"""YouTube RSS feed poller for Meet Kevin channel."""

import logging
from dataclasses import dataclass
from datetime import datetime
from xml.etree import ElementTree as ET

import httpx

logger = logging.getLogger(__name__)

# Atom and YouTube namespace mappings
_NAMESPACES = {
    "a": "http://www.w3.org/2005/Atom",
    "yt": "http://www.youtube.com/xml/schemas/2015",
    "m": "http://search.yahoo.com/mrss/",
}


@dataclass(frozen=True)
class DiscoveredVideo:
    """A video discovered from YouTube RSS feed."""

    youtube_video_id: str
    title: str
    description: str
    published_at: datetime
    thumbnail_url: str


async def fetch_feed(channel_id: str, client: httpx.AsyncClient) -> bytes:
    """Fetch YouTube RSS feed for a channel.

    Args:
        channel_id: YouTube channel ID (e.g., "UCUvvj5lwue7PspotMDjk5UA")
        client: httpx AsyncClient for HTTP requests

    Returns:
        Raw XML bytes from the feed, or empty bytes on error.
        HTTP errors are logged but do not raise.
    """
    url = f"https://www.youtube.com/feeds/videos.xml?channel_id={channel_id}"

    try:
        response = await client.get(url, timeout=15.0)
        response.raise_for_status()
        return response.content
    except httpx.HTTPError as e:
        logger.warning("Failed to fetch feed from %s: %s", url, e)
        return b""


def parse_feed(xml_bytes: bytes) -> list[DiscoveredVideo]:
    """Parse YouTube RSS feed XML and extract videos.

    Args:
        xml_bytes: Raw XML bytes from YouTube RSS feed

    Returns:
        List of DiscoveredVideo objects. Returns empty list on parse error,
        empty input, or if no valid entries found.
        Individual entries with missing required fields are skipped.
    """
    if not xml_bytes:
        return []

    try:
        root = ET.fromstring(xml_bytes)
    except ET.ParseError as e:
        logger.warning("Failed to parse feed XML: %s", e)
        return []

    videos: list[DiscoveredVideo] = []

    for entry in root.findall("a:entry", _NAMESPACES):
        try:
            # Extract required fields
            video_id_elem = entry.find("yt:videoId", _NAMESPACES)
            title_elem = entry.find("a:title", _NAMESPACES)
            published_elem = entry.find("a:published", _NAMESPACES)

            # Extract media group (description and thumbnail)
            media_group = entry.find("m:group", _NAMESPACES)
            desc_elem = None
            thumb_elem = None
            if media_group is not None:
                desc_elem = media_group.find("m:description", _NAMESPACES)
                thumb_elem = media_group.find("m:thumbnail", _NAMESPACES)

            # Skip entries with missing required fields
            if (
                video_id_elem is None
                or video_id_elem.text is None
                or title_elem is None
                or title_elem.text is None
                or published_elem is None
                or published_elem.text is None
                or thumb_elem is None
            ):
                continue

            # Parse published timestamp (handle Z suffix)
            published_text = published_elem.text
            published_text = published_text.replace("Z", "+00:00")
            published_at = datetime.fromisoformat(published_text)

            # Extract description (may be missing)
            description = ""
            if desc_elem is not None and desc_elem.text is not None:
                description = desc_elem.text

            # Extract thumbnail URL
            thumbnail_url = thumb_elem.get("url", "")
            if not thumbnail_url:
                continue

            video = DiscoveredVideo(
                youtube_video_id=video_id_elem.text,
                title=title_elem.text,
                description=description,
                published_at=published_at,
                thumbnail_url=thumbnail_url,
            )
            videos.append(video)

        except (ValueError, AttributeError) as e:
            logger.warning("Failed to parse entry in feed: %s", e)
            continue

    return videos