# app/services/mailer.py
import smtplib
import ssl
from email.message import EmailMessage
from typing import Optional

from loguru import logger
from app.core.config import get_app_settings


def _build_message(*, from_email: str, to_email: str, subject: str, html: str) -> EmailMessage:
    msg = EmailMessage()
    msg["From"] = from_email
    msg["To"] = to_email
    msg["Subject"] = subject
    msg.set_content("Your email client does not support HTML.")
    msg.add_alternative(html, subtype="html")
    return msg


def send_email(to_email: str, subject: str, html: str) -> bool:
    """
    同步发送；成功返回 True，失败返回 False，并打印详细日志。
    - 端口 465：使用 SMTP_SSL
    - 其他端口：使用 SMTP + (可选)STARTTLS
    """
    s = get_app_settings()
    from_email = str(s.mail_from)
    smtp_host = s.smtp_host
    smtp_port = int(s.smtp_port)
    smtp_user: Optional[str] = s.smtp_user.get_secret_value() if s.smtp_user else None
    smtp_pass: Optional[str] = s.smtp_password.get_secret_value() if s.smtp_password else None

    msg = _build_message(from_email=from_email, to_email=to_email, subject=subject, html=html)

    logger.info(
        "SMTP send start → host={} port={} tls={} from={} to={}",
        smtp_host, smtp_port, s.smtp_tls, from_email, to_email,
    )

    try:
        if smtp_port == 465:
            context = ssl.create_default_context()
            with smtplib.SMTP_SSL(smtp_host, smtp_port, context=context, timeout=20) as server:
                if smtp_user and smtp_pass:
                    server.login(smtp_user, smtp_pass)
                server.send_message(msg)
        else:
            with smtplib.SMTP(smtp_host, smtp_port, timeout=20) as server:
                server.ehlo()
                if s.smtp_tls:
                    context = ssl.create_default_context()
                    server.starttls(context=context)
                    server.ehlo()
                if smtp_user and smtp_pass:
                    server.login(smtp_user, smtp_pass)
                server.send_message(msg)

        logger.info("SMTP send OK to {}", to_email)
        return True

    except smtplib.SMTPResponseException as e:
        # 能拿到服务端 code/resp 的错误
        logger.error("SMTPResponseException: code={} msg={}", getattr(e, "smtp_code", None), getattr(e, "smtp_error", None))
        return False
    except Exception as e:
        logger.exception("SMTP send failed: {}", e)
        return False