I've created this repo on github. Right now it's quite a mess, but I'm getting there. Take a look at the files:
Which is where I'm setting up the OAuth dance (which was an enormous pain in the ass), but now it seems to be okay. I'm now in the process of creating an API class and severall classes for updating and reading accounts, invoices etc.
In the end I want to create workflow tasks for this and register this module with only a backend settings menu where you could enter you client_id, secret etc.
Which is where I'm setting up the OAuth dance (which was an enormous pain in the ass), but now it seems to be okay. I'm now in the process of creating an API class and severall classes for updating and reading accounts, invoices etc.
In the end I want to create workflow tasks for this and register this module with only a backend settings menu where you could enter you client_id, secret etc.