Hello Fabio,
I do not know how complicated it would be to build it yourself, I am not a programmer/developer, just a technican. But I am sure there are a lot of people out there that has built what you are looking for and might be able to give you some hints.
I have just been looking into a couple of 3rd party products for our needs.
Sorry that I can't be of any more help.
Regards,
Thomas