Quickbooks extension app

Want an app created to work with quickbooks online. this is how the app should work: it first has to export customers from customer website, if customers have already been exported then do not export. Only new customers are exported. Customer Invoices are to be imported into quickbooks (these invoices have to be mapped to the relevant customer). This is essentially what the app will do. There are security protocols that the app will have in order to connect with QB and these are available in the developer forum (password will be provided to you)