Hi i need that users only view contats that be of this user or belong to the same company to which the user belongs if you do not have an assigned user

For example,

Pepe is contact of company A,

Pedro is contact of company A and is assignet to user Julius

Victor contact of company B

User Julius belong to company A

User Marcos belong to company A

User Petra belong to company B

The user Julius can see the contact Pepe and Juan

The user Marcos only see the contact Pepe

The user Petra only see the contact Victor

How can i do it?