gistfile1.txt

const initialState = {
  orders: []
};

const preparedOrdersReducer = (state = initialState, action) => {
  switch (action.type) {
    case SET_PREPARED_ORDERS:
      return {
        ...state,
        orders: generatePreparedOrder(state.orders, action.payload)
      };

    default:
      return state;
  }
};

const generatePreparedOrder = (orders, data) => {
  //Search with ID
  for (let i = 0; i < orders.length; i++) {
    if (orders[i].id == data.id) {
      //If find the same id order, it will combine items.
      orders[i].items = generatePreparedItem(orders[i].items, data.items);
      return orders;
    }
  }
  //If there is not same id order, new order will be pushed.
  orders = [...orders, data];
  return orders;
};

const generatePreparedItem = (oldItems, items) => {
  //Search with EAN of item
  for (let i = 0; i < items.length; i++) {
    let j = 0;
    for (j = 0; j < oldItems.length; j++) {
      if (items[i].EAN == oldItems[j].EAN) {
        //If you find the same EAN item, it will be replaced.
        oldItems[j] = items[i];
        break;
      }
    }
    if (j == oldItems.length) {
      //Not found with same EAN item, it will be pushed.
      oldItems = [...oldItems, items[i]];
    }
  }

  return oldItems;
};