"""Minimal SMTP sender for owner/customer notifications.

Deliberately stdlib-only (smtplib + email) — no new dependency, no queue, no
broker. Mail is sent on a daemon thread so a slow or dead SMTP host never makes
the visitor wait, and a failure is logged rather than raised: the demo request
is already committed to the database by the time we get here, so the owner can
always see it in /admin/demos even if mail is misconfigured.
"""

import logging
import smtplib
import threading
from email.message import EmailMessage
from email.utils import formataddr, parseaddr

mail_log = logging.getLogger("jqc.mail")


def mail_enabled(config):
    """Mail can only go out with a host and a From address configured."""
    return bool(config.get("SMTP_HOST") and config.get("MAIL_FROM"))


def _clean_header(value):
    """Strip CR/LF so a user-supplied name can't inject extra headers."""
    return " ".join(str(value or "").split())[:200]


def send_email(config, to, subject, body, reply_to=None, reply_name=None):
    """Send one plain-text mail. Returns True on success, False otherwise.
    Never raises — callers treat mail as best-effort."""
    if not mail_enabled(config) or not to:
        mail_log.info("Mail skipped (SMTP not configured): %s", _clean_header(subject))
        return False

    prefix = config.get("MAIL_SUBJECT_PREFIX", "")
    msg = EmailMessage()
    msg["Subject"] = _clean_header(f"{prefix} {subject}".strip())
    msg["From"] = config["MAIL_FROM"]
    msg["To"] = to
    if reply_to:
        addr = parseaddr(_clean_header(reply_to))[1]
        if addr:
            msg["Reply-To"] = formataddr((_clean_header(reply_name), addr))
    msg.set_content(body)

    host = config["SMTP_HOST"]
    port = config.get("SMTP_PORT", 587)
    timeout = config.get("SMTP_TIMEOUT", 20)
    try:
        if config.get("SMTP_USE_SSL"):
            server = smtplib.SMTP_SSL(host, port, timeout=timeout)
        else:
            server = smtplib.SMTP(host, port, timeout=timeout)
        with server:
            server.ehlo()
            if config.get("SMTP_USE_TLS") and not config.get("SMTP_USE_SSL"):
                server.starttls()
                server.ehlo()
            if config.get("SMTP_USER"):
                server.login(config["SMTP_USER"], config.get("SMTP_PASSWORD", ""))
            server.send_message(msg)
        mail_log.info("Mail sent to %s: %s", to, msg["Subject"])
        return True
    except Exception as exc:  # noqa: BLE001 - mail must never break the request
        mail_log.error("Mail to %s failed: %s", to, exc)
        return False


def send_email_async(config, to, subject, body, reply_to=None, reply_name=None):
    """Fire-and-forget wrapper. `config` is copied to a plain dict first so the
    thread never touches the Flask app/request context."""
    cfg = {k: config.get(k) for k in (
        "SMTP_HOST", "SMTP_PORT", "SMTP_USER", "SMTP_PASSWORD", "SMTP_USE_TLS",
        "SMTP_USE_SSL", "SMTP_TIMEOUT", "MAIL_FROM", "MAIL_SUBJECT_PREFIX",
    )}
    thread = threading.Thread(
        target=send_email,
        args=(cfg, to, subject, body),
        kwargs={"reply_to": reply_to, "reply_name": reply_name},
        daemon=True,
    )
    thread.start()
    return thread