from __future__ import absolute_import
from typing import Any, Iterable, Dict, Tuple, Callable, Text, Mapping, Optional

import requests
import json
import sys
import inspect
import logging
import re
from six.moves import urllib
from functools import reduce
from requests import Response

from django.utils.translation import ugettext as _

from zerver.models import Realm, UserProfile, get_realm_by_email_domain, get_user_profile_by_id, get_client, \
    GENERIC_INTERFACE, Service, SLACK_INTERFACE, email_to_domain, get_service_profile
from zerver.lib.actions import check_send_message
from zerver.lib.queue import queue_json_publish
from zerver.lib.validator import check_dict, check_string
from zerver.decorator import JsonableError

MAX_REQUEST_RETRIES = 3

class OutgoingWebhookServiceInterface(object):

    def __init__(self, base_url, token, user_profile, service_name):
        # type: (Text, Text, UserProfile, Text) -> None
        self.base_url = base_url  # type: Text
        self.token = token  # type: Text
        self.user_profile = user_profile  # type: Text
        self.service_name = service_name  # type: Text

    # Given an event that triggers an outgoing webhook operation, returns:
    # - The REST operation that should be performed
    # - The body of the request
    #
    # The REST operation is a dictionary with the following keys:
    # - method
    # - base_url
    # - relative_url_path
    # - request_kwargs
    def process_event(self, event):
        # type: (Dict[Text, Any]) -> Tuple[Dict[str, Any], Any]
        raise NotImplementedError()

    # Given a successful outgoing webhook REST operation, returns the message
    # to sent back to the user (or None if no message should be sent).
    def process_success(self, response, event):
        # type: (Response, Dict[Text, Any]) -> Optional[str]
        raise NotImplementedError()

    # Given a failed outgoing webhook REST operation, returns the message to be
    # sent back to the user (or None if no message should be sent).
    def process_failure(self, response, event):
        # type: (Response, Dict[Text, Any]) -> Optional[str]
        raise NotImplementedError()

class GenericOutgoingWebhookService(OutgoingWebhookServiceInterface):

    def process_event(self, event):
        # type: (Dict[Text, Any]) -> Tuple[Dict[str, Any], Any]
        rest_operation = {'method': 'POST',
                          'relative_url_path': '',
                          'base_url': self.base_url,
                          'request_kwargs': {}}
        request_data = {"data": event['command'],
                        "message": event['message'],
                        "token": self.token}
        return rest_operation, json.dumps(request_data)

    def process_success(self, response, event):
        # type: (Response, Dict[Text, Any]) -> Optional[str]
        response_json = json.loads(response.text)

        if "response_not_required" in response_json and response_json['response_not_required']:
            return None
        if "response_string" in response_json:
            return str(response_json['response_string'])
        else:
            return None

    def process_failure(self, response, event):
        # type: (Response, Dict[Text, Any]) -> Optional[str]
        return str(response.text)

class SlackOutgoingWebhookService(OutgoingWebhookServiceInterface):

    def process_event(self, event):
        # type: (Dict[Text, Any]) -> Tuple[Dict[str, Any], Any]
        rest_operation = {'method': 'POST',
                          'relative_url_path': '',
                          'base_url': self.base_url,
                          'request_kwargs': {}}

        if event['message']['type'] == 'private':
            raise NotImplementedError("Private messaging service not supported.")

        service = get_service_profile(event['user_profile_id'], str(self.service_name))
        request_data = [("token", self.token),
                        ("team_id", event['message']['sender_realm_str']),
                        ("team_domain", email_to_domain(event['message']['sender_email'])),
                        ("channel_id", event['message']['stream_id']),
                        ("channel_name", event['message']['display_recipient']),
                        ("timestamp", event['message']['timestamp']),
                        ("user_id", event['message']['sender_id']),
                        ("user_name", event['message']['sender_full_name']),
                        ("text", event['command']),
                        ("trigger_word", event['trigger']),
                        ("service_id", service.id),
                        ]

        return rest_operation, request_data

    def process_success(self, response, event):
        # type: (Response, Dict[Text, Any]) -> Optional[str]
        response_json = json.loads(response.text)
        if "text" in response_json:
            return response_json["text"]
        else:
            return None

    def process_failure(self, response, event):
        # type: (Response, Dict[Text, Any]) -> Optional[str]
        return str(response.text)

AVAILABLE_OUTGOING_WEBHOOK_INTERFACES = {
    GENERIC_INTERFACE: GenericOutgoingWebhookService,
    SLACK_INTERFACE: SlackOutgoingWebhookService,
}   # type: Dict[Text, Any]

def get_service_interface_class(interface):
    # type: (Text) -> Any
    if interface is None or interface not in AVAILABLE_OUTGOING_WEBHOOK_INTERFACES:
        return AVAILABLE_OUTGOING_WEBHOOK_INTERFACES[GENERIC_INTERFACE]
    else:
        return AVAILABLE_OUTGOING_WEBHOOK_INTERFACES[interface]

def get_outgoing_webhook_service_handler(service):
    # type: (Service) -> Any

    service_interface_class = get_service_interface_class(service.interface_name())
    service_interface = service_interface_class(base_url=service.base_url,
                                                token=service.token,
                                                user_profile=service.user_profile,
                                                service_name=service.name)
    return service_interface

def send_response_message(bot_id, message, response_message_content):
    # type: (str, Dict[str, Any], Text) -> None
    recipient_type_name = message['type']
    bot_user = get_user_profile_by_id(bot_id)
    realm = get_realm_by_email_domain(message['sender_email'])

    if recipient_type_name == 'stream':
        recipients = [message['display_recipient']]
        check_send_message(bot_user, get_client("OutgoingWebhookResponse"), recipient_type_name, recipients,
                           message['subject'], response_message_content, realm, forwarder_user_profile=bot_user)
    else:
        # Private message; only send if the bot is there in the recipients
        recipients = [recipient['email'] for recipient in message['display_recipient']]
        if bot_user.email in recipients:
            check_send_message(bot_user, get_client("OutgoingWebhookResponse"), recipient_type_name, recipients,
                               message['subject'], response_message_content, realm, forwarder_user_profile=bot_user)

def succeed_with_message(event, success_message):
    # type: (Dict[str, Any], Text) -> None
    if success_message is None:
        return
    success_message = "Success! " + success_message
    send_response_message(event['user_profile_id'], event['message'], success_message)

def fail_with_message(event, failure_message):
    # type: (Dict[str, Any], Text) -> None
    if failure_message is None:
        return
    failure_message = "Failure! " + failure_message
    send_response_message(event['user_profile_id'], event['message'], failure_message)

def request_retry(event, failure_message):
    # type: (Dict[str, Any], Text) -> None
    event['failed_tries'] += 1
    if event['failed_tries'] > MAX_REQUEST_RETRIES:
        bot_user = get_user_profile_by_id(event['user_profile_id'])
        failure_message = "Maximum retries exceeded! " + failure_message
        fail_with_message(event, failure_message)
        logging.warning("Maximum retries exceeded for trigger:%s event:%s" % (bot_user.email, event['command']))
    else:
        queue_json_publish("outgoing_webhooks", event, lambda x: None)

def do_rest_call(rest_operation, request_data, event, service_handler, timeout=None):
    # type: (Dict[str, Any], Dict[str, Any], Dict[str, Any], Any, Any) -> None
    rest_operation_validator = check_dict([
        ('method', check_string),
        ('relative_url_path', check_string),
        ('request_kwargs', check_dict([])),
        ('base_url', check_string),
    ])

    error = rest_operation_validator('rest_operation', rest_operation)
    if error:
        raise JsonableError(error)

    http_method = rest_operation['method']
    final_url = urllib.parse.urljoin(rest_operation['base_url'], rest_operation['relative_url_path'])
    request_kwargs = rest_operation['request_kwargs']
    request_kwargs['timeout'] = timeout

    try:
        response = requests.request(http_method, final_url, data=request_data, **request_kwargs)
        if str(response.status_code).startswith('2'):
            response_message = service_handler.process_success(response, event)
            succeed_with_message(event, response_message)

        # On 50x errors, try retry
        elif str(response.status_code).startswith('5'):
            request_retry(event, "Internal Server error at third party.")
        else:
            response_message = service_handler.process_failure(response, event)
            fail_with_message(event, response_message)

    except requests.exceptions.Timeout:
        logging.info("Trigger event %s on %s timed out. Retrying" % (event["command"], event['service_name']))
        request_retry(event, 'Unable to connect with the third party.')

    except requests.exceptions.RequestException as e:
        response_message = "An exception occured for message `%s`! See the logs for more information." % (event["command"],)
        logging.exception("Outhook trigger failed:\n %s" % (e,))
        fail_with_message(event, response_message)