Initial implementation of JSON-LD comment property

Author: AlfredoRamos

README.md

@@ -56,6 +56,7 @@ If available, it will dynamically generate and include the following data inside
 	"@context": "https://schema.org",
 	"@type": "DiscussionForumPosting",
 	"url": "...",
+	"mainEntityOfPage": "...",
 	"headline": "...",
 	"description": "...",
 	"text": "...",
@@ -77,7 +78,16 @@ If available, it will dynamically generate and include the following data inside
 			"width": "...",
 			"height": "..."
 		}
-	}
+	},
+	"comment": [{
+		"@type": "Comment",
+		"text": "...",
+		"author": {
+			"@type": "Person",
+			"name": "...",
+			"url": "..."
+		}
+	}]
 }
 </script>
 ```

includes/helper.php

@@ -180,6 +180,7 @@ public function set_metadata($data = [])
 					'@context' => 'https://schema.org',
 					'@type' => 'DiscussionForumPosting',
 					'url' => $default['url'],
+					'mainEntityOfPage' => $default['url'],
 					'headline' => '',
 					'description' => $default['description'],
 					'text' => $default['description'],
@@ -201,6 +202,17 @@ public function set_metadata($data = [])
 							'width' => (int) $this->config['seo_metadata_json_ld_logo_width'],
 							'height' => (int) $this->config['seo_metadata_json_ld_logo_height']
 						]
+					],
+					'comment' => [
+						[
+							'@type' => 'Comment',
+							'text' => '',
+							'author' => [
+								'@type' => 'Person',
+								'name' => '',
+								'url' => ''
+							]
+						]
 					]
 				]
 			];
@@ -370,6 +382,15 @@ public function metadata_template_vars()
 			unset($data['json_ld']['publisher']['logo']);
 		}
 
+		// JSON-LD comment
+		foreach ($data['json_ld']['comment'] as $key => $value)
+		{
+			if (empty($value['text']))
+			{
+				unset($data['json_ld']['comment'][$key]);
+			}
+		}
+
 		// Ignore disabled options
 		foreach ($data as $key => $value)
 		{
@@ -387,17 +408,19 @@ public function metadata_template_vars()
 		// Assign data to template
 		foreach ($data as $key => $value)
 		{
+			$type = strtoupper($key);
+
 			$this->template->assign_block_vars(
 				'SEO_METADATA',
 				[
-					'NAME' => strtoupper($key),
+					'NAME' => $type,
 				]
 			);
 
 			if ($key === 'json_ld')
 			{
 				$this->template->assign_block_vars(
-					sprintf('SEO_METADATA.%s', strtoupper($key)),
+					sprintf('SEO_METADATA.%s', $type),
 					[
 						'CONTENT' => json_encode($data[$key], JSON_UNESCAPED_SLASHES)
 					]
@@ -409,7 +432,7 @@ public function metadata_template_vars()
 				foreach ($value as $k => $v)
 				{
 					$this->template->assign_block_vars(
-						sprintf('SEO_METADATA.%s', strtoupper($key)),
+						sprintf('SEO_METADATA.%s', $type),
 						[
 							'PROPERTY' => $k,
 							'CONTENT' => $v