Admin: Improve logic of PHP version check on about page.

Props noisysocks, peterwilsoncc.
See #46161.


Built from https://develop.svn.wordpress.org/trunk@44735


git-svn-id: http://core.svn.wordpress.org/trunk@44567 1a063a9b-81f0-0310-95a4-ce76da25c4cd

wp-admin/includes/misc.php

@@ -2011,3 +2011,48 @@ final class WP_Privacy_Policy_Content {
 		wp_add_privacy_policy_content( __( 'WordPress' ), $content );
 	}
 }
+
+/**
+ * Checks if the user needs to update PHP.
+ *
+ * @since 5.1.0
+ *
+ * @return array|false $response Array of PHP version data. False on failure.
+ */
+function wp_check_php_version() {
+	$version = phpversion();
+	$key     = md5( $version );
+
+	$response = get_site_transient( 'php_check_' . $key );
+	if ( false === $response ) {
+		$url = 'http://api.wordpress.org/core/serve-happy/1.0/';
+		if ( wp_http_supports( array( 'ssl' ) ) ) {
+			$url = set_url_scheme( $url, 'https' );
+		}
+
+		$url = add_query_arg( 'php_version', $version, $url );
+
+		$response = wp_remote_get( $url );
+
+		if ( is_wp_error( $response ) || 200 !== wp_remote_retrieve_response_code( $response ) ) {
+			return false;
+		}
+
+		/**
+		 * Response should be an array with:
+		 *  'recommended_version' - string - The PHP version recommended by WordPress.
+		 *  'is_supported' - boolean - Whether the PHP version is actively supported.
+		 *  'is_secure' - boolean - Whether the PHP version receives security updates.
+		 *  'is_acceptable' - boolean - Whether the PHP version is still acceptable for WordPress.
+		 */
+		$response = json_decode( wp_remote_retrieve_body( $response ), true );
+
+		if ( ! is_array( $response ) ) {
+			return false;
+		}
+
+		set_site_transient( 'php_check_' . $key, $response, WEEK_IN_SECONDS );
+	}
+
+	return $response;
+}