import contextlib
import errno
import socket


def find_available_port(host, port=5005):
    """
    Helper method to find open port on host. Tries 5000 ports incremented from the specified port
    """
    # Takes approx 2 seconds to do a scan of 5000 ports on my laptop
    num_ports_to_try = 5000
    for port_to_try in range(port, port + num_ports_to_try):
        if is_port_available(host, port_to_try):
            return port_to_try
    raise socket.error(errno.EADDRINUSE, f"No port in range {port} - {port + num_ports_to_try - 1} available.")


def is_port_available(host, port):
    is_available = False
    with contextlib.closing(socket.socket(socket.AF_INET, socket.SOCK_STREAM)) as s:
        try:
            s.bind((host, port))
            is_available = True
        except socket.error:
            pass
    return is_available