from sqlalchemy import func
from sqlalchemy.orm import Session
import logging
from typing import List, Dict, Any

from models.database_models import User, Product, Stock
from models.api_models import StatsResponse, MarketplaceStatsResponse

logger = logging.getLogger(__name__)


class StatsService:
    """Service class for statistics operations following the application's service pattern"""

    def get_comprehensive_stats(self, db: Session) -> Dict[str, Any]:
        """
        Get comprehensive statistics with marketplace data

        Args:
            db: Database session

        Returns:
            Dictionary containing all statistics data
        """
        # Use more efficient queries with proper indexes
        total_products = db.query(Product).count()

        unique_brands = db.query(Product.brand).filter(
            Product.brand.isnot(None),
            Product.brand != ""
        ).distinct().count()

        unique_categories = db.query(Product.google_product_category).filter(
            Product.google_product_category.isnot(None),
            Product.google_product_category != ""
        ).distinct().count()

        # New marketplace statistics
        unique_marketplaces = db.query(Product.marketplace).filter(
            Product.marketplace.isnot(None),
            Product.marketplace != ""
        ).distinct().count()

        unique_shops = db.query(Product.shop_name).filter(
            Product.shop_name.isnot(None),
            Product.shop_name != ""
        ).distinct().count()

        # Stock statistics
        total_stock_entries = db.query(Stock).count()
        total_inventory = db.query(func.sum(Stock.quantity)).scalar() or 0

        stats_data = {
            "total_products": total_products,
            "unique_brands": unique_brands,
            "unique_categories": unique_categories,
            "unique_marketplaces": unique_marketplaces,
            "unique_shops": unique_shops,
            "total_stock_entries": total_stock_entries,
            "total_inventory_quantity": total_inventory
        }

        logger.info(f"Generated comprehensive stats: {total_products} products, {unique_marketplaces} marketplaces")
        return stats_data

    def get_marketplace_breakdown_stats(self, db: Session) -> List[Dict[str, Any]]:
        """
        Get statistics broken down by marketplace

        Args:
            db: Database session

        Returns:
            List of dictionaries containing marketplace statistics
        """
        # Query to get stats per marketplace
        marketplace_stats = db.query(
            Product.marketplace,
            func.count(Product.id).label('total_products'),
            func.count(func.distinct(Product.shop_name)).label('unique_shops'),
            func.count(func.distinct(Product.brand)).label('unique_brands')
        ).filter(
            Product.marketplace.isnot(None)
        ).group_by(Product.marketplace).all()

        stats_list = [
            {
                "marketplace": stat.marketplace,
                "total_products": stat.total_products,
                "unique_shops": stat.unique_shops,
                "unique_brands": stat.unique_brands
            } for stat in marketplace_stats
        ]

        logger.info(f"Generated marketplace breakdown stats for {len(stats_list)} marketplaces")
        return stats_list

    def get_product_count(self, db: Session) -> int:
        """Get total product count"""
        return db.query(Product).count()

    def get_unique_brands_count(self, db: Session) -> int:
        """Get count of unique brands"""
        return db.query(Product.brand).filter(
            Product.brand.isnot(None),
            Product.brand != ""
        ).distinct().count()

    def get_unique_categories_count(self, db: Session) -> int:
        """Get count of unique categories"""
        return db.query(Product.google_product_category).filter(
            Product.google_product_category.isnot(None),
            Product.google_product_category != ""
        ).distinct().count()

    def get_unique_marketplaces_count(self, db: Session) -> int:
        """Get count of unique marketplaces"""
        return db.query(Product.marketplace).filter(
            Product.marketplace.isnot(None),
            Product.marketplace != ""
        ).distinct().count()

    def get_unique_shops_count(self, db: Session) -> int:
        """Get count of unique shops"""
        return db.query(Product.shop_name).filter(
            Product.shop_name.isnot(None),
            Product.shop_name != ""
        ).distinct().count()

    def get_stock_statistics(self, db: Session) -> Dict[str, int]:
        """
        Get stock-related statistics

        Args:
            db: Database session

        Returns:
            Dictionary containing stock statistics
        """
        total_stock_entries = db.query(Stock).count()
        total_inventory = db.query(func.sum(Stock.quantity)).scalar() or 0

        return {
            "total_stock_entries": total_stock_entries,
            "total_inventory_quantity": total_inventory
        }

    def get_brands_by_marketplace(self, db: Session, marketplace: str) -> List[str]:
        """Get unique brands for a specific marketplace"""
        brands = db.query(Product.brand).filter(
            Product.marketplace == marketplace,
            Product.brand.isnot(None),
            Product.brand != ""
        ).distinct().all()
        return [brand[0] for brand in brands]

    def get_shops_by_marketplace(self, db: Session, marketplace: str) -> List[str]:
        """Get unique shops for a specific marketplace"""
        shops = db.query(Product.shop_name).filter(
            Product.marketplace == marketplace,
            Product.shop_name.isnot(None),
            Product.shop_name != ""
        ).distinct().all()
        return [shop[0] for shop in shops]

    def get_products_by_marketplace(self, db: Session, marketplace: str) -> int:
        """Get product count for a specific marketplace"""
        return db.query(Product).filter(Product.marketplace == marketplace).count()


# Create service instance following the same pattern as other services
stats_service = StatsService()