257 lines
12 KiB
PHP
257 lines
12 KiB
PHP
<?php
|
|
|
|
/**
|
|
* Process HTML DOM to retrieve standard metadata intended for social media embeds and SEO.
|
|
* @param string|object $html Webpage HTML. Supports HTML objects or string objects.
|
|
* @return array Entry generated from Metadata: 'title', 'author', 'timestamp', etc.
|
|
*/
|
|
function html_find_seo_metadata($html)
|
|
{
|
|
if (is_string($html)) {
|
|
$html = getSimpleHTMLDOM($html);
|
|
}
|
|
|
|
$item = [];
|
|
|
|
// == First source of metadata: Meta tags ==
|
|
// Facebook Open Graph (og:KEY) - https://developers.facebook.com/docs/sharing/webmasters
|
|
// Twitter (twitter:KEY) - https://developer.twitter.com/en/docs/twitter-for-websites/cards/guides/getting-started
|
|
// Standard meta tags - https://www.w3schools.com/tags/tag_meta.asp
|
|
// Standard time tag - https://developer.mozilla.org/en-US/docs/Web/HTML/Element/time
|
|
|
|
// Each Entry field mapping defines a list of possible <meta> tags names that contains the expected value
|
|
// There are various source candidates per type of data, listed from most reliable to least reliable
|
|
static $meta_mappings = [
|
|
// <meta property="article:KEY" content="VALUE" />
|
|
// <meta property="og:KEY" content="VALUE" />
|
|
// <meta property="KEY" content="VALUE" />
|
|
// <meta name="twitter:KEY" content="VALUE" />
|
|
// <meta name="KEY" content="VALUE">
|
|
// <link rel="canonical" href="URL" />
|
|
// <time datetime="VALUE">text</time>
|
|
'uri' => [
|
|
'og:url',
|
|
'twitter:url',
|
|
'canonical',
|
|
],
|
|
'title' => [
|
|
'og:title',
|
|
'twitter:title',
|
|
],
|
|
'content' => [
|
|
'og:description',
|
|
'twitter:description',
|
|
'description',
|
|
],
|
|
'timestamp' => [
|
|
'article:published_time',
|
|
'og:article:published_time',
|
|
'releaseDate',
|
|
'releasedate',
|
|
'article:modified_time',
|
|
'og:article:modified_time',
|
|
'lastModified',
|
|
'lastmodified',
|
|
'time',
|
|
],
|
|
'enclosures' => [
|
|
'og:image:secure_url',
|
|
'og:image:url',
|
|
'og:image',
|
|
'twitter:image',
|
|
'thumbnailImg',
|
|
'thumbnailimg',
|
|
],
|
|
'author' => [
|
|
'article:author',
|
|
'og:article:author',
|
|
'author',
|
|
'article:author:username',
|
|
'profile:first_name',
|
|
'profile:last_name',
|
|
'article:author:first_name',
|
|
'article:author:last_name',
|
|
'twitter:creator',
|
|
],
|
|
];
|
|
|
|
$author_first_name = null;
|
|
$author_last_name = null;
|
|
|
|
// For each Entry property, look for corresponding HTML tags using a list of candidates
|
|
foreach ($meta_mappings as $property => $field_list) {
|
|
foreach ($field_list as $field) {
|
|
// Look for HTML meta tag
|
|
$element = null;
|
|
if ($field === 'canonical') {
|
|
$element = $html->find('link[rel=canonical]');
|
|
} else if ($field === 'time') {
|
|
$element = $html->find('time[datetime]');
|
|
} else {
|
|
$element = $html->find("meta[property=$field], meta[name=$field]");
|
|
}
|
|
// Found something? Extract the value and populate Entry field
|
|
if (!empty($element)) {
|
|
$element = $element[0];
|
|
$field_value = '';
|
|
if ($field === 'canonical') {
|
|
$field_value = $element->href;
|
|
} else if ($field === 'time') {
|
|
$field_value = $element->datetime;
|
|
} else {
|
|
$field_value = $element->content;
|
|
}
|
|
if (!empty($field_value)) {
|
|
if ($field === 'article:author:first_name' || $field === 'profile:first_name') {
|
|
$author_first_name = $field_value;
|
|
} else if ($field === 'article:author:last_name' || $field === 'profile:last_name') {
|
|
$author_last_name = $field_value;
|
|
} else {
|
|
$item[$property] = $field_value;
|
|
break; // Stop on first match, e.g. og:url has priority over canonical url.
|
|
}
|
|
}
|
|
}
|
|
}
|
|
}
|
|
|
|
// Populate author from first name and last name if all we have is nothing or Twitter @username
|
|
if ((!isset($item['author']) || $item['author'][0] === '@') && (is_string($author_first_name) || is_string($author_last_name))) {
|
|
$author = '';
|
|
if (is_string($author_first_name)) {
|
|
$author = $author_first_name;
|
|
}
|
|
if (is_string($author_last_name)) {
|
|
$author = $author . ' ' . $author_last_name;
|
|
}
|
|
$item['author'] = trim($author);
|
|
}
|
|
|
|
// == Second source of metadata: Embedded JSON ==
|
|
// JSON linked data - https://www.w3.org/TR/2014/REC-json-ld-20140116/
|
|
// JSON linked data is COMPLEX and MAY BE LESS RELIABLE than <meta> tags. Used for fields not found as <meta> tags.
|
|
// The implementation below will load all ld+json we can understand and attempt to extract relevant information.
|
|
|
|
// ld+json object types that hold article metadata
|
|
// Each mapping define item fields and a list of possible JSON field for this field
|
|
// Each candiate JSON field is either a string (field name) or a list (path to nested field)
|
|
static $ldjson_article_types = ['webpage', 'article', 'newsarticle', 'blogposting'];
|
|
static $ldjson_article_mappings = [
|
|
'uri' => ['url', 'mainEntityOfPage'],
|
|
'title' => ['headline'],
|
|
'content' => ['description'],
|
|
'timestamp' => ['dateModified', 'datePublished'],
|
|
'enclosures' => ['image'],
|
|
'author' => [['author', 'name'], ['author', '@id'], 'author'],
|
|
];
|
|
|
|
// ld+json object types that hold author metadata
|
|
$ldjson_author_types = ['person', 'organization'];
|
|
$ldjson_author_mappings = []; // ID => Name
|
|
$ldjson_author_id = null;
|
|
|
|
// Utility function for checking if JSON array matches one of the desired ld+json object types
|
|
// A JSON object may have a single ld+json @type as a string OR several types at once as a list
|
|
$ldjson_is_of_type = function ($json, $allowed_types) {
|
|
if (isset($json['@type'])) {
|
|
$json_types = $json['@type'];
|
|
if (!is_array($json_types)) {
|
|
$json_types = [ $json_types ];
|
|
}
|
|
foreach ($json_types as $item_type) {
|
|
if (in_array(strtolower($item_type), $allowed_types)) {
|
|
return true;
|
|
}
|
|
}
|
|
}
|
|
return false;
|
|
};
|
|
|
|
// Process ld+json objects embedded in the HTML DOM
|
|
foreach ($html->find('script[type=application/ld+json]') as $html_ldjson_node) {
|
|
$json_raw = json_decode($html_ldjson_node->innertext, true);
|
|
if (is_array($json_raw)) {
|
|
// The JSON we just loaded may contain directly a single ld+json object AND/OR several ones under the '@graph' key
|
|
$json_items = [ $json_raw ];
|
|
if (isset($json_raw['@graph'])) {
|
|
foreach ($json_raw['@graph'] as $json_raw_sub_item) {
|
|
$json_items[] = $json_raw_sub_item;
|
|
}
|
|
}
|
|
// Now that we have a list of distinct JSON items, we can process them individually
|
|
foreach ($json_items as $json) {
|
|
// JSON item that holds an ld+json Article object (or a variant)
|
|
if ($ldjson_is_of_type($json, $ldjson_article_types)) {
|
|
// For each item property, look for corresponding JSON fields and populate the item
|
|
foreach ($ldjson_article_mappings as $property => $field_list) {
|
|
// Skip fields already found as <meta> tags, except Twitter @username (because we might find a better name)
|
|
if (!isset($item[$property]) || ($property === 'author' && $item['author'][0] === '@')) {
|
|
foreach ($field_list as $field) {
|
|
$json_root = $json;
|
|
// If necessary, navigate inside the JSON object to access a nested field
|
|
if (is_array($field)) {
|
|
// At this point, $field = ['author', 'name'] and $json_root = {"author": {"name": "John Doe"}}
|
|
$json_navigate_ok = true;
|
|
while (count($field) > 1) {
|
|
$sub_field = array_shift($field);
|
|
if (array_key_exists($sub_field, $json_root)) {
|
|
$json_root = $json_root[$sub_field];
|
|
if (array_is_list($json_root) && count($json_root) === 1) {
|
|
$json_root = $json_root[0]; // Unwrap list of single item e.g. {"author":[{"name":"John Doe"}]}
|
|
}
|
|
} else {
|
|
// Desired path not found in JSON, stop navigating
|
|
$json_navigate_ok = false;
|
|
break;
|
|
}
|
|
}
|
|
if (!$json_navigate_ok) {
|
|
continue; //Desired path not found in JSON, skip this field
|
|
}
|
|
$field = $field[0];
|
|
// At this point, $field = "name" and $json_root = {"name": "John Doe"}
|
|
}
|
|
// Now we can check for desired field in JSON and populate $item accordingly
|
|
if (isset($json_root[$field])) {
|
|
$field_value = $json_root[$field];
|
|
if (is_array($field_value) && isset($field_value[0])) {
|
|
$field_value = $field_value[0]; // Different versions of the same enclosure? Take the first one
|
|
}
|
|
if (is_string($field_value) && !empty($field_value)) {
|
|
if ($property === 'author' && $field === '@id') {
|
|
$ldjson_author_id = $field_value; // Author is referred to by its ID: We'll see later if we can resolve it
|
|
} else {
|
|
$item[$property] = $field_value;
|
|
break; // Stop on first match, e.g. {"author":{"name":"John Doe"}} has priority over {"author":"John Doe"}
|
|
}
|
|
}
|
|
}
|
|
}
|
|
}
|
|
}
|
|
// JSON item that holds an ld+json Author object (or a variant)
|
|
} else if ($ldjson_is_of_type($json, $ldjson_author_types)) {
|
|
if (isset($json['@id']) && isset($json['name'])) {
|
|
$ldjson_author_mappings[$json['@id']] = $json['name'];
|
|
}
|
|
}
|
|
}
|
|
}
|
|
}
|
|
|
|
// Attempt to resolve ld+json author if all we have is nothing or Twitter @username
|
|
if ((!isset($item['author']) || $item['author'][0] === '@') && !is_null($ldjson_author_id) && isset($ldjson_author_mappings[$ldjson_author_id])) {
|
|
$item['author'] = $ldjson_author_mappings[$ldjson_author_id];
|
|
}
|
|
|
|
// Adjust item field types
|
|
if (isset($item['enclosures'])) {
|
|
$item['enclosures'] = [ $item['enclosures'] ];
|
|
}
|
|
if (isset($item['timestamp'])) {
|
|
$item['timestamp'] = strtotime($item['timestamp']);
|
|
}
|
|
|
|
return $item;
|
|
}
|