import logging
import smtplib
from datetime import datetime
from email.mime.multipart import MIMEMultipart
from email.mime.text import MIMEText
from email.utils import formataddr
from typing import Sequence

from sqlalchemy.orm import Session

from app.core.email_utils import parse_recipient_list
from app.models.system import SendLog
from app.services.config_store import get_config

logger = logging.getLogger("newsletter.smtp")


def get_smtp_settings(db: Session) -> dict[str, str]:
    return {
        "enabled": get_config(db, "smtp.enabled", "false"),
        "host": get_config(db, "smtp.host", ""),
        "port": get_config(db, "smtp.port", "587"),
        "username": get_config(db, "smtp.username", ""),
        "password": get_config(db, "smtp.password", ""),
        "from_email": get_config(db, "smtp.from_email", ""),
        "from_name": get_config(db, "smtp.from_name", ""),
        "reply_to": get_config(db, "smtp.reply_to", ""),
        "use_tls": get_config(db, "smtp.use_tls", "true"),
        "recipients": get_config(db, "smtp.recipients", ""),
        # Zeitplan
        "schedule_enabled": get_config(db, "smtp.schedule_enabled", "false"),
        "schedule_acknowledged": get_config(db, "smtp.schedule_acknowledged", "false"),
        "schedule_frequency": get_config(db, "smtp.schedule_frequency", "monthly"),
        "schedule_time": get_config(db, "smtp.schedule_time", "08:00"),
        "schedule_weekdays": get_config(db, "smtp.schedule_weekdays", "0"),
        "schedule_dom": get_config(db, "smtp.schedule_dom", "1"),
        "last_scheduled_date": get_config(db, "smtp.last_scheduled_date", ""),
        # Generierungs-Vorgaben für den geplanten Versand
        "gen_period": get_config(db, "smtp.gen_period", "last_month"),
        "gen_days": get_config(db, "smtp.gen_days", "30"),
        "gen_article_type": get_config(db, "smtp.gen_article_type", "new"),
        "gen_category": get_config(db, "smtp.gen_category", ""),
    }


def schedule_is_due(settings: dict[str, str], now: datetime) -> bool:
    """Prüft, ob laut Zeitplan jetzt ein Versand fällig ist (mit Tages-Dedupe)."""
    if settings["enabled"].lower() != "true":
        return False
    if (settings.get("schedule_enabled") or "false").lower() != "true":
        return False
    if (settings.get("schedule_acknowledged") or "false").lower() != "true":
        return False
    freq = (settings.get("schedule_frequency") or "off").lower()
    if freq == "off":
        return False

    schedule_time = settings.get("schedule_time") or "08:00"
    if now.strftime("%H:%M") < schedule_time:
        return False

    today = now.strftime("%Y-%m-%d")
    if settings.get("last_scheduled_date") == today:
        return False

    if freq == "daily":
        return True
    if freq == "weekly":
        weekdays = {d.strip() for d in (settings.get("schedule_weekdays") or "").split(",") if d.strip() != ""}
        return str(now.weekday()) in weekdays
    if freq == "monthly":
        try:
            dom = int(settings.get("schedule_dom") or "1")
        except ValueError:
            dom = 1
        return now.day == max(1, min(dom, 28))
    return False


def send_newsletter(
    db: Session,
    subject: str,
    html_content: str,
    text_content: str,
    recipients: Sequence[str],
    scheduled: bool = False,
) -> tuple[str, str]:
    settings = get_smtp_settings(db)
    if settings["enabled"].lower() != "true":
        detail = "SMTP ist deaktiviert. Bitte in der SMTP-Konfiguration aktivieren."
        _log(db, subject, recipients, "skipped", detail, scheduled)
        return "skipped", detail
    if not settings["host"] or not settings["from_email"] or not recipients:
        detail = "SMTP unvollständig konfiguriert (Host, Absender oder Empfänger fehlen)."
        _log(db, subject, recipients, "failed", detail, scheduled)
        return "failed", detail

    try:
        validated_recipients = parse_recipient_list(",".join(recipients))
    except ValueError as exc:
        detail = f"Ungültige Empfängerliste: {exc}"
        _log(db, subject, recipients, "failed", detail, scheduled)
        return "failed", detail

    msg = MIMEMultipart("alternative")
    msg.attach(MIMEText(text_content, "plain", "utf-8"))
    msg.attach(MIMEText(html_content, "html", "utf-8"))
    msg["Subject"] = subject
    if settings.get("from_name"):
        msg["From"] = formataddr((settings["from_name"], settings["from_email"]))
    else:
        msg["From"] = settings["from_email"]
    msg["To"] = settings["from_email"]
    msg["Bcc"] = ", ".join(validated_recipients)
    if settings.get("reply_to"):
        msg["Reply-To"] = settings["reply_to"]

    try:
        port = int(settings["port"])
        with smtplib.SMTP(settings["host"], port, timeout=20) as server:
            if settings["use_tls"].lower() == "true":
                server.starttls()
            if settings["username"]:
                server.login(settings["username"], settings["password"])
            server.sendmail(settings["from_email"], validated_recipients, msg.as_string())
        detail = f"Versand erfolgreich an {len(validated_recipients)} Empfänger."
        _log(db, subject, validated_recipients, "sent", detail, scheduled)
        return "sent", detail
    except Exception as exc:
        logger.exception("SMTP-Versand fehlgeschlagen")
        detail = "Versandfehler: E-Mail konnte nicht zugestellt werden. Details stehen im Server-Log."
        _log(db, subject, validated_recipients, "failed", detail, scheduled)
        return "failed", detail


def mark_scheduled_sent(db: Session, now: datetime) -> None:
    from app.services.config_store import set_config

    set_config(db, "smtp.last_scheduled_date", now.strftime("%Y-%m-%d"))


def _log(db: Session, subject: str, recipients: Sequence[str], status: str, detail: str, scheduled: bool) -> None:
    db.add(
        SendLog(
            subject=subject,
            recipients=", ".join(recipients) if recipients else "-",
            status=status,
            detail=detail,
            scheduled=scheduled,
        )
    )
    db.commit()