"""
仪表盘路由模块

提供进销存系统的仪表盘统计数据，包括：
- 基础数据统计（产品数、供应商数、客户数、仓库数）
- 库存统计（总库存量、库存总价值）
- 订单统计（待处理采购订单、待处理销售订单）
- 低库存产品预警（库存量低于最小库存的产品列表）

路由前缀: /api/dashboard
"""
from fastapi import APIRouter, Depends
from sqlalchemy.ext.asyncio import AsyncSession
from sqlalchemy import select, func

from database.database import get_db_session
from services.auth_service import get_current_active_user
from models.database import (
    User, Product, Supplier, Customer, Warehouse, 
    Inventory, PurchaseOrder, SalesOrder
)

router = APIRouter(prefix="/dashboard", tags=["仪表盘"])


@router.get("")
async def get_dashboard(
    db_session: AsyncSession = Depends(get_db_session),
    current_user: User = Depends(get_current_active_user)
):
    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))
    customer_count = await db_session.scalar(select(func.count(Customer.id)).where(Customer.is_active == True))
    warehouse_count = await db_session.scalar(select(func.count(Warehouse.id)).where(Warehouse.is_active == True))
    
    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")
    )
    pending_sales = await db_session.scalar(
        select(func.count(SalesOrder.id)).where(SalesOrder.status == "pending")
    )
    
    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
    }