"""仪表盘聚合业务服务层

将 dashboard_routes 中的聚合查询与统计编排下沉到此，
路由层只做依赖注入与响应返回。
"""
from sqlalchemy import func, select
from sqlalchemy.ext.asyncio import AsyncSession

from inventory.models import Customer, Inventory, Product, PurchaseOrder, SalesOrder, Supplier, Warehouse


class DashboardService:
    """仪表盘统计服务"""

    @staticmethod
    async def get_dashboard(db_session: AsyncSession) -> dict:
        material_count = await db_session.scalar(
            select(func.count(Product.id)).where(Product.is_active == True, Product.item_type == "material")
        ) or 0
        finished_product_count = await db_session.scalar(
            select(func.count(Product.id)).where(Product.is_active == True, Product.item_type == "finished")
        ) or 0
        supplier_count = await db_session.scalar(select(func.count(Supplier.id)).where(Supplier.is_active == True)) or 0
        customer_count = await db_session.scalar(select(func.count(Customer.id)).where(Customer.is_active == True)) or 0
        warehouse_count = await db_session.scalar(select(func.count(Warehouse.id)).where(Warehouse.is_active == True)) or 0

        total_stock = await db_session.scalar(
            select(func.sum(Inventory.quantity))
            .join(Product, Inventory.product_id == Product.id)
            .where(Product.item_type == "material")
        ) or 0
        total_value = await db_session.scalar(
            select(func.sum(Inventory.quantity * Product.cost_price))
            .join(Product, Inventory.product_id == Product.id)
            .where(Product.item_type == "material")
        ) or 0

        pending_purchase = await db_session.scalar(
            select(func.count(PurchaseOrder.id)).where(PurchaseOrder.status == "pending")
        ) or 0
        pending_sales = await db_session.scalar(
            select(func.count(SalesOrder.id)).where(SalesOrder.status == "pending")
        ) or 0

        low_stock_products = await db_session.execute(
            select(Product, Inventory)
            .join(Inventory, Product.id == Inventory.product_id)
            .where(Product.item_type == "material")
            .where(Inventory.quantity <= Product.min_stock)
            .limit(10)
        )
        low_stock = [
            {"id": p.id, "name": p.name, "sku": p.sku, "quantity": i.quantity, "min_stock": p.min_stock}
            for p, i in low_stock_products.all()
        ]

        return {
            "finished_product_count": finished_product_count,
            "material_count": material_count,
            "supplier_count": supplier_count,
            "customer_count": customer_count,
            "warehouse_count": warehouse_count,
            "total_stock": total_stock,
            "total_value": round(total_value, 2),
            "pending_purchase": pending_purchase,
            "pending_sales": pending_sales,
            "low_stock_products": low_stock,
        }


dashboard_service = DashboardService()