app/utils/news_cache.py

"""
Unified News Caching System
Centralized cache manager for Twitter, Reddit, RSS, and AI/Tech news feeds
"""

import hashlib
import logging
import re
import pandas as pd
from datetime import datetime, timedelta
from typing import List, Dict, Optional, Callable

logger = logging.getLogger(__name__)


class NewsCacheManager:
    """
    Centralized cache manager for news feeds with:
    - Per-source caching with TTL
    - Cross-service deduplication
    - Filtered results caching
    - Force refresh support
    """

    def __init__(self, default_ttl: int = 180):
        """
        Initialize cache manager

        Args:
            default_ttl: Default time-to-live in seconds (default: 180 = 3 minutes)
        """
        self.cache = {
            'twitter': {'raw_news': [], 'last_fetch': None, 'ttl': default_ttl},
            'reddit': {'raw_news': [], 'last_fetch': None, 'ttl': default_ttl},
            'rss': {'raw_news': [], 'last_fetch': None, 'ttl': default_ttl},
            'ai_tech': {'raw_news': [], 'last_fetch': None, 'ttl': default_ttl},
            'predictions': {'raw_news': [], 'last_fetch': None, 'ttl': default_ttl},
            'sectoral_news': {'raw_news': [], 'last_fetch': None, 'ttl': default_ttl},
            'market_events': {'raw_news': [], 'last_fetch': None, 'ttl': default_ttl},
            'economic_calendar': {'raw_news': [], 'last_fetch': None, 'ttl': default_ttl},
            'dedup_index': {},  # Global deduplication index
            'filtered_cache': {}  # Cached filtered results
        }
        logger.info(f"NewsCacheManager initialized with {default_ttl}s TTL")

    def get_news(
        self,
        source: str,
        fetcher_func: Callable,
        force_refresh: bool = False,
        **kwargs
    ) -> List[Dict]:
        """
        Get news from cache or fetch fresh if needed

        Args:
            source: News source ('twitter', 'reddit', 'rss', 'ai_tech')
            fetcher_func: Function to fetch fresh news
            force_refresh: If True, bypass cache and fetch fresh
            **kwargs: Arguments to pass to fetcher_func

        Returns:
            List of news items
        """
        if source not in ['twitter', 'reddit', 'rss', 'ai_tech', 'predictions', 'sectoral_news', 'market_events', 'economic_calendar']:
            logger.error(f"Invalid source: {source}")
            return []

        # Force refresh clears dedup index for that source
        if force_refresh:
            self._clear_source_from_dedup(source)

        # Check if cache is valid
        if not force_refresh and self._is_cache_valid(source):
            logger.info(f"✅ Cache HIT for {source} (age: {self._get_cache_age(source):.1f}s)")
            return self.cache[source]['raw_news']

        # Cache miss or force refresh - fetch fresh news
        logger.info(f"🔄 Cache MISS for {source} - fetching fresh news...")
        try:
            new_items = fetcher_func(**kwargs)

            if not new_items:
                logger.warning(f"No news items fetched for {source}")
                # Return cached data if available, even if expired
                return self.cache[source]['raw_news']

            # Update cache
            self._update_cache(source, new_items)

            # Deduplicate across sources
            deduplicated = self._deduplicate(new_items, source)

            logger.info(f"✅ Fetched {len(new_items)} items for {source}, {len(deduplicated)} unique after dedup")

            return deduplicated

        except Exception as e:
            logger.error(f"Error fetching news for {source}: {e}")
            # Return cached data if available
            return self.cache[source]['raw_news']

    def _is_cache_valid(self, source: str) -> bool:
        """
        Check if cached data is still fresh

        Args:
            source: News source to check

        Returns:
            True if cache is valid, False otherwise
        """
        source_cache = self.cache[source]
        if not source_cache['last_fetch']:
            return False

        age = (datetime.now() - source_cache['last_fetch']).total_seconds()
        is_valid = age < source_cache['ttl']

        return is_valid

    def _get_cache_age(self, source: str) -> float:
        """
        Get age of cached data in seconds

        Args:
            source: News source

        Returns:
            Age in seconds, or -1 if never fetched
        """
        source_cache = self.cache[source]
        if not source_cache['last_fetch']:
            return -1

        return (datetime.now() - source_cache['last_fetch']).total_seconds()

    def _normalize_text(self, text: str) -> str:
        """
        Normalize text for deduplication

        Args:
            text: Text to normalize

        Returns:
            Normalized text
        """
        if not text:
            return ""

        # Convert to lowercase
        text = text.lower().strip()

        # Remove punctuation
        text = re.sub(r'[^\w\s]', '', text)

        # Normalize whitespace
        text = re.sub(r'\s+', ' ', text)

        return text

    def _compute_hash(self, item: Dict) -> str:
        """
        Compute content hash for deduplication

        Args:
            item: News item dict

        Returns:
            MD5 hash string
        """
        title = self._normalize_text(item.get('title', ''))
        summary = self._normalize_text(item.get('summary', '')[:200])  # First 200 chars

        # Combine title and summary
        combined = f"{title}|{summary}"

        return hashlib.md5(combined.encode()).hexdigest()

    def _deduplicate(self, items: List[Dict], source: str) -> List[Dict]:
        """
        Remove duplicates using global dedup index

        Args:
            items: List of news items
            source: Source name

        Returns:
            Deduplicated list of items
        """
        deduplicated = []
        duplicate_count = 0

        for item in items:
            content_hash = self._compute_hash(item)

            if content_hash in self.cache['dedup_index']:
                # Duplicate found - update sources list
                dup_entry = self.cache['dedup_index'][content_hash]
                if source not in dup_entry['sources']:
                    dup_entry['sources'].append(source)
                duplicate_count += 1
            else:
                # New item - add to index and result
                self.cache['dedup_index'][content_hash] = {
                    'first_seen': datetime.now(),
                    'sources': [source],
                    'canonical_item': item
                }
                deduplicated.append(item)

        if duplicate_count > 0:
            logger.info(f"🔍 Deduplication: Found {duplicate_count} duplicates for {source}")

        return deduplicated

    def _update_cache(self, source: str, items: List[Dict]):
        """
        Update cache with new items

        Args:
            source: News source
            items: List of news items
        """
        self.cache[source]['raw_news'] = items
        self.cache[source]['last_fetch'] = datetime.now()
        logger.info(f"📦 Updated cache for {source} with {len(items)} items")

    def get_filtered_news(
        self,
        source_df: pd.DataFrame,
        filters: Dict,
        source_name: str = "unknown"
    ) -> pd.DataFrame:
        """
        Get filtered news with caching

        Args:
            source_df: Source dataframe
            filters: Filter dict with 'category', 'sentiment', 'impact' keys
            source_name: Name of source (for logging)

        Returns:
            Filtered dataframe
        """
        if source_df.empty:
            return source_df

        # Create cache key from filters
        category = filters.get('category', 'all')
        sentiment = filters.get('sentiment', 'all')
        impact = filters.get('impact', 'all')
        cache_key = f"{source_name}_{category}_{sentiment}_{impact}"

        # Check filtered cache
        if cache_key in self.cache['filtered_cache']:
            cached_entry = self.cache['filtered_cache'][cache_key]
            if datetime.now() < cached_entry['expires_at']:
                logger.debug(f"✅ Filtered cache HIT for {cache_key}")
                return cached_entry['results']

        # Apply filters
        filtered_df = source_df.copy()

        if category != 'all':
            filtered_df = filtered_df[filtered_df['category'] == category]

        if sentiment != 'all':
            filtered_df = filtered_df[filtered_df['sentiment'] == sentiment]

        if impact != 'all':
            filtered_df = filtered_df[filtered_df['impact'] == impact]

        logger.debug(f"🔍 Filtered {source_name}: {len(source_df)} → {len(filtered_df)} items")

        # Cache filtered results (5 minute TTL)
        self.cache['filtered_cache'][cache_key] = {
            'results': filtered_df,
            'expires_at': datetime.now() + timedelta(seconds=300)
        }

        return filtered_df

    def _clear_source_from_dedup(self, source: str):
        """
        Remove all entries from dedup index that only belong to this source

        Args:
            source: Source to remove from dedup index
        """
        to_remove = []
        for content_hash, entry in self.cache['dedup_index'].items():
            # Remove source from sources list
            if source in entry['sources']:
                entry['sources'].remove(source)
            # If no sources left, mark for removal
            if not entry['sources']:
                to_remove.append(content_hash)

        # Remove entries with no sources
        for content_hash in to_remove:
            del self.cache['dedup_index'][content_hash]

        if to_remove:
            logger.info(f"🗑️  Removed {len(to_remove)} entries from dedup index for {source}")

    def clear_cache(self, source: Optional[str] = None):
        """
        Clear cache for specific source or all sources

        Args:
            source: Source to clear, or None to clear all
        """
        if source:
            self.cache[source] = {'raw_news': [], 'last_fetch': None, 'ttl': 180}
            self._clear_source_from_dedup(source)
            logger.info(f"🗑️  Cleared cache for {source}")
        else:
            for src in ['twitter', 'reddit', 'rss', 'ai_tech', 'predictions', 'sectoral_news', 'market_events', 'economic_calendar']:
                self.cache[src] = {'raw_news': [], 'last_fetch': None, 'ttl': 180}
            self.cache['dedup_index'] = {}
            self.cache['filtered_cache'] = {}
            logger.info("🗑️  Cleared ALL caches")

    def get_statistics(self) -> Dict:
        """
        Get cache statistics

        Returns:
            Dict with cache stats
        """
        stats = {
            'twitter': {
                'items': len(self.cache['twitter']['raw_news']),
                'age_seconds': self._get_cache_age('twitter'),
                'is_valid': self._is_cache_valid('twitter')
            },
            'reddit': {
                'items': len(self.cache['reddit']['raw_news']),
                'age_seconds': self._get_cache_age('reddit'),
                'is_valid': self._is_cache_valid('reddit')
            },
            'rss': {
                'items': len(self.cache['rss']['raw_news']),
                'age_seconds': self._get_cache_age('rss'),
                'is_valid': self._is_cache_valid('rss')
            },
            'ai_tech': {
                'items': len(self.cache['ai_tech']['raw_news']),
                'age_seconds': self._get_cache_age('ai_tech'),
                'is_valid': self._is_cache_valid('ai_tech')
            },
            'predictions': {
                'items': len(self.cache['predictions']['raw_news']),
                'age_seconds': self._get_cache_age('predictions'),
                'is_valid': self._is_cache_valid('predictions')
            },
            'sectoral_news': {
                'items': len(self.cache['sectoral_news']['raw_news']),
                'age_seconds': self._get_cache_age('sectoral_news'),
                'is_valid': self._is_cache_valid('sectoral_news')
            },
            'market_events': {
                'items': len(self.cache['market_events']['raw_news']),
                'age_seconds': self._get_cache_age('market_events'),
                'is_valid': self._is_cache_valid('market_events')
            },
            'economic_calendar': {
                'items': len(self.cache['economic_calendar']['raw_news']),
                'age_seconds': self._get_cache_age('economic_calendar'),
                'is_valid': self._is_cache_valid('economic_calendar')
            },
            'dedup_index_size': len(self.cache['dedup_index']),
            'filtered_cache_size': len(self.cache['filtered_cache'])
        }

        return stats