youtube-summarizer/backend/api/cache.py

"""Cache management API endpoints."""

from fastapi import APIRouter, Depends, HTTPException, Query
from typing import Dict, Any, Optional

from ..services.enhanced_cache_manager import EnhancedCacheManager, CacheConfig
from ..models.api_models import BaseResponse

router = APIRouter(prefix="/api/cache", tags=["cache"])

# Global instance of enhanced cache manager
_cache_manager_instance: Optional[EnhancedCacheManager] = None


async def get_enhanced_cache_manager() -> EnhancedCacheManager:
    """Get or create enhanced cache manager instance."""
    global _cache_manager_instance
    
    if not _cache_manager_instance:
        config = CacheConfig(
            redis_url="redis://localhost:6379/0",  # TODO: Get from environment
            transcript_ttl_hours=168,  # 7 days
            summary_ttl_hours=72,      # 3 days
            enable_analytics=True
        )
        _cache_manager_instance = EnhancedCacheManager(config)
        await _cache_manager_instance.initialize()
    
    return _cache_manager_instance


@router.get("/analytics", response_model=Dict[str, Any])
async def get_cache_analytics(
    cache_manager: EnhancedCacheManager = Depends(get_enhanced_cache_manager)
) -> Dict[str, Any]:
    """Get comprehensive cache analytics and metrics.
    
    Returns cache performance metrics, hit rates, memory usage, and configuration.
    """
    try:
        analytics = await cache_manager.get_cache_analytics()
        
        return {
            "status": "success",
            "data": analytics
        }
    except Exception as e:
        raise HTTPException(status_code=500, detail=f"Failed to get cache analytics: {str(e)}")


@router.post("/invalidate", response_model=Dict[str, Any])
async def invalidate_cache(
    pattern: Optional[str] = Query(None, description="Optional pattern to match cache keys"),
    cache_manager: EnhancedCacheManager = Depends(get_enhanced_cache_manager)
) -> Dict[str, Any]:
    """Invalidate cache entries.
    
    Args:
        pattern: Optional pattern to match cache keys. If not provided, clears all cache.
    
    Returns:
        Number of entries invalidated.
    """
    try:
        count = await cache_manager.invalidate_cache(pattern)
        
        return {
            "status": "success",
            "message": f"Invalidated {count} cache entries",
            "count": count
        }
    except Exception as e:
        raise HTTPException(status_code=500, detail=f"Failed to invalidate cache: {str(e)}")


@router.get("/stats", response_model=Dict[str, Any])
async def get_cache_stats(
    cache_manager: EnhancedCacheManager = Depends(get_enhanced_cache_manager)
) -> Dict[str, Any]:
    """Get basic cache statistics.
    
    Returns cache hit rate, total operations, and error count.
    """
    try:
        metrics = cache_manager.metrics.to_dict()
        
        return {
            "status": "success",
            "data": {
                "hit_rate": metrics["hit_rate"],
                "total_hits": metrics["hits"],
                "total_misses": metrics["misses"],
                "total_operations": metrics["total_operations"],
                "average_response_time_ms": metrics["average_response_time_ms"],
                "errors": metrics["errors"]
            }
        }
    except Exception as e:
        raise HTTPException(status_code=500, detail=f"Failed to get cache stats: {str(e)}")


@router.post("/warm", response_model=Dict[str, Any])
async def warm_cache(
    video_ids: list[str],
    cache_manager: EnhancedCacheManager = Depends(get_enhanced_cache_manager)
) -> Dict[str, Any]:
    """Warm cache for specific video IDs.
    
    Args:
        video_ids: List of YouTube video IDs to warm cache for.
    
    Returns:
        Status of cache warming operation.
    """
    try:
        # TODO: Implement cache warming logic
        # This would fetch transcripts and generate summaries for the provided video IDs
        
        return {
            "status": "success",
            "message": f"Cache warming initiated for {len(video_ids)} videos",
            "video_count": len(video_ids)
        }
    except Exception as e:
        raise HTTPException(status_code=500, detail=f"Failed to warm cache: {str(e)}")


@router.get("/health", response_model=Dict[str, Any])
async def cache_health_check(
    cache_manager: EnhancedCacheManager = Depends(get_enhanced_cache_manager)
) -> Dict[str, Any]:
    """Check cache system health.
    
    Returns health status of cache components.
    """
    try:
        health = {
            "status": "healthy",
            "components": {
                "memory_cache": True,
                "redis": False,
                "background_tasks": cache_manager._initialized
            }
        }
        
        # Check Redis connection
        if cache_manager.redis_client:
            try:
                await cache_manager.redis_client.ping()
                health["components"]["redis"] = True
            except:
                health["components"]["redis"] = False
        
        # Check hit rate threshold
        if cache_manager.metrics.hit_rate < cache_manager.config.hit_rate_alert_threshold:
            health["warnings"] = [
                f"Hit rate ({cache_manager.metrics.hit_rate:.2%}) below threshold ({cache_manager.config.hit_rate_alert_threshold:.2%})"
            ]
        
        return health
        
    except Exception as e:
        return {
            "status": "unhealthy",
            "error": str(e)
        }