From 1feabf5b11e8eda8feace6c6ac0e69766d0f0436 Mon Sep 17 00:00:00 2001
From: Manan Gupta <35839558+GuptaManan100@users.noreply.github.com>
Date: Fri, 27 Dec 2024 03:33:08 +0530
Subject: [PATCH] Fix week number for date_format evalengine function (#17432)

---
 go/mysql/datetime/spec.go                   | 14 ++++----------
 go/vt/vtgate/evalengine/compiler_test.go    | 20 ++++++++++++++++++++
 go/vt/vtgate/evalengine/testcases/inputs.go |  1 +
 3 files changed, 25 insertions(+), 10 deletions(-)

diff --git a/go/mysql/datetime/spec.go b/go/mysql/datetime/spec.go
index ce19126ce55..fe6b1521e43 100644
--- a/go/mysql/datetime/spec.go
+++ b/go/mysql/datetime/spec.go
@@ -359,10 +359,7 @@ func (t2 fmtFullTime24) parse(t *timeparts, bytes string) (string, bool) {
 type fmtWeek0 struct{}
 
 func (fmtWeek0) format(dst []byte, t DateTime, prec uint8) []byte {
-	year, week := t.Date.SundayWeek()
-	if year < t.Date.Year() {
-		week = 0
-	}
+	week := t.Date.Week(0)
 	return appendInt(dst, week, 2)
 }
 
@@ -374,10 +371,7 @@ func (u fmtWeek0) parse(t *timeparts, bytes string) (string, bool) {
 type fmtWeek1 struct{}
 
 func (fmtWeek1) format(dst []byte, t DateTime, prec uint8) []byte {
-	year, week := t.Date.ISOWeek()
-	if year < t.Date.Year() {
-		week = 0
-	}
+	week := t.Date.Week(1)
 	return appendInt(dst, week, 2)
 }
 
@@ -389,7 +383,7 @@ func (u fmtWeek1) parse(t *timeparts, bytes string) (string, bool) {
 type fmtWeek2 struct{}
 
 func (fmtWeek2) format(dst []byte, t DateTime, prec uint8) []byte {
-	_, week := t.Date.SundayWeek()
+	week := t.Date.Week(2)
 	return appendInt(dst, week, 2)
 }
 
@@ -401,7 +395,7 @@ func (v fmtWeek2) parse(t *timeparts, bytes string) (string, bool) {
 type fmtWeek3 struct{}
 
 func (fmtWeek3) format(dst []byte, t DateTime, prec uint8) []byte {
-	_, week := t.Date.ISOWeek()
+	week := t.Date.Week(3)
 	return appendInt(dst, week, 2)
 }
 
diff --git a/go/vt/vtgate/evalengine/compiler_test.go b/go/vt/vtgate/evalengine/compiler_test.go
index cb9b99e7776..88c13a479ed 100644
--- a/go/vt/vtgate/evalengine/compiler_test.go
+++ b/go/vt/vtgate/evalengine/compiler_test.go
@@ -740,6 +740,26 @@ func TestCompilerSingle(t *testing.T) {
 			expression: `cast(_utf32 0x0000FF as binary)`,
 			result:     `VARBINARY("\x00\x00\x00\xff")`,
 		},
+		{
+			expression: `DATE_FORMAT(timestamp '2024-12-30 10:34:58', "%u")`,
+			result:     `VARCHAR("53")`,
+		},
+		{
+			expression: `WEEK(timestamp '2024-12-30 10:34:58', 0)`,
+			result:     `INT64(52)`,
+		},
+		{
+			expression: `WEEK(timestamp '2024-12-30 10:34:58', 1)`,
+			result:     `INT64(53)`,
+		},
+		{
+			expression: `WEEK(timestamp '2024-01-01 10:34:58', 0)`,
+			result:     `INT64(0)`,
+		},
+		{
+			expression: `WEEK(timestamp '2024-01-01 10:34:58', 1)`,
+			result:     `INT64(1)`,
+		},
 	}
 
 	tz, _ := time.LoadLocation("Europe/Madrid")
diff --git a/go/vt/vtgate/evalengine/testcases/inputs.go b/go/vt/vtgate/evalengine/testcases/inputs.go
index eb94235d9b4..a1c76a1d202 100644
--- a/go/vt/vtgate/evalengine/testcases/inputs.go
+++ b/go/vt/vtgate/evalengine/testcases/inputs.go
@@ -103,6 +103,7 @@ var inputConversions = []string{
 	"time '10:04:58'", "time '31:34:58'", "time '32:34:58'", "time '130:34:58'", "time '5 10:34:58'",
 	"time '10:04:58.1'", "time '31:34:58.4'", "time '32:34:58.5'", "time '130:34:58.6'", "time '5 10:34:58.9'", "date '2000-01-01'",
 	"timestamp '2000-01-01 10:34:58'", "timestamp '2000-01-01 10:34:58.123456'", "timestamp '2000-01-01 10:34:58.978654'",
+	"timestamp '2024-12-30 10:34:58'",
 	"20000101103458", "20000101103458.1234", "20000101103458.123456", "20000101", "103458", "103458.123456",
 	"'20000101103458'", "'20000101103458.1234'", "'20000101103458.123456'", "'20000101'", "'103458'", "'103458.123456'",
 	"'20000101103458foo'", "'20000101103458.1234foo'", "'20000101103458.123456foo'", "'20000101foo'", "'103458foo'", "'103458.123456foo'",