How does Bonita Portal assign Task to User or User Group

Q&A
1

Hello,
I am building a Angular +  Bonita Application.
I am trying to decide the Tasks that are available to a particular user.
I can see 2 Rest API.
/API/bpm/humanTask?p=0&c=10   ---- All the Tasks
/API/bpm/humanTask?p=0&c=10&f=assigned_id%3d2   ---- Assigned to User

How to find out which tasks are available to user but not directly assigned to him.
So basically i want to figure out the Tasks assigned to groups o which the user is member of 

thanks
 

2

is there any API that can be used directly or is custom script required.