import ast
import errno
import hashlib
import importlib
import inspect
import logging
import os
import signal
import socket
import ssl

logger = logging.getLogger(__name__)

def get_module_and_method_from_action(action):
    """ Input  : action=music.mpd.play
        Output : ('music.mpd', 'play') """

    tokens = action.split('.')
    module_name = str.join('.', tokens[:-1])
    method_name = tokens[-1:][0]
    return (module_name, method_name)


def get_message_class_by_type(msgtype):
    """ Gets the class of a message type given as string """

    try:
        module = importlib.import_module('platypush.message.' + msgtype)
    except ImportError as e:
        logger.warning('Unsupported message type {}'.format(msgtype))
        raise RuntimeError(e)

    cls_name = msgtype[0].upper() + msgtype[1:]

    try:
        msgclass = getattr(module, cls_name)
    except AttributeError as e:
        logger.warning('No such class in {}: {}'.format(
            module.__name__, cls_name))
        raise RuntimeError(e)

    return msgclass


def get_event_class_by_type(type):
    """ Gets an event class by type name """
    event_module = importlib.import_module('.'.join(type.split('.')[:-1]))
    return getattr(event_module, type.split('.')[-1])


def set_timeout(seconds, on_timeout):
    """
    Set a function to be called if timeout expires without being cleared.
    It only works on the main thread.

    Params:
        seconds    -- Timeout in seconds
        on_timeout -- Function invoked on timeout unless clear_timeout is called before
    """

    def _sighandler(signum, frame):
        on_timeout()

    signal.signal(signal.SIGALRM, _sighandler)
    signal.alarm(seconds)


def clear_timeout():
    """ Clear any previously set timeout """
    signal.alarm(0)


def get_hash(s):
    """ Get the SHA256 hash hexdigest of a string input """
    return hashlib.sha256(s.encode('utf-8')).hexdigest()


def get_decorators(cls, climb_class_hierarchy=False):
    """
    Get the decorators of a class as a {"decorator_name": [list of methods]} dictionary
    :param climb_class_hierarchy: If set to True (default: False), it will search return the decorators in the parent classes as well
    :type climb_class_hierarchy: bool
    """

    decorators = {}

    def visit_FunctionDef(node):
        for n in node.decorator_list:
            name = ''
            if isinstance(n, ast.Call):
                name = n.func.attr if isinstance(n.func, ast.Attribute) else n.func.id
            else:
                name = n.attr if isinstance(n, ast.Attribute) else n.id

            decorators[name] = decorators.get(name, set())
            decorators[name].add(node.name)

    if climb_class_hierarchy:
        targets = inspect.getmro(cls)
    else:
        targets = [cls]

    node_iter = ast.NodeVisitor()
    node_iter.visit_FunctionDef = visit_FunctionDef

    for target in targets:
        try:
            node_iter.visit(ast.parse(inspect.getsource(target)))
        except TypeError:
            # Ignore built-in classes
            pass

    return decorators


def get_redis_queue_name_by_message(msg):
    from platypush.message import Message

    if not isinstance(msg, Message):
        logger.warning('Not a valid message (type: {}): {}'.format(type(msg), msg))

    return 'platypush/responses/{}'.format(msg.id) if msg.id else None


def _get_ssl_context(context_type=None, ssl_cert=None, ssl_key=None,
                     ssl_cafile=None, ssl_capath=None):
    if not context_type:
        ssl_context = ssl.create_default_context(cafile=ssl_cafile,
                                                 capath=ssl_capath)
    else:
        ssl_context = ssl.SSLContext(context_type)

    ssl_context = ssl.SSLContext(ssl.PROTOCOL_TLS_SERVER)

    if ssl_cafile or ssl_capath:
        ssl_context.load_verify_locations(
            cafile=ssl_cafile, capath=ssl_capath)

    ssl_context.load_cert_chain(
        certfile=os.path.abspath(os.path.expanduser(ssl_cert)),
        keyfile=os.path.abspath(os.path.expanduser(ssl_key)) if ssl_key else None
    )

    return ssl_context


def get_ssl_context(ssl_cert=None, ssl_key=None, ssl_cafile=None,
                    ssl_capath=None):
    return _get_ssl_context(context_type=None,
                            ssl_cert=ssl_cert, ssl_key=ssl_key,
                            ssl_cafile=ssl_cafile, ssl_capath=ssl_capath)


def get_ssl_server_context(ssl_cert=None, ssl_key=None, ssl_cafile=None,
                           ssl_capath=None):
    return _get_ssl_context(context_type=ssl.PROTOCOL_TLS_SERVER,
                            ssl_cert=ssl_cert, ssl_key=ssl_key,
                            ssl_cafile=ssl_cafile, ssl_capath=ssl_capath)


def get_ssl_client_context(ssl_cert=None, ssl_key=None, ssl_cafile=None,
                           ssl_capath=None):
    return _get_ssl_context(context_type=ssl.PROTOCOL_TLS_CLIENT,
                            ssl_cert=ssl_cert, ssl_key=ssl_key,
                            ssl_cafile=ssl_cafile, ssl_capath=ssl_capath)

def set_thread_name(name):
    global logger

    try:
        import prctl
        prctl.set_name(name)
    except ImportError:
        logger.debug('Unable to set thread name: prctl module is missing')

def find_bins_in_path(bin_name):
    return [os.path.join(p, bin_name)
            for p in os.environ.get('PATH', '').split(':')
            if os.path.isfile(os.path.join(p, bin_name))
            and (os.name == 'nt' or
                 os.access(os.path.join(p, bin_name), os.X_OK))]


def find_files_by_ext(directory, *exts):
    """
    Finds all the files in the given directory with the provided extensions
    """

    if not exts:
        raise AttributeError('No extensions provided')

    if not os.path.isdir(directory):
        raise AttributeError('{} is not a valid directory'.format(directory))

    min_len = len(min(exts, key=len))
    max_len = len(max(exts, key=len))
    result = []

    for root, dirs, files in os.walk(directory):
        for i in range(min_len, max_len+1):
            result += [f for f in files if f[-i:] in exts]

    return result


def is_process_alive(pid):
    try:
        os.kill(pid, 0)
        return True
    except OSError:
        return False


def get_ip_or_hostname():
    ip = socket.gethostbyname(socket.gethostname())
    return socket.getfqdn() if ip.startswith('127.') else ip


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