feat: implement MRP kitting calculator for production simulation and shared component analysis

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
 import uuid
 from datetime import datetime
@@ -248,6 +250,117 @@ class BomService:
 
         return detail
 
+    # ====================== MRP 齐套模拟计算 ======================
+    @staticmethod
+    def calculate_kitting(entries: list) -> list:
+        """
+        MRP 齐套模拟计算
+
+        算法步骤：
+        1. 遍历传入的 BOM，取每个 BOM 最新版本的子件
+        2. 按子件 base_id 合并需求量：需求量 = dosage * (1 + loss_rate/100) * target_qty
+        3. 跨 StockBuy / StockSemi / StockProduct 聚合可用库存
+        4. 计算缺口：shortage = available_quantity - required_quantity
+
+        :param entries: [{"bom_no": "BOM-001", "target_qty": 10}, ...]
+        :return: [{base_id, name, spec, unit, required_qty, available_qty, shortage, children: [...]}, ...]
+        """
+        # Step 1: 展开所有 BOM 的子件，聚合需求量
+        demand_map = {}  # child_id -> {base_id, material_name, spec, unit, required_qty, bom_sources: []}
+
+        for entry in entries:
+            bom_no = entry.get('bom_no')
+            target_qty = float(entry.get('target_qty', 0) or 0)
+            if not bom_no or target_qty <= 0:
+                continue
+
+            # 取最新版本
+            latest_version = db.session.query(
+                BomTable.version
+            ).filter_by(
+                bom_no=bom_no
+            ).order_by(
+                BomTable.version.desc()
+            ).limit(1).scalar()
+
+            if not latest_version:
+                continue
+
+            # 查询该 BOM 所有子件
+            rows = db.session.query(
+                BomTable, MaterialBase.name, MaterialBase.spec_model, MaterialBase.unit
+            ).join(
+                MaterialBase, BomTable.child_id == MaterialBase.id
+            ).filter(
+                BomTable.bom_no == bom_no,
+                BomTable.version == latest_version,
+                BomTable.is_enabled == True
+            ).all()
+
+            for bom, child_name, child_spec, child_unit in rows:
+                dosage = float(bom.dosage or 0)
+                loss_rate = float(bom.loss_rate or 0)
+                adj_dosage = dosage * (1 + loss_rate / 100.0)
+                qty_needed = adj_dosage * target_qty
+
+                if bom.child_id not in demand_map:
+                    demand_map[bom.child_id] = {
+                        'base_id': bom.child_id,
+                        'material_name': child_name or '',
+                        'spec': child_spec or '',
+                        'unit': child_unit or '',
+                        'required_qty': 0.0,
+                        'bom_sources': []
+                    }
+                demand_map[bom.child_id]['required_qty'] += qty_needed
+                demand_map[bom.child_id]['bom_sources'].append({
+                    'bom_no': bom_no,
+                    'dosage': dosage,
+                    'loss_rate': loss_rate,
+                    'target_qty': target_qty
+                })
+
+        # Step 2: 批量查询三张库存表的可用库存
+        child_ids = list(demand_map.keys())
+        if not child_ids:
+            return []
+
+        # StockBuy.available_quantity, StockSemi.available_quantity, StockProduct.available_quantity
+        available_map = {cid: 0.0 for cid in child_ids}
+
+        for model_cls in (StockBuy, StockSemi, StockProduct):
+            if model_cls is None:
+                continue
+            rows = db.session.query(
+                model_cls.base_id,
+                func.coalesce(model_cls.available_quantity, 0)
+            ).filter(
+                model_cls.base_id.in_(child_ids)
+            ).all()
+            for base_id, qty in rows:
+                if base_id in available_map:
+                    available_map[base_id] += float(qty)
+
+        # Step 3: 构造结果，计算缺口
+        results = []
+        for base_id, info in demand_map.items():
+            avail = available_map.get(base_id, 0.0)
+            shortage = avail - info['required_qty']
+            results.append({
+                'base_id': base_id,
+                'material_name': info['material_name'],
+                'spec': info['spec'],
+                'unit': info['unit'],
+                'required_qty': round(info['required_qty'], 4),
+                'available_qty': round(avail, 4),
+                'shortage': round(shortage, 4),
+                'bom_sources': info['bom_sources']
+            })
+
+        # 按缺件数量降序排列（最缺的排前面）
+        results.sort(key=lambda x: x['shortage'])
+        return results
+
     # ====================== 兼容旧接口 ======================
     @staticmethod
     def get_bom_no_by_parent(parent_id):