import asyncio
import aiosmtplib
from email.mime.text import MIMEText
from email.mime.multipart import MIMEMultipart
from typing import Optional, Dict, Any
from .settings import settings

class EmailTask:
    def __init__(self, to_email: str, subject: str, body: str, html: Optional[str] = None, **kwargs):
        self.to_email = to_email
        self.subject = subject
        self.body = body
        self.html = html
        self.kwargs = kwargs

class EmailService:
    def __init__(self):
        self.queue = asyncio.Queue()
        self.worker_task: Optional[asyncio.Task] = None
        self.running = False

    async def start(self):
        """Start the email worker"""
        if self.running:
            return
        self.running = True
        self.worker_task = asyncio.create_task(self._worker())

    async def stop(self):
        """Stop the email worker"""
        if not self.running:
            return
        self.running = False
        if self.worker_task:
            self.worker_task.cancel()
            try:
                await self.worker_task
            except asyncio.CancelledError:
                pass

    async def send_email(self, to_email: str, subject: str, body: str, html: Optional[str] = None, **kwargs):
        """Queue an email for sending"""
        task = EmailTask(to_email, subject, body, html, **kwargs)
        await self.queue.put(task)

    async def _worker(self):
        """Email worker coroutine"""
        while self.running:
            try:
                # Wait for a task with timeout to allow checking running flag
                task = await asyncio.wait_for(self.queue.get(), timeout=1.0)
                await self._send_email_task(task)
                self.queue.task_done()
            except asyncio.TimeoutError:
                continue
            except Exception as e:
                # Log error, but continue processing
                print(f"Email worker error: {e}")
                continue

    async def _send_email_task(self, task: EmailTask):
        """Send a single email task"""
        if not settings.SMTP_HOST or not settings.SMTP_USERNAME or not settings.SMTP_PASSWORD:
            print("SMTP not configured, skipping email send")
            return

        msg = MIMEMultipart('alternative')
        msg['From'] = settings.SMTP_SENDER_EMAIL
        msg['To'] = task.to_email
        msg['Subject'] = task.subject

        # Add text part
        text_part = MIMEText(task.body, 'plain')
        msg.attach(text_part)

        # Add HTML part if provided
        if task.html:
            html_part = MIMEText(task.html, 'html')
            msg.attach(html_part)

        try:
            # Use implicit TLS for port 465 or when SMTP_USE_TLS is True
            if settings.SMTP_PORT == 465 or settings.SMTP_USE_TLS:
                async with aiosmtplib.SMTP(
                    hostname=settings.SMTP_HOST,
                    port=settings.SMTP_PORT,
                    username=settings.SMTP_USERNAME,
                    password=settings.SMTP_PASSWORD,
                    use_tls=True
                ) as smtp:
                    await smtp.send_message(msg)
                    print(f"Email sent to {task.to_email}")
            else:
                # Use STARTTLS for other ports
                async with aiosmtplib.SMTP(
                    hostname=settings.SMTP_HOST,
                    port=settings.SMTP_PORT,
                ) as smtp:
                    try:
                        await smtp.starttls()
                    except Exception as tls_error:
                        if "already using" in str(tls_error).lower() or "tls" in str(tls_error).lower():
                            # Connection is already using TLS, proceed without starttls
                            pass
                        else:
                            raise
                    await smtp.login(settings.SMTP_USERNAME, settings.SMTP_PASSWORD)
                    await smtp.send_message(msg)
                    print(f"Email sent to {task.to_email}")
        except Exception as e:
            print(f"Failed to send email to {task.to_email}: {e}")
            raise  # Re-raise to let caller handle

# Global email service instance
email_service = EmailService()

# Convenience functions
async def send_email(to_email: str, subject: str, body: str, html: Optional[str] = None, **kwargs):
    """Send an email asynchronously"""
    await email_service.send_email(to_email, subject, body, html, **kwargs)

def queue_email(to_email: str, subject: str, body: str, html: Optional[str] = None, **kwargs):
    """Queue an email for sending (fire and forget)"""
    asyncio.create_task(email_service.send_email(to_email, subject, body, html, **kwargs))