feat: restrict languages (#6931)

* feat: return 404 or 409 if org reg disallowed

* fix: system limit permissions

* feat: add iam limits api

* feat: disallow public org registrations on default instance

* add integration test

* test: integration

* fix test

* docs: describe public org registrations

* avoid updating docs deps

* fix system limits integration test

* silence integration tests

* fix linting

* ignore strange linter complaints

* review

* improve reset properties naming

* redefine the api

* use restrictions aggregate

* test query

* simplify and test projection

* test commands

* fix unit tests

* move integration test

* support restrictions on default instance

* also test GetRestrictions

* self review

* lint

* abstract away resource owner

* fix tests

* configure supported languages

* fix allowed languages

* fix tests

* default lang must not be restricted

* preferred language must be allowed

* change preferred languages

* check languages everywhere

* lint

* test command side

* lint

* add integration test

* add integration test

* restrict supported ui locales

* lint

* lint

* cleanup

* lint

* allow undefined preferred language

* fix integration tests

* update main

* fix env var

* ignore linter

* ignore linter

* improve integration test config

* reduce cognitive complexity

* compile

* check for duplicates

* remove useless restriction checks

* review

* revert restriction renaming

* fix language restrictions

* lint

* generate

* allow custom texts for supported langs for now

* fix tests

* cleanup

* cleanup

* cleanup

* lint

* unsupported preferred lang is allowed

* fix integration test

* finish reverting to old property name

* finish reverting to old property name

* load languages

* refactor(i18n): centralize translators and fs

* lint

* amplify no validations on preferred languages

* fix integration test

* lint

* fix resetting allowed languages

* test unchanged restrictions

internal/command/restrictions.go

@@ -3,16 +3,38 @@ package command
 import (
 	"context"
 
+	"golang.org/x/text/language"
+
 	"github.com/zitadel/zitadel/internal/api/authz"
 	"github.com/zitadel/zitadel/internal/command/preparation"
 	"github.com/zitadel/zitadel/internal/domain"
-	"github.com/zitadel/zitadel/internal/errors"
+	zitadel_errors "github.com/zitadel/zitadel/internal/errors"
 	"github.com/zitadel/zitadel/internal/eventstore"
+	"github.com/zitadel/zitadel/internal/i18n"
 	"github.com/zitadel/zitadel/internal/repository/restrictions"
 )
 
 type SetRestrictions struct {
 	DisallowPublicOrgRegistration *bool
+	AllowedLanguages              []language.Tag
+}
+
+func (s *SetRestrictions) Validate(defaultLanguage language.Tag) error {
+	if s == nil || (s.DisallowPublicOrgRegistration == nil && s.AllowedLanguages == nil) {
+		return zitadel_errors.ThrowInvalidArgument(nil, "COMMAND-oASwj", "Errors.Restrictions.NoneSpecified")
+	}
+	if s.AllowedLanguages != nil {
+		if err := domain.LanguagesHaveDuplicates(s.AllowedLanguages); err != nil {
+			return err
+		}
+		if err := domain.LanguagesAreSupported(i18n.SupportedLanguages(), s.AllowedLanguages...); err != nil {
+			return err
+		}
+		if err := domain.LanguageIsAllowed(false, s.AllowedLanguages, defaultLanguage); err != nil {
+			return zitadel_errors.ThrowPreconditionFailedf(err, "COMMAND-L0m2u", "Errors.Restrictions.DefaultLanguageMustBeAllowed")
+		}
+	}
+	return nil
 }
 
 // SetRestrictions creates new restrictions or updates existing restrictions.
@@ -60,10 +82,10 @@ func (c *Commands) getRestrictionsWriteModel(ctx context.Context, instanceId, re
 
 func (c *Commands) SetRestrictionsCommand(a *restrictions.Aggregate, wm *restrictionsWriteModel, setRestrictions *SetRestrictions) preparation.Validation {
 	return func() (preparation.CreateCommands, error) {
-		if setRestrictions == nil || setRestrictions.DisallowPublicOrgRegistration == nil {
-			return nil, errors.ThrowInvalidArgument(nil, "COMMAND-oASwj", "Errors.Restrictions.NoneSpecified")
-		}
 		return func(ctx context.Context, _ preparation.FilterToQueryReducer) ([]eventstore.Command, error) {
+			if err := setRestrictions.Validate(authz.GetInstance(ctx).DefaultLanguage()); err != nil {
+				return nil, err
+			}
 			changes := wm.NewChanges(setRestrictions)
 			if len(changes) == 0 {
 				return nil, nil