src/app/services/project_requirements_cache.py

"""
Project Requirements Cache Service

Caches project completion requirements (photo_requirements, activation_requirements)
to avoid repeated database queries. Uses cachetools for in-memory caching.
"""

from cachetools import TTLCache
from threading import RLock
from typing import Dict, Any, Optional
from uuid import UUID
from datetime import datetime
import logging

logger = logging.getLogger(__name__)

# Thread-safe requirements cache with 24-hour TTL
# Stores up to 500 project requirements in memory
requirements_cache = TTLCache(maxsize=500, ttl=86400)  # 24 hours
requirements_cache_lock = RLock()


class ProjectRequirementsCache:
    """Cache for project completion requirements"""
    
    @staticmethod
    def get(project_id: UUID) -> Optional[Dict[str, Any]]:
        """
        Get cached project requirements
        
        Returns:
            Dict with photo_requirements and field_requirements, or None if not cached
        """
        try:
            with requirements_cache_lock:
                key = f"requirements:{str(project_id)}"
                cached_data = requirements_cache.get(key)
                if cached_data:
                    logger.debug(f"Requirements cache HIT: {project_id}")
                return cached_data
        except Exception as e:
            logger.error(f"Error retrieving from requirements cache: {e}")
            return None
    
    @staticmethod
    def set(project_id: UUID, photo_requirements: list, field_requirements: list):
        """
        Cache project requirements
        
        Args:
            project_id: Project ID
            photo_requirements: List of photo requirement dicts
            field_requirements: Combined list of all field requirements (activation + inventory)
        """
        try:
            with requirements_cache_lock:
                key = f"requirements:{str(project_id)}"
                cache_data = {
                    "photo_requirements": photo_requirements,
                    "field_requirements": field_requirements,
                    "cached_at": datetime.utcnow().isoformat()
                }
                requirements_cache[key] = cache_data
                logger.debug(f"Requirements cache SET: {project_id}")
        except Exception as e:
            logger.error(f"Error setting requirements cache: {e}")
    
    @staticmethod
    def invalidate(project_id: UUID):
        """
        Invalidate cached project requirements
        
        Call this when project requirements are updated
        """
        try:
            with requirements_cache_lock:
                key = f"requirements:{str(project_id)}"
                requirements_cache.pop(key, None)
                logger.info(f"Invalidated requirements cache for project {project_id}")
        except Exception as e:
            logger.error(f"Error invalidating requirements cache: {e}")