Laravel passport, oauth scopes and roles and permissions

Hi! I am developing SPA in angular and backend API in laravel 5.3. I have integrated laravel passport for oauth.

I have to make roles and permissions impl using views on tables from other database which is maintained by other system. In this system user has 1 role. And role has self reference so there is hierarchical structure, for example:

• canSeeAnimals
• canSeeMammals (child of canSeeAnimals)
• canSeeWolf (child of canSeeMammals)

So I am thinking of following workflow but not sure how to implement it:

1. Another system manage users, roles and permissions
2. API server(under my control) has access to another system tables via views:
   • user
   • role
   • v_role_level (in this table is defined parent child relationship between roles)
3. Client app(angular) request resource from the API server
4. API server load users data with roles and permissions and generate token with scope which is mapped to roles and permissions.

Point 4 is under the question. How I can manage to intercept/override token generation in order generate token with scope which depends on user roles and permissions?