"""Optional SMTP delivery of tenant reports."""
import asyncio
import smtplib
from email.mime.multipart import MIMEMultipart
from email.mime.text import MIMEText

from config import Settings


class MailNotConfigured(RuntimeError):
    pass


def _send_sync(s: Settings, to: str, subject: str, html: str):
    msg = MIMEMultipart("alternative")
    msg["Subject"] = subject
    msg["From"] = s.smtp_from
    msg["To"] = to
    msg.attach(MIMEText(html, "html"))

    with smtplib.SMTP(s.smtp_host, s.smtp_port, timeout=30) as server:
        if s.smtp_tls:
            server.starttls()
        if s.smtp_user:
            server.login(s.smtp_user, s.smtp_password)
        server.send_message(msg)


async def send_report(s: Settings, to: str, subject: str, html: str):
    if not s.smtp_host:
        raise MailNotConfigured(
            "SMTP not configured — set BILLING_SMTP_HOST etc. in .env"
        )
    await asyncio.to_thread(_send_sync, s, to, subject, html)