Some direction with remote input gateway

[Sync365License]

Hey all, 
I am driving myself crazy trying to work out the correct sequence of events here and am not getting very clear from the documentation.

I am trying to create a remote input gateway. 
My credit card processor has a javascript element we can insert and just provide the client id and an intent ID to. This will then provide the CC details field, do the processing and return a result so we can then store the token.

I am a bit lost on how this should work.

 

Should it work this way?

1. Gateway file in the _remoteinput section, this checks for an existing client and creates or gets the client id from the API

2. This has the php page which has the element in it and posts the intent and client id to it with a callback to a callback file.

3. on success, the callback has the instructions to save the card details and token into the WHMCS customer?

 

Or should the create/get client ID phase be part of the php page that has the javascript element?

 

 

No doco seems to relate to requiring info/client id's etc from the cc processor so I am just lost at which step this should be occurring at to send the required details through to the element for the credit card.

 

Thank you