import uuid
from datetime import datetime
from sqlalchemy import or_
from app.extensions import db
from app.models.outbound import TransOutbound

# 导入所有库存实体模型，用于查找和扣减
from app.models.inbound.buy import StockBuy
from app.models.inbound.semi import StockSemi
from app.models.inbound.product import StockProduct


class OutboundService:

    @staticmethod
    def generate_outbound_no():
        """生成出库单号: OUT-yyyyMMdd-随机码"""
        date_str = datetime.now().strftime('%Y%m%d')
        short_uuid = uuid.uuid4().hex[:6].upper()
        return f"OUT-{date_str}-{short_uuid}"

    @staticmethod
    def get_stock_by_barcode(barcode):
        """
        根据条码在各个库存表中查找
        优先级: 成品 -> 半成品 -> 采购件
        """
        if not barcode:
            return None

        # 1. 查成品
        prod = StockProduct.query.filter_by(barcode=barcode).first()
        if prod:
            return OutboundService._format_scan_result(prod, 'stock_product', prod.sku)

        # 2. 查半成品
        semi = StockSemi.query.filter_by(barcode=barcode).first()
        if semi:
            return OutboundService._format_scan_result(semi, 'stock_semi', semi.sku)

        # 3. 查采购件
        buy = StockBuy.query.filter_by(barcode=barcode).first()
        if buy:
            # 采购件可能需要关联 material_base 获取名称，这里假设 base_id 关联已建立
            name = buy.base.name if buy.base else "未知采购件"
            spec = buy.base.spec_model if buy.base else ""
            return OutboundService._format_scan_result(buy, 'stock_buy', buy.sku, name, spec)

        return None

    @staticmethod
    def _format_scan_result(item, table_name, sku, name=None, spec=None):
        """格式化返回给前端的数据结构"""
        # 如果没有传 name (例如成品/半成品)，尝试通过关联获取，或者直接用 SKU 代替
        item_name = name
        item_spec = spec

        if not item_name and hasattr(item, 'base') and item.base:
            item_name = item.base.name
            item_spec = item.base.spec_model

        return {
            'id': item.id,
            'sku': sku,
            'name': item_name or sku,
            'spec_model': item_spec or '',
            'source_table': table_name,
            'stock_quantity': float(item.stock_quantity),
            'available_quantity': float(item.available_quantity),
            'batch_number': getattr(item, 'batch_number', ''),
            'warehouse_location': getattr(item, 'warehouse_location', '')
        }

    @staticmethod
    def create_outbound(data, operator_name='System'):
        """执行出库逻辑：扣减库存 + 记录日志"""
        source_table = data.get('source_table')
        stock_id = data.get('stock_id')
        quantity = float(data.get('quantity', 0))

        if quantity <= 0:
            raise ValueError("出库数量必须大于0")

        # 1. 获取对应的库存记录模型
        model_map = {
            'stock_buy': StockBuy,
            'stock_semi': StockSemi,
            'stock_product': StockProduct
        }

        ModelClass = model_map.get(source_table)
        if not ModelClass:
            raise ValueError(f"未知的库存来源表: {source_table}")

        # 2. 锁定并查询库存 (使用 with_for_update 防止并发扣减)
        stock_item = ModelClass.query.with_for_update().get(stock_id)
        if not stock_item:
            raise ValueError("库存记录不存在")

        if stock_item.available_quantity < quantity:
            raise ValueError(f"库存不足！当前可用: {stock_item.available_quantity}, 请求出库: {quantity}")

        try:
            # 3. 扣减库存
            stock_item.stock_quantity -= quantity
            stock_item.available_quantity -= quantity

            # 4. 创建出库记录
            new_outbound = TransOutbound(
                outbound_no=OutboundService.generate_outbound_no(),
                sku=data.get('sku'),
                source_table=source_table,
                stock_id=stock_id,
                barcode=data.get('barcode'),
                outbound_type=data.get('outbound_type', 'SALES'),
                quantity=quantity,
                consumer_name=data.get('consumer_name'),
                signature_path=data.get('signature_path'),  # 存储签名的 URL
                operator_name=operator_name,
                remark=data.get('remark')
            )

            db.session.add(new_outbound)
            db.session.commit()

            return new_outbound

        except Exception as e:
            db.session.rollback()
            raise e

    @staticmethod
    def get_list(page=1, per_page=10, keyword=None, start_date=None, end_date=None):
        query = TransOutbound.query.order_by(TransOutbound.outbound_time.desc())

        if keyword:
            query = query.filter(or_(
                TransOutbound.outbound_no.ilike(f'%{keyword}%'),
                TransOutbound.consumer_name.ilike(f'%{keyword}%'),
                TransOutbound.sku.ilike(f'%{keyword}%')
            ))

        if start_date and end_date:
            # 假设传入的是 'YYYY-MM-DD'，需要处理时间范围
            query = query.filter(TransOutbound.outbound_time.between(start_date, end_date))

        pagination = query.paginate(page=page, per_page=per_page, error_out=False)
        return {
            'items': [item.to_dict() for item in pagination.items],
            'total': pagination.total,
            'pages': pagination.pages,
            'current_page': page
        }