"""Collector for facebook metrics."""

import requests

from social_analytics import config
from social_analytics.constants import collectors


def collect_facebook_metrics(profile_id, facebook_access_token):
    """
    Collect facebook metrics for a given profile id.

    Args:
        profile_id (str): the id by which to query the facebook API.
        facebook_access_token (str): the facebook auth token.
    Returns:
        dict: facebook API's json response dict.
    """
    url = construct_facebook_url(profile_id, facebook_access_token)
    result = requests.get(url)

    return result.json()


def construct_facebook_url(profile_id, facebook_access_token):
    """
    Generate a facebook api url based on a profile id.

    Args:
        profile_id (str): the id for which to generate a facebook API url.
        facebook_access_token (str): the facebook auth token.
    Returns:
        Response: a facebook API url for the given id.
    """
    url = '{base_url}v2.7/{profile_id}?fields={query_fields}&' \
          'access_token={access_token}'.format(
            base_url=collectors.FACEBOOK_BASE_URL,
            profile_id=profile_id,
            query_fields=collectors.FACEBOOK_QUERY_FIELDS,
            access_token=facebook_access_token)

    return url


def refresh_token():
    """Refresh facebook access token.

    Returns:
        (str): The facebook access token.
    """
    # Get the code needed to refresh the long lived token.
    code_params = {
        'access_token': config.FACEBOOK_ACCESS_TOKEN,
        'client_secret': config.FACEBOOK_CLIENT_SECRET,
        'client_id': config.FACEBOOK_CLIENT_ID,
        'redirect_uri': config.FACEBOOK_REDIRECT_URI
    }

    code_response = requests.get(
        collectors.FACEBOOK_AUTHORIZATION_CODE_URL, params=code_params)
    code = code_response.json()['code']

    # Use the code to get access token.
    token_params = {
        'code': code,
        'client_id': config.FACEBOOK_CLIENT_ID,
        'machine_id': config.FACEBOOK_MACHINE_ID,
        'redirect_uri': config.FACEBOOK_REDIRECT_URI
    }

    token_response = requests.get(
        collectors.FACEBOOK_AUTHORIZATION_TOKEN_URL, params=token_params)

    token = token_response.json()['access_token']
    return token


def recommend_facebook_profile(platform_name, facebook_access_token):
    """Recommend facebook profile.

    Args:
        platform_name (str): The profile name of the artist e.g. Shakira
        facebook_access_token (str): The Facebook access token.
    Returns:
        Dict or None: A dictionary with the suggested profile or None when
        there is not any profile for the given profile name.
    """
    if not facebook_access_token:
        facebook_access_token = refresh_token()

    url = (
        '{base_url}v2.7/search?q={platform_name}&type=page&'
        'fields={query_fields}&access_token={access_token}'.format(
            base_url=collectors.FACEBOOK_BASE_URL,
            platform_name=platform_name,
            query_fields=collectors.FACEBOOK_QUERY_FIELDS,
            access_token=facebook_access_token))

    result = requests.get(url)
    result_json = result.json()

    if 'data' in result_json and result_json['data']:
        profiles = result_json['data']
        profile_with_most_likes = (
            max(
                profiles, key=lambda item: item[
                    'fan_count'] if item['is_verified'] is True else item[
                    'fan_count']))

        return {
            'platform': 'facebook',
            'platform_id': profile_with_most_likes['id'],
            'platform_name': profile_with_most_likes['name'],
            'is_verified': profile_with_most_likes['is_verified'],
            'metric_value': profile_with_most_likes['fan_count']
        }
    else:
        return None


def verify_facebook_profile(platform_id):
    """Verify facebook profile.

    Args:
        platform_id (str): The profile id of the artist e.g. 123444453
    Returns:
        Dict or None: A dictionary with the verified profile or None when
        there is not any profile for the given profile name.
    """
    token = refresh_token()
    url = construct_facebook_url(platform_id, token)

    result = requests.get(url)
    result_json = result.json()

    if 'error' in result_json:
        return None

    return {
            'platform': 'facebook',
            'platform_id': result_json['id'],
            'platform_name': result_json['name'],
            'is_verified': result_json['is_verified'],
            'metric_value': result_json['fan_count']
        }