app/services/cache_service.py

import json
import os
import time
import hashlib
import logging
from typing import Dict, Any, Optional, List
from pathlib import Path
from cachetools import TTLCache, LRUCache
from threading import Lock

from app.utils.config import Config

logger = logging.getLogger(__name__)

class CacheService:
    """Service for caching LinkedIn search results and profile data"""
    
    def __init__(self):
        self.cache_enabled = Config.CACHE_ENABLED
        self.cache_ttl = Config.CACHE_TTL
        self.cache_max_size = Config.CACHE_MAX_SIZE
        self.cache_file_path = Config.CACHE_FILE_PATH
        
        # Initialize caches
        self._init_caches()
        
        # Thread safety
        self._lock = Lock()
        
        logger.info(f"🔧 Cache service initialized - Enabled: {self.cache_enabled}, TTL: {self.cache_ttl}s, Max Size: {self.cache_max_size}")
    
    def _init_caches(self):
        """Initialize different types of caches"""
        if not self.cache_enabled:
            self.search_cache = None
            self.profile_cache = None
            self.query_cache = None
            return
        
        # TTL cache for search results (expires after TTL)
        self.search_cache = TTLCache(
            maxsize=self.cache_max_size,
            ttl=self.cache_ttl
        )
        
        # TTL cache for individual profile data (longer TTL for profile data)
        self.profile_cache = TTLCache(
            maxsize=self.cache_max_size * 2,  # More space for profiles
            ttl=self.cache_ttl * 2  # Longer TTL for profile data
        )
        
        # LRU cache for query results (no TTL, just size limit)
        self.query_cache = LRUCache(
            maxsize=self.cache_max_size // 2
        )
        
        # Load persistent cache from file
        self._load_persistent_cache()
        
        logger.info("✅ Caches initialized successfully")
    
    def _load_persistent_cache(self):
        """Load cache data from persistent storage"""
        try:
            cache_file = Path(self.cache_file_path)
            if cache_file.exists():
                with open(cache_file, 'r') as f:
                    cache_data = json.load(f)
                
                # Load search cache
                if 'search_cache' in cache_data:
                    for key, value in cache_data['search_cache'].items():
                        if self._is_cache_entry_valid(value):
                            self.search_cache[key] = value['data']
                
                # Load profile cache
                if 'profile_cache' in cache_data:
                    for key, value in cache_data['profile_cache'].items():
                        if self._is_cache_entry_valid(value):
                            self.profile_cache[key] = value['data']
                
                logger.info(f"📁 Loaded persistent cache from {cache_file}")
            else:
                logger.info("📁 No existing cache file found, starting fresh")
                
        except Exception as e:
            logger.warning(f"⚠️ Failed to load persistent cache: {str(e)}")
    
    def _save_persistent_cache(self):
        """Save cache data to persistent storage"""
        if not self.cache_enabled:
            return
        
        try:
            cache_file = Path(self.cache_file_path)
            cache_file.parent.mkdir(parents=True, exist_ok=True)
            
            cache_data = {
                'search_cache': {},
                'profile_cache': {},
                'timestamp': time.time()
            }
            
            # Save search cache
            if self.search_cache:
                for key, value in self.search_cache.items():
                    cache_data['search_cache'][key] = {
                        'data': value,
                        'timestamp': time.time()
                    }
            
            # Save profile cache
            if self.profile_cache:
                for key, value in self.profile_cache.items():
                    cache_data['profile_cache'][key] = {
                        'data': value,
                        'timestamp': time.time()
                    }
            
            with open(cache_file, 'w') as f:
                json.dump(cache_data, f, indent=2)
            
            logger.info(f"💾 Saved persistent cache to {cache_file}")
            
        except Exception as e:
            logger.warning(f"⚠️ Failed to save persistent cache: {str(e)}")
    
    def _is_cache_entry_valid(self, entry: Dict) -> bool:
        """Check if a cache entry is still valid (not expired)"""
        if not isinstance(entry, dict) or 'timestamp' not in entry:
            return False
        
        timestamp = entry.get('timestamp', 0)
        return (time.time() - timestamp) < self.cache_ttl
    
    def _generate_cache_key(self, *args, **kwargs) -> str:
        """Generate a unique cache key from function arguments"""
        # Create a string representation of the arguments
        key_parts = []
        
        # Add positional arguments
        for arg in args:
            if isinstance(arg, str):
                key_parts.append(arg)
            else:
                key_parts.append(str(arg))
        
        # Add keyword arguments (sorted for consistency)
        for key, value in sorted(kwargs.items()):
            if isinstance(value, str):
                key_parts.append(f"{key}:{value}")
            else:
                key_parts.append(f"{key}:{str(value)}")
        
        # Create hash of the combined string
        key_string = "|".join(key_parts)
        return hashlib.md5(key_string.encode()).hexdigest()
    
    def get_search_results(self, job_description: str, location: Optional[str] = None, max_results: int = 10) -> Optional[List[Dict]]:
        """Get cached search results for a job description"""
        if not self.cache_enabled or not self.search_cache:
            return None
        
        cache_key = self._generate_cache_key(
            "search", 
            job_description, 
            location or "any", 
            max_results
        )
        
        with self._lock:
            try:
                results = self.search_cache.get(cache_key)
                if results:
                    logger.info(f"🎯 Cache HIT for search: {job_description[:50]}...")
                    return results
                else:
                    logger.info(f"❌ Cache MISS for search: {job_description[:50]}...")
                    return None
            except Exception as e:
                logger.warning(f"⚠️ Error accessing search cache: {str(e)}")
                return None
    
    def set_search_results(self, job_description: str, location: Optional[str] = None, max_results: int = 10, results: List[Dict] = None):
        """Cache search results for a job description"""
        if not self.cache_enabled or not self.search_cache or not results:
            return
        
        cache_key = self._generate_cache_key(
            "search", 
            job_description, 
            location or "any", 
            max_results
        )
        
        with self._lock:
            try:
                self.search_cache[cache_key] = results
                logger.info(f"💾 Cached search results for: {job_description[:50]}...")
                
                # Periodically save to persistent storage
                if len(self.search_cache) % 10 == 0:  # Save every 10 entries
                    self._save_persistent_cache()
                    
            except Exception as e:
                logger.warning(f"⚠️ Error caching search results: {str(e)}")
    
    def get_profile_data(self, profile_url: str) -> Optional[Dict]:
        """Get cached profile data for a LinkedIn profile URL"""
        if not self.cache_enabled or not self.profile_cache:
            return None
        
        cache_key = self._generate_cache_key("profile", profile_url)
        
        with self._lock:
            try:
                profile_data = self.profile_cache.get(cache_key)
                if profile_data:
                    logger.info(f"🎯 Cache HIT for profile: {profile_url}")
                    return profile_data
                else:
                    logger.info(f"❌ Cache MISS for profile: {profile_url}")
                    return None
            except Exception as e:
                logger.warning(f"⚠️ Error accessing profile cache: {str(e)}")
                return None
    
    def set_profile_data(self, profile_url: str, profile_data: Dict):
        """Cache profile data for a LinkedIn profile URL"""
        if not self.cache_enabled or not self.profile_cache or not profile_data:
            return
        
        cache_key = self._generate_cache_key("profile", profile_url)
        
        with self._lock:
            try:
                self.profile_cache[cache_key] = profile_data
                logger.info(f"💾 Cached profile data for: {profile_url}")
                
                # Periodically save to persistent storage
                if len(self.profile_cache) % 20 == 0:  # Save every 20 entries
                    self._save_persistent_cache()
                    
            except Exception as e:
                logger.warning(f"⚠️ Error caching profile data: {str(e)}")
    
    def get_query_results(self, query: str, max_results: int = 10) -> Optional[List[Dict]]:
        """Get cached Google search query results"""
        if not self.cache_enabled or not self.query_cache:
            return None
        
        cache_key = self._generate_cache_key("query", query, max_results)
        
        with self._lock:
            try:
                results = self.query_cache.get(cache_key)
                if results:
                    logger.info(f"🎯 Cache HIT for query: {query[:50]}...")
                    return results
                else:
                    logger.info(f"❌ Cache MISS for query: {query[:50]}...")
                    return None
            except Exception as e:
                logger.warning(f"⚠️ Error accessing query cache: {str(e)}")
                return None
    
    def set_query_results(self, query: str, max_results: int = 10, results: List[Dict] = None):
        """Cache Google search query results"""
        if not self.cache_enabled or not self.query_cache or not results:
            return
        
        cache_key = self._generate_cache_key("query", query, max_results)
        
        with self._lock:
            try:
                self.query_cache[cache_key] = results
                logger.info(f"💾 Cached query results for: {query[:50]}...")
            except Exception as e:
                logger.warning(f"⚠️ Error caching query results: {str(e)}")
    
    def clear_cache(self, cache_type: str = "all"):
        """Clear specified cache or all caches"""
        with self._lock:
            try:
                if cache_type == "all" or cache_type == "search":
                    if self.search_cache:
                        self.search_cache.clear()
                        logger.info("🧹 Cleared search cache")
                
                if cache_type == "all" or cache_type == "profile":
                    if self.profile_cache:
                        self.profile_cache.clear()
                        logger.info("🧹 Cleared profile cache")
                
                if cache_type == "all" or cache_type == "query":
                    if self.query_cache:
                        self.query_cache.clear()
                        logger.info("🧹 Cleared query cache")
                
                # Save empty cache to persistent storage
                self._save_persistent_cache()
                
            except Exception as e:
                logger.warning(f"⚠️ Error clearing cache: {str(e)}")
    
    def get_cache_stats(self) -> Dict[str, Any]:
        """Get statistics about the cache usage"""
        stats = {
            'cache_enabled': self.cache_enabled,
            'cache_ttl': self.cache_ttl,
            'cache_max_size': self.cache_max_size
        }
        
        if self.cache_enabled:
            stats.update({
                'search_cache_size': len(self.search_cache) if self.search_cache else 0,
                'profile_cache_size': len(self.profile_cache) if self.profile_cache else 0,
                'query_cache_size': len(self.query_cache) if self.query_cache else 0,
                'search_cache_currsize': self.search_cache.currsize if self.search_cache else 0,
                'profile_cache_currsize': self.profile_cache.currsize if self.profile_cache else 0,
                'query_cache_currsize': self.query_cache.currsize if self.query_cache else 0
            })
        
        return stats
    
    def cleanup_expired_entries(self):
        """Clean up expired entries from all caches"""
        if not self.cache_enabled:
            return
        
        with self._lock:
            try:
                # TTLCache automatically handles expiration
                # Just trigger expiration check
                if self.search_cache:
                    self.search_cache.expire()
                
                if self.profile_cache:
                    self.profile_cache.expire()
                
                logger.info("🧹 Cleaned up expired cache entries")
                
            except Exception as e:
                logger.warning(f"⚠️ Error cleaning up expired entries: {str(e)}")
    
    def __del__(self):
        """Cleanup when the cache service is destroyed"""
        try:
            self._save_persistent_cache()
        except:
            pass  # Ignore errors during cleanup