from typing import List, Union
from django.core.mail import send_mail, EmailMessage
from django.contrib.auth import get_user_model
from django.template.loader import render_to_string
from django.conf import settings # To access EMAIL_HOST_USER, etc.
from recruitment.models import Message

UserModel = get_user_model()
User = UserModel # Type alias for clarity

class EmailService:
    """
    A service class for sending single or bulk emails.
    """

    def _send_email_internal(
        self,
        subject: str,
        body: str,
        recipient_list: List[str],
        context:dict,
        from_email: str = settings.DEFAULT_FROM_EMAIL,
        html_content: Union[str, None] = None,
    ) -> int:
        """
        Internal method to handle the actual sending using Django's email backend.
        """

        try:
            # Using EmailMessage for more control (e.g., HTML content)
           
            for recipient in recipient_list:
                email = EmailMessage(
                    subject=subject,
                    body=body,
                    from_email=from_email,
                    to=[recipient],
                )

                if html_content:
                    email.content_subtype = "html"  # Main content is HTML
                    email.body = html_content # Overwrite body with HTML

                # Returns the number of successfully sent emails (usually 1 or the count of recipients)
                result=email.send(fail_silently=False)
                recipient_user=User.objects.filter(email=recipient).first()
                if result and recipient_user and not context["message_created"]:
                    Message.objects.create(sender=context['sender_user'],recipient=recipient_user,job=context['job'],subject=subject,content=context['email_message'],message_type='DIRECT',is_read=False)
                

            return len(recipient_list)

        except Exception as e:
            # Log the error (in a real app, use Django's logger)
            print(f"Error sending email to {recipient_list}: {e}")
            return 0


    # def send_single_email(
    #     self,
    #     user: User,
    #     subject: str,
    #     template_name: str,
    #     context: dict,
    #     from_email: str = settings.DEFAULT_FROM_EMAIL
    # ) -> int:
    #     """
    #     Sends a single, template-based email to one user.
    #     """
    #     recipient_list = [user.email]

    #     # 1. Render content from template
    #     html_content = render_to_string(template_name, context)
    #     # You can optionally render a plain text version as well:
    #     # text_content = strip_tags(html_content)

    #     # 2. Call internal sender
    #     return self._send_email_internal(
    #         subject=subject,
    #         body="", # Can be empty if html_content is provided
    #         recipient_list=recipient_list,
    #         from_email=from_email,
    #         html_content=html_content
    #     )

    def send_email_service(
        self,
        recipient_emails: List[str],
        subject: str,
        template_name: str,
        context: dict,
        from_email: str = settings.DEFAULT_FROM_EMAIL
    ) -> int:
        """
        Sends the same template-based email to a list of email addresses.

        Note: Django's EmailMessage can handle multiple recipients in one
        transaction, which is often more efficient than sending them one-by-one.
        """

        # 1. Render content from template (once)
        html_content = render_to_string(template_name, context)

        # 2. Call internal sender with all recipients
        # The result here is usually 1 if successful, as it uses a single
        # EmailMessage call for all recipients.
        sent_count = self._send_email_internal(
            subject=subject,
            body="",
            recipient_list=recipient_emails,
            context=context,
            from_email=from_email,
            html_content=html_content,
            
        )

        # Return the count of recipients if successful, or 0 if failure
        return len(recipient_emails) if sent_count > 0 else 0