Addition of row in Despatch Schedule

i = 0;
for each  rec_sn in input.Despatch_Schedule
{
	i = i + 1;
	row.S_No=i;
}
//For Delivery Schedule
clear row.Part_No;
item_list = List();
deliv_list = List();
for each  an_item in input.Item_Details
{
	item_list.add(an_item.Part_Description);
}
for each  deliv in input.Despatch_Schedule
{
	if(deliv.Part_No != null && deliv.Full_Quantity == true)
	{
		deliv_list.add(deliv.Part_No);
	}
}
item_list.removeAll(deliv_list);
row.Part_No:ui.add(item_list.sort(true));
if(item_list.size() > 0)
{
	row.Part_No=item_list.get(0);
	//Setting Quantity
	for each  rec in input.Item_Details
	{
		if(rec.Qty < 1)
		{
			alert "Please enter quantity for all the item(s) in Item Details ";
			row.Quantity=null;
		}
		else
		{
			tot = 0.0;
			for each  rec1 in input.Despatch_Schedule
			{
				if(rec1.Part_No == rec.Part_Description)
				{
					tot = tot + ifnull(rec1.Quantity,0.0);
				}
			}
			if(rec.Part_Description == row.Part_No)
			{
				row.Quantity=if(tot > 0,rec.Qty - tot,rec.Qty);
				row.Delivery_Date=if(tot > 0,null,input.Expected_Shipment_Date);
				row.Specification=rec.Remarks_multiline;
				row.Full_Quantity=true;
			}
		}
	}
}