import json

import numpy as np

def get_model():
    with open('model_spec/base_dummy_playlist.json') as mm:
        model = json.load(mm)
    return model

def streams(pop_5, playlists):
    """Apply streams model based on popularity after 5 days and playlist that the track exists on

    Parameters
    ----------
    pop_5: int
        Popularity after 5 days
    playlists: set[String]
        Set with playlist ids

    Returns
    -------
    Predicted total streams after 5 days INCLUDING the first five days

    """
    model = get_model()
    play_list_contribution = sum([model[pp] for pp in playlists])
    return np.exp(model['const'] + pop_5 * model['pop_5'] + play_list_contribution)