```ruby
module Kaui
  class Ability
    include CanCan::Ability

    def initialize(user)
      # user is a Kaui::User object (from Devise)
      user.permissions.each do |permission|
        # permission is something like invoice:item_adjust or payment:refund
        # We rely on a naming convention where the left part refers to a Kaui model
        model, action = permission.split(':')
        if model == '*' and action == '*'
          # All permissions!
          can :manage, :all
        elsif model == '*' and action != '*'
          # TODO
        elsif action == '*'
          # TODO Not sure the :all is really working (but we don't use it)
          can :all, ('Kaui::' + model.camelize).constantize rescue nil
        else
          can action.to_sym, ('Kaui::' + model.camelize).constantize rescue nil
        end
      end
    rescue KillBillClient::API::Unauthorized => e
    end
  end
end
```

Fix Permission.java (killbill-api) to have clean model and fix'up CanCan to make the correct translation to KAUI models
user
```ruby
module Kaui
  class Ability
    include CanCan::Ability

    def initialize(user)
      # user is a Kaui::User object (from Devise)
      user.permissions.each do |permission|
        # permission is something like invoice:item_adjust or payment:refund
        # We rely on a naming convention where the left part refers to a Kaui model
        model, action = permission_to_model_action(permission)
        if model == '*' and action == '*'
          # All permissions!
          can :manage, :all
        elsif model == '*' and action != '*'
          # TODO
        elsif action == '*'
          # TODO Not sure the :all is really working (but we don't use it)
          can :all, ('Kaui::' + model.camelize).constantize rescue nil
        else
          can action.to_sym, ('Kaui::' + model.camelize).constantize rescue nil
        end
      end
    rescue KillBillClient::API::Unauthorized => e
    end

    def permission_to_model_action(permission)
      #
      # Permissions are defined in Kill Kill apis (https://github.com/killbill/killbill-api/blob/master/src/main/java/org/killbill/billing/security/Permission.java)
      # and they look something like 'invoice:item_adjust' or 'payment:refund', where the first part is the Kill Bill module and the second the action.
      #
      # For most of those the Kill Bill module maps to the Kaui model, but for a few, the naming convention breaks, so in order to keep the API clean, we do the fix up
      # in KAUI itself:
      #
      to_be_model, action = permission.split(':')
      # Currently the only actions implemented for overdue and catalog (upload_config) are those implemented at the tenant level:
      if to_be_model == 'tenant' || 'overdue' || 'catalog'
        to_be_model = 'admin_tenant'
      end
      [to_be_model, action]
    end
  end
end
```
assistant