+
+ /**
+ * Fix weird date formats.
+ *
+ * Note: This method isn't meant to sanitize valid date/time strings, for example it will mangle relative date
+ * strings like "now - 3 days".
+ *
+ * @see \Friendica\Test\src\Util\DateTimeFormatTest::dataFix() for a list of examples handled by this method.
+ * @param string $dateString
+ * @return string
+ */
+ public static function fix(string $dateString): string
+ {
+ $search = ['Mär', 'März', 'Mai', 'Juni', 'Juli', 'Okt', 'Dez', 'ET' , 'ZZ', ' - ', '+', '+', ' (Coordinated Universal Time)'];
+ $replace = ['Mar', 'Mar' , 'May', 'Jun' , 'Jul' , 'Oct', 'Dec', 'EST', 'Z' , ', ' , '+' , '+' , ''];
+
+ $dateString = str_replace($search, $replace, $dateString);
+
+ $pregPatterns = [
+ ['#(\w+), (\d+ \w+ \d+) (\d+:\d+:\d+) (.+)#', '$2 $3 $4'],
+ ['#(\d+:\d+) (\w+), (\w+) (\d+), (\d+)#', '$1 $2 $3 $4 $5'],
+ ];
+
+ foreach ($pregPatterns as $pattern) {
+ $dateString = preg_replace($pattern[0], $pattern[1], $dateString);
+ }
+
+ return $dateString;
+ }
+
+ /**
+ * Checks, if the given string is a date with the pattern YYYY-MM
+ *
+ * @param string $dateString The given date
+ *
+ * @return boolean True, if the date is a valid pattern
+ */
+ public function isYearMonth(string $dateString)
+ {
+ // Check format (2019-01, 2019-1, 2019-10)
+ if (!preg_match('/^([12]\d{3}-(1[0-2]|0[1-9]|\d))$/', $dateString)) {
+ return false;
+ }
+
+ $date = DateTime::createFromFormat('Y-m', $dateString);
+
+ if (!$date) {
+ return false;
+ }
+
+ try {
+ $now = new DateTime();
+ } catch (\Throwable $t) {
+ return false;
+ }
+
+ if ($date > $now) {
+ return false;
+ }
+
+ return true;
+ }
+
+ /**
+ * Checks, if the given string is a date with the pattern YYYY-MM-DD
+ *
+ * @param string $dateString The given date
+ *
+ * @return boolean True, if the date is a valid pattern
+ */
+ public function isYearMonthDay(string $dateString)
+ {
+ $date = DateTime::createFromFormat('Y-m-d', $dateString);
+ if (!$date) {
+ return false;
+ }
+
+ if (DateTime::getLastErrors()['error_count'] || DateTime::getLastErrors()['warning_count']) {
+ return false;
+ }
+
+ return true;
+ }