From 3dcc14870e7acba326cde6dd9ca25a365a42ecd9 Mon Sep 17 00:00:00 2001
From: Oliver Tan <otan@cockroachlabs.com>
Date: Thu, 7 May 2020 14:22:17 -0700
Subject: [PATCH] encode: fix 2400 time encoding for time/timetz

Note that Postgres supports 24:00 for both time and timetz operations.

When evaluating "24:00" for both Time and TimeTZ datatypes, the
time.Time library does not recognise 24 as a legitimate hour. This
requires special parsing for it to work. As such, work around the
problem by subtracting a day, and adding it back later when we recognize
it as 24:00 time.
---
 encode.go      | 20 +++++++++++++
 encode_test.go | 79 ++++++++++++++++++++++++++++++++++++++++++++++++++
 2 files changed, 99 insertions(+)

diff --git a/encode.go b/encode.go
index 73cafb89..c4dafe27 100644
--- a/encode.go
+++ b/encode.go
@@ -8,6 +8,7 @@ import (
 	"errors"
 	"fmt"
 	"math"
+	"regexp"
 	"strconv"
 	"strings"
 	"sync"
@@ -16,6 +17,8 @@ import (
 	"github.com/lib/pq/oid"
 )
 
+var time2400Regex = regexp.MustCompile(`^(24:00(?::00(?:\.0+)?)?)(?:[Z+-].*)?$`)
+
 func binaryEncode(parameterStatus *parameterStatus, x interface{}) []byte {
 	switch v := x.(type) {
 	case []byte:
@@ -202,10 +205,27 @@ func mustParse(f string, typ oid.Oid, s []byte) time.Time {
 		str[len(str)-3] == ':' {
 		f += ":00"
 	}
+	// Special case for 24:00 time.
+	// Unfortunately, golang does not parse 24:00 as a proper time.
+	// In this case, we want to try "round to the next day", to differentiate.
+	// As such, we find if the 24:00 time matches at the beginning; if so,
+	// we default it back to 00:00 but add a day later.
+	var is2400Time bool
+	switch typ {
+	case oid.T_timetz, oid.T_time:
+		if matches := time2400Regex.FindStringSubmatch(str); matches != nil {
+			// Concatenate timezone information at the back.
+			str = "00:00:00" + str[len(matches[1]):]
+			is2400Time = true
+		}
+	}
 	t, err := time.Parse(f, str)
 	if err != nil {
 		errorf("decode: %s", err)
 	}
+	if is2400Time {
+		t = t.Add(24 * time.Hour)
+	}
 	return t
 }
 
diff --git a/encode_test.go b/encode_test.go
index 813643c2..3406c315 100644
--- a/encode_test.go
+++ b/encode_test.go
@@ -197,6 +197,85 @@ func TestFormatTsBackend(t *testing.T) {
 	}
 }
 
+func TestTimeWithoutTimezone(t *testing.T) {
+	db := openTestConn(t)
+	defer db.Close()
+
+	tx, err := db.Begin()
+	if err != nil {
+		t.Fatal(err)
+	}
+	defer tx.Rollback()
+
+	for _, tc := range []struct {
+		refTime      string
+		expectedTime time.Time
+	}{
+		{"11:59:59", time.Date(0, 1, 1, 11, 59, 59, 0, time.UTC)},
+		{"24:00", time.Date(0, 1, 2, 0, 0, 0, 0, time.UTC)},
+		{"24:00:00", time.Date(0, 1, 2, 0, 0, 0, 0, time.UTC)},
+		{"24:00:00.0", time.Date(0, 1, 2, 0, 0, 0, 0, time.UTC)},
+		{"24:00:00.000000", time.Date(0, 1, 2, 0, 0, 0, 0, time.UTC)},
+	} {
+		t.Run(
+			fmt.Sprintf("%s => %s", tc.refTime, tc.expectedTime.Format(time.RFC3339)),
+			func(t *testing.T) {
+				var gotTime time.Time
+				row := tx.QueryRow("select $1::time", tc.refTime)
+				err = row.Scan(&gotTime)
+				if err != nil {
+					t.Fatal(err)
+				}
+
+				if !tc.expectedTime.Equal(gotTime) {
+					t.Errorf("timestamps not equal: %s != %s", tc.expectedTime, gotTime)
+				}
+			},
+		)
+	}
+}
+
+func TestTimeWithTimezone(t *testing.T) {
+	db := openTestConn(t)
+	defer db.Close()
+
+	tx, err := db.Begin()
+	if err != nil {
+		t.Fatal(err)
+	}
+	defer tx.Rollback()
+
+	for _, tc := range []struct {
+		refTime      string
+		expectedTime time.Time
+	}{
+		{"11:59:59+00:00", time.Date(0, 1, 1, 11, 59, 59, 0, time.UTC)},
+		{"11:59:59+04:00", time.Date(0, 1, 1, 11, 59, 59, 0, time.FixedZone("+04", 4*60*60))},
+		{"24:00+00", time.Date(0, 1, 2, 0, 0, 0, 0, time.UTC)},
+		{"24:00Z", time.Date(0, 1, 2, 0, 0, 0, 0, time.UTC)},
+		{"24:00-04:00", time.Date(0, 1, 2, 0, 0, 0, 0, time.FixedZone("-04", -4*60*60))},
+		{"24:00:00+00", time.Date(0, 1, 2, 0, 0, 0, 0, time.UTC)},
+		{"24:00:00.0+00", time.Date(0, 1, 2, 0, 0, 0, 0, time.UTC)},
+		{"24:00:00.000000+00", time.Date(0, 1, 2, 0, 0, 0, 0, time.UTC)},
+	} {
+		t.Run(
+			fmt.Sprintf("%s => %s", tc.refTime, tc.expectedTime.Format(time.RFC3339)),
+			func(t *testing.T) {
+				var gotTime time.Time
+				row := tx.QueryRow("select $1::timetz", tc.refTime)
+				err = row.Scan(&gotTime)
+				if err != nil {
+					t.Fatal(err)
+				}
+
+				if !tc.expectedTime.Equal(gotTime) {
+					t.Errorf("timestamps not equal: %s != %s", tc.expectedTime, gotTime)
+				}
+			},
+		)
+	}
+}
+
 func TestTimestampWithTimeZone(t *testing.T) {
 	db := openTestConn(t)
 	defer db.Close()