+
+/**
+ * Get cURL callback function for CURLOPT_WRITEFUNCTION
+ *
+ * @param string $charset to extract from the downloaded page (reference)
+ * @param string $curlGetInfo Optionally overrides curl_getinfo function
+ *
+ * @return Closure
+ */
+function get_curl_header_callback(
+ &$charset,
+ $curlGetInfo = 'curl_getinfo'
+) {
+ $isRedirected = false;
+
+ return function ($ch, $data) use ($curlGetInfo, &$charset, &$isRedirected) {
+ $responseCode = $curlGetInfo($ch, CURLINFO_RESPONSE_CODE);
+ $chunkLength = strlen($data);
+ if (!empty($responseCode) && in_array($responseCode, [301, 302])) {
+ $isRedirected = true;
+ return $chunkLength;
+ }
+ if (!empty($responseCode) && $responseCode !== 200) {
+ return false;
+ }
+ // After a redirection, the content type will keep the previous request value
+ // until it finds the next content-type header.
+ if (! $isRedirected || strpos(strtolower($data), 'content-type') !== false) {
+ $contentType = $curlGetInfo($ch, CURLINFO_CONTENT_TYPE);
+ }
+ if (!empty($contentType) && strpos($contentType, 'text/html') === false) {
+ return false;
+ }
+ if (!empty($contentType) && empty($charset)) {
+ $charset = header_extract_charset($contentType);
+ }
+
+ return $chunkLength;
+ };
+}
+
+/**
+ * Get cURL callback function for CURLOPT_WRITEFUNCTION
+ *
+ * @param string $charset to extract from the downloaded page (reference)
+ * @param string $title to extract from the downloaded page (reference)
+ * @param string $description to extract from the downloaded page (reference)
+ * @param string $keywords to extract from the downloaded page (reference)
+ * @param bool $retrieveDescription Automatically tries to retrieve description and keywords from HTML content
+ * @param string $curlGetInfo Optionally overrides curl_getinfo function
+ *
+ * @return Closure
+ */
+function get_curl_download_callback(
+ &$charset,
+ &$title,
+ &$description,
+ &$keywords,
+ $retrieveDescription,
+ $tagsSeparator
+) {
+ $currentChunk = 0;
+ $foundChunk = null;
+
+ /**
+ * cURL callback function for CURLOPT_WRITEFUNCTION (called during the download).
+ *
+ * While downloading the remote page, we check that the HTTP code is 200 and content type is 'html/text'
+ * Then we extract the title and the charset and stop the download when it's done.
+ *
+ * @param resource $ch cURL resource
+ * @param string $data chunk of data being downloaded
+ *
+ * @return int|bool length of $data or false if we need to stop the download
+ */
+ return function ($ch, $data) use (
+ $retrieveDescription,
+ $tagsSeparator,
+ &$charset,
+ &$title,
+ &$description,
+ &$keywords,
+ &$currentChunk,
+ &$foundChunk
+ ) {
+ $chunkLength = strlen($data);
+ $currentChunk++;
+
+ if (empty($charset)) {
+ $charset = html_extract_charset($data);
+ }
+ if (empty($title)) {
+ $title = html_extract_title($data);
+ $foundChunk = ! empty($title) ? $currentChunk : $foundChunk;
+ }
+ if (empty($title)) {
+ $title = html_extract_tag('title', $data);
+ $foundChunk = ! empty($title) ? $currentChunk : $foundChunk;
+ }
+ if ($retrieveDescription && empty($description)) {
+ $description = html_extract_tag('description', $data);
+ $foundChunk = ! empty($description) ? $currentChunk : $foundChunk;
+ }
+ if ($retrieveDescription && empty($keywords)) {
+ $keywords = html_extract_tag('keywords', $data);
+ if (! empty($keywords)) {
+ $foundChunk = $currentChunk;
+ // Keywords use the format tag1, tag2 multiple words, tag
+ // So we split the result with `,`, then if a tag contains the separator we replace it by `-`.
+ $keywords = tags_array2str(array_map(function(string $keyword) use ($tagsSeparator): string {
+ return tags_array2str(tags_str2array($keyword, $tagsSeparator), '-');
+ }, tags_str2array($keywords, ',')), $tagsSeparator);
+ }
+ }
+
+ // We got everything we want, stop the download.
+ // If we already found either the title, description or keywords,
+ // it's highly unlikely that we'll found the other metas further than
+ // in the same chunk of data or the next one. So we also stop the download after that.
+ if ((!empty($responseCode) && !empty($contentType) && !empty($charset)) && $foundChunk !== null
+ && (! $retrieveDescription
+ || $foundChunk < $currentChunk
+ || (!empty($title) && !empty($description) && !empty($keywords))
+ )
+ ) {
+ return false;
+ }
+
+ return $chunkLength;
+ };
+}