"""
Cache utilities for dashboard and other high-frequency data.

Uses cachetools for in-memory caching with TTL (Time To Live).
No external dependencies like Redis needed - perfect for HuggingFace Spaces.
"""
from cachetools import TTLCache
from threading import RLock
from typing import Optional, Any
import logging

logger = logging.getLogger(__name__)

# Thread-safe dashboard cache with 5-minute TTL
# Stores up to 1000 project dashboards in memory
dashboard_cache = TTLCache(maxsize=1000, ttl=300)
dashboard_cache_lock = RLock()

# Trends cache with 10-minute TTL (trends change less frequently)
trends_cache = TTLCache(maxsize=500, ttl=600)
trends_cache_lock = RLock()

# Project overview cache with 12-hour TTL (structure changes rarely)
# Stores project structure: regions, roles, subcontractors, team info
overview_cache = TTLCache(maxsize=500, ttl=43200)  # 12 hours = 43200 seconds
overview_cache_lock = RLock()


def get_cached_dashboard(project_id: str, user_id: str) -> Optional[dict]:
    """
    Get cached dashboard data for a project and user.
    
    Args:
        project_id: UUID of the project
        user_id: UUID of the user
        
    Returns:
        Cached dashboard dict or None if not found/expired
    """
    try:
        with dashboard_cache_lock:
            key = f"dashboard:{project_id}:{user_id}"
            cached_data = dashboard_cache.get(key)
            if cached_data:
                logger.debug(f"Cache HIT: {key}")
            return cached_data
    except Exception as e:
        logger.error(f"Error retrieving from cache: {e}")
        return None


def set_cached_dashboard(project_id: str, user_id: str, data: dict) -> None:
    """
    Cache dashboard data for a project and user.
    
    Args:
        project_id: UUID of the project
        user_id: UUID of the user
        data: Dashboard data to cache
    """
    try:
        with dashboard_cache_lock:
            key = f"dashboard:{project_id}:{user_id}"
            dashboard_cache[key] = data
            logger.debug(f"Cache SET: {key}")
    except Exception as e:
        logger.error(f"Error setting cache: {e}")


def invalidate_dashboard_cache(project_id: str) -> None:
    """
    Invalidate all cached dashboards for a project.
    Called when project data changes (new ticket, sales order, etc.)
    
    Args:
        project_id: UUID of the project
    """
    try:
        with dashboard_cache_lock:
            # Find all keys for this project
            keys_to_delete = [
                k for k in dashboard_cache.keys() 
                if k.startswith(f"dashboard:{project_id}:")
            ]
            
            # Delete them
            for key in keys_to_delete:
                dashboard_cache.pop(key, None)
                
            if keys_to_delete:
                logger.info(f"Invalidated {len(keys_to_delete)} cache entries for project {project_id}")
    except Exception as e:
        logger.error(f"Error invalidating cache: {e}")


def get_cached_trends(project_id: str, metric: str, period: str) -> Optional[dict]:
    """
    Get cached trend data.
    
    Args:
        project_id: UUID of the project
        metric: Metric name (sales_orders, tickets, etc.)
        period: Time period (7days, 30days, etc.)
        
    Returns:
        Cached trends dict or None if not found/expired
    """
    try:
        with trends_cache_lock:
            key = f"trends:{project_id}:{metric}:{period}"
            cached_data = trends_cache.get(key)
            if cached_data:
                logger.debug(f"Trends cache HIT: {key}")
            return cached_data
    except Exception as e:
        logger.error(f"Error retrieving trends from cache: {e}")
        return None


def set_cached_trends(project_id: str, metric: str, period: str, data: dict) -> None:
    """
    Cache trend data.
    
    Args:
        project_id: UUID of the project
        metric: Metric name
        period: Time period
        data: Trends data to cache
    """
    try:
        with trends_cache_lock:
            key = f"trends:{project_id}:{metric}:{period}"
            trends_cache[key] = data
            logger.debug(f"Trends cache SET: {key}")
    except Exception as e:
        logger.error(f"Error setting trends cache: {e}")


def invalidate_trends_cache(project_id: str, metric: Optional[str] = None) -> None:
    """
    Invalidate trend cache for a project.
    
    Args:
        project_id: UUID of the project
        metric: Specific metric to invalidate, or None for all
    """
    try:
        with trends_cache_lock:
            if metric:
                # Invalidate specific metric
                keys_to_delete = [
                    k for k in trends_cache.keys()
                    if k.startswith(f"trends:{project_id}:{metric}:")
                ]
            else:
                # Invalidate all trends for project
                keys_to_delete = [
                    k for k in trends_cache.keys()
                    if k.startswith(f"trends:{project_id}:")
                ]
            
            for key in keys_to_delete:
                trends_cache.pop(key, None)
                
            if keys_to_delete:
                logger.info(f"Invalidated {len(keys_to_delete)} trends cache entries")
    except Exception as e:
        logger.error(f"Error invalidating trends cache: {e}")


def clear_all_caches() -> None:
    """
    Clear all caches. Use with caution.
    Typically only needed for testing or maintenance.
    """
    try:
        with dashboard_cache_lock:
            dashboard_cache.clear()
            logger.info("Cleared dashboard cache")
            
        with trends_cache_lock:
            trends_cache.clear()
            logger.info("Cleared trends cache")
    except Exception as e:
        logger.error(f"Error clearing caches: {e}")


def get_cached_overview(project_id: str, user_id: str) -> Optional[dict]:
    """
    Get cached project overview data.
    
    Args:
        project_id: UUID of the project
        user_id: UUID of the user
        
    Returns:
        Cached overview dict or None if not found/expired
    """
    try:
        with overview_cache_lock:
            key = f"overview:{project_id}:{user_id}"
            cached_data = overview_cache.get(key)
            if cached_data:
                logger.debug(f"Overview cache HIT: {key}")
            return cached_data
    except Exception as e:
        logger.error(f"Error retrieving overview from cache: {e}")
        return None


def set_cached_overview(project_id: str, user_id: str, data: dict) -> None:
    """
    Cache project overview data.
    
    Args:
        project_id: UUID of the project
        user_id: UUID of the user
        data: Overview data to cache
    """
    try:
        with overview_cache_lock:
            key = f"overview:{project_id}:{user_id}"
            overview_cache[key] = data
            logger.debug(f"Overview cache SET: {key}")
    except Exception as e:
        logger.error(f"Error setting overview cache: {e}")


def invalidate_overview_cache(project_id: str) -> None:
    """
    Invalidate all cached overviews for a project.
    Called when project structure changes (regions, roles, team, subcontractors).
    
    Args:
        project_id: UUID of the project
    """
    try:
        with overview_cache_lock:
            keys_to_delete = [
                k for k in overview_cache.keys() 
                if k.startswith(f"overview:{project_id}:")
            ]
            
            for key in keys_to_delete:
                overview_cache.pop(key, None)
                
            if keys_to_delete:
                logger.info(f"Invalidated {len(keys_to_delete)} overview cache entries for project {project_id}")
    except Exception as e:
        logger.error(f"Error invalidating overview cache: {e}")


def get_cache_stats() -> dict:
    """
    Get cache statistics for monitoring.
    
    Returns:
        Dict with cache size, hits, etc.
    """
    try:
        with dashboard_cache_lock, trends_cache_lock, overview_cache_lock:
            return {
                "dashboard_cache": {
                    "size": len(dashboard_cache),
                    "maxsize": dashboard_cache.maxsize,
                    "ttl": dashboard_cache.ttl
                },
                "trends_cache": {
                    "size": len(trends_cache),
                    "maxsize": trends_cache.maxsize,
                    "ttl": trends_cache.ttl
                },
                "overview_cache": {
                    "size": len(overview_cache),
                    "maxsize": overview_cache.maxsize,
                    "ttl": overview_cache.ttl
                }
            }
    except Exception as e:
        logger.error(f"Error getting cache stats: {e}")
        return {}