Clean up template locale usage (#27856)

After many refactoring PRs for the "locale" and "template context
function", now the ".locale" is not needed for web templates any more.

This PR does a clean up for:

1. Remove `ctx.Data["locale"]` for web context.
2. Use `ctx.Locale` in `500.tmpl`, for consistency.
3. Add a test check for `500 page` locale usage.
4. Remove the `Str2html` and `DotEscape` from mail template context
data, they are copy&paste errors introduced by #19169 and #16200 . These
functions are template functions (provided by the common renderer), but
not template data variables.
5. Make email `SendAsync` function mockable (I was planning to add more
tests but it would make this PR much too complex, so the tests could be
done in another PR)

10 files changed, 33 insertions, 65 deletions

diff --git a/modules/context/context.go b/modules/context/context.go
index 47ad310b09..8a94e958b5 100644
--- a/modules/context/context.go
+++ b/modules/context/context.go
@@ -157,7 +157,6 @@ func Contexter() func(next http.Handler) http.Handler {
 			ctx.Data["Context"] = ctx // TODO: use "ctx" in template and remove this
 			ctx.Data["CurrentURL"] = setting.AppSubURL + req.URL.RequestURI()
 			ctx.Data["Link"] = ctx.Link
-			ctx.Data["locale"] = ctx.Locale
 
 			// PageData is passed by reference, and it will be rendered to `window.config.pageData` in `head.tmpl` for JavaScript modules
 			ctx.PageData = map[string]any{}
diff --git a/routers/common/errpage.go b/routers/common/errpage.go
index 9c8ccc3388..923421a29c 100644
--- a/routers/common/errpage.go
+++ b/routers/common/errpage.go
@@ -9,6 +9,7 @@ import (
 
 	user_model "code.gitea.io/gitea/models/user"
 	"code.gitea.io/gitea/modules/base"
+	"code.gitea.io/gitea/modules/context"
 	"code.gitea.io/gitea/modules/httpcache"
 	"code.gitea.io/gitea/modules/log"
 	"code.gitea.io/gitea/modules/setting"
@@ -35,20 +36,18 @@ func RenderPanicErrorPage(w http.ResponseWriter, req *http.Request, err any) {
 	httpcache.SetCacheControlInHeader(w.Header(), 0, "no-transform")
 	w.Header().Set(`X-Frame-Options`, setting.CORSConfig.XFrameOptions)
 
-	data := middleware.GetContextData(req.Context())
-	if data["locale"] == nil {
-		data = middleware.CommonTemplateContextData()
-		data["locale"] = middleware.Locale(w, req)
-	}
+	tmplCtx := context.TemplateContext{}
+	tmplCtx["Locale"] = middleware.Locale(w, req)
+	ctxData := middleware.GetContextData(req.Context())
 
 	// This recovery handler could be called without Gitea's web context, so we shouldn't touch that context too much.
 	// Otherwise, the 500-page may cause new panics, eg: cache.GetContextWithData, it makes the developer&users couldn't find the original panic.
-	user, _ := data[middleware.ContextDataKeySignedUser].(*user_model.User)
+	user, _ := ctxData[middleware.ContextDataKeySignedUser].(*user_model.User)
 	if !setting.IsProd || (user != nil && user.IsAdmin) {
-		data["ErrorMsg"] = "PANIC: " + combinedErr
+		ctxData["ErrorMsg"] = "PANIC: " + combinedErr
 	}
 
-	err = templates.HTMLRenderer().HTML(w, http.StatusInternalServerError, string(tplStatus500), data, nil)
+	err = templates.HTMLRenderer().HTML(w, http.StatusInternalServerError, string(tplStatus500), ctxData, tmplCtx)
 	if err != nil {
 		log.Error("Error occurs again when rendering error page: %v", err)
 		w.WriteHeader(http.StatusInternalServerError)
diff --git a/routers/common/errpage_test.go b/routers/common/errpage_test.go
index 58a633b2a4..4fd63ba49e 100644
--- a/routers/common/errpage_test.go
+++ b/routers/common/errpage_test.go
@@ -26,6 +26,7 @@ func TestRenderPanicErrorPage(t *testing.T) {
 	respContent := w.Body.String()
 	assert.Contains(t, respContent, `class="page-content status-page-500"`)
 	assert.Contains(t, respContent, `</html>`)
+	assert.Contains(t, respContent, `lang="en-US"`) // make sure the locale work
 
 	// the 500 page doesn't have normal pages footer, it makes it easier to distinguish a normal page and a failed page.
 	// especially when a sub-template causes page error, the HTTP response code is still 200,
diff --git a/services/mailer/mail.go b/services/mailer/mail.go
index 0210128046..1f139d233f 100644
--- a/services/mailer/mail.go
+++ b/services/mailer/mail.go
@@ -26,7 +26,6 @@ import (
 	"code.gitea.io/gitea/modules/markup"
 	"code.gitea.io/gitea/modules/markup/markdown"
 	"code.gitea.io/gitea/modules/setting"
-	"code.gitea.io/gitea/modules/templates"
 	"code.gitea.io/gitea/modules/timeutil"
 	"code.gitea.io/gitea/modules/translation"
 	incoming_payload "code.gitea.io/gitea/services/mailer/incoming/payload"
@@ -68,15 +67,12 @@ func SendTestMail(email string) error {
 func sendUserMail(language string, u *user_model.User, tpl base.TplName, code, subject, info string) {
 	locale := translation.NewLocale(language)
 	data := map[string]any{
+		"locale":            locale,
 		"DisplayName":       u.DisplayName(),
 		"ActiveCodeLives":   timeutil.MinutesToFriendly(setting.Service.ActiveCodeLives, locale),
 		"ResetPwdCodeLives": timeutil.MinutesToFriendly(setting.Service.ResetPwdCodeLives, locale),
 		"Code":              code,
 		"Language":          locale.Language(),
-		// helper
-		"locale":    locale,
-		"Str2html":  templates.Str2html,
-		"DotEscape": templates.DotEscape,
 	}
 
 	var content bytes.Buffer
@@ -119,15 +115,12 @@ func SendActivateEmailMail(u *user_model.User, email *user_model.EmailAddress) {
 	}
 	locale := translation.NewLocale(u.Language)
 	data := map[string]any{
+		"locale":          locale,
 		"DisplayName":     u.DisplayName(),
 		"ActiveCodeLives": timeutil.MinutesToFriendly(setting.Service.ActiveCodeLives, locale),
 		"Code":            u.GenerateEmailActivateCode(email.Email),
 		"Email":           email.Email,
 		"Language":        locale.Language(),
-		// helper
-		"locale":    locale,
-		"Str2html":  templates.Str2html,
-		"DotEscape": templates.DotEscape,
 	}
 
 	var content bytes.Buffer
@@ -152,13 +145,10 @@ func SendRegisterNotifyMail(u *user_model.User) {
 	locale := translation.NewLocale(u.Language)
 
 	data := map[string]any{
+		"locale":      locale,
 		"DisplayName": u.DisplayName(),
 		"Username":    u.Name,
 		"Language":    locale.Language(),
-		// helper
-		"locale":    locale,
-		"Str2html":  templates.Str2html,
-		"DotEscape": templates.DotEscape,
 	}
 
 	var content bytes.Buffer
@@ -185,14 +175,11 @@ func SendCollaboratorMail(u, doer *user_model.User, repo *repo_model.Repository)
 
 	subject := locale.Tr("mail.repo.collaborator.added.subject", doer.DisplayName(), repoName)
 	data := map[string]any{
+		"locale":   locale,
 		"Subject":  subject,
 		"RepoName": repoName,
 		"Link":     repo.HTMLURL(),
 		"Language": locale.Language(),
-		// helper
-		"locale":    locale,
-		"Str2html":  templates.Str2html,
-		"DotEscape": templates.DotEscape,
 	}
 
 	var content bytes.Buffer
@@ -259,6 +246,7 @@ func composeIssueCommentMessages(ctx *mailCommentContext, lang string, recipient
 	locale := translation.NewLocale(lang)
 
 	mailMeta := map[string]any{
+		"locale":          locale,
 		"FallbackSubject": fallback,
 		"Body":            body,
 		"Link":            link,
@@ -275,10 +263,6 @@ func composeIssueCommentMessages(ctx *mailCommentContext, lang string, recipient
 		"ReviewComments":  reviewComments,
 		"Language":        locale.Language(),
 		"CanReply":        setting.IncomingEmail.Enabled && commentType != issues_model.CommentTypePullRequestPush,
-		// helper
-		"locale":    locale,
-		"Str2html":  templates.Str2html,
-		"DotEscape": templates.DotEscape,
 	}
 
 	var mailSubject bytes.Buffer
@@ -469,7 +453,7 @@ func SendIssueAssignedMail(ctx context.Context, issue *issues_model.Issue, doer
 		if err != nil {
 			return err
 		}
-		SendAsyncs(msgs)
+		SendAsync(msgs...)
 	}
 	return nil
 }
diff --git a/services/mailer/mail_issue.go b/services/mailer/mail_issue.go
index baa9f1d9ab..fab3315be2 100644
--- a/services/mailer/mail_issue.go
+++ b/services/mailer/mail_issue.go
@@ -162,7 +162,7 @@ func mailIssueCommentBatch(ctx *mailCommentContext, users []*user_model.User, vi
 			if err != nil {
 				return err
 			}
-			SendAsyncs(msgs)
+			SendAsync(msgs...)
 			receivers = receivers[:i]
 		}
 	}
diff --git a/services/mailer/mail_release.go b/services/mailer/mail_release.go
index 7bc3db3fe6..88973a6be2 100644
--- a/services/mailer/mail_release.go
+++ b/services/mailer/mail_release.go
@@ -14,7 +14,6 @@ import (
 	"code.gitea.io/gitea/modules/markup"
 	"code.gitea.io/gitea/modules/markup/markdown"
 	"code.gitea.io/gitea/modules/setting"
-	"code.gitea.io/gitea/modules/templates"
 	"code.gitea.io/gitea/modules/translation"
 )
 
@@ -69,13 +68,10 @@ func mailNewRelease(ctx context.Context, lang string, tos []string, rel *repo_mo
 
 	subject := locale.Tr("mail.release.new.subject", rel.TagName, rel.Repo.FullName())
 	mailMeta := map[string]any{
+		"locale":   locale,
 		"Release":  rel,
 		"Subject":  subject,
 		"Language": locale.Language(),
-		// helper
-		"locale":    locale,
-		"Str2html":  templates.Str2html,
-		"DotEscape": templates.DotEscape,
 	}
 
 	var mailBody bytes.Buffer
@@ -95,5 +91,5 @@ func mailNewRelease(ctx context.Context, lang string, tos []string, rel *repo_mo
 		msgs = append(msgs, msg)
 	}
 
-	SendAsyncs(msgs)
+	SendAsync(msgs...)
 }
diff --git a/services/mailer/mail_repo.go b/services/mailer/mail_repo.go
index e9c1991b5b..b89dcd43b5 100644
--- a/services/mailer/mail_repo.go
+++ b/services/mailer/mail_repo.go
@@ -12,7 +12,6 @@ import (
 	repo_model "code.gitea.io/gitea/models/repo"
 	user_model "code.gitea.io/gitea/models/user"
 	"code.gitea.io/gitea/modules/setting"
-	"code.gitea.io/gitea/modules/templates"
 	"code.gitea.io/gitea/modules/translation"
 )
 
@@ -65,6 +64,7 @@ func sendRepoTransferNotifyMailPerLang(lang string, newOwner, doer *user_model.U
 	}
 
 	data := map[string]any{
+		"locale":      locale,
 		"Doer":        doer,
 		"User":        repo.Owner,
 		"Repo":        repo.FullName(),
@@ -72,10 +72,6 @@ func sendRepoTransferNotifyMailPerLang(lang string, newOwner, doer *user_model.U
 		"Subject":     subject,
 		"Language":    locale.Language(),
 		"Destination": destination,
-		// helper
-		"locale":    locale,
-		"Str2html":  templates.Str2html,
-		"DotEscape": templates.DotEscape,
 	}
 
 	if err := bodyTemplates.ExecuteTemplate(&content, string(mailRepoTransferNotify), data); err != nil {
diff --git a/services/mailer/mail_team_invite.go b/services/mailer/mail_team_invite.go
index 88ad0c9836..ab32beefac 100644
--- a/services/mailer/mail_team_invite.go
+++ b/services/mailer/mail_team_invite.go
@@ -14,7 +14,6 @@ import (
 	"code.gitea.io/gitea/modules/base"
 	"code.gitea.io/gitea/modules/log"
 	"code.gitea.io/gitea/modules/setting"
-	"code.gitea.io/gitea/modules/templates"
 	"code.gitea.io/gitea/modules/translation"
 )
 
@@ -53,16 +52,13 @@ func MailTeamInvite(ctx context.Context, inviter *user_model.User, team *org_mod
 
 	subject := locale.Tr("mail.team_invite.subject", inviter.DisplayName(), org.DisplayName())
 	mailMeta := map[string]any{
+		"locale":       locale,
 		"Inviter":      inviter,
 		"Organization": org,
 		"Team":         team,
 		"Invite":       invite,
 		"Subject":      subject,
 		"InviteURL":    inviteURL,
-		// helper
-		"locale":    locale,
-		"Str2html":  templates.Str2html,
-		"DotEscape": templates.DotEscape,
 	}
 
 	var mailBody bytes.Buffer
diff --git a/services/mailer/mailer.go b/services/mailer/mailer.go
index 42d7d5ad5d..5e8e3dbb38 100644
--- a/services/mailer/mailer.go
+++ b/services/mailer/mailer.go
@@ -425,15 +425,12 @@ func NewContext(ctx context.Context) {
 	go graceful.GetManager().RunWithCancel(mailQueue)
 }
 
-// SendAsync send mail asynchronously
-func SendAsync(msg *Message) {
-	SendAsyncs([]*Message{msg})
-}
+// SendAsync send emails asynchronously (make it mockable)
+var SendAsync = sendAsync
 
-// SendAsyncs send mails asynchronously
-func SendAsyncs(msgs []*Message) {
+func sendAsync(msgs ...*Message) {
 	if setting.MailService == nil {
-		log.Error("Mailer: SendAsyncs is being invoked but mail service hasn't been initialized")
+		log.Error("Mailer: SendAsync is being invoked but mail service hasn't been initialized")
 		return
 	}
 
diff --git a/templates/status/500.tmpl b/templates/status/500.tmpl
index e5570bde73..edcb90f9a4 100644
--- a/templates/status/500.tmpl
+++ b/templates/status/500.tmpl
@@ -1,12 +1,12 @@
 {{/* This page should only depend the minimal template functions/variables, to avoid triggering new panics.
 * base template functions: AppName, AssetUrlPrefix, AssetVersion, AppSubUrl, ThemeName, Str2html
-* locale
-* Flash
-* ErrorMsg
-* SignedUser (optional)
+* ctx.Locale
+* .Flash
+* .ErrorMsg
+* .SignedUser (optional)
 */}}
 <!DOCTYPE html>
-<html lang="{{.locale.Lang}}" data-theme="{{ThemeName .SignedUser}}">
+<html lang="{{ctx.Locale.Lang}}" data-theme="{{ThemeName .SignedUser}}">
 <head>
 	<meta name="viewport" content="width=device-width, initial-scale=1">
 	<title>Internal Server Error - {{AppName}}</title>
@@ -19,8 +19,8 @@
 		<nav class="ui secondary menu gt-border-secondary-bottom">
 			<div class="ui container gt-df">
 				<div class="item gt-f1">
-					<a href="{{AppSubUrl}}/" aria-label="{{.locale.Tr "home"}}">
-						<img width="30" height="30" src="{{AssetUrlPrefix}}/img/logo.svg" alt="{{.locale.Tr "logo"}}" aria-hidden="true">
+					<a href="{{AppSubUrl}}/" aria-label="{{ctx.Locale.Tr "home"}}">
+						<img width="30" height="30" src="{{AssetUrlPrefix}}/img/logo.svg" alt="{{ctx.Locale.Tr "logo"}}" aria-hidden="true">
 					</a>
 				</div>
 				<div class="item">
@@ -37,12 +37,12 @@
 			<div class="divider"></div>
 			<div class="ui container gt-my-5">
 				{{if .ErrorMsg}}
-					<p>{{.locale.Tr "error.occurred"}}:</p>
+					<p>{{ctx.Locale.Tr "error.occurred"}}:</p>
 					<pre class="gt-whitespace-pre-wrap gt-break-all">{{.ErrorMsg}}</pre>
 				{{end}}
 				<div class="center gt-mt-5">
-					{{if or .SignedUser.IsAdmin .ShowFooterVersion}}<p>{{.locale.Tr "admin.config.app_ver"}}: {{AppVer}}</p>{{end}}
-					{{if .SignedUser.IsAdmin}}<p>{{.locale.Tr "error.report_message" | Str2html}}</p>{{end}}
+					{{if or .SignedUser.IsAdmin .ShowFooterVersion}}<p>{{ctx.Locale.Tr "admin.config.app_ver"}}: {{AppVer}}</p>{{end}}
+					{{if .SignedUser.IsAdmin}}<p>{{ctx.Locale.Tr "error.report_message" | Str2html}}</p>{{end}}
 				</div>
 			</div>
 		</div>