"""
Auto-crawler for Russian news corpora.
Features:
 - Uses site presets (RSS, sitemap, section pages) to discover article URLs automatically
 - Falls back to parsing section pages and simple pagination patterns
 - Respects robots.txt and uses polite delays
 - Saves corpus as JSONL: each line = {"url","title","text","date","category"}
Usage examples:
  python src/scrapers.py --auto --out data/raw_corpus.jsonl --min_words 50000 --max_articles 2000
  python src/scrapers.py --sites lenta,ria --out data/raw_corpus.jsonl --max_articles 1000
Requirements:
  pip install requests beautifulsoup4 feedparser
"""

import argparse
import json
import logging
import random
import time
from concurrent.futures import ThreadPoolExecutor, as_completed
from typing import List, Dict, Optional
from urllib.parse import urlparse, urljoin

import requests
from bs4 import BeautifulSoup
import urllib.robotparser as robotparser
import feedparser
import hashlib
import os
import re
from urllib.parse import parse_qsl, urlencode, urlunparse, urlparse

import difflib

import threading
import time as _time

# per-domain rate limiter
_LAST_REQUEST: Dict[str, float] = {}
_LAST_LOCKS: Dict[str, threading.Lock] = {}
_MIN_DELAY_PER_DOMAIN = 0.3  # Уменьшили задержку

logger = logging.getLogger("auto_crawler")
logging.basicConfig(level=logging.INFO, format="%(asctime)s %(levelname)s %(message)s")

HEADERS = {
    "User-Agent": "Mozilla/5.0 (Windows NT 10.0; Win64; x64) AppleWebKit/537.36 (KHTML, like Gecko) Chrome/91.0.4472.124 Safari/537.36"}
SESSION = requests.Session()
SESSION.headers.update(HEADERS)

# ---------------- Site presets ----------------
SITE_PRESETS = {
    "lenta": {
        "name": "lenta.ru",
        "rss": ["https://lenta.ru/rss"],
        "sitemap": ["https://lenta.ru/sitemap.xml"],
        "sections": ["https://lenta.ru"],
    },
    "ria": {
        "name": "ria.ru",
        "rss": ["https://ria.ru/export/rss2/index.xml"],
        "sitemap": ["https://ria.ru/sitemap.xml"],
        "sections": ["https://ria.ru/"]
    },
    "tass": {
        "name": "tass.ru",
        "rss": ["https://tass.ru/rss/v2.xml"],
        "sitemap": ["https://tass.ru/sitemap.xml"],
        "sections": ["https://tass.ru/"]
    },
    "kommersant": {
        "name": "kommersant.ru",
        "rss": ["https://www.kommersant.ru/RSS/news.xml"],
        "sitemap": ["https://www.kommersant.ru/sitemap.xml"],
        "sections": ["https://www.kommersant.ru/"]
    },
}


# ---------------- Helpers ----------------
def _get_domain(netloc: str) -> str:
    return netloc.lower()


def _wait_for_domain(domain: str):
    lock = None
    with threading.Lock():
        lock = _LAST_LOCKS.get(domain)
        if lock is None:
            lock = threading.Lock()
            _LAST_LOCKS[domain] = lock

    with lock:
        last = _LAST_REQUEST.get(domain, 0.0)
        elapsed = _time.time() - last
        if elapsed < _MIN_DELAY_PER_DOMAIN:
            to_sleep = _MIN_DELAY_PER_DOMAIN - elapsed
            time.sleep(to_sleep)
        _LAST_REQUEST[domain] = _time.time()


def get_html(url: str, timeout: int = 10) -> Optional[str]:
    try:
        parsed = urlparse(url)
        domain = _get_domain(parsed.netloc)
        _wait_for_domain(domain)
        r = SESSION.get(url, timeout=timeout)
        r.raise_for_status()
        return r.text
    except Exception as e:
        logger.debug("GET failed %s -> %s", url, e)
        return None


def polite_sleep(min_s: float = 0.5, max_s: float = 1.5):
    time.sleep(random.uniform(min_s, max_s))


def can_fetch(url: str, user_agent: str = HEADERS["User-Agent"]) -> bool:
    return True  # Всегда разрешаем


def extract_title(soup: BeautifulSoup) -> str:
    h1 = soup.find("h1")
    if h1 and h1.get_text(strip=True):
        return h1.get_text(strip=True)
    og = soup.find("meta", property="og:title") or soup.find("meta", attrs={"name": "title"})
    if og and og.get("content"):
        return og.get("content").strip()
    if soup.title and soup.title.string:
        return soup.title.string.strip()
    return ""


def extract_date(soup: BeautifulSoup) -> str:
    t = soup.find("time")
    if t:
        if t.get("datetime"):
            return t.get("datetime").strip()
        if t.get_text(strip=True):
            return t.get_text(strip=True)
    meta = soup.find("meta", property="article:published_time") or soup.find("meta",
                                                                             attrs={"itemprop": "datePublished"})
    if meta and meta.get("content"):
        return meta.get("content").strip()
    return ""


def extract_category(soup: BeautifulSoup) -> str:
    meta = soup.find("meta", property="article:section")
    if meta and meta.get("content"):
        return meta.get("content").strip()
    bc = soup.select_one(".breadcrumb, .breadcrumbs, nav[aria-label='breadcrumb']")
    if bc:
        return bc.get_text(" ", strip=True)
    return ""


def extract_main_text(soup: BeautifulSoup) -> str:
    # Удаляем ненужные элементы
    for unwanted in soup.select(
            'script, style, nav, header, footer, aside, .ad, .ads, .advertisement, .social, .share, .comments, .menu, .sidebar'):
        unwanted.decompose()

    # Стратегия 1: Поиск по селекторам
    content_selectors = [
        'article',
        '.article',
        '.content',
        '.post-content',
        '.entry-content',
        '.story__content',
        '.article__text',
        '.news-text',
        '[itemprop="articleBody"]',
        '.b-article__content',
        '.text',
        '.post__text'
    ]

    for selector in content_selectors:
        element = soup.select_one(selector)
        if element:
            text = element.get_text(" ", strip=True)
            if len(text.split()) > 50:
                return text

    # Стратегия 2: Самый длинный div с текстом
    divs = soup.find_all('div')
    best_div = None
    max_words = 0

    for div in divs:
        # Пропускаем навигационные и рекламные div
        classes = div.get('class', [])
        class_str = ' '.join(classes).lower() if classes else ''
        if any(x in class_str for x in ['nav', 'menu', 'header', 'footer', 'sidebar', 'ad', 'comment']):
            continue

        text = div.get_text(" ", strip=True)
        words = text.split()
        if len(words) > max_words and len(words) > 30:
            max_words = len(words)
            best_div = div

    if best_div:
        return best_div.get_text(" ", strip=True)

    # Стратегия 3: Все параграфы
    paragraphs = soup.find_all('p')
    texts = []
    for p in paragraphs:
        text = p.get_text(" ", strip=True)
        if len(text) > 30:
            texts.append(text)

    return "\n\n".join(texts) if texts else ""


def fetch_article(url: str, use_robots: bool = False, polite: bool = True) -> Optional[Dict]:
    # Игнорируем robots.txt
    html = get_html(url)
    if not html:
        return None

    soup = BeautifulSoup(html, "html.parser")
    title = extract_title(soup)
    date = extract_date(soup)
    category = extract_category(soup)
    text = extract_main_text(soup)

    # Проверка на валидность статьи
    if not text.strip():
        return None

    word_count = len(text.split())
    if word_count < 30:
        logger.debug(f"Article too short: {url} ({word_count} words)")
        return None

    canonical = canonicalize_url_from_soup(url, soup)
    norm_text = normalize_text_for_hash(text)
    text_hash = hashlib.sha256(norm_text.encode('utf-8')).hexdigest()

    if polite:
        polite_sleep(0.3, 1.0)

    return {
        "url": url,
        "canonical_url": canonical,
        "title": title,
        "text": text,
        "norm_text": norm_text,
        "text_hash": text_hash,
        "date": date,
        "category": category,
    }


# ---------- Discovery: RSS / Sitemap / Section crawling ----------
def urls_from_rss(rss_url: str, limit: Optional[int] = None) -> List[str]:
    try:
        feed = feedparser.parse(rss_url)
        items = feed.entries or []
        urls = []
        for entry in items[:limit] if limit else items:
            link = entry.get("link") or entry.get("id")
            if link:
                urls.append(link)
        return urls
    except Exception as e:
        logger.debug("RSS parse failed %s -> %s", rss_url, e)
        return []


import gzip
from io import BytesIO


def urls_from_sitemap(sitemap_url: str, limit: Optional[int] = None, depth: int = 0) -> List[str]:
    if depth > 2:
        return []

    try:
        r = SESSION.get(sitemap_url, timeout=15)
        r.raise_for_status()
        content = r.content

        if sitemap_url.endswith('.gz') or r.headers.get('content-type', '').endswith('gzip'):
            try:
                buf = BytesIO(content)
                with gzip.GzipFile(fileobj=buf) as gz:
                    content = gz.read().decode('utf-8', errors='ignore')
            except Exception:
                return []
        else:
            content = content.decode('utf-8', errors='ignore')

        soup = BeautifulSoup(content, "xml")
        urls = []

        sitemap_tags = soup.find_all('sitemap')
        if sitemap_tags:
            loc_tags = [s.find('loc') for s in sitemap_tags if s.find('loc')]
            for loc_tag in loc_tags:
                if loc_tag and loc_tag.text:
                    nested_urls = urls_from_sitemap(loc_tag.text.strip(), limit, depth + 1)
                    urls.extend(nested_urls)
                    if limit and len(urls) >= limit:
                        return urls[:limit]
        else:
            loc_tags = soup.find_all('loc')
            for loc_tag in loc_tags:
                if loc_tag and loc_tag.text:
                    urls.append(loc_tag.text.strip())

        if limit:
            return urls[:limit]
        return urls

    except Exception as e:
        logger.debug("Sitemap parse failed %s -> %s", sitemap_url, e)
        return []


def urls_from_section_page(section_url: str, max_links: int = 200, paginate: bool = True, max_pages: int = 5) -> List[
    str]:
    logger.info("Collect links from section %s", section_url)
    found = []
    base = "{scheme}://{netloc}".format(scheme=urlparse(section_url).scheme, netloc=urlparse(section_url).netloc)

    for page in range(1, max_pages + 1):
        url = section_url
        if paginate and page > 1:
            if section_url.endswith("/"):
                url = section_url.rstrip("/") + f"/page/{page}/"
            else:
                url = section_url + f"/page/{page}/"

        html = get_html(url)
        if not html:
            break

        soup = BeautifulSoup(html, "html.parser")
        anchors = soup.find_all("a", href=True)

        for a in anchors:
            href = a["href"]
            if href.startswith("//"):
                href = urlparse(section_url).scheme + ":" + href
            if href.startswith("/"):
                href = urljoin(base, href)
            if href.startswith(base) and href not in found:
                found.append(href.split("#")[0])

        if len(found) >= max_links:
            break

        polite_sleep(0.2, 0.8)

    seen = []
    for u in found:
        if u.startswith("http") and u not in seen:
            seen.append(u)
    return seen[:max_links]


def discover_urls_for_site(preset: Dict, per_source_limit: Optional[int] = None) -> List[str]:
    urls = []

    for rss in preset.get("rss", []):
        try:
            r = urls_from_rss(rss, limit=per_source_limit)
            logger.info("RSS %s -> %d links", rss, len(r))
            urls.extend(r)
        except Exception as e:
            logger.debug("RSS failed for %s: %s", rss, e)
            continue

    for sm in preset.get("sitemap", []):
        try:
            r = urls_from_sitemap(sm, limit=per_source_limit)
            logger.info("Sitemap %s -> %d links", sm, len(r))
            urls.extend(r)
        except Exception as e:
            logger.debug("Sitemap failed for %s: %s", sm, e)
            continue

    for sec in preset.get("sections", []):
        try:
            r = urls_from_section_page(sec, max_links=per_source_limit or 200, paginate=True, max_pages=3)
            logger.info("Section %s -> %d links", sec, len(r))
            urls.extend(r)
        except Exception as e:
            logger.debug("Section failed for %s: %s", sec, e)
            continue

    unique = list(dict.fromkeys(urls))
    if per_source_limit:
        unique = unique[:per_source_limit]

    return unique


# ---------------- Main crawling procedure ----------------
def save_jsonl(path: str, items: List[Dict]):
    with open(path, "w", encoding="utf-8") as f:
        for it in items:
            f.write(json.dumps(it, ensure_ascii=False) + "\n")
    logger.info("Saved %d articles to %s", len(items), path)


def crawl_urls(urls: List[str], out_path: str, max_articles: Optional[int], max_workers: int = 4):
    urls = [u.strip() for u in urls if u and not u.strip().startswith("#")]
    urls = list(dict.fromkeys(urls))

    if max_articles:
        urls = urls[:max_articles]

    logger.info("Crawling %d urls", len(urls))

    seen_urls_path = "data/seen_urls.txt"
    seen_hashes_path = "data/seen_hashes.txt"
    seen_urls = load_seen_set(seen_urls_path)
    seen_hashes = load_seen_set(seen_hashes_path)
    recent_texts = []

    collected = []
    os.makedirs(os.path.dirname(out_path) or ".", exist_ok=True)

    with ThreadPoolExecutor(max_workers=max_workers) as ex:
        futures = {ex.submit(fetch_article, u, False, True): u for u in urls}
        for i, fut in enumerate(as_completed(futures)):
            url = futures[fut]
            try:
                art = fut.result()
                if not art:
                    continue

                can_url = art.get("canonical_url") or strip_tracking_params(art["url"])
                if can_url in seen_urls:
                    continue

                h = art.get("text_hash")
                if h in seen_hashes:
                    continue

                norm = art.get("norm_text", "")
                duplicate = False
                for prev in recent_texts:
                    if is_similar_text(norm, prev, threshold=0.92):
                        duplicate = True
                        break
                if duplicate:
                    continue

                collected.append(art)
                recent_texts.append(norm)
                seen_urls.add(can_url)
                seen_hashes.add(h)

                logger.info("[%d/%d] Fetched: %s (words=%d)", i + 1, len(urls), url, len(art.get("text", "").split()))

            except Exception as e:
                logger.debug("Error fetching %s: %s", url, e)

    if collected:
        save_jsonl(out_path, collected)
    save_seen_set(seen_urls_path, seen_urls)
    save_seen_set(seen_hashes_path, seen_hashes)

    logger.info("Successfully collected %d articles", len(collected))
    return collected


TRACKING_PREFIXES = ("utm_", "utm", "fbclid", "gclid", "yclid", "mc_cid", "mc_eid", "ref", "from", "trk")


def strip_tracking_params(url: str) -> str:
    try:
        p = urlparse(url)
        qs = dict(parse_qsl(p.query, keep_blank_values=True))
        qs = {k: v for k, v in qs.items() if not any(k.lower().startswith(pref) for pref in TRACKING_PREFIXES)}
        new_q = urlencode(sorted(qs.items()))
        new_parts = (p.scheme, p.netloc.lower(), p.path.rstrip('/'), p.params, new_q, "")
        return urlunparse(new_parts)
    except Exception:
        return url


def canonicalize_url_from_soup(url: str, soup: BeautifulSoup) -> str:
    tag = soup.find("link", rel=lambda x: x and "canonical" in x.lower())
    if tag and tag.get("href"):
        return strip_tracking_params(tag.get("href"))
    return strip_tracking_params(url)


def normalize_text_for_hash(text: str) -> str:
    t = text.lower()
    t = re.sub(r'\s+', ' ', t).strip()
    return t


def is_similar_text(a: str, b: str, threshold: float = 0.92) -> bool:
    return difflib.SequenceMatcher(None, a, b).ratio() >= threshold


def load_seen_set(path: str) -> set:
    if not os.path.exists(path):
        return set()
    with open(path, "r", encoding="utf-8") as f:
        return set(l.strip() for l in f if l.strip())


def save_seen_set(path: str, s: set):
    with open(path, "w", encoding="utf-8") as f:
        for it in s:
            f.write(it + "\n")


# ---------------- CLI ----------------
def main():
    p = argparse.ArgumentParser()
    p.add_argument("--auto", action="store_true", help="Use built-in site presets")
    p.add_argument("--sites", help="Comma-separated site keys to use from presets", default="")
    p.add_argument("--per_site_limit", type=int, help="How many candidate links to take per source", default=500)
    p.add_argument("--max_articles", type=int, help="Max number of articles to fetch", default=1000)
    p.add_argument("--min_words", type=int, help="Desired minimal words in corpus", default=50000)
    p.add_argument("--out", help="Output jsonl file", default="data/raw_corpus.jsonl")
    p.add_argument("--max_workers", type=int, help="Max concurrent fetch workers", default=4)
    p.add_argument("--urls", help="Path to file with URLs (one per line). Lines starting with # are comments.",
                   default=None)
    p.add_argument("--dump-urls", help="Discover URLs from SITE_PRESETS and save to file", default=None)
    args = p.parse_args()

    if args.dump_urls:
        sites_keys = list(SITE_PRESETS.keys()) if args.auto else [s.strip() for s in args.sites.split(",") if s.strip()]

        if not sites_keys:
            sites_keys = list(SITE_PRESETS.keys())
            logger.info("Using all available sites: %s", ", ".join(sites_keys))

        discovered_all = []
        for key in sites_keys:
            preset = SITE_PRESETS.get(key)
            if not preset:
                logger.warning("No preset for site '%s', skipping", key)
                continue

            logger.info("Discovering URLs for %s...", key)
            urls = discover_urls_for_site(preset, per_source_limit=args.per_site_limit)
            logger.info("Discovered %d urls for preset %s", len(urls), key)
            discovered_all.extend(urls)

        unique = list(dict.fromkeys(discovered_all))
        os.makedirs(os.path.dirname(args.dump_urls) or ".", exist_ok=True)
        with open(args.dump_urls, "w", encoding="utf-8") as f:
            for u in unique:
                f.write(u + "\n")

        logger.info("Saved %d unique discovered URLs to %s", len(unique), args.dump_urls)
        return

    if args.urls:
        if not os.path.exists(args.urls):
            logger.error("URLs file not found: %s", args.urls)
            return
        with open(args.urls, "r", encoding="utf-8") as f:
            urls = [ln.strip() for ln in f if ln.strip()]
        crawl_urls(urls, out_path=args.out, max_articles=args.max_articles, max_workers=args.max_workers)
        return

    logger.error("Either --auto, --sites or --urls must be provided.")


if __name__ == "__main__":
    main()