using System;

using System.Collections.Generic;

using Microsoft.AspNetCore.WebUtilities;

using System.Net.Http;

using System.Net.Http.Json;

using System.Threading.Tasks;

using System.Text.Json;

public class Program

{

    public static async Task Main()

    {

        using (var httpClient = new HttpClient())

        {

            httpClient.BaseAddress = new Uri("https://datausa.io/");

            var parameters = new Dictionary<string, string?>

            {

                { "drilldowns", "Nation" },

                { "measures", "Population" }

            };

            string requestUrl = "api/dataxx";

            requestUrl = QueryHelpers.AddQueryString(requestUrl, parameters);

            var response = await httpClient.GetAsync(requestUrl);

            if (!response.IsSuccessStatusCode)

            {

                Console.WriteLine($"{response.StatusCode}:{response.ReasonPhrase}");

            }

            var nationList = await response.Content.ReadFromJsonAsync<NationListDto>();

            Console.WriteLine(JsonSerializer.Serialize(nationList));

        }

    }

    public class NationListDto

    {

        public IEnumerable<NationDto> Data { get; init; } = []; 

    }

    public class NationDto

    {

        public string Nation { get; init; }

        public int Year { get; init; }

        public double Population { get; init; }

    }

}