feat: core inventory API and secure operation routers

backend/routers/operations.py

@@ -0,0 +1,62 @@
+from fastapi import APIRouter, Depends, HTTPException, status
+from sqlalchemy.orm import Session
+from .. import models, schemas
+from ..database import get_db
+
+router = APIRouter(
+    prefix="/operations",
+    tags=["Operations"]
+)
+
+@router.post("/check-in", response_model=schemas.Item)
+def check_in_item(op: schemas.OperationCreate, db: Session = Depends(get_db)):
+    if op.quantity <= 0:
+         raise HTTPException(status_code=400, detail="Quantity must be greater than zero")
+         
+    item = db.query(models.Item).filter(models.Item.barcode == op.barcode).first()
+    if not item:
+        raise HTTPException(status_code=404, detail="Item not found. Register item first.")
+        
+    # Update quantity
+    item.quantity += op.quantity
+    
+    # Create Mandatory Audit Log
+    audit = models.AuditLog(
+        user_id=op.user_id,
+        action="CHECK_IN",
+        target_item_id=item.id,
+        quantity_change=op.quantity
+    )
+    
+    db.add(audit)
+    db.commit()
+    db.refresh(item)
+    return item
+
+@router.post("/check-out", response_model=schemas.Item)
+def check_out_item(op: schemas.OperationCreate, db: Session = Depends(get_db)):
+    if op.quantity <= 0:
+         raise HTTPException(status_code=400, detail="Quantity must be greater than zero")
+         
+    item = db.query(models.Item).filter(models.Item.barcode == op.barcode).first()
+    if not item:
+        raise HTTPException(status_code=404, detail="Item not found")
+        
+    if item.quantity < op.quantity:
+        raise HTTPException(status_code=status.HTTP_400_BAD_REQUEST, detail="Insufficient stock")
+        
+    # Update quantity
+    item.quantity -= op.quantity
+        
+    # Create Mandatory Audit Log
+    audit = models.AuditLog(
+        user_id=op.user_id,
+        action="CHECK_OUT",
+        target_item_id=item.id,
+        quantity_change=-op.quantity
+    )
+    
+    db.add(audit)
+    db.commit()
+    db.refresh(item)
+    return item