"""Faellige Erinnerungen als Mail verschicken.

Der Scheduler fragt die Datenbank ab, statt Timer im Speicher zu halten:
laeuft der Server zum Zeitpunkt einer Erinnerung nicht, wird sie beim
naechsten Start nachgeholt.
"""
import asyncio
import logging
from datetime import datetime, timezone

from . import config, db, mailer

log = logging.getLogger(__name__)

INTERVAL_SECONDS = 60


def _now() -> str:
    return datetime.now(timezone.utc).isoformat()


def _body(row) -> str:
    who = row["full_name"] or row["company"] or "Unbekannter Kontakt"
    lines = [row["text"], "", "-" * 40, f"Kontakt: {who}"]
    if row["company"] and row["full_name"]:
        lines.append(f"Firma: {row['company']}")
    if row["email"]:
        lines.append(f"E-Mail: {row['email']}")
    if row["phone"]:
        lines.append(f"Telefon: {row['phone']}")
    if row["mobile"]:
        lines.append(f"Mobil: {row['mobile']}")
    if row["place"]:
        lines.append(f"Kennengelernt in: {row['place']}")
    if config.PUBLIC_BASE_URL:
        lines += ["", f"{config.PUBLIC_BASE_URL}/#/karte/{row['card_id']}"]
    return "\n".join(lines)


def due_reminders() -> list:
    return db.query(
        """
        SELECT r.id, r.card_id, r.text, r.due_at,
               c.full_name, c.company, c.email, c.phone, c.mobile, c.place
        FROM reminders r
        JOIN cards c ON c.id = r.card_id
        WHERE r.sent_at IS NULL AND r.due_at <= ?
        ORDER BY r.due_at
        """,
        (_now(),),
    )


def process_due() -> int:
    """Alle faelligen Erinnerungen abarbeiten, Anzahl der Versendeten zurueck."""
    rows = due_reminders()
    if not rows:
        return 0
    if not mailer.configured():
        log.warning("%d faellige Erinnerung(en), aber kein SMTP konfiguriert", len(rows))
        return 0

    sent = 0
    for row in rows:
        who = row["full_name"] or row["company"] or "Kontakt"
        try:
            mailer.send(f"Erinnerung: {who}", _body(row))
        except Exception as exc:
            log.exception("Erinnerung %s konnte nicht verschickt werden", row["id"])
            db.execute(
                "UPDATE reminders SET send_error = ? WHERE id = ?",
                (f"{type(exc).__name__}: {exc}", row["id"]),
            )
            continue
        db.execute(
            "UPDATE reminders SET sent_at = ?, send_error = NULL WHERE id = ?",
            (_now(), row["id"]),
        )
        sent += 1
    return sent


async def run_forever() -> None:
    log.info("Erinnerungs-Scheduler gestartet (Intervall %ds)", INTERVAL_SECONDS)
    while True:
        try:
            await asyncio.to_thread(process_due)
        except Exception:
            log.exception("Scheduler-Durchlauf fehlgeschlagen")
        await asyncio.sleep(INTERVAL_SECONDS)