from django.core.mail.backends.base import BaseEmailBackend

from .models import Message
from .tasks import send_message


class EmailBackend(BaseEmailBackend):
    '''
    A wrapper that manages a queued SMTP system.
    '''
    def send_messages(self, email_messages):
        if not email_messages:
            return
        num_sent = 0
        # TODO if multiple messages queue, else async?
        for message in email_messages:
            priority = message.extra_headers.get('X-Mail-Priority', Message.NORMAL)
            if priority == Message.CRITICAL:
                send_message(message).apply_async()
            else:
                content = message.message().as_string()
                for to_email in message.recipients():
                    message = Message.objects.create(
                        priority=priority,
                        to_address=to_email,
                        from_address=message.from_email,
                        subject=message.subject,
                        content=content,
                    )
            num_sent += 1
        return num_sent