"""Util functions related to extracting a notification from a sqs.Message."""

import base64
import json
import re

from notifications_delivery.constants.exceptions import IgnoredMessageError
from notifications_delivery.constants.notifications import (
    FEED_ID_ENCODING,
    ORCHARD_NOTIFICATIONS_REQUIRED_FIELDS,
)


def parse_message(message, fmt):
    """Parse message and return a formatted notification dict.

    Args:
        message (sqs.Message): message pulled from SQS-message.
        fmt (str): message type
    Returns:
        dict: the formatted notification.
    """
    notification = None
    if fmt == 'orchard':
        notification = parse_orchard_message(message)
    elif fmt == 'stream':
        notification = parse_stream_message(message)

    return notification


def parse_orchard_message(notification):
    """Parse and validate a message coming from The Orchard.

    Args:
        notification (dict): the message body

    Returns:
        dict: the validated notification
    """
    if not all(key in notification for key in
               ORCHARD_NOTIFICATIONS_REQUIRED_FIELDS):
        return None

    return notification


def parse_stream_message(message_body):
    """Parse and validate a message coming from Stream (getstream.io).

    Args:
        message_body (str): the base64 encoded message body

    Returns:
        dict: the validated notification
    """
    try:
        decoded_message_body = base64.b64decode(message_body)
        stream_message = json.loads(decoded_message_body)
        return map_to_notification(stream_message)
    except IgnoredMessageError:
        # Special case. Empty messages should be ignored. Just rerise here. Will be handled further.
        raise
    except Exception:
        return None


def map_to_notification(stream_message):
    """Map a Stream message to an Orchard notification.

    Args:
        stream_message (list): the Stream message

    Returns:
        dict: the orchard notification
    """
    user_feeds = [item['feed'] for item in stream_message]

    user_ids = []
    user_emails = []
    for user_feed in user_feeds:
        user_feed_id = user_feed.split(':')[1]

        if re.match('(oa|alw)_[0-9]+', user_feed_id):
            user_ids.append(user_feed_id.replace('_', ':'))
        else:
            for key, value in FEED_ID_ENCODING.items():
                user_feed_id = user_feed_id.replace(key, value)
            user_emails.append(user_feed_id)

    if not stream_message[0]['new']:
        raise IgnoredMessageError('Message is empty')

    activity = stream_message[0]['new'][0]
    # origin is set by getstream when the activity flows through follow stream.
    # new activities will be writen directly to user stream with original_feed.
    feed = activity.get('origin') or activity.get('original_feed')
    if not feed:
        return None
    feed_name = feed.split(':')[0]
    feed_id = feed.split(':')[1]

    if activity.get('template_name'):
        template = activity.get('template_name')
    elif 'orchard_trending_tracks_' in feed_name:
        template = 'trending_tracks'
    elif 'email_notification_rejection' in feed_name:
        template = 'release_rejection'
    else:
        template = feed_name.replace('label_', '', 1)

    return {
        'user_ids': user_ids,
        'user_emails': user_emails,
        'feed_name': feed_name,
        'feed_id': feed_id,
        'template': template,
        'payload': activity
    }