンドラとして扱い、
+            // Acceptヘッダには */* を足さないことにする。
+            $acceptTypes = array_diff(array_keys($this->mimeTypes), ['*/*']);
+
+            $client = new \GuzzleHttp\Client();
+            $res = $client->request('GET', $url, [
+                'headers' => [
+                    'Accept' => implode(', ', $acceptTypes)
+                ]
+            ]);
+
+            if ($res->getStatusCode() === 200) {
+                preg_match('/^[^;\s]+/', $res->getHeaderLine('Content-Type'), $matches);
+                $mimeType = $matches[0];
+
+                if (isset($this->mimeTypes[$mimeType])) {
+                    $class = $this->mimeTypes[$mimeType];
+                    $parser = new $class();
+
+                    return $parser->parse($res->getBody());
+                }
+
+                if (isset($this->mimeTypes['*/*'])) {
+                    $class = $this->mimeTypes['*/*'];
+                    $parser = new $class();
+
+                    return $parser->parse($res->getBody());
+                }
+            } else {
+                // code < 400 && code !== 200 => fallback
+            }
+        } catch (ClientException $e) {
+            // 406 Not Acceptable は多分Acceptが原因なので無視してフォールバック
+            if ($e->getResponse()->getStatusCode() !== 406) {
+                throw $e;
+            }
+        } catch (ServerException $e) {
+            // 5xx は変なAcceptが原因かもしれない（？）ので無視してフォールバック
+        }
+
+        return null;
+    }
 }

app/MetadataResolver/OGPResolver.php

@@ -2,7 +2,7 @@
 
 namespace App\MetadataResolver;
 
-class OGPResolver implements Resolver
+class OGPResolver implements Resolver, Parser
 {
     public function resolve(string $url): Metadata
     {

app/MetadataResolver/Parser.php

@@ -0,0 +1,8 @@
+<?php
+
+namespace App\MetadataResolver;
+
+interface Parser
+{
+    public function parse(string $body): Metadata;
+}