started another importer overhaul

Signed-off-by: Stephan Richter <s.richter@srsoftware.de>

de.srsoftware.cal.base/src/main/java/de/srsoftware/cal/Util.java

@@ -2,12 +2,17 @@
 package de.srsoftware.cal;
 
 import static de.srsoftware.tools.Error.error;
+import static de.srsoftware.tools.Result.transform;
 
 import de.srsoftware.cal.api.Coords;
 import de.srsoftware.tools.Payload;
 import de.srsoftware.tools.Result;
+import java.time.LocalDate;
+import java.time.LocalDateTime;
+import java.time.LocalTime;
 import java.time.format.DateTimeFormatter;
 import java.util.ArrayList;
+import java.util.regex.Pattern;
 
 public class Util {
 	public static final String BEGIN = "BEGIN";
@@ -26,8 +31,18 @@ public class Util {
 	public static final String VEVENT = "VEVENT";
 	public static final String VCALENDAR = "VCALENDAR";
 
+	public static final Pattern GERMAN_DATE_PATTERN = Pattern.compile("\\D(\\d\\d?)\\.(\\d\\d?)\\.(\\d{4})\\D");
+	public static final Pattern GERMAN_TIME_PATTERN = Pattern.compile("\\D(\\d\\d?):(\\d\\d?)(:(\\d\\d?))?\\D");
+
 	private Util(){}
 
+
+	public static Result<LocalDateTime> combine(Result<LocalDate> date, Result<LocalTime> time) {
+		if (date.optional().isEmpty())return transform(date);
+		if (time.optional().isEmpty())return transform(time);
+		return Payload.of(LocalDateTime.of(date.optional().get(),time.optional().get()));
+	}
+
 	/**
 	 * formats a content line as defined in <a href="https://datatracker.ietf.org/doc/html/rfc5545#section-3.1">iCalendar spec</a>
 	 * @param key the content line key
@@ -76,6 +91,28 @@ public class Util {
 				.replace(":","/");
 	}
 
+	public static Result<LocalDate> parseGermanDate(String s){
+		var match = GERMAN_DATE_PATTERN.matcher(s);
+		if (match.find()){
+			var day = Integer.parseInt(match.group(1));
+			var month = Integer.parseInt(match.group(2));
+			var year = Integer.parseInt(match.group(3));
+			return Payload.of(LocalDate.of(year,month,day));
+		}
+		return error("Failed to find date");
+	}
+
+	public static Result<LocalTime> parseGermanTime(String s){
+		var match = GERMAN_TIME_PATTERN.matcher(s);
+		if (match.find()){
+			var hour = Integer.parseInt(match.group(1));
+			var minute = Integer.parseInt(match.group(2));
+			var sec = match.group(4);
+			var second = sec == null ? 0 : Integer.parseInt(sec);
+			return Payload.of(LocalTime.of(hour,minute,second));
+		}
+		return error("Failed to find date");
+	}
 
 	/**
 	 * wraps a text (list of vevents in a vcalendar, as described in th <a href="https://datatracker.ietf.org/doc/html/rfc5545#section-3.4">iCalendar spec</a>