"""Effective notification channel config (DB overrides env)."""

from __future__ import annotations

from dataclasses import dataclass

from sqlalchemy import select
from sqlalchemy.orm import Session

from app.config import get_settings
from app.models.notification_channel import NotificationChannel

VALID_SEVERITIES = frozenset({"info", "warning", "high", "critical"})
CHANNEL_TELEGRAM = "telegram"


@dataclass(frozen=True)
class TelegramConfig:
    enabled: bool
    bot_token: str
    chat_id: str
    min_severity: str
    source: str  # env | db

    @property
    def configured(self) -> bool:
        return bool(self.bot_token.strip() and self.chat_id.strip())

    @property
    def active(self) -> bool:
        return self.enabled and self.configured


def _telegram_from_env() -> TelegramConfig:
    settings = get_settings()
    return TelegramConfig(
        enabled=bool(settings.telegram_enabled),
        bot_token=settings.telegram_bot_token.strip(),
        chat_id=settings.telegram_chat_id.strip(),
        min_severity=settings.telegram_min_severity.strip() or "high",
        source="env",
    )


def get_effective_telegram_config(db: Session | None = None) -> TelegramConfig:
    if db is None:
        from app.database import SessionLocal

        session = SessionLocal()
        try:
            return get_effective_telegram_config(session)
        finally:
            session.close()

    row = db.scalar(select(NotificationChannel).where(NotificationChannel.channel == CHANNEL_TELEGRAM))
    env_cfg = _telegram_from_env()
    if row is None:
        return env_cfg

    token = (row.bot_token or "").strip() or env_cfg.bot_token
    chat_id = (row.chat_id or "").strip() or env_cfg.chat_id
    min_sev = (row.min_severity or "").strip() or env_cfg.min_severity
    if min_sev not in VALID_SEVERITIES:
        min_sev = env_cfg.min_severity

    return TelegramConfig(
        enabled=bool(row.enabled),
        bot_token=token,
        chat_id=chat_id,
        min_severity=min_sev,
        source="db",
    )


def upsert_telegram_channel(
    db: Session,
    *,
    enabled: bool | None = None,
    bot_token: str | None = None,
    chat_id: str | None = None,
    min_severity: str | None = None,
) -> TelegramConfig:
    row = db.scalar(select(NotificationChannel).where(NotificationChannel.channel == CHANNEL_TELEGRAM))
    env_cfg = _telegram_from_env()

    if row is None:
        row = NotificationChannel(
            channel=CHANNEL_TELEGRAM,
            enabled=env_cfg.enabled,
            bot_token=env_cfg.bot_token or None,
            chat_id=env_cfg.chat_id or None,
            min_severity=env_cfg.min_severity,
        )
        db.add(row)

    if enabled is not None:
        row.enabled = enabled
    if min_severity is not None:
        if min_severity not in VALID_SEVERITIES:
            raise ValueError(f"invalid min_severity: {min_severity}")
        row.min_severity = min_severity
    if bot_token is not None and bot_token.strip():
        row.bot_token = bot_token.strip()
    if chat_id is not None and chat_id.strip():
        row.chat_id = chat_id.strip()

    db.commit()
    db.refresh(row)
    return get_effective_telegram_config(db)