import pandas as pd
import numpy as np
from geopy.distance import geodesic

def closest_city(point, df=None, population_threshold=0):

    """Get the name, population, and distance to the point of the closest city"""

    if df is None:
        df = pd.read_csv("africapolis.csv", index_col=0)
    df = df[df["Population"] > population_threshold]
    distances = df.apply(lambda row: geodesic(point, (row["Latitude"], row["Longitude"])), axis=1)
    min_index = distances.idxmin()
    city = df.loc[min_index]
    return {
        "name": city["Name"],
        "population": np.int64(city["Population"]),
        "distance": np.float64(distances[min_index].km),
        "location": (city["Latitude"], city["Longitude"])
    }