"""SMTP email notifications from SAC."""

from __future__ import annotations

import logging
import re
import smtplib
from email.mime.text import MIMEText

from sqlalchemy.orm import Session

from app.models import Event, Problem
from app.services.notification_severity import severity_meets_minimum
from app.services.notification_settings import EmailConfig, get_effective_email_config

logger = logging.getLogger(__name__)


class EmailNotConfiguredError(Exception):
    """Email disabled or missing SMTP settings."""


class EmailSendError(Exception):
    pass


def parse_mail_recipients(mail_to: str) -> list[str]:
    return [part.strip() for part in re.split(r"[,;]", mail_to) if part.strip()]


def send_email_message(
    subject: str,
    body: str,
    *,
    config: EmailConfig | None = None,
    force: bool = False,
) -> None:
    cfg = config or get_effective_email_config()
    if not force and not cfg.active:
        return
    if not cfg.configured:
        if force:
            raise EmailNotConfiguredError("SMTP: не задан host, from или to")
        return

    recipients = parse_mail_recipients(cfg.mail_to)
    if not recipients:
        if force:
            raise EmailNotConfiguredError("SMTP: список получателей пуст")
        return

    msg = MIMEText(body, "plain", "utf-8")
    msg["Subject"] = subject
    msg["From"] = cfg.mail_from
    msg["To"] = ", ".join(recipients)

    try:
        if cfg.smtp_ssl:
            server: smtplib.SMTP = smtplib.SMTP_SSL(cfg.smtp_host, cfg.smtp_port, timeout=12)
        else:
            server = smtplib.SMTP(cfg.smtp_host, cfg.smtp_port, timeout=12)
        with server:
            server.ehlo()
            if cfg.smtp_starttls and not cfg.smtp_ssl:
                server.starttls()
                server.ehlo()
            if cfg.smtp_user:
                server.login(cfg.smtp_user, cfg.smtp_password)
            server.sendmail(cfg.mail_from, recipients, msg.as_string())
    except Exception as exc:
        logger.exception("smtp send failed")
        raise EmailSendError(str(exc)) from exc


def send_email_test_message(*, config: EmailConfig | None = None) -> None:
    cfg = config or get_effective_email_config()
    if not cfg.enabled:
        raise EmailNotConfiguredError("Email отключён (enabled=false)")
    if not cfg.configured:
        raise EmailNotConfiguredError("Не задан SMTP host, from или to")
    send_email_message(
        "SAC: тестовое письмо",
        "Тестовое сообщение Security Alert Center.\nКанал SMTP для оповещений работает.",
        config=cfg,
        force=True,
    )


def notify_event(event: Event, *, db: Session | None = None, apply_policy_gate: bool = True) -> None:
    cfg = get_effective_email_config(db)
    if not cfg.active:
        return
    if apply_policy_gate and not severity_meets_minimum(event.severity, cfg.min_severity):
        return
    host = event.host.hostname if event.host else "unknown"
    body = (
        f"SAC событие\n"
        f"Host: {host}\n"
        f"Severity: {event.severity}\n"
        f"Type: {event.type}\n"
        f"Title: {event.title}\n"
        f"Summary: {event.summary}"
    )
    try:
        send_email_message(f"SAC: {event.type} ({event.severity})", body, config=cfg)
    except EmailSendError:
        logger.exception("notify_event email failed event_id=%s", event.event_id)


def notify_problem(problem: Problem, event: Event | None = None, *, db: Session | None = None, apply_policy_gate: bool = True) -> None:
    cfg = get_effective_email_config(db)
    if not cfg.active:
        return
    if apply_policy_gate and not severity_meets_minimum(problem.severity, cfg.min_severity):
        return
    host = problem.host.hostname if problem.host else "unknown"
    related = ""
    if event is not None:
        related = f"\nEvent: {event.type} ({event.severity})"
    body = (
        f"SAC Problem opened\n"
        f"Host: {host}\n"
        f"Severity: {problem.severity}\n"
        f"Rule: {problem.rule_id or '-'}\n"
        f"Title: {problem.title}\n"
        f"Summary: {problem.summary}{related}"
    )
    try:
        send_email_message(f"SAC Problem: {problem.title}", body, config=cfg)
    except EmailSendError:
        logger.exception("notify_problem email failed problem_id=%s", problem.id)