Add option to split and translate times with start and end dates

Close #1

src/NodaTimeSplitter.php

@@ -963,6 +963,73 @@ final class NodaTimeSplitter {
 
     }
 
+    /**
+     * Checks if the string is a time span with given start and end dates.
+     *
+     * @param string $datum Date.
+     *
+     * @return array<array<string>>
+     */
+    public static function check_is_timespan_from_till(string $datum):array {
+
+        if (substr_count($datum, '-') !== 1) return [];
+
+        list($start_str, $end_str) = explode('-', $datum);
+
+        if (empty($start = self::attempt_splitting($start_str))) {
+            return [];
+        }
+
+        if (empty($end = self::attempt_splitting($end_str))) {
+            return [];
+        }
+
+        return [$start, $end];
+
+    }
+
+    /**
+     * Checks if the string is a time span with given start and end dates.
+     *
+     * @param string $datum Date.
+     *
+     * @return array<array<string>>
+     */
+    public static function attempt_splitting_from_till(string $datum):array {
+
+        if (empty($startEnd = self::check_is_timespan_from_till($datum))) {
+            return [];
+        }
+        list($start, $end) = $startEnd;
+
+        if ($start[4] === '-') return [];
+
+        $startDate = new DateTime($start[4] . $start[0] . '-' . $start[2] . '-' . $start[3]);
+        $endDate = new DateTime($end[4] . $end[1] . '-' . $end[2] . '-' . $end[3]);
+
+        $interval = $startDate->diff($endDate);
+        $days_diff = (int)$interval->format('%a');
+
+        $middle_substraction = round($days_diff / 2);
+
+        $middle_day = date('Y-m-d',
+            strtotime('+' . $middle_substraction . ' days', strtotime($startDate->format('Y-m-d'))));
+
+        $output = [
+            "start_name" => self::timePartsToTimeName($start),
+            "end_name" => self::timePartsToTimeName($end),
+            "start_year" => $start[0],
+            "end_year" => $end[1],
+            "counting_time_year" => substr($middle_day, 0, 4),
+            "counting_time_month" => substr($middle_day, 5, 2),
+            "counting_time_day" => substr($middle_day, 8, 2),
+            "counting_time_bcce" => "+",
+        ];
+
+        return $output;
+
+    }
+
     /**
      * Wrapper to check if any splitting command works.
      *