"""Twitch live-stream status checks."""

import logging
from dataclasses import dataclass
from datetime import datetime, timedelta

import httpx

from app.config import settings

logger = logging.getLogger(__name__)

TWITCH_STREAMS_URL = "https://api.twitch.tv/helix/streams"
TWITCH_TOKEN_URL = "https://id.twitch.tv/oauth2/token"


@dataclass
class TwitchLiveStatus:
    """Cached Twitch live status for a channel."""

    channel_name: str
    is_live: bool
    checked_at: datetime
    title: str | None = None
    game_name: str | None = None
    started_at: str | None = None
    viewer_count: int | None = None
    reason: str | None = None

    def to_dict(self) -> dict:
        """Return a response-safe representation."""
        return {
            "channel": self.channel_name,
            "is_live": self.is_live,
            "checked_at": self.checked_at.isoformat(),
            "title": self.title,
            "game_name": self.game_name,
            "started_at": self.started_at,
            "viewer_count": self.viewer_count,
            "reason": self.reason,
        }


def _bearer_token(access_token: str) -> str:
    """Normalize a Twitch token for Helix Authorization."""
    token = access_token.strip()
    if token.startswith("oauth:"):
        return token.removeprefix("oauth:")
    return token


class TwitchLiveStatusService:
    """Small cached client for Twitch Helix stream status."""

    def __init__(self, cache_seconds: int = 60):
        self.cache_duration = timedelta(seconds=max(1, cache_seconds))
        self._cache: dict[str, TwitchLiveStatus] = {}
        self._app_access_token: str | None = None
        self._app_access_token_expires_at: datetime | None = None

    async def get_status(
        self,
        channel_name: str,
        force_refresh: bool = False,
    ) -> TwitchLiveStatus:
        """Return current live status for a channel, using a short cache."""
        normalized_channel = channel_name.strip().lower().lstrip("#")
        now = datetime.utcnow()
        cached = self._cache.get(normalized_channel)
        if (
            cached
            and not force_refresh
            and now - cached.checked_at < self.cache_duration
        ):
            return cached

        status = await self._fetch_status(normalized_channel, now)
        self._cache[normalized_channel] = status
        return status

    async def _fetch_status(
        self,
        channel_name: str,
        checked_at: datetime,
    ) -> TwitchLiveStatus:
        """Fetch live status from Twitch Helix."""
        if not settings.TWITCH_CLIENT_ID or not settings.TWITCH_ACCESS_TOKEN:
            return TwitchLiveStatus(
                channel_name=channel_name,
                is_live=False,
                checked_at=checked_at,
                reason="twitch_api_not_configured",
            )

        headers = {
            "Client-ID": settings.TWITCH_CLIENT_ID,
            "Authorization": f"Bearer {_bearer_token(settings.TWITCH_ACCESS_TOKEN)}",
        }
        params = {"user_login": channel_name}

        try:
            async with httpx.AsyncClient(timeout=10) as client:
                response = await client.get(
                    TWITCH_STREAMS_URL,
                    headers=headers,
                    params=params,
                )
                if response.status_code == 401:
                    app_access_token = await self._get_app_access_token(client)
                    if app_access_token:
                        headers["Authorization"] = f"Bearer {app_access_token}"
                        response = await client.get(
                            TWITCH_STREAMS_URL,
                            headers=headers,
                            params=params,
                        )
                response.raise_for_status()
        except Exception as e:
            logger.warning("Failed to check Twitch live status: %s", e)
            return TwitchLiveStatus(
                channel_name=channel_name,
                is_live=False,
                checked_at=checked_at,
                reason="twitch_api_error",
            )

        streams = response.json().get("data", [])
        if not streams:
            return TwitchLiveStatus(
                channel_name=channel_name,
                is_live=False,
                checked_at=checked_at,
                reason="stream_offline",
            )

        stream = streams[0]
        return TwitchLiveStatus(
            channel_name=channel_name,
            is_live=True,
            checked_at=checked_at,
            title=stream.get("title"),
            game_name=stream.get("game_name"),
            started_at=stream.get("started_at"),
            viewer_count=stream.get("viewer_count"),
        )

    async def _get_app_access_token(self, client: httpx.AsyncClient) -> str | None:
        """Get a Twitch app access token for Helix reads."""
        now = datetime.utcnow()
        if (
            self._app_access_token
            and self._app_access_token_expires_at
            and now < self._app_access_token_expires_at
        ):
            return self._app_access_token

        if not settings.TWITCH_CLIENT_ID or not settings.TWITCH_CLIENT_SECRET:
            return None

        try:
            response = await client.post(
                TWITCH_TOKEN_URL,
                data={
                    "client_id": settings.TWITCH_CLIENT_ID,
                    "client_secret": settings.TWITCH_CLIENT_SECRET,
                    "grant_type": "client_credentials",
                },
            )
            response.raise_for_status()
        except Exception as e:
            logger.warning("Failed to get Twitch app access token: %s", e)
            return None

        payload = response.json()
        access_token = payload.get("access_token")
        expires_in = int(payload.get("expires_in", 0))
        if not access_token:
            return None

        self._app_access_token = access_token
        self._app_access_token_expires_at = now + timedelta(
            seconds=max(60, expires_in - 60)
        )
        return access_token