"""
Utility functions for managing ports in tests.
"""
import socket
from typing import List


def find_free_port(start_port: int = 8000, max_attempts: int = 100) -> int:
    """
    Find a free port starting from the specified port.
    
    Args:
        start_port: Starting port to check
        max_attempts: Maximum number of ports to check
        
    Returns:
        Free port number
    """
    for port in range(start_port, start_port + max_attempts):
        try:
            with socket.socket(socket.AF_INET, socket.SOCK_STREAM) as s:
                s.bind(('127.0.0.1', port))
                return port
        except OSError:
            continue
    raise RuntimeError(f"Could not find free port in range {start_port}-{start_port + max_attempts}")


def get_test_ports() -> dict:
    """
    Get a set of unique ports for testing.
    
    Returns:
        Dictionary with port assignments
    """
    return {
        'opcua_port': find_free_port(4840),
        'modbus_port': find_free_port(5020),
        'rest_api_port': find_free_port(8000)
    }