using System;
using System.Net.Http;
using System.Text.Json;

var jsonSerializerOptions = new JsonSerializerOptions { PropertyNameCaseInsensitive = true };

using var httpClient = new HttpClient();
var response = await httpClient.GetAsync("https://date.nager.at/api/v3/publicholidays/2022/US");
if (response.IsSuccessStatusCode)
{
    using var jsonStream = await response.Content.ReadAsStreamAsync();
    var publicHolidays = JsonSerializer.Deserialize<PublicHoliday[]>(jsonStream, jsonSerializerOptions);
}

class PublicHoliday
{
    public DateTime Date { get; set; }
    public string LocalName { get; set; }
    public string Name { get; set; }
    public string CountryCode { get; set; }
    public bool Fixed { get; set; }
    public bool Global { get; set; }
    public string[] Counties { get; set; }
    public int? LaunchYear { get; set; }
    public string[] Types { get; set; }
}

DateSystem.LicenseKey = "LicenseKey1234";

var publicHolidays = DateSystem.GetPublicHolidays(2021, "DE");
foreach (var publicHoliday in publicHolidays)
{
    //publicHoliday...
    //publicHoliday.Date -> The date
    //publicHoliday.LocalName -> The local name
    //publicHoliday.Name -> The english name
    //publicHoliday.Fixed -> Is this public holiday every year on the same date
    //publicHoliday.Global -> Is this public holiday in every county (federal state)
    //publicHoliday.Counties -> Is the public holiday only valid for a special county ISO-3166-2 - Federal states
    //publicHoliday.Type -> Public, Bank, School, Authorities, Optional, Observance
}

var startDate = new DateTime(2016, 5, 1);
var endDate = new DateTime(2021, 5, 31);
var publicHolidays = DateSystem.GetPublicHolidays(startDate, endDate, CountryCode.DE);
foreach (var publicHoliday in publicHolidays)
{
	//publicHoliday...
}

var date = new DateTime(2021, 1, 1);
if (DateSystem.IsPublicHoliday(date, CountryCode.DE))
{
    Console.WriteLine("Is public holiday");
}

var date = new DateTime(2021, 1, 1);
if (DateSystem.IsWeekend(date, CountryCode.DE))
{
    Console.WriteLine("Is weekend");
}