btcpayserver/BTCPayServer.Rating/Providers/BitpayRateProvider.cs

using System.Linq;
using System.Net.Http;
using System.Threading;
using System.Threading.Tasks;
using BTCPayServer.Rating;
using Newtonsoft.Json.Linq;

namespace BTCPayServer.Services.Rates
{
    public class BitpayRateProvider : IRateProvider
    {
        private readonly HttpClient _httpClient;
        public BitpayRateProvider(HttpClient httpClient)
        {
            _httpClient = httpClient ?? new HttpClient();
        }

        public RateSourceInfo RateSourceInfo => new("bitpay", "Bitpay", "https://bitpay.com/rates");

        public async Task<PairRate[]> GetRatesAsync(CancellationToken cancellationToken)
        {
            using var response = await _httpClient.GetAsync("https://bitpay.com/rates", cancellationToken);
            if (response.Content.Headers.ContentType?.MediaType is not "application/json")
                throw new HttpRequestException($"Unexpected content type when querying currency rates from Bitpay ({response.Content.Headers.ContentType?.MediaType})");
            var jarray = (JArray)(await response.Content.ReadAsAsync<JObject>(cancellationToken))["data"];
            return jarray
                .Children<JObject>()
                .Select(jobj => new PairRate(new CurrencyPair("BTC", jobj["code"].Value<string>()), new BidAsk(jobj["rate"].Value<decimal>())))
                .Where(o => o.CurrencyPair.Right != "BTC")
                .ToArray();
        }
    }
}