import asyncio
from datetime import datetime

import requests

RSS_URL_ARTICLES = "https://habr.com/ru/rss/hubs/artificial_intelligence/articles/top/daily/?fl=ru"
RSS_URL_POSTS = "https://habr.com/ru/rss/hubs/artificial_intelligence/news/top/daily/?fl=ru"

_session = requests.Session()


async def fetch_rss(url):
    """Скачать и распарсить RSS-ленту (RSS 2.0 / Atom)."""
    from xml.etree import ElementTree

    try:
        response = await asyncio.to_thread(_session.get, url, timeout=10)
        response.raise_for_status()
        root = ElementTree.fromstring(response.content)

        # RSS 2.0
        ns_dc = {"dc": "http://purl.org/dc/elements/1.1/"}
        items = root.findall(".//item")
        if not items:
            # Atom
            ns = {"atom": "http://www.w3.org/2005/Atom"}
            items = root.findall("atom:entry", ns)
        if not items:
            return []

        articles = []
        for entry in items:
            # RSS 2.0
            title_el = entry.find("title")
            date_el = entry.find("pubDate")
            creator_el = entry.find("dc:creator", ns_dc)
            categories = entry.findall("category")

            # guid с isPermaLink="true" для чистого URL
            guid_el = entry.find("guid[@isPermaLink='true']")
            link = guid_el.text if guid_el is not None else ""

            # Atom fallback
            if title_el is None:
                ns = {"atom": "http://www.w3.org/2005/Atom"}
                title_el = entry.find("atom:title", ns)
                link_el = entry.find("atom:link", ns)
                link = link_el.get("href", "") if link_el is not None else ""
                date_el = entry.find("atom:published", ns)
                creator_el = entry.find("atom:author/atom:name", ns)
                categories = entry.findall("atom:category", ns)

            title = title_el.text if title_el is not None else "Без названия"
            pub_date = date_el.text if date_el is not None else ""
            creator = creator_el.text if creator_el is not None else ""
            tags = [cat.text for cat in categories if cat.text] if categories else []

            articles.append({
                "title": title,
                "link": link,
                "pub_date": pub_date,
                "creator": creator,
                "tags": tags,
            })
        return articles[:10]
    except requests.exceptions.RequestException:
        return None


def _parse_date(pub_date):
    """Парсить дату из RSS в строку 'дд.мм.гггг' или вернуть часть даты."""
    if not pub_date:
        return ""
    try:
        d = pub_date.replace(" GMT", " +0000")
        dt = datetime.strptime(d, "%a, %d %b %Y %H:%M:%S %z")
        return dt.strftime("%d.%m.%Y")
    except ValueError:
        return pub_date[:10].replace("-", ".")


def truncate_title(title, max_len=60):
    """Обрезать заголовок, если он длиннее max_len."""
    if len(title) > max_len:
        return title[:max_len] + "..."
    return title


def format_articles(articles, title, link):
    """Сформировать список строк для вывода статей/постов."""
    lines = [f"**{title}**\n<{link}>"]
    for i, article in enumerate(articles[:5], 1):
        date_str = _parse_date(article["pub_date"])
        short_title = truncate_title(article["title"])
        lines.append(f"{short_title}\n{date_str}   <{article['link']}>")
    return lines