[feature] Allow full BCP 47 in language inputs (#2067)

* Allow full BCP 47 in language inputs

Fixes #2066

* Fuse validation and normalization for languages

* Remove outdated comment line

* Move post language canonicalization test

4 files changed, 40 insertions, 5 deletions

diff --git a/internal/processing/account/create.go b/internal/processing/account/create.go
index 1a172b865..32a59d1ef 100644
--- a/internal/processing/account/create.go
+++ b/internal/processing/account/create.go
@@ -34,8 +34,7 @@ import (
 // Create processes the given form for creating a new account,
 // returning an oauth token for that account if successful.
 //
-// Fields on the form should have already been validated by the
-// caller, before this function is called.
+// Precondition: the form's fields should have already been validated and normalized by the caller.
 func (p *Processor) Create(
 	ctx context.Context,
 	appToken oauth2.TokenInfo,
diff --git a/internal/processing/account/update.go b/internal/processing/account/update.go
index 01c62d7e3..f75b3c8d9 100644
--- a/internal/processing/account/update.go
+++ b/internal/processing/account/update.go
@@ -222,10 +222,11 @@ func (p *Processor) Update(ctx context.Context, account *gtsmodel.Account, form
 
 	if form.Source != nil {
 		if form.Source.Language != nil {
-			if err := validate.Language(*form.Source.Language); err != nil {
+			language, err := validate.Language(*form.Source.Language)
+			if err != nil {
 				return nil, gtserror.NewErrorBadRequest(err)
 			}
-			account.Language = *form.Source.Language
+			account.Language = language
 		}
 
 		if form.Source.Sensitive != nil {
diff --git a/internal/processing/status/create.go b/internal/processing/status/create.go
index 2d9c3a196..36842ee07 100644
--- a/internal/processing/status/create.go
+++ b/internal/processing/status/create.go
@@ -37,6 +37,8 @@ import (
 )
 
 // Create processes the given form to create a new status, returning the api model representation of that status if it's OK.
+//
+// Precondition: the form's fields should have already been validated and normalized by the caller.
 func (p *Processor) Create(ctx context.Context, account *gtsmodel.Account, application *gtsmodel.Application, form *apimodel.AdvancedStatusCreateForm) (*apimodel.Status, gtserror.WithCode) {
 	accountURIs := uris.GenerateURIsForAccount(account.Username)
 	thisStatusID := id.NewULID()
@@ -55,7 +57,6 @@ func (p *Processor) Create(ctx context.Context, account *gtsmodel.Account, appli
 		ContentWarning:           text.SanitizePlaintext(form.SpoilerText),
 		ActivityStreamsType:      ap.ObjectNote,
 		Sensitive:                &sensitive,
-		Language:                 form.Language,
 		CreatedWithApplicationID: application.ID,
 		Text:                     form.Status,
 	}
diff --git a/internal/processing/status/create_test.go b/internal/processing/status/create_test.go
index 2a797516d..2c86e5a29 100644
--- a/internal/processing/status/create_test.go
+++ b/internal/processing/status/create_test.go
@@ -208,6 +208,40 @@ func (suite *StatusCreateTestSuite) TestProcessMediaDescriptionTooShort() {
 	suite.Nil(apiStatus)
 }
 
+func (suite *StatusCreateTestSuite) TestProcessLanguageWithScriptPart() {
+	ctx := context.Background()
+
+	creatingAccount := suite.testAccounts["local_account_1"]
+	creatingApplication := suite.testApplications["application_1"]
+
+	statusCreateForm := &apimodel.AdvancedStatusCreateForm{
+		StatusCreateRequest: apimodel.StatusCreateRequest{
+			Status:      "你好世界", // hello world
+			MediaIDs:    []string{},
+			Poll:        nil,
+			InReplyToID: "",
+			Sensitive:   false,
+			SpoilerText: "",
+			Visibility:  apimodel.VisibilityPublic,
+			ScheduledAt: "",
+			Language:    "zh-Hans",
+			ContentType: apimodel.StatusContentTypePlain,
+		},
+		AdvancedVisibilityFlagsForm: apimodel.AdvancedVisibilityFlagsForm{
+			Federated: nil,
+			Boostable: nil,
+			Replyable: nil,
+			Likeable:  nil,
+		},
+	}
+
+	apiStatus, err := suite.status.Create(ctx, creatingAccount, creatingApplication, statusCreateForm)
+	suite.NoError(err)
+	suite.NotNil(apiStatus)
+
+	suite.Equal("zh-Hans", *apiStatus.Language)
+}
+
 func TestStatusCreateTestSuite(t *testing.T) {
 	suite.Run(t, new(StatusCreateTestSuite))
 }