新增 /cascade-inventory 级联库存缺口查询接口，供 AI 调用 BOM 出库缺口分析

inventory-backend/app/services/bom_service.py

@@ -2,6 +2,8 @@ from app.extensions import db
 from app.models.bom import BomTable
 from app.models.base import MaterialBase
 from app.models.inbound.buy import StockBuy
+from app.models.inbound.semi import StockSemi
+from app.models.inbound.product import StockProduct
 from sqlalchemy import func, distinct, or_, case
 from collections import defaultdict
 import uuid
@@ -457,4 +459,69 @@ class BomService:
         bom_no = BomService.get_bom_no_by_parent(parent_id)
         if not bom_no: return []
         detail = BomService.get_bom_with_stock_by_bom_no(bom_no)
-        return detail['children'] if detail else []
+        return detail['children'] if detail else []
+
+    @staticmethod
+    def calculate_cascade_inventory(bom_no, order_qty):
+        """
+        根据 bom_no 和订单数量，计算所有子件的级联库存缺口。
+        返回结构供 AI 消费，每个子件包含：parent_name / spec / name / level_type /
+        need_qty / available_stock / suggested_qty / gap
+        若 BOM 不存在返回 None。
+        """
+        # 1. 获取 BOM 明细
+        detail = BomService.get_bom_detail(bom_no)
+        if not detail or not detail.get('children'):
+            return None
+
+        parent_name = detail.get('parent_name', '')
+
+        # 2. 提取所有子件 ID，查询采购库存（stock_buy）
+        child_ids = [child['child_id'] for child in detail['children']]
+
+        buy_stats = db.session.query(
+            StockBuy.base_id,
+            func.coalesce(func.sum(StockBuy.available_quantity), 0).label('total_qty')
+        ).filter(
+            StockBuy.base_id.in_(child_ids)
+        ).group_by(StockBuy.base_id).all()
+
+        buy_map = {stat.base_id: float(stat.total_qty) for stat in buy_stats}
+
+        # 3. 提取所有子件的基础物料信息（名称/规格/类型）
+        materials = db.session.query(
+            MaterialBase.id,
+            MaterialBase.name,
+            MaterialBase.spec_model
+        ).filter(MaterialBase.id.in_(child_ids)).all()
+
+        mat_map = {
+            m.id: {'name': m.name or '', 'spec': m.spec_model or ''}
+            for m in materials
+        }
+
+        # 4. 遍历子件，计算每个子件的缺口数据
+        results = []
+        for child in detail['children']:
+            child_id = child['child_id']
+            dosage = float(child.get('dosage') or 0)
+            need_qty = dosage * order_qty
+
+            available_stock = buy_map.get(child_id, 0)
+            suggested_qty = max(0.0, min(need_qty, available_stock))
+            gap = available_stock - need_qty
+
+            mat_info = mat_map.get(child_id, {'name': '', 'spec': ''})
+
+            results.append({
+                'parent_name':   parent_name,
+                'spec':          mat_info['spec'],
+                'name':          mat_info['name'],
+                'level_type':    'child',
+                'need_qty':      round(need_qty, 4),
+                'available_stock': round(available_stock, 4),
+                'suggested_qty':   round(suggested_qty, 4),
+                'gap':             round(gap, 4),
+            })
+
+        return results