Add TimeUtil for later

00-backend/src/main/java/de/htwsaar/webshop/util/TimeUtil.java

@@ -0,0 +1,53 @@
+package de.htwsaar.webshop.util;
+
+/**
+ * Helper Class for Unix-Millis related Things
+ */
+public class TimeUtil {
+
+    /**
+     * Amount millis representing one minute
+     */
+    public static final long MILLIS_TO_MINUTE = 60 * 1000;
+
+    /**
+     * Amount millis representing one hour
+     */
+    public static final long MILLIS_TO_HOUR = MILLIS_TO_MINUTE * 60;
+
+    /**
+     * Amount millis representing one day
+     */
+    private static final long MILLIS_TO_DAY = MILLIS_TO_HOUR * 24;
+
+    /**
+     * Amount millis representing one week
+     */
+    public static final long MILLIS_TO_WEEK = MILLIS_TO_DAY * 7;
+
+    /**
+     * Amount millis in the first second of 2025
+     */
+    public static final long VALID_MIN_MILLIS_TIMESTAMP = 1735686000000L;
+
+
+    /**
+     * Now in X days, represented as Unix Millis
+     *
+     * @param days how many days to add
+     * @return the calculated Unix-Millis
+     */
+    public static long nowPlusDays(long days) {
+        return System.currentTimeMillis() + (days * MILLIS_TO_DAY);
+    }
+
+    /**
+     * Check whether the Unix-Millis are valid
+     *
+     * @param time the Millis to Check
+     * @return whether the Time <b>can</b> be valid
+     */
+    public static boolean isValidTime(long time) {
+        return time >= VALID_MIN_MILLIS_TIMESTAMP;
+    }
+}