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

from sqlalchemy.orm import Session

from app.models.system import SendLog
from app.services.config_store import get_config


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", ""),
        "use_tls": get_config(db, "smtp.use_tls", "true"),
        "recipients": get_config(db, "smtp.recipients", ""),
        "schedule_time": get_config(db, "smtp.schedule_time", "08:00"),
        "last_scheduled_date": get_config(db, "smtp.last_scheduled_date", ""),
    }


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

    msg = MIMEMultipart("alternative")
    msg.attach(MIMEText(text_content, "plain", "utf-8"))
    msg.attach(MIMEText(html_content, "html", "utf-8"))
    msg["Subject"] = subject
    msg["From"] = settings["from_email"]
    msg["To"] = ", ".join(recipients)

    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"], list(recipients), msg.as_string())
        detail = f"Versand erfolgreich an {len(recipients)} Empfänger."
        _log(db, subject, recipients, "sent", detail, scheduled)
        return "sent", detail
    except Exception as exc:
        detail = f"Versandfehler: {exc}"
        _log(db, subject, recipients, "failed", detail, scheduled)
        return "failed", detail


def run_scheduled_send_if_due(db: Session, subject: str, html_content: str, text_content: str) -> None:
    settings = get_smtp_settings(db)
    if settings["enabled"].lower() != "true":
        return
    now = datetime.now()
    schedule_time = settings["schedule_time"] or "08:00"
    if now.strftime("%H:%M") < schedule_time:
        return
    today = now.strftime("%Y-%m-%d")
    if settings["last_scheduled_date"] == today:
        return
    recipients = [r.strip() for r in settings["recipients"].split(",") if r.strip()]
    send_newsletter(db, subject, html_content, text_content, recipients, scheduled=True)
    from app.services.config_store import set_config

    set_config(db, "smtp.last_scheduled_date", today)


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()