TF-3515 Add save email as template feature

lib/features/email/domain/repository/email_repository.dart

@@ -131,6 +131,24 @@ abstract class EmailRepository {
     {CancelToken? cancelToken}
   );
 
+  Future<Email> saveEmailAsTemplate(
+    Session session,
+    AccountId accountId,
+    Email email,
+    {
+      CreateNewMailboxRequest? createNewMailboxRequest,
+      CancelToken? cancelToken
+    }
+  );
+
+  Future<Email> updateEmailTemplate(
+    Session session,
+    AccountId accountId,
+    Email newEmail,
+    EmailId oldEmailId,
+    {CancelToken? cancelToken}
+  );
+
   Future<({
     List<EmailId> emailIdsSuccess,
     Map<Id, SetError> mapErrors,

lib/features/email/domain/state/save_template_email_state.dart

@@ -0,0 +1,18 @@
+import 'package:core/presentation/state/failure.dart';
+import 'package:core/presentation/state/success.dart';
+import 'package:jmap_dart_client/jmap/mail/email/email.dart';
+
+class SavingTemplateEmail extends LoadingState {}
+
+class SaveTemplateEmailSuccess extends UIState {
+  SaveTemplateEmailSuccess(this.emailId);
+
+  final EmailId emailId;
+
+  @override
+  List<Object> get props => [emailId];
+}
+
+class SaveTemplateEmailFailure extends FeatureFailure {
+  SaveTemplateEmailFailure({super.exception});
+}

lib/features/email/domain/state/update_template_email_state.dart

@@ -0,0 +1,18 @@
+import 'package:core/presentation/state/failure.dart';
+import 'package:core/presentation/state/success.dart';
+import 'package:jmap_dart_client/jmap/mail/email/email.dart';
+
+class UpdatingTemplateEmail extends LoadingState {}
+
+class UpdateTemplateEmailSuccess extends UIState {
+  UpdateTemplateEmailSuccess(this.emailId);
+
+  final EmailId emailId;
+
+  @override
+  List<Object> get props => [emailId];
+}
+
+class UpdateTemplateEmailFailure extends FeatureFailure {
+  UpdateTemplateEmailFailure({super.exception});
+}

lib/features/email/domain/usecases/save_template_email_interactor.dart

@@ -0,0 +1,83 @@
+import 'package:core/presentation/state/failure.dart';
+import 'package:core/presentation/state/success.dart';
+import 'package:core/utils/app_logger.dart';
+import 'package:dartz/dartz.dart';
+import 'package:dio/dio.dart';
+import 'package:jmap_dart_client/jmap/mail/email/email.dart';
+import 'package:tmail_ui_user/features/composer/domain/repository/composer_repository.dart';
+import 'package:tmail_ui_user/features/composer/domain/state/generate_email_state.dart';
+import 'package:tmail_ui_user/features/composer/presentation/model/create_email_request.dart';
+import 'package:tmail_ui_user/features/email/domain/exceptions/email_exceptions.dart';
+import 'package:tmail_ui_user/features/email/domain/repository/email_repository.dart';
+import 'package:tmail_ui_user/features/email/domain/state/save_template_email_state.dart';
+import 'package:tmail_ui_user/features/email/domain/state/update_template_email_state.dart';
+import 'package:tmail_ui_user/features/mailbox/domain/model/create_new_mailbox_request.dart';
+
+class SaveTemplateEmailInteractor {
+  const SaveTemplateEmailInteractor(
+    this._composerRepository,
+    this._emailRepository,
+  );
+
+  final ComposerRepository _composerRepository;
+  final EmailRepository _emailRepository;
+
+  Stream<Either<Failure, Success>> execute({
+    required CreateEmailRequest createEmailRequest,
+    required CreateNewMailboxRequest? createNewMailboxRequest,
+    CancelToken? cancelToken,
+  }) async* {
+    yield Right(GenerateEmailLoading());
+
+    try {
+      final emailCreated = await _createEmailObject(createEmailRequest);
+
+      if (emailCreated == null) {
+        yield Left(GenerateEmailFailure(CannotCreateEmailObjectException()));
+        return;
+      }
+
+      if (createEmailRequest.templateEmailId != null) {
+        yield Right(UpdatingTemplateEmail());
+        final emailTemplateSaved = await _emailRepository.updateEmailTemplate(
+          createEmailRequest.session,
+          createEmailRequest.accountId,
+          emailCreated,
+          createEmailRequest.templateEmailId!,
+          cancelToken: cancelToken,
+        );
+        yield Right(UpdateTemplateEmailSuccess(emailTemplateSaved.id!));
+      } else {
+        yield Right(SavingTemplateEmail());
+        final emailTemplateSaved = await _emailRepository.saveEmailAsTemplate(
+          createEmailRequest.session,
+          createEmailRequest.accountId,
+          emailCreated,
+          createNewMailboxRequest: createNewMailboxRequest,
+          cancelToken: cancelToken,
+        );
+        yield Right(SaveTemplateEmailSuccess(emailTemplateSaved.id!));
+      }
+    } catch (e) {
+      logError('SaveTemplateEmailInteractor::execute(): $e');
+      if (createEmailRequest.templateEmailId != null) {
+        yield Left(UpdateTemplateEmailFailure(exception: e));
+      } else {
+        yield Left(SaveTemplateEmailFailure(exception: e));
+      }
+    }
+  }
+
+  Future<Email?> _createEmailObject(CreateEmailRequest createEmailRequest) async {
+    try {
+      final emailCreated = await _composerRepository.generateEmail(
+        createEmailRequest,
+        withIdentityHeader: true,
+        isTemplate: true);
+      return emailCreated;
+    } catch (e) {
+      logError('CreateNewAndSaveEmailToDraftsInteractor::_createEmailObject: Exception: $e');
+      return null;
+    }
+  }
+}