24.DesignPermissionandRoleManagementSystem.py

# Design a simple Permission and Role Management System that can:
# add users, define roles and permissions, assign roles to users, and check 
# whether a user has a specific permission — all in-memory without any external database.

class PermissionSystem:
    def __init__(self):
        self.role_permissions = {}
        self.user_roles = {}

    def add_role(self, role_name):
        if role_name not in self.role_permissions:
            self.role_permissions[role_name] = set()

    def add_permission_to_role(self, role_name, permission):
        if role_name not in self.role_permissions:
            self.add_role(role_name)
        self.role_permissions[role_name].add(permission)

    def add_user(self, username):
        if username not in self.user_roles:
            self.user_roles[username] = set()

    def assign_role_to_user(self, username, role_name):
        if username not in self.user_roles:
            self.add_user(username)
        self.user_roles[username].add(role_name)

    def check_user_permission(self, username, permission):
        roles = self.user_roles.get(username, [])
        for role in roles:
            if permission in self.role_permissions.get(role, []):
                return True
            return False
        
    def display_user_access(self, username):
        if username not in self.user_roles:
            return f" User '{username}' not found."
        roles = self.user_roles[username]
        permissions = set()
        for role in roles:
            permissions |= self.role_permissions.get(role, set())
        return f"User: {username}\nRoles: {roles}\nPermissions: {permissions}"
    
if __name__ == "__main__":
    ps = PermissionSystem()

    # Define roles and permissions
    ps.add_role("Admin")
    ps.add_role("Editor")

    ps.add_permission_to_role("Admin", "add_user")
    ps.add_permission_to_role("Admin", "delete_user")
    ps.add_permission_to_role("Editor", "edit_content")

    # Create users
    ps.add_user("Alice")
    ps.add_user("Bob")

    # Assign roles
    ps.assign_role_to_user("Alice", "Admin")
    ps.assign_role_to_user("Bob", "Editor")

    # Display user access
    print(ps.display_user_access("Alice"))
    print(ps.display_user_access("Bob"))

    # Check permissions
    print("Can Alice delete user?", ps.check_user_permission("Alice", "delete_user"))
    print("Can Bob delete user?", ps.check_user_permission("Bob", "delete_user"))