Replace DateTime with proper functions (#32402)

Follow #32383

This PR cleans up the "Deadline" usages in templates, make them call
`ParseLegacy` first to get a `Time` struct then display by `DateUtils`.

Now it should be pretty clear how "deadline string" works, it makes it
possible to do further refactoring and correcting.

modules/templates/helper.go

@@ -54,7 +54,7 @@ func NewFuncMap() template.FuncMap {
 		"StringUtils": NewStringUtils,
 		"SliceUtils":  NewSliceUtils,
 		"JsonUtils":   NewJsonUtils,
-		"DateUtils":   NewDateUtils, // TODO: to be replaced by DateUtils
+		"DateUtils":   NewDateUtils,
 
 		// -----------------------------------------------------------------
 		// svg / avatar / icon / color
@@ -71,7 +71,7 @@ func NewFuncMap() template.FuncMap {
 		"CountFmt":      base.FormatNumberSI,
 		"TimeSince":     timeutil.TimeSince,
 		"TimeSinceUnix": timeutil.TimeSinceUnix,
-		"DateTime":      timeutil.DateTime,
+		"DateTime":      dateTimeLegacy, // for backward compatibility only, do not use it anymore
 		"Sec2Time":      util.SecToTime,
 		"LoadTimes": func(startTime time.Time) string {
 			return fmt.Sprint(time.Since(startTime).Nanoseconds()/1e6) + "ms"

modules/templates/util_date.go

@@ -6,7 +6,9 @@ package templates
 import (
 	"context"
 	"html/template"
+	"time"
 
+	"code.gitea.io/gitea/modules/setting"
 	"code.gitea.io/gitea/modules/timeutil"
 )
 
@@ -32,3 +34,27 @@ func (du *DateUtils) AbsoluteLong(time any) template.HTML {
 func (du *DateUtils) FullTime(time any) template.HTML {
 	return timeutil.DateTime("full", time)
 }
+
+// ParseLegacy parses the datetime in legacy format, eg: "2016-01-02" in server's timezone.
+// It shouldn't be used in new code. New code should use Time or TimeStamp as much as possible.
+func (du *DateUtils) ParseLegacy(datetime string) time.Time {
+	return parseLegacy(datetime)
+}
+
+func parseLegacy(datetime string) time.Time {
+	t, err := time.Parse(time.RFC3339, datetime)
+	if err != nil {
+		t, _ = time.ParseInLocation(time.DateOnly, datetime, setting.DefaultUILocation)
+	}
+	return t
+}
+
+func dateTimeLegacy(format string, datetime any, _ ...string) template.HTML {
+	if !setting.IsProd || setting.IsInTesting {
+		panic("dateTimeLegacy is for backward compatibility only, do not use it in new code")
+	}
+	if s, ok := datetime.(string); ok {
+		datetime = parseLegacy(s)
+	}
+	return timeutil.DateTime(format, datetime)
+}

modules/templates/util_date_test.go

@@ -0,0 +1,51 @@
+// Copyright 2023 The Gitea Authors. All rights reserved.
+// SPDX-License-Identifier: MIT
+
+package templates
+
+import (
+	"testing"
+	"time"
+
+	"code.gitea.io/gitea/modules/setting"
+	"code.gitea.io/gitea/modules/test"
+	"code.gitea.io/gitea/modules/timeutil"
+
+	"github.com/stretchr/testify/assert"
+)
+
+func TestDateTime(t *testing.T) {
+	testTz, _ := time.LoadLocation("America/New_York")
+	defer test.MockVariableValue(&setting.DefaultUILocation, testTz)()
+	defer test.MockVariableValue(&setting.IsInTesting, false)()
+
+	du := NewDateUtils(nil)
+
+	refTimeStr := "2018-01-01T00:00:00Z"
+	refDateStr := "2018-01-01"
+	refTime, _ := time.Parse(time.RFC3339, refTimeStr)
+	refTimeStamp := timeutil.TimeStamp(refTime.Unix())
+
+	assert.EqualValues(t, "-", du.AbsoluteShort(nil))
+	assert.EqualValues(t, "-", du.AbsoluteShort(0))
+	assert.EqualValues(t, "-", du.AbsoluteShort(time.Time{}))
+	assert.EqualValues(t, "-", du.AbsoluteShort(timeutil.TimeStamp(0)))
+
+	actual := dateTimeLegacy("short", "invalid")
+	assert.EqualValues(t, `-`, actual)
+
+	actual = dateTimeLegacy("short", refTimeStr)
+	assert.EqualValues(t, `<absolute-date weekday="" year="numeric" month="short" day="numeric" date="2018-01-01T00:00:00Z">2018-01-01</absolute-date>`, actual)
+
+	actual = du.AbsoluteShort(refTime)
+	assert.EqualValues(t, `<absolute-date weekday="" year="numeric" month="short" day="numeric" date="2018-01-01T00:00:00Z">2018-01-01</absolute-date>`, actual)
+
+	actual = dateTimeLegacy("short", refDateStr)
+	assert.EqualValues(t, `<absolute-date weekday="" year="numeric" month="short" day="numeric" date="2018-01-01T00:00:00-05:00">2018-01-01</absolute-date>`, actual)
+
+	actual = du.AbsoluteShort(refTimeStamp)
+	assert.EqualValues(t, `<absolute-date weekday="" year="numeric" month="short" day="numeric" date="2017-12-31T19:00:00-05:00">2017-12-31</absolute-date>`, actual)
+
+	actual = du.FullTime(refTimeStamp)
+	assert.EqualValues(t, `<relative-time weekday="" year="numeric" format="datetime" month="short" day="numeric" hour="numeric" minute="numeric" second="numeric" data-tooltip-content data-tooltip-interactive="true" datetime="2017-12-31T19:00:00-05:00">2017-12-31 19:00:00 -05:00</relative-time>`, actual)
+}