# Copyright (c) 2012-2014 Roger Light <roger@atchoo.org>
#
# All rights reserved. This program and the accompanying materials
# are made available under the terms of the Eclipse Public License v1.0
# and Eclipse Distribution License v1.0 which accompany this distribution.
#
# The Eclipse Public License is available at
#    http://www.eclipse.org/legal/epl-v10.html
# and the Eclipse Distribution License is available at
#   http://www.eclipse.org/org/documents/edl-v10.php.
#
# Contributors:
#    Roger Light - initial API and implementation

"""
This is an MQTT v3.1 client module. MQTT is a lightweight pub/sub messaging
protocol that is easy to implement and suitable for low powered devices.
"""
import collections
import errno
import os
import platform
import select
import socket

try:
    import ssl
except ImportError:
    ssl = None

import struct
import sys
import threading

import time
import uuid
import base64
import string
import hashlib
import logging

try:
    # Use monotonic clock if available
    time_func = time.monotonic
except AttributeError:
    time_func = time.time

try:
    import dns.resolver
except ImportError:
    HAVE_DNS = False
else:
    HAVE_DNS = True

from .matcher import MQTTMatcher

if platform.system() == 'Windows':
    EAGAIN = errno.WSAEWOULDBLOCK
else:
    EAGAIN = errno.EAGAIN

MQTTv31 = 3
MQTTv311 = 4

if sys.version_info[0] >= 3:
    # define some alias for python2 compatibility
    unicode = str
    basestring = str

# Message types
CONNECT = 0x10
CONNACK = 0x20
PUBLISH = 0x30
PUBACK = 0x40
PUBREC = 0x50
PUBREL = 0x60
PUBCOMP = 0x70
SUBSCRIBE = 0x80
SUBACK = 0x90
UNSUBSCRIBE = 0xA0
UNSUBACK = 0xB0
PINGREQ = 0xC0
PINGRESP = 0xD0
DISCONNECT = 0xE0

# Log levels
MQTT_LOG_INFO = 0x01
MQTT_LOG_NOTICE = 0x02
MQTT_LOG_WARNING = 0x04
MQTT_LOG_ERR = 0x08
MQTT_LOG_DEBUG = 0x10
LOGGING_LEVEL = {
    MQTT_LOG_DEBUG: logging.DEBUG,
    MQTT_LOG_INFO: logging.INFO,
    MQTT_LOG_NOTICE: logging.INFO,  # This has no direct equivalent level
    MQTT_LOG_WARNING: logging.WARNING,
    MQTT_LOG_ERR: logging.ERROR,
}

# CONNACK codes
CONNACK_ACCEPTED = 0
CONNACK_REFUSED_PROTOCOL_VERSION = 1
CONNACK_REFUSED_IDENTIFIER_REJECTED = 2
CONNACK_REFUSED_SERVER_UNAVAILABLE = 3
CONNACK_REFUSED_BAD_USERNAME_PASSWORD = 4
CONNACK_REFUSED_NOT_AUTHORIZED = 5

# Connection state
mqtt_cs_new = 0
mqtt_cs_connected = 1
mqtt_cs_disconnecting = 2
mqtt_cs_connect_async = 3

# Message state
mqtt_ms_invalid = 0
mqtt_ms_publish = 1
mqtt_ms_wait_for_puback = 2
mqtt_ms_wait_for_pubrec = 3
mqtt_ms_resend_pubrel = 4
mqtt_ms_wait_for_pubrel = 5
mqtt_ms_resend_pubcomp = 6
mqtt_ms_wait_for_pubcomp = 7
mqtt_ms_send_pubrec = 8
mqtt_ms_queued = 9

# Error values
MQTT_ERR_AGAIN = -1
MQTT_ERR_SUCCESS = 0
MQTT_ERR_NOMEM = 1
MQTT_ERR_PROTOCOL = 2
MQTT_ERR_INVAL = 3
MQTT_ERR_NO_CONN = 4
MQTT_ERR_CONN_REFUSED = 5
MQTT_ERR_NOT_FOUND = 6
MQTT_ERR_CONN_LOST = 7
MQTT_ERR_TLS = 8
MQTT_ERR_PAYLOAD_SIZE = 9
MQTT_ERR_NOT_SUPPORTED = 10
MQTT_ERR_AUTH = 11
MQTT_ERR_ACL_DENIED = 12
MQTT_ERR_UNKNOWN = 13
MQTT_ERR_ERRNO = 14
MQTT_ERR_QUEUE_SIZE = 15

MQTT_CLIENT = 0
MQTT_BRIDGE = 1

sockpair_data = b"0"

class WebsocketConnectionError(ValueError):
    pass


class WouldBlockError(Exception):
    pass


def error_string(mqtt_errno):
    """Return the error string associated with an mqtt error number."""
    if mqtt_errno == MQTT_ERR_SUCCESS:
        return "No error."
    elif mqtt_errno == MQTT_ERR_NOMEM:
        return "Out of memory."
    elif mqtt_errno == MQTT_ERR_PROTOCOL:
        return "A network protocol error occurred when communicating with the broker."
    elif mqtt_errno == MQTT_ERR_INVAL:
        return "Invalid function arguments provided."
    elif mqtt_errno == MQTT_ERR_NO_CONN:
        return "The client is not currently connected."
    elif mqtt_errno == MQTT_ERR_CONN_REFUSED:
        return "The connection was refused."
    elif mqtt_errno == MQTT_ERR_NOT_FOUND:
        return "Message not found (internal error)."
    elif mqtt_errno == MQTT_ERR_CONN_LOST:
        return "The connection was lost."
    elif mqtt_errno == MQTT_ERR_TLS:
        return "A TLS error occurred."
    elif mqtt_errno == MQTT_ERR_PAYLOAD_SIZE:
        return "Payload too large."
    elif mqtt_errno == MQTT_ERR_NOT_SUPPORTED:
        return "This feature is not supported."
    elif mqtt_errno == MQTT_ERR_AUTH:
        return "Authorisation failed."
    elif mqtt_errno == MQTT_ERR_ACL_DENIED:
        return "Access denied by ACL."
    elif mqtt_errno == MQTT_ERR_UNKNOWN:
        return "Unknown error."
    elif mqtt_errno == MQTT_ERR_ERRNO:
        return "Error defined by errno."
    else:
        return "Unknown error."


def connack_string(connack_code):
    """Return the string associated with a CONNACK result."""
    if connack_code == CONNACK_ACCEPTED:
        return "Connection Accepted."
    elif connack_code == CONNACK_REFUSED_PROTOCOL_VERSION:
        return "Connection Refused: unacceptable protocol version."
    elif connack_code == CONNACK_REFUSED_IDENTIFIER_REJECTED:
        return "Connection Refused: identifier rejected."
    elif connack_code == CONNACK_REFUSED_SERVER_UNAVAILABLE:
        return "Connection Refused: broker unavailable."
    elif connack_code == CONNACK_REFUSED_BAD_USERNAME_PASSWORD:
        return "Connection Refused: bad user name or password."
    elif connack_code == CONNACK_REFUSED_NOT_AUTHORIZED:
        return "Connection Refused: not authorised."
    else:
        return "Connection Refused: unknown reason."


def base62(num, base=string.digits + string.ascii_letters, padding=1):
    """Convert a number to base-62 representation."""
    assert num >= 0
    digits = []
    while num:
        num, rest = divmod(num, 62)
        digits.append(base[rest])
    digits.extend(base[0] for _ in range(len(digits), padding))
    return ''.join(reversed(digits))


def topic_matches_sub(sub, topic):
    """Check whether a topic matches a subscription.

    For example:

    foo/bar would match the subscription foo/# or +/bar
    non/matching would not match the subscription non/+/+
    """
    matcher = MQTTMatcher()
    matcher[sub] = True
    try:
        next(matcher.iter_match(topic))
        return True
    except StopIteration:
        return False


def _socketpair_compat():
    """TCP/IP socketpair including Windows support"""
    listensock = socket.socket(socket.AF_INET, socket.SOCK_STREAM, socket.IPPROTO_IP)
    listensock.setsockopt(socket.SOL_SOCKET, socket.SO_REUSEADDR, 1)
    listensock.bind(("127.0.0.1", 0))
    listensock.listen(1)

    iface, port = listensock.getsockname()
    sock1 = socket.socket(socket.AF_INET, socket.SOCK_STREAM, socket.IPPROTO_IP)
    sock1.setblocking(0)
    try:
        sock1.connect(("127.0.0.1", port))
    except socket.error as err:
        if err.errno != errno.EINPROGRESS and err.errno != errno.EWOULDBLOCK and err.errno != EAGAIN:
            raise
    sock2, address = listensock.accept()
    sock2.setblocking(0)
    listensock.close()
    return (sock1, sock2)


class MQTTMessageInfo(object):
    """This is a class returned from Client.publish() and can be used to find
    out the mid of the message that was published, and to determine whether the
    message has been published, and/or wait until it is published.
    """

    __slots__ = 'mid', '_published', '_condition', 'rc', '_iterpos'

    def __init__(self, mid):
        self.mid = mid
        self._published = False
        self._condition = threading.Condition()
        self.rc = 0
        self._iterpos = 0

    def __str__(self):
        return str((self.rc, self.mid))

    def __iter__(self):
        self._iterpos = 0
        return self

    def __next__(self):
        return self.next()

    def next(self):
        if self._iterpos == 0:
            self._iterpos = 1
            return self.rc
        elif self._iterpos == 1:
            self._iterpos = 2
            return self.mid
        else:
            raise StopIteration

    def __getitem__(self, index):
        if index == 0:
            return self.rc
        elif index == 1:
            return self.mid
        else:
            raise IndexError("index out of range")

    def _set_as_published(self):
        with self._condition:
            self._published = True
            self._condition.notify()

    def wait_for_publish(self):
        """Block until the message associated with this object is published."""
        if self.rc == MQTT_ERR_QUEUE_SIZE:
            raise ValueError('Message is not queued due to ERR_QUEUE_SIZE')
        with self._condition:
            while not self._published:
                self._condition.wait()

    def is_published(self):
        """Returns True if the message associated with this object has been
        published, else returns False."""
        if self.rc == MQTT_ERR_QUEUE_SIZE:
            raise ValueError('Message is not queued due to ERR_QUEUE_SIZE')
        with self._condition:
            return self._published


class MQTTMessage(object):
    """ This is a class that describes an incoming or outgoing message. It is
    passed to the on_message callback as the message parameter.

    Members:

    topic : String/bytes. topic that the message was published on.
    payload : String/bytes the message payload.
    qos : Integer. The message Quality of Service 0, 1 or 2.
    retain : Boolean. If true, the message is a retained message and not fresh.
    mid : Integer. The message id.

    On Python 3, topic must be bytes.
    """

    __slots__ = 'timestamp', 'state', 'dup', 'mid', '_topic', 'payload', 'qos', 'retain', 'info'

    def __init__(self, mid=0, topic=b""):
        self.timestamp = 0
        self.state = mqtt_ms_invalid