Fix HitBTC provider

BTCPayServer.Rating/Providers/HitBTCRateProvider.cs

@@ -0,0 +1,39 @@
+using System;
+using System.Collections.Generic;
+using System.Linq;
+using System.Net.Http;
+using System.Text;
+using System.Threading;
+using System.Threading.Tasks;
+using BTCPayServer.Services.Rates;
+using Newtonsoft.Json.Linq;
+
+namespace BTCPayServer.Rating
+{
+    public class HitBTCRateProvider : IRateProvider
+    {
+        private readonly HttpClient _httpClient;
+        public HitBTCRateProvider(HttpClient httpClient)
+        {
+            _httpClient = httpClient ?? new HttpClient();
+        }
+
+        public async Task<PairRate[]> GetRatesAsync(CancellationToken cancellationToken)
+        {
+            var response = await _httpClient.GetAsync("https://api.hitbtc.com/api/2/public/ticker", cancellationToken);
+            var jarray = await response.Content.ReadAsAsync<JArray>(cancellationToken);
+            return jarray
+                .Children<JObject>()
+                .Where(p => CurrencyPair.TryParse(p["symbol"].Value<string>(), out _))
+                .Select(p => new PairRate(CurrencyPair.Parse(p["symbol"].Value<string>()), CreateBidAsk(p)))
+                .ToArray();
+        }
+
+        private BidAsk CreateBidAsk(JObject p)
+        {
+            var bid = p["bid"].Value<decimal>();
+            var ask = p["ask"].Value<decimal>();
+            return new BidAsk(bid, ask);
+        }
+    }
+}