from typing import Any, Dict, Optional, Text

from django.http import HttpRequest, HttpResponse

from zerver.decorator import api_key_only_webhook_view
from zerver.lib.actions import check_send_stream_message
from zerver.lib.request import REQ, has_request_variables
from zerver.lib.response import json_success
from zerver.models import UserProfile

import time


@api_key_only_webhook_view('Raygun')
@has_request_variables
def api_raygun_webhook(request: HttpRequest, user_profile: UserProfile,
                       payload: Dict[str, Any] = REQ(argument_type='body'),
                       stream: Text = REQ(default='raygun'),
                       topic: Optional[Text] = REQ(default='test')) -> HttpResponse:
    # The payload contains 'event' key. This 'event' key has a value of either
    # 'error_notification' or 'error_activity'. 'error_notification' happens
    # when an error is caught in an application, where as 'error_activity'
    # happens when an action is being taken for the error itself
    # (ignored/resolved/assigned/etc.).
    event = payload['event']

    # Because we wanted to create a message for all of the payloads, it is best
    # to handle them separately. This is because some payload keys don't exist
    # in the other event.

    if event == 'error_notification':
        message = compose_notification_message(payload)
    elif event == 'error_activity':
        message = compose_activity_message(payload)
    else:
        message = "Unsupported event type: {}".format(event)

    check_send_stream_message(user_profile, request.client, stream, topic,
                              message)

    return json_success()


def make_user_stats_chunk(error_dict: Dict[str, Any]) -> Text:
    """Creates a stat chunk about total occurrences and users affected for the
    error.

    Example: usersAffected: 2, totalOccurrences: 10
    Output: 2 users affected with 10 total occurrences

    :param error_dict: The error dictionary containing the error keys and
    values
    :returns: A message chunk that will be added to the main message
    """
    users_affected = error_dict['usersAffected']
    total_occurrences = error_dict['totalOccurrences']

    # One line is subjectively better than two lines for this.
    return "{} users affected with {} total occurrences\n".format(
        users_affected, total_occurrences)


def make_time_chunk(error_dict: Dict[str, Any]) -> Text:
    """Creates a time message chunk.

    Example: firstOccurredOn: "X", lastOccurredOn: "Y"
    Output:
    First occurred: X
    Last occurred: Y

    :param error_dict: The error dictionary containing the error keys and
    values
    :returns: A message chunk that will be added to the main message
    """
    # Make the timestamp more readable to a human.
    time_first = parse_time(error_dict['firstOccurredOn'])
    time_last = parse_time(error_dict['lastOccurredOn'])

    # Provide time information about this error,
    return "First occurred: {}\nLast occurred: {}\n".format(time_first,
                                                            time_last)


def make_message_chunk(message: Text) -> Text:
    """Creates a message chunk if exists.

    Example: message: "This is an example message" returns "Message: This is an
    example message". Whereas message: "" returns "".

    :param message: The value of message inside of the error dictionary
    :returns: A message chunk if there exists an additional message, otherwise
    returns an empty string.
    """
    # "Message" shouldn't be included if there is none supplied.
    return "Message: {}\n".format(message) if message != "" else ""


def make_app_info_chunk(app_dict: Dict[str, str]) -> Text:
    """Creates a message chunk that contains the application info and the link
    to the Raygun dashboard about the application.

    :param app_dict: The application dictionary obtained from the payload
    :returns: A message chunk that will be added to the main message
    """
    app_name = app_dict['name']
    app_url = app_dict['url']
    return "Application details: [{}]({})\n".format(app_name, app_url)


def notification_message_follow_up(payload: Dict[str, Any]) -> Text:
    """Creates a message for a repeating error follow up

    :param payload: Raygun payload
    :return: Returns the message, somewhat beautifully formatted
    """
    message = ""

    # Link to Raygun about the follow up
    followup_link_md = "[follow-up error]({})".format(payload['error']['url'])

    followup_type = payload['eventType']

    if followup_type == "HourlyFollowUp":
        prefix = "Hourly"
    else:
        # Cut the "MinuteFollowUp" from the possible event types, then add "
        # minute" after that. So prefix for "OneMinuteFollowUp" is "One
        # minute", where "FiveMinuteFollowUp" is "Five minute".
        prefix = followup_type[:len(followup_type) - 14] + " minute"

    message += "{} {}\n".format(prefix, followup_link_md)

    # Get the message of the error.
    payload_msg = payload['error']['message']

    message += make_message_chunk(payload_msg)
    message += make_time_chunk(payload['error'])
    message += make_user_stats_chunk(payload['error'])
    message += make_app_info_chunk(payload['application'])

    return message


def notification_message_error_occurred(payload: Dict[str, Any]) -> Text:
    """Creates a message for a new error or reoccurred error

    :param payload: Raygun payload
    :return: Returns the message, somewhat beautifully formatted
    """
    message = ""

    # Provide a clickable link that goes to Raygun about this error.
    error_link_md = "[Error]({})".format(payload['error']['url'])

    # Stylize the message based on the event type of the error.
    if payload['eventType'] == "NewErrorOccurred":
        message += "**{}**\n".format("New {} occurred!".format(error_link_md))
    elif payload['eventType'] == "ErrorReoccurred":
        message += "{}\n".format("{} reoccurred.".format(error_link_md))

    # Get the message of the error. This value can be empty (as in "").
    payload_msg = payload['error']['message']

    message += make_message_chunk(payload_msg)
    message += make_time_chunk(payload['error'])
    message += make_user_stats_chunk(payload['error'])

    # Only NewErrorOccurred and ErrorReoccurred contain an error instance.
    error_instance = payload['error']['instance']

    # Extract each of the keys and values in error_instance for easier handle

    # Contains list of tags for the error. Can be empty (null)
    tags = error_instance['tags']

    # Contains the identity of affected user at the moment this error
    # happened. This surprisingly can be null. Somehow.
    affected_user = error_instance['affectedUser']

    # Contains custom data for this particular error (if supplied). Can be
    # null.
    custom_data = error_instance['customData']

    if tags is not None:
        message += "Tags: {}\n".format(", ".join(tags))

    if affected_user is not None:
        user_uuid = affected_user['UUID']
        message += "Affected user: {}...{}\n".format(user_uuid[:6],
                                                     user_uuid[-5:])

    if custom_data is not None:
        # We don't know what the keys and values beforehand, so we are forced
        # to iterate.
        for key in sorted(custom_data.keys()):
            message += "{}: {}\n".format(key, custom_data[key])

    message += make_app_info_chunk(payload['application'])

    return message


def compose_notification_message(payload: Dict[str, Any]) -> Text:
    """Composes a message that contains information on the error

    :param payload: Raygun payload
    :return: Returns a response message
    """

    # Get the event type of the error. This can be "NewErrorOccurred",
    # "ErrorReoccurred", "OneMinuteFollowUp", "FiveMinuteFollowUp", ...,
    # "HourlyFollowUp" for notification error.
    event_type = payload['eventType']

    # "NewErrorOccurred" and "ErrorReoccurred" contain error instance
    # information, meaning that it has payload['error']['instance']. The other
    # event type (the follow ups) doesn't have this instance.

    # We now split this main function again into two functions. One is for
    # "NewErrorOccurred" and "ErrorReoccurred", and one is for the rest. Both
    # functions will return a text message that is formatted for the chat.
    if event_type == "NewErrorOccurred" or event_type == "ErrorReoccurred":
        return notification_message_error_occurred(payload)
    elif "FollowUp" in event_type:
        return notification_message_follow_up(payload)
    else:
        return "Unsupported event_type type: {}".format(event_type)


def activity_message(payload: Dict[str, Any]) -> Text:
    """Creates a message from an activity that is being taken for an error

    :param payload: Raygun payload
    :return: Returns the message, somewhat beautifully formatted
    """
    message = ""

    error_link_md = "[Error]({})".format(payload['error']['url'])

    event_type = payload['eventType']

    user = payload['error']['user']
    if event_type == "StatusChanged":
        error_status = payload['error']['status']
        message += "{} status changed to: {} by {}\n".format(error_link_md,
                                                             error_status,
                                                             user)
    elif event_type == "CommentAdded":
        comment = payload['error']['comment']
        message += "{} left a comment on {}: {}\n".format(user,
                                                          error_link_md,
                                                          comment)
    elif event_type == "AssignedToUser":
        assigned_to = payload['error']['assignedTo']
        message += "{} assigned {} to {}\n".format(user,
                                                   error_link_md,
                                                   assigned_to)

    message += "Timestamp: {}\n".format(parse_time(payload['error']
                                                   ['activityDate']))

    message += make_app_info_chunk(payload['application'])

    return message


def compose_activity_message(payload: Dict[str, Any]) -> Text:
    """Composes a message that contains an activity that is being taken to
    an error, such as commenting, assigning an error to a user, ignoring the
    error, etc.

    :param payload: Raygun payload
    :return: Returns a response message
    """

    event_type = payload['eventType']

    # Activity is separated into three main categories: status changes (
    # ignores, resolved), error is assigned to user, and comment added to
    # an error,

    # But, they all are almost identical and the only differences between them
    # are the keys at line 9 (check fixtures). So there's no need to split
    # the function like the notification one.
    if event_type == "StatusChanged" or event_type == "AssignedToUser" \
            or event_type == "CommentAdded":
        return activity_message(payload)
    else:
        return "Unsupported event_type type: {}".format(event_type)


def parse_time(timestamp: Text) -> Text:
    """Parses and returns the timestamp provided

    :param timestamp: The timestamp provided by the payload
    :returns: A string containing the time
    """

    # Raygun provides two timestamp format, one with the Z at the end,
    # and one without the Z.

    format = "%Y-%m-%dT%H:%M:%S"
    format += "Z" if timestamp[-1:] == "Z" else ""
    parsed_time = time.strftime("%c", time.strptime(timestamp,
                                                    format))
    return parsed_time