"""
Utility module for cache management in the SciPaperLoader application.
This module contains functions for managing the hourly quota cache and other caching mechanisms.
"""
from datetime import datetime
from .models import ActivityLog

# Global cache for hourly quota
HOURLY_QUOTA_CACHE = {
    'hour': None,  # Current hour
    'quota': None,  # Calculated quota
    'last_config_update': None,  # Last time volume or schedule config was updated
}

def invalidate_hourly_quota_cache(calculate_function=None):
    """
    Invalidate the hourly quota cache when configuration changes.
    
    Args:
        calculate_function (callable, optional): Function to recalculate quota immediately.
            If None, recalculation will happen during next get_cached_hourly_quota() call.
    """
    global HOURLY_QUOTA_CACHE
    HOURLY_QUOTA_CACHE['last_config_update'] = None
    
    # If a calculation function is provided, recalculate immediately
    if calculate_function:
        current_hour = datetime.now().hour
        quota = calculate_function()
        HOURLY_QUOTA_CACHE['hour'] = current_hour
        HOURLY_QUOTA_CACHE['quota'] = quota
        HOURLY_QUOTA_CACHE['last_config_update'] = datetime.now()
        
        ActivityLog.log_scraper_activity(
            action="cache_recalculated",
            status="info",
            description=f"Hourly quota immediately recalculated after config change: {quota} papers"
        )
    else:
        # Log the cache invalidation
        ActivityLog.log_scraper_activity(
            action="cache_invalidated",
            status="info",
            description="Hourly quota cache was invalidated due to configuration changes"
        )

def get_cached_hourly_quota(calculate_function):
    """
    Get the cached hourly quota if it's still valid, or recalculate if needed.
    
    Args:
        calculate_function: Function to call when recalculation is needed
    
    Returns:
        int: Number of papers to download this hour
    """
    global HOURLY_QUOTA_CACHE
    current_hour = datetime.now().hour
    
    # Check if we need to recalculate
    if (HOURLY_QUOTA_CACHE['hour'] != current_hour or 
        HOURLY_QUOTA_CACHE['quota'] is None or 
        HOURLY_QUOTA_CACHE['last_config_update'] is None):
        
        # Recalculate and update cache
        quota = calculate_function()
        HOURLY_QUOTA_CACHE['hour'] = current_hour
        HOURLY_QUOTA_CACHE['quota'] = quota
        HOURLY_QUOTA_CACHE['last_config_update'] = datetime.now()
        
        # Log cache update
        ActivityLog.log_scraper_activity(
            action="cache_updated",
            status="info",
            description=f"Hourly quota cache updated for hour {current_hour}: {quota} papers"
        )
        
        return quota
    else:
        # Use cached value
        return HOURLY_QUOTA_CACHE['quota']