Xamarin APP for warehouse management

It is required to develop an APP with Visual Studio Tools for Xamarin with Visual Studio 2015 and C # language. This APP must be able to manage both online and offline loads, unloads and warehouse transfers. The APP must work on both Android and IOS systems. The development must be done using only Visual Studio 2015 and Visual Studio Tools for Xamarin with language c#: libraries and third-party controls are not allowed. The APP must provide authentication with login and password. The user of the APP must be able to perform the loads, unloads and warehouse transfer operations by reading a barcode, searching an item by barcode (digiting it), searching product by code, category or description. Once the items are acquired for loads, unloads or transfer, the user based on the presence or not of the internet connection can save movements in a local database (and then synchronize they later) or synchronize they immediately. In addition to the development of the APP, all webservices for connecting to a MS SQL SERVER database must be developed for synchronization of warehouse movements. The MS SQL SERVER database will be provided. To get an idea of ​​how to implement the APP, look the video in file upload "[login to view URL]".