Add support for Favicons (#11)

* wip

* wip

* wip

* Update tests/Pest/FaviconTest.php

Co-authored-by: Samuel Štancl <samuel.stancl@gmail.com>

* Update tests/Pest/FaviconTest.php

Co-authored-by: Samuel Štancl <samuel.stancl@gmail.com>

* Update README.md

Co-authored-by: Samuel Štancl <samuel.stancl@gmail.com>

src/SEOManager.php

@@ -5,7 +5,9 @@ declare(strict_types=1);
 namespace ArchTech\SEO;
 
 use Closure;
+use Exception;
 use Illuminate\Support\Str;
+use Intervention\Image\ImageManager;
 
 /**
  * @method $this title(string $title = null, ...$args) Set the title.
@@ -176,6 +178,40 @@ class SEOManager
         return $this->set('image', "https://s.useflipp.com/{$template}.png?s={$signature}&v={$query}");
     }
 
+    /** Enable favicon extension. */
+    public function favicon(string $path): static
+    {
+        if (! class_exists(ImageManager::class)) {
+            throw new Exception('Intervention not available, please run `composer require intervention/image`');
+        }
+
+        $this->extensions['favicon'] = true;
+
+        $doesntHaveFavicon = ! file_exists(public_path('favicon.ico'));
+        $sourceIconDoesntExist = ! file_exists($path);
+
+        if ($sourceIconDoesntExist) {
+            throw new Exception("Given icon path `{$path}` does not exist.");
+        }
+
+        if ($doesntHaveFavicon) {
+            // GD driver doesn't support .ico, that's why we use ImageMagick.
+            $manager = new ImageManager(['driver' => 'imagick']);
+
+            $manager
+                ->make($path)
+                ->resize(32, 32)
+                ->save(public_path('favicon.ico'));
+
+            $manager
+                ->make($path)
+                ->resize(32, 32)
+                ->save(public_path('favicon.png'));
+        }
+
+        return $this;
+    }
+
     /** Append canonical URL tags to the document head. */
     public function withUrl(): static
     {