"""Spotify monthly listeners parser."""

import json

import requests
from requests.exceptions import HTTPError
from bs4 import BeautifulSoup


class ParsingError(Exception):
    def __init__(self, details):
        self.details = f'Failed to parse Spotify response: {details}'

    def __str__(self):
        return self.details


def handler(event: dict, context: dict) -> dict:
    """Lambda entry point."""
    try:
        status_code = 200
        spotify_id = event.get('pathParameters').get('artist_id')
        if not spotify_id:
            raise ValueError('Error, empty spotify artist_id')
        listeners = get_spotify_monthly_listeners(spotify_id)
        response_str = {'monthly_listeners': listeners}
    except ValueError as e:
        status_code = 400
        response_str = str(e)
    except ParsingError as e:
        status_code = 500
        response_str = str(e)
    except HTTPError as e:
        status_code = e.response.status_code
        response_str = str(e)
    return {
        'statusCode': status_code,
        'headers': {'content-type': 'application/json'},
        'body': json.dumps({'response': response_str})
    }


def get_spotify_monthly_listeners(spotify_id):
    """Get spotify monthly listeners.

    Listeners HTML block example:
    <div class="insights__column">
        <h3 class="insights__column__number">100</h3>
        <span class="insights__column__label">Monthly Listeners</span>
    </div>

    Args:
        spotify_id (str): the id of the model.

    Raises:
        HTTPError: Spotify returned an error (usually 404).
        ParsingError: Failed to parse the spotify artist page.
    """
    listeners_count = None
    url = f'https://open.spotify.com/artist/{spotify_id}'
    response = requests.get(url)
    response.raise_for_status()
    if response.ok:
        soup = BeautifulSoup(response.text)
        listeners_label = soup.find(
            'span',
            {'class': 'insights__column__label'},
            text='Monthly Listeners')
        if not listeners_label:
            # TODO: we need to send an alert to Sentry if the parsing fails.
            raise ParsingError(
                '<span class="insights__column__label">Monthly Listeners</span>'
                ' element was not found.')
        listeners_span = listeners_label.parent.find(
            'h3', {'class': 'insights__column__number'})
        if not listeners_span:
            # TODO: we need to send an alert to Sentry if the parsing fails.
            raise ParsingError(
                '<h3 class="insights__column__number">100</h3> element was '
                'not found.')
        listeners_count = int(listeners_span.text.replace(',', ''))

    return listeners_count