RhSolutions-AddIn/RhSolutions.AddIn/Services/CurrencyClient.cs

using System.Net;
using System.Net.Http;
using System.Threading.Tasks;
using System.Xml.Linq;

namespace RhSolutions.Services;

public class CurrencyClient : ICurrencyClient
{
    private readonly HttpClient _httpClient;
    private const string _requestAddress = @"https://www.cbr.ru/scripts/XML_daily.asp?date_req=";
    public HttpStatusCode StatusCode { get; private set; }

    public CurrencyClient(HttpClient httpClient)
    {
        _httpClient = httpClient;
    }

    public async Task<decimal?> GetExchangeRate(DateTime date)
    {
        string request = $"{_requestAddress}{date.Date:dd/MM/yyyy}";
        HttpResponseMessage response = await _httpClient.GetAsync(request);
        try
        {
            response.EnsureSuccessStatusCode();
            string xml = await response.Content.ReadAsStringAsync();
            XElement valCourses = XElement.Parse(xml);

            decimal? exchangeRate = decimal.Parse(valCourses.Elements("Valute")
                .Where(e => e.Element("Name").Value == "Евро")
                .FirstOrDefault()
                .Element("Value").Value);
            return exchangeRate;
        }
        catch
        {
            StatusCode = response.StatusCode;
            return null;
        }
    }
}