"""
Shipment 模块业务逻辑层
"""
from __future__ import annotations

from typing import List

from django.db import transaction
from django.db.models import QuerySet

from shipment.models import ExternalFinishedProduct, SalesItem, Shipment


def get_sales_items_by_printing_order(
    printing_order_id: int,
    include_already_has_shipment: bool = False,
) -> QuerySet[SalesItem]:
    """
    通过生产订单ID查询对应的销售品
    
    Args:
        printing_order_id: 生产订单ID
        include_already_has_shipment: 是否包含已关联出货单的销售品，默认为 False
        
    Returns:
        SalesItem 查询集
    """
    from printing.models import PrintingJob
    
    # 1. 获取该生产订单下所有 PrintingJob 的 ID
    job_ids = PrintingJob.objects.filter(
        printing_order_id=printing_order_id
    ).values_list('id', flat=True)
    
    # 2. 查询 SalesItem，过滤 printing_job_id 在这些 job_ids 中
    queryset = SalesItem.objects.filter(printing_job_id__in=list(job_ids))
    
    # 3. 根据参数决定是否过滤已出货的销售品
    if not include_already_has_shipment:
        queryset = queryset.filter(shipment__isnull=True)
    
    return queryset.select_related('shipment').order_by('id')


@transaction.atomic
def create_shipment(
    customer_id: int,
    shipment_date,
    sales_item_ids: List[int],
    created_by,
    remark: str = '',
    area: str = '',
) -> Shipment:
    """
    创建出货单并关联销售品
    
    Args:
        customer_id: 客户ID
        shipment_date: 出货日期
        sales_item_ids: 要关联的销售品ID列表
        created_by: 创建人
        remark: 备注
        
    Returns:
        创建的 Shipment 实例
        
    Raises:
        ValueError: 如果销售品不存在或已被关联到其他出货单
    """
    from basic_info.models import Customer
    
    # 验证客户存在
    try:
        customer = Customer.objects.get(id=customer_id)
    except Customer.DoesNotExist:
        raise ValueError(f'客户 {customer_id} 不存在')

    # merchant 隔离：必须能解析出当前用户 merchant
    emp = getattr(created_by, 'employee', None)
    merchant = getattr(emp, 'merchant', None) if emp else None
    if not merchant:
        # superuser 也必须绑定 merchant（避免产生无法隔离的数据）
        raise ValueError('用户未关联商户，无法创建出货单')
    if customer.merchant_id != merchant.id:
        raise ValueError('无权限为该客户创建出货单')
    
    # 验证销售品
    if sales_item_ids:
        # 查询销售品
        sales_items = SalesItem.objects.filter(id__in=sales_item_ids)
        found_ids = set(sales_items.values_list('id', flat=True))
        missing_ids = set(sales_item_ids) - found_ids
        
        if missing_ids:
            raise ValueError(f'以下销售品不存在: {list(missing_ids)}')
        
        # 检查是否有已关联出货单的销售品
        already_shipped = sales_items.filter(shipment__isnull=False)
        if already_shipped.exists():
            shipped_ids = list(already_shipped.values_list('id', flat=True))
            raise ValueError(f'以下销售品已关联到其他出货单: {shipped_ids}')
    
    # 创建出货单
    shipment = Shipment.objects.create(
        merchant=merchant,
        customer=customer,
        shipment_date=shipment_date,
        area=(area or '').strip(),
        remark=remark,
        created_by=created_by,
    )
    
    # 关联销售品
    if sales_item_ids:
        updated = SalesItem.objects.filter(id__in=sales_item_ids, merchant=merchant).update(shipment=shipment)
        if updated != len(sales_item_ids):
            raise ValueError('存在不属于当前商户的销售品，无法关联到出货单')
    
    return shipment


@transaction.atomic
def create_external_shipment(
    customer_id: int,
    shipment_date,
    external_id: str,
    external_finished_products: List[dict],
    created_by,
    remark: str = '',
    area: str = '',
) -> Shipment:
    """
    创建出货单（external 版），并批量写入外部成品表并关联到出货单。
    
    特点：
    - 不绑定任何 SalesItem
    - external_id 必填
    - external_finished_products 必填（至少 1 条）
    """
    from basic_info.models import Customer

    # 验证客户存在
    try:
        customer = Customer.objects.get(id=customer_id)
    except Customer.DoesNotExist:
        raise ValueError(f'客户 {customer_id} 不存在')

    # merchant 隔离
    emp = getattr(created_by, 'employee', None)
    merchant = getattr(emp, 'merchant', None) if emp else None
    if not merchant:
        raise ValueError('用户未关联商户，无法创建出货单')
    if customer.merchant_id != merchant.id:
        raise ValueError('无权限为该客户创建出货单')

    external_id = (external_id or '').strip()
    if not external_id:
        raise ValueError('external_id 不能为空')
    if not external_finished_products:
        raise ValueError('external_finished_products 不能为空')

    shipment = Shipment.objects.create(
        merchant=merchant,
        customer=customer,
        shipment_date=shipment_date,
        area=(area or '').strip(),
        remark=remark,
        created_by=created_by,
        external_id=external_id,
    )

    objs = []
    for item in external_finished_products:
        objs.append(ExternalFinishedProduct(
            shipment=shipment,
            style_name=item.get('style_name', ''),
            num_of_rolls=item.get('num_of_rolls', 0),
            remark=item.get('remark') or '',
            created_by=created_by,
        ))

    ExternalFinishedProduct.objects.bulk_create(objs)
    return shipment