feat(i18n): add language preference management functionality

[Ang-m4]

Language Management Module

Description

This PR intents to add a new LanguageManager module to standardize language switching functionality. The module provides a new API for handling language changes from any component in the application.

Key Features

• Unified Language Management: Centralizes all language-related operations into a single module
• Complete Language Switching Flow: Handles the entire language change process through a single function call
• User Preference Persistence: Updates both client-side cookies and server-side user preferences
• Session Management: Integrates with LMS backend to ensure consistent language experience
• RTL Support: Automatically handles right-to-left language adjustments
• Event System Integration: Publishes events when locale changes to allow components to react

Implementation Details

New Functions

• changeUserSessionLanguage(languageCode): Main public function that orchestrates the language change process:

  • Sets the language cookie
  • Updates authenticated user preferences in the backend (if applicable)
  • Updates the session language
  • Publishes a locale change event
  • Handles RTL adjustments

• updateUserPreferences(username, preferenceData): Updates server-side user language preferences via the API

• setSessionLanguage(languageCode): Sets the language for the current session using the LMS setlang endpoint

API Usage

Components can now implement language switching with a single function call:

import { changeUserSessionLanguage } from '@edx/frontend-platform/i18n';

// When a user selects a new language
changeUserSessionLanguage('ar'); // Switch to Arabic

Related Work

This functionality is a core dependency for the Language Selector Implementation.

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[dcoa]

I was thinking about the list of supported languages to display

I'm thinking as default use an array provided for frontend-platform using the messages object here that is configured during the MFE initialize. So the manager could return a function or variable with the list of locales Object.keys(messages)

@arbrandes what do you thing?

In that way we can get rid of SITE_SUPPORTED_LANGUAGES here, and in any case someone want to pass a more restricted or controlled list, they can do it by the plugin configuration.

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Codecov Report

:x: Patch coverage is 96.42857% with 1 line in your changes missing coverage. Please review. :white_check_mark: Project coverage is 87.31%. Comparing base (acf0d46) to head (729b314). :warning: Report is 7 commits behind head on master.

Files with missing lines	Patch %	Lines
src/i18n/lib.js	85.71%	1 Missing :warning:

Additional details and impacted files

@@            Coverage Diff             @@
##           master     #786      +/-   ##
==========================================
+ Coverage   87.13%   87.31%   +0.18%     
==========================================
  Files          48       50       +2     
  Lines        1407     1435      +28     
  Branches      297      305       +8     
==========================================
+ Hits         1226     1253      +27     
- Misses        168      169       +1     
  Partials       13       13              

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[Ang-m4]

Hi @arbrandes,

I made some changes to the code as you requested. Please let me know what you think:

• Created a new languageApi module for easier testing.
• Added an optional flag for reloading the page if needed.
• Added a unit test.

and i would like to know your thoughts on @dcoa’s comments!

The endpoint request a CSRF token as you can see here. I just want to make sure the following line of code is correct as a suggested change from the frontend-platform perspective (getAuthenticatedHttpClient is the right service to use? -@arbrandes could you help me with this doubt?-).

---

I'm thinking as default use an array provided for frontend-platform using the messages object here that is configured during the MFE initialize. So the manager could return a function or variable with the list of locales Object.keys(messages)

Thank you so much for your time on this!

[dcoa]

@arbrandes friendly tag for reviewing here. Thank you!

[felipemontoya]

@arbrandes friendly ping again. To not be a constant bother since I know you are deepdiving in the frontendbase stuff, I'd like to ask if you need to pass this to someone else to be a reviewer here.

[dcoa]

This LGTM!! thank you, @Ang-m4 .

@arbrandes the PR was updated accordingly to the feedback, could you please verify?

[Asespinel]

We've successfully implemented the language selector feature on our end and everything is working well.

The only question we have is regarding the getSupportedLocaleList() function behavior. Currently, this function returns all available languages with translations, rather than filtering based on the SITE_SUPPORTED_LANGUAGES configuration.

We implemented a client-side workaround in the LanguageSelector component to filter the languages

Is this the intended behavior, or should getSupportedLocaleList() respect the SITE_SUPPORTED_LANGUAGES configuration automatically? @arbrandes Would you mind taking a look at this when you get a chance? Would appreciate your thoughts on the expected behavior here. Thanks!