Adding date / time ITs & Fix functions

core/src/main/java/org/opensearch/sql/calcite/udf/datetimeUDF/DateDiffFunction.java

@@ -0,0 +1,41 @@
+/*
+ * Copyright OpenSearch Contributors
+ * SPDX-License-Identifier: Apache-2.0
+ */
+
+package org.opensearch.sql.calcite.udf.datetimeUDF;
+
+import java.time.Instant;
+import java.time.LocalDateTime;
+import java.time.ZoneOffset;
+import org.apache.calcite.sql.type.SqlTypeName;
+import org.opensearch.sql.calcite.udf.UserDefinedFunction;
+import org.opensearch.sql.calcite.utils.datetime.InstantUtils;
+import org.opensearch.sql.data.model.ExprTimestampValue;
+import org.opensearch.sql.data.model.ExprValue;
+import org.opensearch.sql.expression.datetime.DateTimeFunctions;
+import org.opensearch.sql.expression.function.FunctionProperties;
+
+/**
+ * Calculates the difference of date parts of given values. If the first argument is time, today's
+ * date is used.
+ *
+ * <p>(DATE/TIMESTAMP/TIME, DATE/TIMESTAMP/TIME) -> LONG
+ */
+public class DateDiffFunction implements UserDefinedFunction {
+  @Override
+  public Object eval(Object... args) {
+    SqlTypeName sqlTypeName1 = (SqlTypeName) args[1];
+    Instant timestamp1 = InstantUtils.convertToInstant(args[0], sqlTypeName1);
+    SqlTypeName sqlTypeName2 = (SqlTypeName) args[3];
+    Instant timestamp2 = InstantUtils.convertToInstant(args[2], sqlTypeName2);
+    LocalDateTime localDateTime1 = LocalDateTime.ofInstant(timestamp1, ZoneOffset.UTC);
+    LocalDateTime localDateTime2 = LocalDateTime.ofInstant(timestamp2, ZoneOffset.UTC);
+    ExprValue diffResult =
+        DateTimeFunctions.exprDateDiff(
+            new FunctionProperties(),
+            new ExprTimestampValue(localDateTime1),
+            new ExprTimestampValue(localDateTime2));
+    return diffResult.longValue();
+  }
+}

core/src/main/java/org/opensearch/sql/calcite/udf/datetimeUDF/DatetimeFunction.java

@@ -14,6 +14,15 @@
 import org.opensearch.sql.data.model.ExprValue;
 import org.opensearch.sql.expression.datetime.DateTimeFunctions;
 
+/**
+ * DATETIME(timestamp)/ DATETIME(date, to_timezone) Converts the datetime to a new timezone. If not
+ * specified, the timestamp is regarded to be in system time zone.
+ *
+ * <p>(TIMESTAMP, STRING) -> TIMESTAMP <br>
+ * (TIMESTAMP) -> TIMESTAMP
+ *
+ * <p>Converting timestamp with timezone to the second argument timezone.
+ */
 public class DatetimeFunction implements UserDefinedFunction {
   @Override
   public Object eval(Object... args) {

core/src/main/java/org/opensearch/sql/calcite/udf/datetimeUDF/MakeDateFunction.java

@@ -0,0 +1,45 @@
+/*
+ * Copyright OpenSearch Contributors
+ * SPDX-License-Identifier: Apache-2.0
+ */
+
+package org.opensearch.sql.calcite.udf.datetimeUDF;
+
+import static org.opensearch.sql.expression.function.FunctionDSL.nullMissingHandling;
+
+import com.google.common.collect.ImmutableList;
+import java.util.Arrays;
+import org.apache.calcite.runtime.SqlFunctions;
+import org.opensearch.sql.calcite.udf.UserDefinedFunction;
+import org.opensearch.sql.calcite.utils.UserDefinedFunctionUtils;
+import org.opensearch.sql.data.model.ExprDoubleValue;
+import org.opensearch.sql.data.model.ExprValue;
+import org.opensearch.sql.expression.datetime.DateTimeFunctions;
+
+/**
+ * Returns a date, given year and day-of-year values. dayofyear must be greater than 0 or the result
+ * is NULL. The result is also NULL if either argument is NULL. Arguments are rounded to an integer.
+ *
+ * <p>Limitations: - Zero year interpreted as 2000; - Negative year is not accepted; - day-of-year
+ * should be greater than zero; - day-of-year could be greater than 365/366, calculation switches to
+ * the next year(s)
+ */
+public class MakeDateFunction implements UserDefinedFunction {
+  @Override
+  public Object eval(Object... args) {
+    UserDefinedFunctionUtils.validateArgumentCount("MAKE_DATE", 2, args.length, false);
+    UserDefinedFunctionUtils.validateArgumentTypes(
+        Arrays.asList(args),
+        ImmutableList.of(Number.class, Number.class),
+        ImmutableList.of(true, true));
+
+    ExprDoubleValue v1 = new ExprDoubleValue((Number) args[0]);
+    ExprDoubleValue v2 = new ExprDoubleValue((Number) args[1]);
+    ExprValue date = nullMissingHandling(DateTimeFunctions::exprMakeDate).apply(v1, v2);
+
+    if (date.isNull()) {
+      return null;
+    }
+    return SqlFunctions.toInt(java.sql.Date.valueOf(date.dateValue()));
+  }
+}

core/src/main/java/org/opensearch/sql/calcite/udf/datetimeUDF/periodNameFunction.java

@@ -13,6 +13,7 @@
 import java.util.Objects;
 import org.apache.calcite.sql.type.SqlTypeName;
 import org.opensearch.sql.calcite.udf.UserDefinedFunction;
+import org.opensearch.sql.calcite.utils.datetime.DateTimeParser;
 import org.opensearch.sql.calcite.utils.datetime.InstantUtils;
 
 /**
@@ -28,7 +29,7 @@ public Object eval(Object... args) {
     LocalDate localDate;
     if (candiate instanceof String) {
       // First transfer it to LocalDate
-      localDate = LocalDate.parse((String) candiate);
+      localDate = DateTimeParser.parse(candiate.toString()).toLocalDate();
     } else if (argumentType == SqlTypeName.DATE) { // date
       localDate =
           LocalDate.ofInstant(InstantUtils.fromInternalDate((int) candiate), ZoneOffset.UTC);
@@ -40,6 +41,7 @@ public Object eval(Object... args) {
       throw new IllegalArgumentException("something wrong");
     }
     String nameType = (String) type;
+    // TODO: Double-check whether it is ok to always return US week & month names
     if (Objects.equals(nameType, "MONTHNAME")) {
       return localDate.getMonth().getDisplayName(TextStyle.FULL, Locale.getDefault());
     } else if (Objects.equals(nameType, "DAYNAME")) {