Rework time parsing utils

src/main/java/wtf/beatrice/hidekobot/util/FormatUtil.java

@@ -1,29 +1,49 @@
 package wtf.beatrice.hidekobot.util;
 
-import wtf.beatrice.hidekobot.Cache;
+import org.jetbrains.annotations.NotNull;
+import org.jetbrains.annotations.Nullable;
 
 import java.time.Duration;
+import java.time.Instant;
 import java.time.LocalDateTime;
 import java.time.temporal.ChronoUnit;
+import java.time.temporal.TemporalAccessor;
+import java.time.temporal.TemporalUnit;
+import java.util.Arrays;
+import java.util.Locale;
+import java.util.concurrent.TimeUnit;
 
 public class FormatUtil
 {
 
     /**
-     * Generate a nicely formatted uptime String that omits unnecessary data
+     * Generate a nicely formatted time-diff String that omits unnecessary data
      * (e.g. 0 days, 0 hours, 4 minutes, 32 seconds -> 4m 32s)
      *
-     * @return the formatter String
+     * @return the formatted String
      */
     public static String getNiceTimeDiff(LocalDateTime start)
     {
         LocalDateTime now = LocalDateTime.now();
         long uptimeSeconds = ChronoUnit.SECONDS.between(start, now);
+
         Duration uptime = Duration.ofSeconds(uptimeSeconds);
-        long seconds = uptime.toSecondsPart();
-        long minutes = uptime.toMinutesPart();
-        long hours = uptime.toHoursPart();
-        long days = uptime.toDays();
+
+        return getNiceDuration(uptime);
+    }
+
+    /**
+     * Generate a nicely formatted duration String that omits unnecessary data
+     * (e.g. 0 days, 0 hours, 4 minutes, 32 seconds -> 4m 32s)
+     *
+     * @return the formatted String
+     */
+    public static String getNiceDuration(Duration duration)
+    {
+        long seconds = duration.toSecondsPart();
+        long minutes = duration.toMinutesPart();
+        long hours = duration.toHoursPart();
+        long days = duration.toDays();
 
         StringBuilder uptimeStringBuilder = new StringBuilder();
         if(days == 0)
@@ -47,4 +67,81 @@ public class FormatUtil
 
         return uptimeStringBuilder.toString();
     }
+
+    /**
+     * Method to parse a string into a duration.
+     * Warning: this only supports up to days; months and longer timeframes are unsupported.
+     *
+     * @param duration the String to parse.
+     * @return a Duration of the parsed timeframe, or null if parsing failed.
+     */
+    @Nullable
+    public static Duration parseDuration(String duration)
+    {
+        // sanitize a bit to avoid cluttering with garbled strings
+        if(duration.length() > 16) duration = duration.substring(0, 16);
+        duration = duration.replaceAll("[^\\w]", ""); //only keep digits and word characters
+        duration = duration.toLowerCase();
+
+        /* the following regex matches any number followed by any amount of characters, any amount of times.
+        eg: 3d, 33hours, 32048dojg, 3d2h5m22s.
+        it does not match if the [digits and characters] blocks are missing.
+        eg: 33, asd, 3g5hj, 4 asd.
+         */
+        if(!duration.matches("(\\d+[a-zA-Z]+)+"))
+            return null;
+
+        String[] durationTimes = duration.split("[a-zA-Z]+");
+        String[] durationUnits = duration.split("\\d+");
+
+        // remove first element, because it will always be empty (there's nothing before the first character)
+        durationUnits = Arrays.copyOfRange(durationUnits, 1, durationUnits.length);
+
+        Duration fullDuration = Duration.ZERO;
+
+        for(int i = 0; i < durationTimes.length; i++)
+        {
+            String durationTimeStr = durationTimes[i];
+            String durationUnitStr = durationUnits[i];
+
+            int durationValue = Integer.parseInt(durationTimeStr);
+            TemporalUnit unit = parseTimeUnit(durationUnitStr);
+
+            if(unit != null)
+                fullDuration = fullDuration.plus(durationValue, unit);
+            else return null; // if we failed finding the time unit, instantly quit with failed parsing.
+        }
+
+        return fullDuration;
+    }
+
+    @Nullable
+    private static TemporalUnit parseTimeUnit(@NotNull String unitName)
+    {
+        // we won't do any sanitization, because this is a private method, and
+        // we are only accessing it with things that we know for sure are already sanitized.
+        unitName = unitName.toLowerCase();
+        TemporalUnit timeUnit = null;
+
+        /*
+        parsing table
+        s, se, sec, second, seconds -> SECOND
+        m, mi, min, minute, minutes -> MINUTE
+        h, ho, hr, hour, hours -> HOUR
+        d, day, days -> DAY
+
+        (months and longer timeframes are unsupported due to Discord restrictions)
+         */
+
+        switch (unitName)
+        {
+            case "s", "se", "sec", "second", "seconds" -> timeUnit = ChronoUnit.SECONDS;
+            case "m", "mi", "min", "minute", "minutes" -> timeUnit = ChronoUnit.MINUTES;
+            case "h", "ho", "hr", "hour", "hours" -> timeUnit = ChronoUnit.HOURS;
+            case "d", "day", "days" -> timeUnit = ChronoUnit.DAYS;
+        }
+
+        return timeUnit;
+
+    }
 }