[BugFix] Support cast constant time type to DateTime (#55804)

Signed-off-by: Jiao Mingye <[email protected]>
(cherry picked from commit f91fcfa)

fe/fe-core/src/main/java/com/starrocks/sql/optimizer/operator/scalar/ConstantOperator.java

@@ -35,6 +35,7 @@
 import java.text.DecimalFormat;
 import java.time.LocalDate;
 import java.time.LocalDateTime;
+import java.time.LocalTime;
 import java.time.temporal.ChronoUnit;
 import java.util.List;
 import java.util.Objects;
@@ -373,6 +374,11 @@ public String toString() {
         } else if (type.isDate()) {
             LocalDateTime time = (LocalDateTime) Optional.ofNullable(value).orElse(LocalDateTime.MIN);
             return time.format(DateUtils.DATE_FORMATTER_UNIX);
+        } else if (type.isTime()) {
+            // Time is a double value but we only need int when casting to datetime
+            if (value instanceof Double) {
+                return String.valueOf(((Double) value).intValue());
+            }
         } else if (type.isFloatingPointType()) {
             double val = (double) Optional.ofNullable(value).orElse((double) 0);
             BigDecimal decimal = BigDecimal.valueOf(val);
@@ -499,8 +505,8 @@ public Optional<ConstantOperator> castToStrictly(Type type) {
     }
 
     public Optional<ConstantOperator> castTo(Type desc) {
-        if (type.isTime() || desc.isTime()) {
-            // Don't support constant time cast in FE
+        if ((type.isTime() || desc.isTime()) && !(type.isTime() && desc.isDatetime())) {
+            // Don't support constant time cast to types other than datetime in FE
             return Optional.empty();
         }
 
@@ -558,12 +564,25 @@ public Optional<ConstantOperator> castTo(Type desc) {
                 }
                 res = ConstantOperator.createDouble(Double.parseDouble(childString));
             } else if (desc.isDate() || desc.isDatetime()) {
-                String dateStr = StringUtils.strip(childString, "\r\n\t ");
-                LocalDateTime dateTime = DateUtils.parseStrictDateTime(dateStr);
-                if (Type.DATE.equals(desc)) {
-                    dateTime = dateTime.truncatedTo(ChronoUnit.DAYS);
+                if (type.isTime()) {
+                    // Cast time to datetime
+                    String timeStr = StringUtils.strip(childString, "\r\n\t ");
+                    int time = Integer.parseInt(timeStr);
+                    int hours = time / 3600;
+                    int minutes = (time % 3600) / 60;
+                    int seconds = time % 60;
+                    LocalDate date = LocalDate.now();
+                    LocalTime localTime = LocalTime.of(hours, minutes, seconds);
+                    LocalDateTime dateTime = LocalDateTime.of(date, localTime);
+                    res = ConstantOperator.createDatetime(dateTime, desc);
+                } else {
+                    String dateStr = StringUtils.strip(childString, "\r\n\t ");
+                    LocalDateTime dateTime = DateUtils.parseStrictDateTime(dateStr);
+                    if (Type.DATE.equals(desc)) {
+                        dateTime = dateTime.truncatedTo(ChronoUnit.DAYS);
+                    }
+                    res = ConstantOperator.createDatetime(dateTime, desc);
                 }
-                res = ConstantOperator.createDatetime(dateTime, desc);
             } else if (desc.isDecimalV2()) {
                 res = ConstantOperator.createDecimal(BigDecimal.valueOf(Double.parseDouble(childString)), Type.DECIMALV2);
             } else if (desc.isDecimalV3()) {

fe/fe-core/src/main/java/com/starrocks/sql/optimizer/rewrite/ScalarOperatorFunctions.java

@@ -702,6 +702,18 @@ public static ConstantOperator fromUnixTime(ConstantOperator unixTime, ConstantO
         return dateFormat(dl, fmtLiteral);
     }
 
+    @ConstantFunction.List(list = {
+            @ConstantFunction(name = "curtime", argTypes = {}, returnType = TIME),
+            @ConstantFunction(name = "current_time", argTypes = {}, returnType = TIME)
+    })
+    public static ConstantOperator curTime() {
+        ConnectContext connectContext = ConnectContext.get();
+        LocalDateTime startTime = Instant.ofEpochMilli(connectContext.getStartTime() / 1000 * 1000)
+                .atZone(TimeUtils.getTimeZone().toZoneId()).toLocalDateTime();
+        double second = startTime.getHour() * 3600D + startTime.getMinute() * 60D + startTime.getSecond();
+        return ConstantOperator.createTime(second);
+    }
+
     @ConstantFunction.List(list = {
             @ConstantFunction(name = "now", argTypes = {}, returnType = DATETIME),
             @ConstantFunction(name = "current_timestamp", argTypes = {}, returnType = DATETIME),

fe/fe-core/src/test/java/com/starrocks/sql/optimizer/operator/operator/ConstantOperatorTest.java

@@ -62,7 +62,7 @@ public void testCastToDateValid() throws Exception {
     }
 
     @Test
-    public void testCaseToDateInvalid() {
+    public void testCastToDateInvalid() {
         String[] testCases = {
                 // Invalid year.
                 "20190-05-31",
@@ -110,7 +110,7 @@ public void testCaseToDateInvalid() {
     }
 
     @Test
-    public void testCaseDateToNumber() throws Exception {
+    public void testCastDateToNumber() throws Exception {
         ConstantOperator date = ConstantOperator.createDate(LocalDateTime.of(2023, 01, 01, 0, 0));
         ConstantOperator datetime = ConstantOperator.createDatetime(LocalDateTime.of(2023, 01, 01, 0, 0, 0));
 
@@ -142,6 +142,14 @@ public void testCaseDateToNumber() throws Exception {
         Assert.assertEquals(datetimeDoubleNumber, datetime.castTo(Type.DOUBLE).get());
     }
 
+    @Test
+    public void testCastTimeToDateTime() {
+        LocalDateTime now = LocalDateTime.now().withNano(0);
+        ConstantOperator time = ConstantOperator.createTime(now.getHour() * 3600D + now.getMinute() * 60D + now.getSecond());
+        ConstantOperator datetime = ConstantOperator.createDatetime(now);
+        Assert.assertEquals(datetime, time.castTo(Type.DATETIME).get());
+    }
+
     @Test
     public void testDistance() {
         {

fe/fe-core/src/test/java/com/starrocks/sql/optimizer/rewrite/ScalarOperatorFunctionsTest.java

@@ -1373,6 +1373,8 @@ public void testNow() {
         LocalDateTime expected = Instant.ofEpochMilli(ctx.getStartTime() / 1000 * 1000)
                 .atZone(TimeUtils.getTimeZone().toZoneId()).toLocalDateTime();
         assertEquals(expected, ScalarOperatorFunctions.now().getDatetime());
+        double expectedTime = expected.getHour() * 3600D + expected.getMinute() * 60D + expected.getSecond();
+        assertEquals(expectedTime, ScalarOperatorFunctions.curTime().getTime(), 0.1);
     }
 
     @Test