METRON-1816: Date format Stellar function

metron-stellar/stellar-common/README.md

@@ -169,6 +169,7 @@ Where:
 | [ `CHOP`](#chop)                                                                                   |
 | [ `CHOMP`](#chomp)                                                                                 |
 | [ `COUNT_MATCHES`](#count_matches)                                                                 |
+| [ `DATE_FORMAT`](#date_format)
 | [ `DAY_OF_MONTH`](#day_of_month)                                                                   |
 | [ `DAY_OF_WEEK`](#day_of_week)                                                                     |
 | [ `DAY_OF_YEAR`](#day_of_year)                                                                     |
@@ -379,6 +380,14 @@ Where:
     * substring/character - the substring or character to count, may be null.
   * Returns: the number of non-overlapping occurrences, 0 if either CharSequence is null.
 
+### `DATE_FORMAT`
+  * Description: Takes an epoch timestamp and converts it to a date format.
+  * Input:
+    * format - DateTime format as a String.
+    * timestampField - Optional epoch time in Long format.  Defaults to now.
+    * timezone - Optional timezone in String format.
+  * Returns: Formatted date.
+
 ### `DAY_OF_MONTH`
   * Description: The numbered day within the month.  The first day within the month has a value of 1.
   * Input:

metron-stellar/stellar-common/src/main/java/org/apache/metron/stellar/dsl/functions/DateFunctions.java

@@ -28,6 +28,7 @@
 import java.text.ParseException;
 import java.text.SimpleDateFormat;
 import java.util.Calendar;
+import java.util.Date;
 import java.util.List;
 import java.util.Optional;
 import java.util.TimeZone;
@@ -109,6 +110,13 @@ public static long getEpochTime(String date, String format, Optional<String> tim
     return sdf.parse(date).getTime();
   }
 
+  public static String getDateFormat(String format, Optional<Long> epochTime, Optional<String> timezone) {
+    Long time = epochTime.orElseGet(System::currentTimeMillis);
+    TimezonedFormat fmt = timezone.map(s -> new TimezonedFormat(format, s)).orElseGet(() -> new TimezonedFormat(format));
+    SimpleDateFormat sdf = formatCache.get(fmt).get();
+    return sdf.format(new Date(time));
+  }
+
 
   /**
    * Stellar Function: TO_EPOCH_TIMESTAMP
@@ -144,6 +152,40 @@ public Object apply(List<Object> objects) {
     }
   }
 
+  @Stellar( name="DATE_FORMAT",
+          description = "Takes an epoch timestamp and converts it to a date format.",
+          params = {"format - DateTime format as a String."
+                  , "timestampField - Optional epoch time in Long format.  Defaults to now."
+                  , "timezone - Optional timezone in String format."},
+          returns="Formatted date."
+  )
+  public static class DateFormat extends BaseStellarFunction {
+
+    public Object apply(List<Object> objects) {
+      int size = objects.size();
+      Optional<Object> formatObj = Optional.ofNullable(objects.get(0));
+      Optional<Long> epochObj = Optional.empty();
+      Optional<String> tzObj = Optional.empty();
+      if (size > 1) {
+        if (size == 2) {
+          if (objects.get(1) == null) {
+            return null;
+          }
+          epochObj = objects.get(1) instanceof Long ? Optional.of((Long) objects.get(1)) : Optional.empty();
+          tzObj = objects.get(1) instanceof String ? Optional.of((String) objects.get(1)) : Optional.empty();
+        } else {
+          epochObj = Optional.ofNullable((Long) objects.get(1));
+          tzObj = Optional.ofNullable((String) objects.get(2));
+        }
+      }
+      if(formatObj.isPresent()) {
+        return getDateFormat(formatObj.get().toString(), epochObj, tzObj);
+      } else {
+        return null;
+      }
+    }
+  }
+
   /**
    * Gets the value from a list of arguments.
    *

metron-stellar/stellar-common/src/test/java/org/apache/metron/stellar/dsl/functions/DateFunctionsTest.java

@@ -31,6 +31,7 @@
 import java.util.Calendar;
 import java.util.HashMap;
 import java.util.Map;
+import java.util.TimeZone;
 
 import static org.junit.Assert.assertEquals;
 import static org.junit.Assert.assertTrue;
@@ -225,4 +226,36 @@ public void testDayOfYearNow() {
   public void testDayOfYearNull() {
     Object result = run("DAY_OF_YEAR(nada)");
   }
+
+  @Test
+  public void testDateFormat() {
+    Object result = run("DATE_FORMAT('EEE MMM dd yyyy hh:mm:ss zzz', epoch, 'EST')");
+    assertEquals("Thu Aug 25 2016 08:27:10 EST", result);
+  }
+
+  @Test
+  public void testDateFormatDefault() {
+    Object result = run("DATE_FORMAT('EEE MMM dd yyyy hh:mm:ss zzzz')");
+    assertTrue(result.toString().endsWith(TimeZone.getDefault().getDisplayName(true, 1)));
+  }
+
+  @Test
+  public void testDateFormatNow() {
+    Object result = run("DATE_FORMAT('EEE MMM dd yyyy hh:mm:ss zzz', 'GMT')");
+    assertTrue(result.toString().endsWith("GMT"));
+  }
+
+  @Test
+  public void testDateFormatDefaultTimezone() {
+    Object result = run("DATE_FORMAT('EEE MMM dd yyyy hh:mm:ss zzzz', epoch)");
+    assertTrue(result.toString().endsWith(TimeZone.getDefault().getDisplayName(true, 1)));
+  }
+
+  /**
+   * If refer to variable that does not exist, expect ParseException.
+   */
+  @Test(expected = ParseException.class)
+  public void testDateFormatNull() {
+    Object result = run("DATE_FORMAT('EEE MMM dd yyyy hh:mm:ss zzz', nada, 'EST')");
+  }
 }