add email sending functionality with Django Ninja API

api/services.py

@@ -0,0 +1,64 @@
+from typing import Any
+
+from django.core.mail import get_connection, EmailMessage, EmailMultiAlternatives
+
+from api.models import MailProvider
+from api.schema import NewMailMessageIn, NewBulkMailMessageIn
+
+
+class MailProviderNotFound(Exception):
+    pass
+
+class EmailService:
+    def _get_mail_provider(self, from_email: str) -> MailProvider:
+        mail_provider = MailProvider.objects.filter(
+            from_email=from_email,
+        )
+
+        if not mail_provider.exists():
+            raise MailProviderNotFound()
+
+        return mail_provider.first()
+
+    def _get_connection(self, mail_provider: MailProvider):
+        return get_connection(
+            host=mail_provider.host,
+            port=mail_provider.port,
+            username=mail_provider.host_user,
+            password=mail_provider.host_password,
+            use_tls=mail_provider.use_tls,
+        )
+
+    def _build_email(self, dto: NewMailMessageIn, connection: Any) -> EmailMultiAlternatives:
+        email = EmailMultiAlternatives(
+            subject=dto.subject,
+            body=dto.body,
+            from_email=dto.from_email,
+            to=[dto.to],
+            cc=[dto.cc] if dto.cc else None,
+            bcc=[dto.bcc] if dto.bcc else None,
+            connection=connection,
+        )
+
+        if dto.html_body:
+            email.attach_alternative(dto.html_body, "text/html")
+
+        for attachment in dto.attachments:
+            email.attach(*attachment)
+
+        return email
+
+    def send_email(self, dto: NewMailMessageIn):
+        mail_provider = self._get_mail_provider(dto.from_email)
+        connection = self._get_connection(mail_provider)
+        email = self._build_email(dto, connection)
+        email.send()
+
+
+    def send_bulk_email(self, dto: NewBulkMailMessageIn):
+        mail_provider = self._get_mail_provider(dto.from_email)
+        connection = self._get_connection(mail_provider)
+        messages = [self._build_email(dto, connection) for dto in dto.messages]
+        connection.send_messages(messages)
+
+