SQL: Enhance timestamp escaped literal parsing (elastic#52097)

Allow also whitespace ` ` (together with `T`) as a separator between
date and time parts of the timestamp string. E.g.:
```
{ts '2020-02-08 12.10.45'}
```
or
```
{ts '2020-02-08T12.10.45'}
```

Fixes: elastic#46069

x-pack/plugin/sql/src/main/java/org/elasticsearch/xpack/sql/util/DateUtils.java

@@ -32,11 +32,16 @@ public final class DateUtils {
     public static final LocalDate EPOCH = LocalDate.of(1970, 1, 1);
     public static final long DAY_IN_MILLIS = 60 * 60 * 24 * 1000L;
 
-    private static final DateTimeFormatter DATE_TIME_ESCAPED_LITERAL_FORMATTER = new DateTimeFormatterBuilder()
-        .append(ISO_LOCAL_DATE)
-        .appendLiteral(" ")
-        .append(ISO_LOCAL_TIME)
-        .toFormatter().withZone(UTC);
+    private static final DateTimeFormatter DATE_TIME_ESCAPED_LITERAL_FORMATTER_WHITESPACE = new DateTimeFormatterBuilder()
+            .append(ISO_LOCAL_DATE)
+            .appendLiteral(' ')
+            .append(ISO_LOCAL_TIME)
+            .toFormatter().withZone(UTC);
+    private static final DateTimeFormatter DATE_TIME_ESCAPED_LITERAL_FORMATTER_T_LITERAL = new DateTimeFormatterBuilder()
+            .append(ISO_LOCAL_DATE)
+            .appendLiteral('T')
+            .append(ISO_LOCAL_TIME)
+            .toFormatter().withZone(UTC);
 
     private static final DateFormatter UTC_DATE_TIME_FORMATTER = DateFormatter.forPattern("date_optional_time").withZone(UTC);
     private static final int DEFAULT_PRECISION_FOR_CURRENT_FUNCTIONS = 3;
@@ -105,7 +110,13 @@ public static ZonedDateTime asDateTime(String dateFormat) {
     }
 
     public static ZonedDateTime ofEscapedLiteral(String dateFormat) {
-        return ZonedDateTime.parse(dateFormat, DATE_TIME_ESCAPED_LITERAL_FORMATTER.withZone(UTC));
+        int separatorIdx = dateFormat.lastIndexOf('-') + 3;
+        // Avoid index out of bounds - it will lead to DateTimeParseException anyways
+        if (separatorIdx >= dateFormat.length() || dateFormat.charAt(separatorIdx) == 'T') {
+            return ZonedDateTime.parse(dateFormat, DATE_TIME_ESCAPED_LITERAL_FORMATTER_T_LITERAL.withZone(UTC));
+        } else {
+            return ZonedDateTime.parse(dateFormat, DATE_TIME_ESCAPED_LITERAL_FORMATTER_WHITESPACE.withZone(UTC));
+        }
     }
 
     public static String toString(ZonedDateTime dateTime) {

x-pack/plugin/sql/src/test/java/org/elasticsearch/xpack/sql/parser/EscapedFunctionsTests.java

@@ -62,6 +62,33 @@ private Literal timestampLiteral(String date) {
         return (Literal) exp;
     }
 
+    private String buildDate() {
+        StringBuilder sb = new StringBuilder();
+        int length = randomIntBetween(4, 9);
+
+        if (randomBoolean()) {
+            sb.append('-');
+        } else {
+            if (length > 4) {
+                sb.append('-');
+            }
+        }
+
+        for (int i = 1; i <= length; i++) {
+            sb.append(i);
+        }
+        sb.append("-05-10");
+        return sb.toString();
+    }
+
+    private String buildSecsAndFractional() {
+        if (randomBoolean()) {
+            return ":55" + randomFrom("", ".1", ".12", ".123", ".1234", ".12345", ".123456",
+                    ".1234567", ".12345678", ".123456789");
+        }
+        return "";
+    }
+
     private Literal guidLiteral(String guid) {
         Expression exp = parser.createExpression(buildExpression("guid", "'%s'", guid));
         assertThat(exp, instanceOf(Expression.class));
@@ -185,7 +212,7 @@ public void testFunctionWithFunctionWithArgAndParams() {
     }
 
     public void testDateLiteral() {
-        Literal l = dateLiteral("2012-01-01");
+        Literal l = dateLiteral(buildDate());
         assertThat(l.dataType(), is(DATE));
     }
 
@@ -197,7 +224,7 @@ public void testDateLiteralValidation() {
     }
 
     public void testTimeLiteral() {
-        Literal l = timeLiteral("12:23:56");
+        Literal l = timeLiteral("12:23" + buildSecsAndFractional());
         assertThat(l.dataType(), is(TIME));
     }
 
@@ -209,14 +236,27 @@ public void testTimeLiteralValidation() {
     }
 
     public void testTimestampLiteral() {
-        Literal l = timestampLiteral("2012-01-01 10:01:02.3456");
+        Literal l = timestampLiteral(buildDate() + " 10:20" + buildSecsAndFractional());
+        assertThat(l.dataType(), is(DATETIME));
+        l = timestampLiteral(buildDate() + "T11:22" + buildSecsAndFractional());
         assertThat(l.dataType(), is(DATETIME));
     }
 
     public void testTimestampLiteralValidation() {
-        ParsingException ex = expectThrows(ParsingException.class, () -> timestampLiteral("2012-01-01T10:01:02.3456"));
+        String date = buildDate();
+        ParsingException ex = expectThrows(ParsingException.class, () -> timestampLiteral(date+ "_AB 10:01:02.3456"));
+        assertEquals(
+                "line 1:2: Invalid timestamp received; Text '" + date + "_AB 10:01:02.3456' could not be parsed at index " +
+                        date.length(),
+                ex.getMessage());
+        ex = expectThrows(ParsingException.class, () -> timestampLiteral("20120101_AB 10:01:02.3456"));
+        assertEquals(
+                "line 1:2: Invalid timestamp received; Text '20120101_AB 10:01:02.3456' could not be parsed at index 0",
+                ex.getMessage());
+
+        ex = expectThrows(ParsingException.class, () -> timestampLiteral(date));
         assertEquals(
-                "line 1:2: Invalid timestamp received; Text '2012-01-01T10:01:02.3456' could not be parsed at index 10",
+                "line 1:2: Invalid timestamp received; Text '" + date + "' could not be parsed at index " + date.length(),
                 ex.getMessage());
     }