Make template `DateTime` show proper tooltip (#28677)

There was a question about "how to improve the datetime display for
SSH/PGP/WebAuthn"
https://github.com/go-gitea/gitea/pull/28262#issuecomment-1831141611

The root problem is that `DateTime` misses the "data-tooltip-content"
attribute, which should be used to make the tooltip popup smoothly.

Now the UI is consistent and the end users could see the detailed
hour/minute/second easily by hovering the element.


![image](https://github.com/go-gitea/gitea/assets/2114189/2211336f-d59d-4f64-a83b-099f8ef6d29b)


![image](https://github.com/go-gitea/gitea/assets/2114189/f02a9c86-476d-48d6-aece-85a800235fbd)

2 files changed, 19 insertions, 16 deletions

diff --git a/modules/timeutil/datetime.go b/modules/timeutil/datetime.go
index d254a56a74..62b94f7cf4 100644
--- a/modules/timeutil/datetime.go
+++ b/modules/timeutil/datetime.go
@@ -12,7 +12,7 @@ import (
 )
 
 // DateTime renders an absolute time HTML element by datetime.
-func DateTime(format string, datetime any, attrs ...string) template.HTML {
+func DateTime(format string, datetime any, extraAttrs ...string) template.HTML {
 	if p, ok := datetime.(*time.Time); ok {
 		datetime = *p
 	}
@@ -49,15 +49,20 @@ func DateTime(format string, datetime any, attrs ...string) template.HTML {
 		panic(fmt.Sprintf("Unsupported time type %T", datetime))
 	}
 
-	extraAttrs := strings.Join(attrs, " ")
+	attrs := make([]string, 0, 10+len(extraAttrs))
+	attrs = append(attrs, extraAttrs...)
+	attrs = append(attrs, `data-tooltip-content`, `data-tooltip-interactive="true"`)
+	attrs = append(attrs, `format="datetime"`, `weekday=""`, `year="numeric"`)
 
 	switch format {
 	case "short":
-		return template.HTML(fmt.Sprintf(`<relative-time %s format="datetime" year="numeric" month="short" day="numeric" weekday="" datetime="%s">%s</relative-time>`, extraAttrs, datetimeEscaped, textEscaped))
+		attrs = append(attrs, `month="short"`, `day="numeric"`)
 	case "long":
-		return template.HTML(fmt.Sprintf(`<relative-time %s format="datetime" year="numeric" month="long" day="numeric" weekday="" datetime="%s">%s</relative-time>`, extraAttrs, datetimeEscaped, textEscaped))
+		attrs = append(attrs, `month="long"`, `day="numeric"`)
 	case "full":
-		return template.HTML(fmt.Sprintf(`<relative-time %s format="datetime" weekday="" year="numeric" month="short" day="numeric" hour="numeric" minute="numeric" second="numeric" datetime="%s">%s</relative-time>`, extraAttrs, datetimeEscaped, textEscaped))
+		attrs = append(attrs, `month="short"`, `day="numeric"`, `hour="numeric"`, `minute="numeric"`, `second="numeric"`)
+	default:
+		panic(fmt.Sprintf("Unsupported format %s", format))
 	}
-	panic(fmt.Sprintf("Unsupported format %s", format))
+	return template.HTML(fmt.Sprintf(`<relative-time %s datetime="%s">%s</relative-time>`, strings.Join(attrs, " "), datetimeEscaped, textEscaped))
 }
diff --git a/modules/timeutil/datetime_test.go b/modules/timeutil/datetime_test.go
index 387e6274a7..26494b8475 100644
--- a/modules/timeutil/datetime_test.go
+++ b/modules/timeutil/datetime_test.go
@@ -8,16 +8,14 @@ import (
 	"time"
 
 	"code.gitea.io/gitea/modules/setting"
+	"code.gitea.io/gitea/modules/test"
 
 	"github.com/stretchr/testify/assert"
 )
 
 func TestDateTime(t *testing.T) {
-	oldTz := setting.DefaultUILocation
-	setting.DefaultUILocation, _ = time.LoadLocation("America/New_York")
-	defer func() {
-		setting.DefaultUILocation = oldTz
-	}()
+	testTz, _ := time.LoadLocation("America/New_York")
+	defer test.MockVariableValue(&setting.DefaultUILocation, testTz)()
 
 	refTimeStr := "2018-01-01T00:00:00Z"
 	refTime, _ := time.Parse(time.RFC3339, refTimeStr)
@@ -29,17 +27,17 @@ func TestDateTime(t *testing.T) {
 	assert.EqualValues(t, "-", DateTime("short", TimeStamp(0)))
 
 	actual := DateTime("short", "invalid")
-	assert.EqualValues(t, `<relative-time  format="datetime" year="numeric" month="short" day="numeric" weekday="" datetime="invalid">invalid</relative-time>`, actual)
+	assert.EqualValues(t, `<relative-time data-tooltip-content data-tooltip-interactive="true" format="datetime" weekday="" year="numeric" month="short" day="numeric" datetime="invalid">invalid</relative-time>`, actual)
 
 	actual = DateTime("short", refTimeStr)
-	assert.EqualValues(t, `<relative-time  format="datetime" year="numeric" month="short" day="numeric" weekday="" datetime="2018-01-01T00:00:00Z">2018-01-01T00:00:00Z</relative-time>`, actual)
+	assert.EqualValues(t, `<relative-time data-tooltip-content data-tooltip-interactive="true" format="datetime" weekday="" year="numeric" month="short" day="numeric" datetime="2018-01-01T00:00:00Z">2018-01-01T00:00:00Z</relative-time>`, actual)
 
 	actual = DateTime("short", refTime)
-	assert.EqualValues(t, `<relative-time  format="datetime" year="numeric" month="short" day="numeric" weekday="" datetime="2018-01-01T00:00:00Z">2018-01-01</relative-time>`, actual)
+	assert.EqualValues(t, `<relative-time data-tooltip-content data-tooltip-interactive="true" format="datetime" weekday="" year="numeric" month="short" day="numeric" datetime="2018-01-01T00:00:00Z">2018-01-01</relative-time>`, actual)
 
 	actual = DateTime("short", refTimeStamp)
-	assert.EqualValues(t, `<relative-time  format="datetime" year="numeric" month="short" day="numeric" weekday="" datetime="2017-12-31T19:00:00-05:00">2017-12-31</relative-time>`, actual)
+	assert.EqualValues(t, `<relative-time data-tooltip-content data-tooltip-interactive="true" format="datetime" weekday="" year="numeric" month="short" day="numeric" datetime="2017-12-31T19:00:00-05:00">2017-12-31</relative-time>`, actual)
 
 	actual = DateTime("full", refTimeStamp)
-	assert.EqualValues(t, `<relative-time  format="datetime" weekday="" year="numeric" month="short" day="numeric" hour="numeric" minute="numeric" second="numeric" datetime="2017-12-31T19:00:00-05:00">2017-12-31 19:00:00 -05:00</relative-time>`, actual)
+	assert.EqualValues(t, `<relative-time data-tooltip-content data-tooltip-interactive="true" format="datetime" weekday="" year="numeric" month="short" day="numeric" hour="numeric" minute="numeric" second="numeric" datetime="2017-12-31T19:00:00-05:00">2017-12-31 19:00:00 -05:00</relative-time>`, actual)
 }