"""Notifications logic."""

import hashlib
import re

import flask
from oto import response
from oto import status
from oto.adaptors.flask import flaskify
from owsrequest import request as requests

from notifications.config import SYSTEM_ORCHARD_USER_ID
from notifications.constants import error
from notifications.constants.header import ORCHARD_USER_ID
from notifications.constants.notifications import EMAIL_FEED_NAME
from notifications.constants.notifications import NOTIFICATION_NAMES
from notifications.constants.notifications import TOKEN_SECRET
from notifications.constants.service_name import OWS_NOTIFICATIONS
from notifications.logic import segment


def unsubscribe(user_id, feed_name, feed_id, token):
    """Unsubscribe a user from a feed by calling ows-notifications.

    Args:
        user_id (str): the orchard user id.
        feed_name (str): the feed name.
        feed_id (str): the feed id.
        token (str): the sha1 hashed token.

    Returns:
        jinja2.Template: the unsubscribed template.
    """
    generated_hash = hashlib.sha1()
    generated_hash.update(user_id.encode('utf-8'))
    generated_hash.update(feed_name.encode('utf-8'))
    generated_hash.update(feed_id.encode('utf-8'))
    generated_hash.update(TOKEN_SECRET.encode('utf-8'))
    generated_token = generated_hash.hexdigest()
    if generated_token != token:
        return flaskify(response.create_error_response(
            status=status.UNAUTHORIZED,
            code=error.ERROR_CODE_AUTHORIZATION,
            message=error.ERROR_MESSAGE_INVALID_TOKEN))

    path = '/unsubscribe'
    headers = {}
    json = {}
    if re.match('(oa|alw):[0-9]+', user_id):
        headers[ORCHARD_USER_ID] = user_id
        json['user_feed_name'] = EMAIL_FEED_NAME
        json['feed_name'] = feed_name
        json['feed_id'] = feed_id
    else:
        headers[ORCHARD_USER_ID] = SYSTEM_ORCHARD_USER_ID
        json['user_feed_id'] = user_id
        json['user_feed_name'] = EMAIL_FEED_NAME
        json['feed_name'] = feed_name
        json['feed_id'] = feed_id

    result = requests.post(
        OWS_NOTIFICATIONS, path, headers=headers, json=json)

    if result.status_code != 200:
        return flaskify(response.create_error_response(
            status=result.status_code,
            code=error.ERROR_CODE_OWS_NOTIFICATIONS_REQUEST,
            message=result.json()))

    segment.track_unsubscribe(user_id, feed_name, feed_id)

    if re.match('^orchard_', feed_name):
        return flask.render_template(
            'unsubscribed_orchard.html',
            notification_name=NOTIFICATION_NAMES[feed_name])

    return flask.render_template(
        'unsubscribed.html',
        notification_name=NOTIFICATION_NAMES[feed_name])