feat(i18n): add language support for registration, password recovery,… Integrated i18n support in MailService for email templates

[lifefloating]

Email Internationalization (i18n) Implementation

Hi

Hi team, I hope you’re all doing well! I noticed in the project requirements that there’s a need to enhance internationalization support, so I’ve put together this PR to address that.

This PR adds complete internationalization support for the email system and optimizes the code implementation, making it more concise and maintainable.

I’d love to get your feedback on how this fits with our goals!

Source of Requirements

• Brocoders Boilerplates (view)

Functional Improvements

1. Internationalization Support

• Support for internationalized text in all email templates
• Currently supported languages: Ukrainian, English, Chinese, Spanish, French, German, Japanese, Russian, Portuguese, Arabic, Italian

2. Email Language Selection Logic

Implemented multi-level language selection logic:

• First prioritize the language specified by the user in the request
• Then use the language setting in the request header (x-custom-lang)
• Finally fall back to the system default language

3. Code Optimization

• Refactored MailService and MailerService to improve code readability and maintainability
• Extracted common methods, reducing code duplication

Email Template Improvements

• All email templates now support using the {{t 'key'}} syntax to retrieve translated text
• Complete internationalization for three types of emails:
  • Account activation emails
  • Password reset emails
  • New email confirmation emails

Authentication Process and User Experience

• Users can specify language preferences during registration
• Password recovery process supports language selection
• Support for obtaining language preferences from HTTP request headers

Testing

The internationalization functionality can be tested through the following methods:

1. Using the API for user registration and specifying the language parameter in the request body
2. Using the x-custom-lang request header to specify the language
3. Not specifying any language parameters to test default language behavior

This PR improves the user experience by ensuring email content aligns with users' language preferences while adding support for new languages to the system.

Thanks, best regards

test screenshots

[lifefloating]

@Shchepotin @sars @akhedrane @quarryman @gornostal
Hi @maintainers, just wanted to check if there’s any feedback or updates on this PR. Happy to address any questions or make adjustments if needed! Thanks!

[Shchepotin]

@lifefloating Excuse me for the long answer. All functionalities related to i18n have already been implemented. All information you can find here https://github.com/brocoders/nestjs-boilerplate/blob/main/docs/translations.md

[lifefloating]

thanks