# -*- coding: utf-8 -*-
#
# Copyright (C) 2021 Chris Caron <lead2gold@gmail.com>
# All rights reserved.
#
# This code is licensed under the MIT License.
#
# Permission is hereby granted, free of charge, to any person obtaining a copy
# of this software and associated documentation files(the "Software"), to deal
# in the Software without restriction, including without limitation the rights
# to use, copy, modify, merge, publish, distribute, sublicense, and / or sell
# copies of the Software, and to permit persons to whom the Software is
# furnished to do so, subject to the following conditions :
#
# The above copyright notice and this permission notice shall be included in
# all copies or substantial portions of the Software.
#
# THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS OR
# IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY,
# FITNESS FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT.IN NO EVENT SHALL THE
# AUTHORS OR COPYRIGHT HOLDERS BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER
# LIABILITY, WHETHER IN AN ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING FROM,
# OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS IN
# THE SOFTWARE.

# PAHO MQTT Documentation:
#  https://www.eclipse.org/paho/index.php?page=clients/python/docs/index.php
#
# Looking at the PAHO MQTT Source can help shed light on what's going on too
# as their inline documentation is pretty good!
#   https://github.com/eclipse/paho.mqtt.python\
#           /blob/master/src/paho/mqtt/client.py
import ssl
import re
import six
from time import sleep
from datetime import datetime
from os.path import isfile
from .NotifyBase import NotifyBase
from ..URLBase import PrivacyMode
from ..common import NotifyType
from ..utils import parse_list
from ..utils import parse_bool
from ..AppriseLocale import gettext_lazy as _

# Default our global support flag
NOTIFY_MQTT_SUPPORT_ENABLED = False

if six.PY2:
    # handle Python v2.7 suport
    class ConnectionError(Exception):
        pass

try:
    # 3rd party modules
    import paho.mqtt.client as mqtt

    # We're good to go!
    NOTIFY_MQTT_SUPPORT_ENABLED = True

    MQTT_PROTOCOL_MAP = {
        # v3.1.1
        "311": mqtt.MQTTv311,
        # v3.1
        "31": mqtt.MQTTv31,
        # v5.0
        "5": mqtt.MQTTv5,
        # v5.0 (alias)
        "50": mqtt.MQTTv5,
    }

except ImportError:
    # No problem; we just simply can't support this plugin because we're
    # either using Linux, or simply do not have pywin32 installed.
    MQTT_PROTOCOL_MAP = {}

# A lookup map for relaying version to user
HUMAN_MQTT_PROTOCOL_MAP = {
    "v3.1.1": "311",
    "v3.1": "31",
    "v5.0": "5",
}


class NotifyMQTT(NotifyBase):
    """
    A wrapper for MQTT Notifications
    """

    # Set our global enabled flag
    enabled = NOTIFY_MQTT_SUPPORT_ENABLED

    requirements = {
        # Define our required packaging in order to work
        'packages_required': 'paho-mqtt'
    }

    # The default descriptive name associated with the Notification
    service_name = 'MQTT Notification'

    # The default protocol
    protocol = 'mqtt'

    # Secure protocol
    secure_protocol = 'mqtts'

    # A URL that takes you to the setup/help of the specific protocol
    setup_url = 'https://github.com/caronc/apprise/wiki/Notify_mqtt'

    # MQTT does not have a title
    title_maxlen = 0

    # The maximum length a body can be set to
    body_maxlen = 268435455

    # Use a throttle; but it doesn't need to be so strict since most
    # MQTT server hostings can handle the small bursts of packets and are
    # locally hosted anyway
    request_rate_per_sec = 0.5

    # Port Defaults (unless otherwise specified)
    mqtt_insecure_port = 1883

    # The default secure port to use (if mqtts://)
    mqtt_secure_port = 8883

    # The default mqtt keepalive value
    mqtt_keepalive = 30

    # The default mqtt transport
    mqtt_transport = "tcp"

    # The number of seconds to wait for a publish to occur at before
    # checking to see if it's been sent yet.
    mqtt_block_time_sec = 0.2

    # Set the maximum number of messages with QoS>0 that can be part way
    # through their network flow at once.
    mqtt_inflight_messages = 200

    # Taken from https://golang.org/src/crypto/x509/root_linux.go
    CA_CERTIFICATE_FILE_LOCATIONS = [
        # Debian/Ubuntu/Gentoo etc.
        "/etc/ssl/certs/ca-certificates.crt",
        # Fedora/RHEL 6
        "/etc/pki/tls/certs/ca-bundle.crt",
        # OpenSUSE
        "/etc/ssl/ca-bundle.pem",
        # OpenELEC
        "/etc/pki/tls/cacert.pem",
        # CentOS/RHEL 7
        "/etc/pki/ca-trust/extracted/pem/tls-ca-bundle.pem",
    ]

    # Define object templates
    templates = (
        '{schema}://{user}@{host}/{topic}',
        '{schema}://{user}@{host}:{port}/{topic}',
        '{schema}://{user}:{password}@{host}/{topic}',
        '{schema}://{user}:{password}@{host}:{port}/{topic}',
    )

    template_tokens = dict(NotifyBase.template_tokens, **{
        'host': {
            'name': _('Hostname'),
            'type': 'string',
            'required': True,
        },
        'port': {
            'name': _('Port'),
            'type': 'int',
            'min': 1,
            'max': 65535,
        },
        'user': {
            'name': _('User Name'),
            'type': 'string',
            'required': True,
        },
        'password': {
            'name': _('Password'),
            'type': 'string',
            'private': True,
            'required': True,
        },
        'topic': {
            'name': _('Target Queue'),
            'type': 'string',
            'map_to': 'targets',
        },
        'targets': {
            'name': _('Targets'),
            'type': 'list:string',
        },
    })

    # Define our template arguments
    template_args = dict(NotifyBase.template_args, **{
        'to': {
            'alias_of': 'targets',
        },
        'qos': {
            'name': _('QOS'),
            'type': 'int',
            'default': 0,
            'min': 0,
            'max': 2,
        },
        'version': {
            'name': _('Version'),
            'type': 'choice:string',
            'values': HUMAN_MQTT_PROTOCOL_MAP,
            'default': "v3.1.1",
        },
        'client_id': {
            'name': _('Client ID'),
            'type': 'string',
        },
        'session': {
            'name': _('Use Session'),
            'type': 'bool',
            'default': False,
        },
    })

    def __init__(self, targets=None, version=None, qos=None,
                 client_id=None, session=None, **kwargs):
        """
        Initialize MQTT Object
        """

        super(NotifyMQTT, self).__init__(**kwargs)

        # Initialize topics
        self.topics = parse_list(targets)

        if version is None:
            self.version = self.template_args['version']['default']
        else:
            self.version = version

        # Save our client id if specified
        self.client_id = client_id

        # Maintain our session (associated with our user id if set)
        self.session = self.template_args['session']['default'] \
            if session is None or not self.client_id \
            else parse_bool(session)

        # Set up our Quality of Service (QoS)
        try:
            self.qos = self.template_args['qos']['default'] \
                if qos is None else int(qos)

            if self.qos < self.template_args['qos']['min'] \
                    or self.qos > self.template_args['qos']['max']:
                # Let error get handle on exceptio higher up
                raise ValueError("")

        except (ValueError, TypeError):
            msg = 'An invalid MQTT QOS ({}) was specified.'.format(qos)
            self.logger.warning(msg)
            raise TypeError(msg)

        if not self.port:
            # Assign port (if not otherwise set)
            self.port = self.mqtt_secure_port \
                if self.secure else self.mqtt_insecure_port

        self.ca_certs = None
        if self.secure:
            # verify SSL key or abort
            self.ca_certs = next(
                (cert for cert in self.CA_CERTIFICATE_FILE_LOCATIONS
                 if isfile(cert)), None)

        # Set up our MQTT Publisher
        try:
            # Get our protocol
            self.mqtt_protocol = \
                MQTT_PROTOCOL_MAP[re.sub(r'[^0-9]+', '', self.version)]

        except (KeyError):
            msg = 'An invalid MQTT Protocol version ' \
                '({}) was specified.'.format(version)
            self.logger.warning(msg)
            raise TypeError(msg)

        # Our MQTT Client Object
        self.client = mqtt.Client(
            client_id=self.client_id,
            clean_session=not self.session, userdata=None,
            protocol=self.mqtt_protocol, transport=self.mqtt_transport,
        )

        # Our maximum number of in-flight messages
        self.client.max_inflight_messages_set(self.mqtt_inflight_messages)

        # Toggled to False once our connection has been established at least
        # once
        self.__initial_connect = True

    def send(self, body, title='', notify_type=NotifyType.INFO, **kwargs):
        """
        Perform MQTT Notification
        """

        if len(self.topics) == 0:
            # There were no services to notify
            self.logger.warning('There were no MQTT topics to notify.')
            return False

        # For logging:
        url = '{host}:{port}'.format(host=self.host, port=self.port)

        try:
            if self.__initial_connect:
                # Our initial connection
                if self.user:
                    self.client.username_pw_set(
                        self.user, password=self.password)

                if self.secure:
                    if self.ca_certs is None:
                        self.logger.warning(
                            'MQTT Secure comunication can not be verified; '
                            'no local CA certificate file')
                        return False

                    self.client.tls_set(
                        ca_certs=self.ca_certs, certfile=None, keyfile=None,
                        cert_reqs=ssl.CERT_REQUIRED,
                        tls_version=ssl.PROTOCOL_TLS,
                        ciphers=None)

                    # Set our TLS Verify Flag
                    self.client.tls_insecure_set(self.verify_certificate)

                # Establish our connection
                if self.client.connect(
                        self.host, port=self.port,
                        keepalive=self.mqtt_keepalive) \
                        != mqtt.MQTT_ERR_SUCCESS:
                    self.logger.warning(
                        'An MQTT connection could not be established for {}'.
                        format(url))
                    return False

                # Start our client loop
                self.client.loop_start()

                # Throttle our start otherwise the starting handshaking doesnt
                # work. I'm not sure if this is a bug or not, but with qos=0,
                # and without this sleep(), the messages randomly fails to be
                # delivered.
                sleep(0.01)

                # Toggle our flag since we never need to enter this area again
                self.__initial_connect = False

            # Create a copy of the subreddits list
            topics = list(self.topics)

            has_error = False
            while len(topics) > 0 and not has_error:
                # Retrieve our subreddit
                topic = topics.pop()

                # For logging:
                url = '{host}:{port}/{topic}'.format(
                    host=self.host,
                    port=self.port,
                    topic=topic)

                # Always call throttle before any remote server i/o is made
                self.throttle()

                # handle a re-connection
                if not self.client.is_connected() and \
                        self.client.reconnect() != mqtt.MQTT_ERR_SUCCESS:
                    self.logger.warning(
                        'An MQTT connection could not be sustained for {}'.
                        format(url))
                    has_error = True
                    break

                # Some Debug Logging
                self.logger.debug('MQTT POST URL: {} (cert_verify={})'.format(
                    url, self.verify_certificate))
                self.logger.debug('MQTT Payload: %s' % str(body))

                result = self.client.publish(
                    topic, payload=body, qos=self.qos, retain=False)

                if result.rc != mqtt.MQTT_ERR_SUCCESS:
                    # Toggle our status
                    self.logger.warning(
                        'An error (rc={}) occured when sending MQTT to {}'.
                        format(result.rc, url))
                    has_error = True
                    break

                elif not result.is_published():
                    self.logger.debug(
                        'Blocking until MQTT payload is published...')
                    reference = datetime.now()
                    while not has_error and not result.is_published():
                        # Throttle
                        sleep(self.mqtt_block_time_sec)

                        # Our own throttle so we can abort eventually....
                        elapsed = (datetime.now() - reference).total_seconds()
                        if elapsed >= self.socket_read_timeout:
                            self.logger.warning(
                                'The MQTT message could not be delivered')
                            has_error = True

                # if we reach here; we're at the bottom of our loop
                # we loop around and do the next topic now

        except ConnectionError as e:
            self.logger.warning(
                'MQTT Connection Error received from {}'.format(url))
            self.logger.debug('Socket Exception: %s' % str(e))
            return False

        except ssl.CertificateError as e:
            self.logger.warning(
                'MQTT SSL Certificate Error received from {}'.format(url))
            self.logger.debug('Socket Exception: %s' % str(e))
            return False

        except ValueError as e:
            # ValueError's are thrown from publish() call if there is a problem
            self.logger.warning(
                'MQTT Publishing error received: from {}'.format(url))
            self.logger.debug('Socket Exception: %s' % str(e))
            return False

        return not has_error

    def url(self, privacy=False, *args, **kwargs):
        """
        Returns the URL built dynamically based on specified arguments.
        """

        # Define any URL parameters
        params = {
            'version': self.version,
            'qos': str(self.qos),
            'session': 'yes' if self.session else 'no',
        }

        if self.client_id:
            # Our client id is set if specified
            params['client_id'] = self.client_id

        # Extend our parameters
        params.update(self.url_parameters(privacy=privacy, *args, **kwargs))

        # Determine Authentication
        auth = ''
        if self.user and self.password:
            auth = '{user}:{password}@'.format(
                user=NotifyMQTT.quote(self.user, safe=''),
                password=self.pprint(
                    self.password, privacy, mode=PrivacyMode.Secret, safe=''),
            )
        elif self.user:
            auth = '{user}@'.format(
                user=NotifyMQTT.quote(self.user, safe=''),
            )

        default_port = self.mqtt_secure_port \
            if self.secure else self.mqtt_insecure_port

        return '{schema}://{auth}{hostname}{port}/{targets}?{params}'.format(
            schema=self.secure_protocol if self.secure else self.protocol,
            auth=auth,
            # never encode hostname since we're expecting it to be a valid one
            hostname=self.host,
            port='' if self.port is None or self.port == default_port
                 else ':{}'.format(self.port),
            targets=','.join(
                [NotifyMQTT.quote(x, safe='/') for x in self.topics]),
            params=NotifyMQTT.urlencode(params),
        )

    @staticmethod
    def parse_url(url):
        """
        There are no parameters nessisary for this protocol; simply having
        windows:// is all you need.  This function just makes sure that
        is in place.

        """

        results = NotifyBase.parse_url(url)
        if not results:
            # We're done early as we couldn't load the results
            return results

        try:
            # Acquire topic(s)
            results['targets'] = parse_list(
                NotifyMQTT.unquote(results['fullpath'].lstrip('/')))

        except AttributeError:
            # No 'fullpath' specified
            results['targets'] = []

        # The MQTT protocol version to use
        if 'version' in results['qsd'] and len(results['qsd']['version']):
            results['version'] = \
                NotifyMQTT.unquote(results['qsd']['version'])

        # The MQTT Client ID
        if 'client_id' in results['qsd'] and len(results['qsd']['client_id']):
            results['client_id'] = \
                NotifyMQTT.unquote(results['qsd']['client_id'])

        if 'session' in results['qsd'] and len(results['qsd']['session']):
            results['session'] = parse_bool(results['qsd']['session'])

        # The MQTT Quality of Service to use
        if 'qos' in results['qsd'] and len(results['qsd']['qos']):
            results['qos'] = \
                NotifyMQTT.unquote(results['qsd']['qos'])

        # The 'to' makes it easier to use yaml configuration
        if 'to' in results['qsd'] and len(results['qsd']['to']):
            results['targets'].extend(
                NotifyMQTT.parse_list(results['qsd']['to']))

        # return results
        return results