import requests
from bs4 import BeautifulSoup
import feedparser
import trafilatura
from urllib.parse import urlparse
import time
import logging
from datetime import datetime
from typing import List, Dict, Optional, Set
import hashlib
import re
from langdetect import detect
import random
from requests.adapters import HTTPAdapter
from urllib3.util.retry import Retry

logger = logging.getLogger(__name__)

class NewsletterScraper:
    """Robust news scraper with multiple sources, redirect resolution, and deduplication"""

    def __init__(self):
        self.session = self._create_session()
        self.scraped_urls: Set[str] = set()
        self.content_hashes: Set[str] = set()

        # News sources configuration
        self.rss_sources = {
            'google_news': 'https://news.google.com/rss/search?q={}&hl=en&gl=US&ceid=US:en',
            'yahoo_finance': 'https://feeds.finance.yahoo.com/rss/2.0/headline',
            'reuters_business': 'https://www.reutersagency.com/feed/?best-topics=business-finance&post_type=best',
            'bbc_business': 'http://feeds.bbci.co.uk/news/business/rss.xml',
            'cnbc': 'https://www.cnbc.com/id/100003114/device/rss/rss.html',
            'marketwatch': 'http://feeds.marketwatch.com/marketwatch/topstories/',
            'financial_times': 'https://www.ft.com/rss/home',
            'bloomberg': 'https://feeds.bloomberg.com/politics/news.rss'
        }

        self.user_agents = [
            'Mozilla/5.0 (Windows NT 10.0; Win64; x64) AppleWebKit/537.36 (KHTML, like Gecko) Chrome/123.0.0.0 Safari/537.36',
            'Mozilla/5.0 (Macintosh; Intel Mac OS X 13_0) AppleWebKit/605.1.15 (KHTML, like Gecko) Version/16.0 Safari/605.1.15',
            'Mozilla/5.0 (X11; Linux x86_64) AppleWebKit/537.36 (KHTML, like Gecko) Chrome/123.0.0.0 Safari/537.36',
            'Mozilla/5.0 (Windows NT 10.0; Win64; x64; rv:121.0) Gecko/20100101 Firefox/121.0',
            'Mozilla/5.0 (Macintosh; Intel Mac OS X 12.6; rv:121.0) Gecko/20100101 Firefox/121.0'
        ]

        logger.info("NewsletterScraper initialized")

    # -------------------------------------------------------------------------
    # Session + headers
    # -------------------------------------------------------------------------
    def _create_session(self) -> requests.Session:
        """Create a session with retry strategy and default timeouts."""
        session = requests.Session()

        retry_strategy = Retry(
            total=3,
            backoff_factor=1,
            status_forcelist=[429, 500, 502, 503, 504],
            allowed_methods=["GET", "HEAD"],
            raise_on_status=False,
        )

        adapter = HTTPAdapter(max_retries=retry_strategy, pool_connections=20, pool_maxsize=20)
        session.mount("http://", adapter)
        session.mount("https://", adapter)

        # Default timeouts for all requests via session
        session.request = self._with_timeout(session.request, timeout=10)
        return session

    @staticmethod
    def _with_timeout(func, timeout: int = 10):
        """Wrap session.request to always include a timeout unless explicitly provided."""
        def wrapper(method, url, **kwargs):
            if "timeout" not in kwargs:
                kwargs["timeout"] = timeout
            return func(method, url, **kwargs)
        return wrapper

    def _get_random_headers(self) -> Dict[str, str]:
        """Get randomized headers to avoid blocking."""
        return {
            'User-Agent': random.choice(self.user_agents),
            'Accept': 'text/html,application/xhtml+xml,application/xml;q=0.9,image/webp,*/*;q=0.8',
            'Accept-Language': 'en-US,en;q=0.9',
            'Accept-Encoding': 'gzip, deflate, br',
            'Connection': 'keep-alive',
            'Upgrade-Insecure-Requests': '1',
        }

    # -------------------------------------------------------------------------
    # Public entrypoint
    # -------------------------------------------------------------------------
    def scrape_news(self, query: str, max_articles: int = 20) -> List[Dict]:
        """Main scraping function."""
        logger.info(f"Starting news scraping for query: {query}")
        all_articles: List[Dict] = []
        self.scraped_urls.clear()
        self.content_hashes.clear()

        try:
            # Primary: Google News RSS
            from requests.utils import quote
            google_url = self.rss_sources['google_news'].format(quote(query))
            google_articles = self._scrape_google_news(google_url, query, max_articles // 2 or 5)
            all_articles.extend(google_articles)

            # Secondary: a few other RSS sources
            for source_name, rss_url in list(self.rss_sources.items())[1:4]:
                if len(all_articles) >= max_articles:
                    break
                try:
                    source_articles = self._scrape_rss_source(rss_url, query, 5)
                    all_articles.extend(source_articles)
                except Exception as e:
                    logger.warning(f"Failed to scrape {source_name}: {str(e)}")
                    continue

            # Deduplicate and filter
            articles = self._deduplicate_articles(all_articles)
            articles = self._filter_articles(articles, query)
            articles = articles[:max_articles]

            # Extract full content (after resolving redirects)
            for article in articles:
                try:
                    full_content = self._extract_full_content(article['url'])
                    if full_content and len(full_content) > 200:
                        article['content'] = full_content
                    else:
                        # Fallback to cleaned summary/title
                        fallback = article.get('summary') or article.get('title', '')
                        article['content'] = clean_html(fallback) if '<' in fallback else fallback
                except Exception as e:
                    logger.warning(f"Failed to extract content from {article['url']}: {str(e)}")
                    fallback = article.get('summary') or article.get('title', '')
                    article['content'] = clean_html(fallback) if '<' in fallback else fallback

            # Filter by language (English only)
            articles = [a for a in articles if self._is_english(a.get('content', ''))]

            logger.info(f"Successfully scraped {len(articles)} articles")
            return articles

        except Exception as e:
            logger.error(f"Error in scrape_news: {str(e)}")
            return []

    # -------------------------------------------------------------------------
    # Source-specific + generic RSS
    # -------------------------------------------------------------------------
    def _scrape_google_news(self, url: str, query: str, max_articles: int) -> List[Dict]:
        """Scrape Google News RSS and resolve to publisher URLs."""
        try:
            headers = self._get_random_headers()
            response = self.session.get(url, headers=headers)
            if response.status_code != 200:
                logger.warning(f"Google News RSS returned status {response.status_code}")
                return []

            feed = feedparser.parse(response.content)
            articles: List[Dict] = []
            q = query.lower()

            for entry in feed.entries[:max_articles * 2]:  # extra for filtering
                try:
                    raw_title = entry.get('title', '') or ''
                    raw_summary = entry.get('summary', '') or ''
                    link = entry.get('link', '') or ''

                    # Strip HTML if present in title/summary
                    title = clean_html(raw_title) if '<' in raw_title else raw_title
                    summary = clean_html(raw_summary) if '<' in raw_summary else raw_summary

                    # Soft query match
                    if not (q in title.lower() or q in summary.lower()):
                        continue

                    article = {
                        'title': title.strip(),
                        'url': link,
                        'summary': summary.strip(),
                        'date': self._parse_date(entry.get('published', '')),
                        'source': 'Google News'
                    }

                    # Try to resolve redirect to publisher and set clean source
                    try:
                        r = self.session.get(link, headers=headers, allow_redirects=True)
                        final_url = r.url if r is not None and r.url else link
                        article['url'] = final_url
                        article['source'] = self._extract_source_name(final_url)
                    except Exception as e:
                        logger.debug(f"Redirect resolution failed for Google link: {e}")

                    if article['url'] in self.scraped_urls:
                        continue

                    self.scraped_urls.add(article['url'])
                    articles.append(article)

                except Exception as e:
                    logger.warning(f"Error parsing Google News entry: {str(e)}")
                    continue

            return articles

        except Exception as e:
            logger.error(f"Error scraping Google News: {str(e)}")
            return []

    def _scrape_rss_source(self, rss_url: str, query: str, max_articles: int) -> List[Dict]:
        """Scrape a generic RSS source and soft-filter by query."""
        try:
            headers = self._get_random_headers()
            response = self.session.get(rss_url, headers=headers)
            if response.status_code != 200:
                return []

            feed = feedparser.parse(response.content)
            articles: List[Dict] = []
            q = query.lower()

            for entry in feed.entries[:max_articles * 3]:
                try:
                    title = entry.get('title', '') or ''
                    summary = entry.get('summary', '') or ''
                    link = entry.get('link', '') or ''

                    if not (q in title.lower() or q in summary.lower()):
                        continue

                    # Clean HTML artifacts
                    title = clean_html(title) if '<' in title else title
                    summary = clean_html(summary) if '<' in summary else summary

                    article = {
                        'title': title.strip(),
                        'url': link,
                        'summary': summary.strip(),
                        'date': self._parse_date(entry.get('published', '')),
                        'source': self._extract_source_name(rss_url)
                    }

                    # Resolve potential redirects to get publisher domain
                    try:
                        r = self.session.get(link, headers=headers, allow_redirects=True)
                        final_url = r.url if r is not None and r.url else link
                        article['url'] = final_url
                        article['source'] = self._extract_source_name(final_url)
                    except Exception:
                        pass

                    if article['url'] in self.scraped_urls:
                        continue

                    self.scraped_urls.add(article['url'])
                    articles.append(article)

                    if len(articles) >= max_articles:
                        break

                except Exception as e:
                    logger.warning(f"Error parsing RSS entry: {str(e)}")
                    continue

            time.sleep(0.4)  # be polite
            return articles

        except Exception as e:
            logger.error(f"Error scraping RSS {rss_url}: {str(e)}")
            return []

    # -------------------------------------------------------------------------
    # Extraction + cleaning
    # -------------------------------------------------------------------------
    def _extract_full_content(self, url: str) -> Optional[str]:
        """
        Extract full article content; resolve redirects; parse with trafilatura.
        """
        try:
            headers = self._get_random_headers()

            # If it's a Google News link, follow redirects to the publisher URL
            parsed = urlparse(url)
            if parsed.netloc.endswith("news.google.com"):
                try:
                    resp = self.session.get(url, headers=headers, allow_redirects=True)
                    if resp is not None and resp.url and resp.status_code in (200, 301, 302):
                        url = resp.url
                except Exception as e:
                    logger.warning(f"Failed to resolve Google News redirect: {e}")

            # 1st try: fetch HTML with our session (so we control headers)
            downloaded_html = None
            try:
                r = self.session.get(url, headers=headers, allow_redirects=True)
                if r is not None and r.status_code == 200:
                    downloaded_html = r.text
            except Exception as e:
                logger.debug(f"requests fetch failed, will try trafilatura.fetch_url: {e}")

            # Fallback: let trafilatura fetch the URL itself (no headers param)
            if not downloaded_html:
                downloaded_html = trafilatura.fetch_url(url)

            if not downloaded_html:
                return None

            # Extract readable text
            text = trafilatura.extract(
                downloaded_html,
                include_comments=False,
                include_tables=False,
                include_formatting=False,
                no_fallback=False,
            )
            if text and len(text.strip()) > 100:
                return text.strip()
            return None

        except Exception as e:
            logger.warning(f"Error extracting content from {url}: {str(e)}")
            return None

    # -------------------------------------------------------------------------
    # Post-processing helpers
    # -------------------------------------------------------------------------
    def _deduplicate_articles(self, articles: List[Dict]) -> List[Dict]:
        """Remove duplicate articles based on title+summary similarity."""
        unique_articles: List[Dict] = []

        for article in articles:
            content_for_hash = f"{article.get('title','')} {article.get('summary','')}"
            content_hash = hashlib.md5(content_for_hash.encode()).hexdigest()

            if content_hash not in self.content_hashes:
                self.content_hashes.add(content_hash)
                unique_articles.append(article)

        logger.info(f"Deduplicated {len(articles)} -> {len(unique_articles)} articles")
        return unique_articles

    def _filter_articles(self, articles: List[Dict], query: str) -> List[Dict]:
        """Filter articles for relevance and quality."""
        filtered: List[Dict] = []
        q = query.lower()

        for a in articles:
            title_summary = f"{a.get('title','')} {a.get('summary','')}".strip()
            if len(title_summary) < 50:
                continue

            title_l = a.get('title', '').lower()
            summary_l = a.get('summary', '').lower()

            if (q in title_l) or (q in summary_l) or any(word in title_l for word in q.split()):
                filtered.append(a)

        logger.info(f"Filtered {len(articles)} -> {len(filtered)} articles for relevance")
        return filtered

    def _is_english(self, text: str) -> bool:
        """Check if text is in English using language detection."""
        try:
            if len(text.strip()) < 20:
                return True  # too short to decide; keep it
            detected_lang = detect(text[:1000])
            return detected_lang == 'en'
        except Exception:
            # If detection fails, assume English
            return True

    def _parse_date(self, date_str: str) -> Optional[datetime]:
        """Parse date from RSS feed."""
        if not date_str:
            return datetime.now()
        try:
            for fmt in [
                '%a, %d %b %Y %H:%M:%S %Z',
                '%a, %d %b %Y %H:%M:%S %z',
                '%Y-%m-%dT%H:%M:%SZ',
                '%Y-%m-%d %H:%M:%S',
            ]:
                try:
                    return datetime.strptime(date_str.strip(), fmt)
                except ValueError:
                    continue
            return datetime.now()
        except Exception:
            return datetime.now()

    def _extract_source_name(self, url: str) -> str:
        """Extract source name from URL."""
        try:
            domain = urlparse(url).netloc
            domain = domain.replace('www.', '').replace('feeds.', '')

            domain_mapping = {
                'news.google.com': 'Google News',
                'finance.yahoo.com': 'Yahoo Finance',
                'reuters.com': 'Reuters',
                'reutersagency.com': 'Reuters',
                'bbc.co.uk': 'BBC',
                'bbc.com': 'BBC',
                'cnbc.com': 'CNBC',
                'marketwatch.com': 'MarketWatch',
                'ft.com': 'Financial Times',
                'bloomberg.com': 'Bloomberg'
            }
            return domain_mapping.get(domain, domain.title())
        except Exception:
            return 'Unknown'

    def get_available_sources(self) -> List[str]:
        """Get list of available news sources."""
        return list(self.rss_sources.keys())


# -------------------------------------------------------------------------
# Module-level helpers
# -------------------------------------------------------------------------
def clean_html(html_content: str) -> str:
    """Clean HTML content and extract readable text."""
    try:
        soup = BeautifulSoup(html_content, 'html.parser')

        # Remove script and style elements
        for script in soup(["script", "style"]):
            script.extract()

        text = soup.get_text(separator=" ")

        # Clean up whitespace
        lines = (line.strip() for line in text.splitlines())
        chunks = (phrase.strip() for line in lines for phrase in line.split("  "))
        text = ' '.join(chunk for chunk in chunks if chunk)

        # Remove leftover html entities / excessive spaces
        text = re.sub(r'\s+', ' ', text)
        return text.strip()

    except Exception as e:
        logger.error(f"Error cleaning HTML: {str(e)}")
        return ""

def is_valid_article_url(url: str) -> bool:
    """Check if URL is likely to be a valid article URL."""
    try:
        parsed = urlparse(url)

        # Skip certain file types
        skip_extensions = ['.pdf', '.jpg', '.png', '.gif', '.mp4', '.mp3', '.webp']
        if any(url.lower().endswith(ext) for ext in skip_extensions):
            return False

        # Skip obvious non-article URLs
        skip_patterns = ['login', 'register', 'subscribe', 'newsletter', 'sitemap']
        if any(pattern in url.lower() for pattern in skip_patterns):
            return False

        return True

    except Exception:
        return False