from abc import ABCMeta

import zmq

from robot_interface.core.config import settings


class SocketBase(object):
    """
    Base class for endpoints associated with a ZeroMQ socket.

    :ivar identifier: The identifier of the endpoint.
    :vartype identifier: str

    :ivar port: The port used by the socket, set by `create_socket`.
    :vartype port: int | None

    :ivar socket: The ZeroMQ socket object, set by `create_socket`.
    :vartype socket: zmq.Socket | None

    :ivar bound: Whether the socket is bound or connected, set by `create_socket`.
    :vartype bound: bool | None
    """
    __metaclass__ = ABCMeta

    name = None
    socket = None

    def __init__(self, identifier):
        self.identifier = identifier
        self.port = None  # Set later by `create_socket`
        self.socket = None  # Set later by `create_socket`
        self.bound = None  # Set later by `create_socket`

    def create_socket(self, zmq_context, socket_type, port, options=[], bind=True):
        """
        Create a ZeroMQ socket.

        :param zmq_context: The ZeroMQ context to use.
        :type zmq_context: zmq.Context

        :param socket_type: The type of socket to create. Use zmq constants, e.g. zmq.SUB or zmq.REP.
        :type socket_type: int

        :param port: The port to use.
        :type port: int

        :param options: A list of tuples where the first element contains the option and the second the value.
        :type options: list[tuple[int, int]]

        :param bind: Whether to bind the socket or connect to it.
        :type bind: bool
        """
        self.port = port
        self.socket = zmq_context.socket(socket_type)

        for option, arg in options:
            self.socket.setsockopt(option,arg)

        self.bound = bind
        if bind:
            self.socket.bind("tcp://*:{}".format(port))
        else:
            self.socket.connect("tcp://{}:{}".format(settings.agent_settings.control_backend_host, port))

    def close(self):
        """Close the ZeroMQ socket."""
        if not self.socket: return
        self.socket.close()
        self.socket = None

    def endpoint_description(self):
        """
        Description of the endpoint. Used for negotiation.

        :return: A dictionary with the following keys: id, port, bind. See API specification at:
            https://utrechtuniversity.youtrack.cloud/articles/N25B-A-14/RI-CB-Communication#negotiation
        :rtype: dict
        """
        return {
            "id": self.identifier,
            "port": self.port,
            "bind": not self.bound
        }