How to get max_amount, min_amount from Contribution Page
what is that you have in the param?

I would suggest you to use the api explorer, it should guide you and the generated code can be copy/pasted in your plugin

Just to be clear: the min_amount and max_amount are the amounts a user CAN enter, it doesn't show how much has been given already. for that, you should look at the contribution api.getcount (and filter it by contribution_page)