1 files changed, 91 insertions, 0 deletions
diff --git a/Digitigrade/LinkPreview.php b/Digitigrade/LinkPreview.php
new file mode 100644
index 0000000..4716cc8
--- /dev/null
+++ b/Digitigrade/LinkPreview.php
@@ -0,0 +1,91 @@
+<?php
+namespace Digitigrade;
+
+class LinkPreview implements \JsonSerializable {
+    public string $url;
+    public string $siteName;
+    public string $title;
+    public string $description;
+    public string $style;
+    public ?string $imageUrl = null;
+
+    /**
+     * Generates a link preview for the given URL.
+     * @param string $url
+     * @return LinkPreview|null the link preview, or null if none is available
+     */
+    public static function generate(string $url): ?self {
+        $p = new self();
+        $p->url = $url;
+        return $p->update() ? $p : null;
+    }
+
+    /**
+     * Updates the information for this link preview.
+     * @return bool true if successful
+     */
+    public function update(): bool {
+        if (!(str_starts_with($this->url, "https://") || str_starts_with($this->url, "http://"))) {
+            return false;
+        }
+
+        $d = new \DOMDocument();
+        $c = @file_get_contents($this->url);
+        if (!$c)
+            return false;
+        @$d->loadHTML($c);
+
+        $url = $this->url;
+        $siteName = hostname_from_uri($this->url);
+        $style = 'text';
+        $title = $d->getElementsByTagName('title')->item(0)?->textContent;
+        $metas = $d->getElementsByTagName('meta');
+        foreach ($metas as $tag) {
+            if ($tag->attributes->getNamedItem('name')?->textContent == 'description') {
+                // <meta name="description" content="...">
+                $description = $tag->attributes->getNamedItem('content')?->textContent;
+            } elseif ($prop = $tag->attributes->getNamedItem('property')) {
+                // <meta property="og:..." content="...">
+                $content = $tag->attributes->getNamedItem('content')?->textContent;
+                match ($prop->textContent) {
+                    'og:title' => $title = $content,
+                    'og:description' => $description = $content,
+                    'og:url' => $url = $content,
+                    'og:site_name' => $siteName = $content,
+                    'og:image' => $imageUrl = $content,
+                    default => null
+                };
+
+            } elseif ($tag->attributes->getNamedItem('name')?->textContent == 'twitter:card'
+                && $tag->attributes->getNamedItem("content")?->textContent == 'summary_large_image') {
+                // <meta name="twitter:card" content="summary_large_image">
+                $style = 'largeImage';
+            }
+        }
+        // turn text into smallImage if an image is present
+        $style = ($style == 'text' && isset($imageUrl)) ? 'smallImage' : $style;
+
+        if (!isset($title, $description))
+            return false;
+
+        $this->url = $url;
+        $this->siteName = $siteName;
+        $this->title = $title;
+        $this->description = $description;
+        $this->style = $style;
+        $this->imageUrl = $imageUrl ?? null;
+
+        return true;
+    }
+
+    public function jsonSerialize(): array {
+        return [
+            'url' => $this->url,
+            'siteName' => $this->siteName,
+            'title' => $this->title,
+            'description' => $this->description,
+            'style' => $this->style,
+            'imageUrl' => $this->imageUrl
+        ];
+    }
+}
+\ No newline at end of file