Add Timespan add/subtract/diff methods (#7883)

* add/subtract methods

* return a new timespan instead

* method reference

* split the code

Author: erenkarakal

src/main/java/ch/njol/skript/classes/data/DefaultOperations.java

@@ -4,7 +4,6 @@
 import ch.njol.skript.util.Timespan;
 import ch.njol.skript.util.Timespan.TimePeriod;
 import ch.njol.skript.util.Utils;
-import ch.njol.util.Math2;
 import org.bukkit.util.Vector;
 import org.skriptlang.skript.lang.arithmetic.Arithmetics;
 import org.skriptlang.skript.lang.arithmetic.Operator;
@@ -91,9 +90,9 @@ public class DefaultOperations {
 		});
 
 		// Timespan - Timespan
-		Arithmetics.registerOperation(Operator.ADDITION, Timespan.class, (left, right) -> new Timespan(Math2.addClamped(left.getAs(TimePeriod.MILLISECOND), right.getAs(TimePeriod.MILLISECOND))));
-		Arithmetics.registerOperation(Operator.SUBTRACTION, Timespan.class, (left, right) -> new Timespan(Math.max(0, left.getAs(TimePeriod.MILLISECOND) - right.getAs(TimePeriod.MILLISECOND))));
-		Arithmetics.registerDifference(Timespan.class, (left, right) -> new Timespan(Math.abs(left.getAs(TimePeriod.MILLISECOND) - right.getAs(TimePeriod.MILLISECOND))));
+		Arithmetics.registerOperation(Operator.ADDITION, Timespan.class, Timespan::add);
+		Arithmetics.registerOperation(Operator.SUBTRACTION, Timespan.class, Timespan::subtract);
+		Arithmetics.registerDifference(Timespan.class, Timespan::difference);
 		Arithmetics.registerDefaultValue(Timespan.class, Timespan::new);
 
 		// Timespan - Number

src/main/java/ch/njol/skript/util/Timespan.java

@@ -5,6 +5,7 @@
 import ch.njol.skript.localization.GeneralWords;
 import ch.njol.skript.localization.Language;
 import ch.njol.skript.localization.Noun;
+import ch.njol.util.Math2;
 import ch.njol.util.NonNullPair;
 import ch.njol.util.coll.CollectionUtils;
 import ch.njol.yggdrasil.YggdrasilSerializable;
@@ -254,6 +255,36 @@ public Duration getDuration() {
 		return Duration.ofMillis(millis);
 	}
 
+	/**
+	 * Safely adds the specified timespan to this timespan, handling potential overflow.
+	 * @param timespan The timespan to add to this timespan
+	 * @return a new Timespan object
+	 */
+	public Timespan add(Timespan timespan) {
+		long millis = Math2.addClamped(this.millis, timespan.getAs(TimePeriod.MILLISECOND));
+		return new Timespan(millis);
+	}
+
+	/**
+	 * Safely subtracts the specified timespan from this timespan, handling potential underflow.
+	 * @param timespan The timespan to subtract from this timespan
+	 * @return a new Timespan object
+	 */
+	public Timespan subtract(Timespan timespan) {
+		long millis = Math.max(0, this.millis - timespan.getAs(TimePeriod.MILLISECOND));
+		return new Timespan(millis);
+	}
+
+	/**
+	 * Calculates the difference between the specified timespan and this timespan.
+	 * @param timespan The timespan to get the difference of
+	 * @return a new Timespan object
+	 */
+	public Timespan difference(Timespan timespan) {
+		long millis = Math.abs(this.millis - timespan.getAs(TimePeriod.MILLISECOND));
+		return new Timespan(millis);
+	}
+
 	@Override
 	public long get(TemporalUnit unit) {
 		if (unit instanceof TimePeriod period)