btcpayserver/BTCPayServer.Rating/Providers/CoinGeckoRateProvider.cs

using System;
using System.Collections.Generic;
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 CoinGeckoRateProvider : IRateProvider
    {
        public const string CoinGeckoName = "coingecko";
        
        internal static readonly Dictionary<string, RateSourceInfo> SupportedExchanges;

        static CoinGeckoRateProvider()
        {
            // https://api.coingecko.com/api/v3/exchanges/list
            SupportedExchanges = JArray.Parse("[{\"id\":\"1bch\",\"name\":\"1BCH\"},{\"id\":\"3xcalibur\",\"name\":\"3xcalibur\"},{\"id\":\"aave\",\"name\":\"Aave\"},{\"id\":\"aax\",\"name\":\"AAX\"},{\"id\":\"aax_futures\",\"name\":\"AAX Futures\"},{\"id\":\"abcc\",\"name\":\"ABCC\"},{\"id\":\"acala_swap\",\"name\":\"Acala Swap\"},{\"id\":\"acdx\",\"name\":\"ACDX\"},{\"id\":\"ace\",\"name\":\"Ace\"},{\"id\":\"acsi_finance\",\"name\":\"Acsi Finance\"},{\"id\":\"agora_swap\",\"name\":\"Agora Swap\"},{\"id\":\"alexgo\",\"name\":\"ALEX\"},{\"id\":\"algebra_finance\",\"name\":\"Algebra finance\"},{\"id\":\"alpha_five\",\"name\":\"Alpha5\"},{\"id\":\"altcointrader\",\"name\":\"AltcoinTrader\"},{\"id\":\"alterdice\",\"name\":\"AlterDice\"},{\"id\":\"altmarkets\",\"name\":\"Altmarkets\"},{\"id\":\"amaterasu\",\"name\":\"Amaterasu Finance\"},{\"id\":\"apeswap_bsc\",\"name\":\"ApeSwap\"},{\"id\":\"apeswap_polygon\",\"name\":\"ApeSwap (Polygon)\"},{\"id\":\"apeswap_telos\",\"name\":\"Apeswap (Telos)\"},{\"id\":\"apex_pro\",\"name\":\"ApeX Pro\"},{\"id\":\"aprobit\",\"name\":\"Aprobit\"},{\"id\":\"arthswap\",\"name\":\"ArthSwap\"},{\"id\":\"astroport\",\"name\":\"Astroport (Classic)\"},{\"id\":\"auroraswap\",\"name\":\"AuroraSwap\"},{\"id\":\"autoshark_finance\",\"name\":\"AutoShark Finance\"},{\"id\":\"azbit\",\"name\":\"Azbit\"},{\"id\":\"b2bx\",\"name\":\"B2BX\"},{\"id\":\"babydogeswap\",\"name\":\"BabyDogeSwap\"},{\"id\":\"babyswap\",\"name\":\"BabySwap\"},{\"id\":\"baguette\",\"name\":\"Baguette\"},{\"id\":\"bakeryswap\",\"name\":\"Bakeryswap\"},{\"id\":\"bakkt\",\"name\":\"Bakkt\"},{\"id\":\"balanced_network\",\"name\":\"Balanced Network\"},{\"id\":\"balancer\",\"name\":\"Balancer (v2)\"},{\"id\":\"balancer_arbitrum\",\"name\":\"Balancer (Arbitrum)\"},{\"id\":\"balancer_polygon\",\"name\":\"Balancer (Polygon)\"},{\"id\":\"balancer_v1\",\"name\":\"Balancer (v1)\"},{\"id\":\"bancor\",\"name\":\"Bancor (V2)\"},{\"id\":\"bancor_v3\",\"name\":\"Bancor (V3)\"},{\"id\":\"baryon_network\",\"name\":\"Baryon Network\"},{\"id\":\"basefex\",\"name\":\"BaseFEX\"},{\"id\":\"beamswap\",\"name\":\"Beamswap\"},{\"id\":\"beaxy\",\"name\":\"Beaxy\"},{\"id\":\"beethovenx\",\"name\":\"Beethoven X\"},{\"id\":\"benswap_smart_bitcoin_cash\",\"name\":\"Benswap\"},{\"id\":\"bgogo\",\"name\":\"Bgogo\"},{\"id\":\"bibox\",\"name\":\"Bibox\"},{\"id\":\"bibox_futures\",\"name\":\"Bibox (Futures)\"},{\"id\":\"biconomy\",\"name\":\"Biconomy\"},{\"id\":\"bigone\",\"name\":\"BigONE\"},{\"id\":\"bigone_futures\",\"name\":\"BigONE Futures\"},{\"id\":\"bilaxy\",\"name\":\"Bilaxy\"},{\"id\":\"binance\",\"name\":\"Binance\"},{\"id\":\"binance_dex\",\"name\":\"Binance DEX\"},{\"id\":\"binance_dex_mini\",\"name\":\"Binance DEX (Mini)\"},{\"id\":\"binance_futures\",\"name\":\"Binance (Futures)\"},{\"id\":\"binance_us\",\"name\":\"Binance US\"},{\"id\":\"bingx\",\"name\":\"BingX\"},{\"id\":\"bingx_futures\",\"name\":\"BingX (Futures)\"},{\"id\":\"bione\",\"name\":\"BiONE\"},{\"id\":\"birake\",\"name\":\"Birake\"},{\"id\":\"bisq\",\"name\":\"Bisq\"},{\"id\":\"biswap\",\"name\":\"Biswap\"},{\"id\":\"bit2c\",\"name\":\"Bit2c\"},{\"id\":\"bitazza\",\"name\":\"Bitazza\"},{\"id\":\"bitbank\",\"name\":\"Bitbank\"},{\"id\":\"bitbay\",\"name\":\"Zonda\"},{\"id\":\"bitbegin\",\"name\":\"Bitbegin\"},{\"id\":\"bitbns\",\"name\":\"BitBNS\"},{\"id\":\"bitbox\",\"name\":\"BITFRONT\"},{\"id\":\"bitbuy\",\"name\":\"Bitbuy\"},{\"id\":\"bitci\",\"name\":\"Bitci\"},{\"id\":\"bitcoin_com\",\"name\":\"FMFW.io\"},{\"id\":\"bit_com\",\"name\":\"BIT\"},{\"id\":\"bit_com_futures\",\"name\":\"BIT (Futures)\"},{\"id\":\"bitexbook\",\"name\":\"BITEXBOOK\"},{\"id\":\"bitexen\",\"name\":\"Bitexen\"},{\"id\":\"bitexlive\",\"name\":\"Bitexlive\"},{\"id\":\"bitfex\",\"name\":\"Bitfex\"},{\"id\":\"bitfinex\",\"name\":\"Bitfinex\"},{\"id\":\"bitfinex_futures\",\"name\":\"Bitfinex (Futures)\"},{\"id\":\"bitflyer\",\"name\":\"bitFlyer\"},{\"id\":\"bitflyer_futures\",\"name\":\"Bitflyer (Futures)\"},{\"id\":\"bitforex\",\"name\":\"Bitforex\"},{\"id\":\"bitforex_futures\",\"name\":\"Bitforex (Futures)\"},{\
            .ToDictionary(c =>
                c["id"].Value<string>(),
                c => new RateSourceInfo(c["id"].ToString().ToLowerInvariant(), c["name"].ToString() + " (via CoinGecko)", $"https://api.coingecko.com/api/v3/exchanges/{c["id"]}/tickers", RateSource.Coingecko));
        }

        private readonly HttpClient Client;


        string _UnderlyingExchange;
        public string UnderlyingExchange
        {
            get
            {
                return _UnderlyingExchange;
            }
            set
            {
                _UnderlyingExchange = value;
                if (value is null)
                    RateSourceInfo = new("coingecko", "CoinGecko", "https://api.coingecko.com/api/v3/exchange_rates");
                else
                {
                    RateSourceInfo = SupportedExchanges[value];
                }
            }
        }

        public RateSourceInfo RateSourceInfo { get; private set; }

        public CoinGeckoRateProvider(IHttpClientFactory httpClientFactory)
        {
            UnderlyingExchange = null;
            Client = httpClientFactory.CreateClient();
            Client.BaseAddress = new Uri("https://api.coingecko.com/api/v3/");
            Client.DefaultRequestHeaders.Add("Accept", "application/json");
        }

        public virtual Task<PairRate[]> GetRatesAsync(CancellationToken cancellationToken)
        {
            return UnderlyingExchange is null ? GetCoinGeckoRates(cancellationToken) : GetCoinGeckoExchangeSpecificRates(1, cancellationToken);
        }

        private async Task<PairRate[]> GetCoinGeckoRates(CancellationToken cancellationToken)
        {
            using var resp = await GetWithBackoffAsync("exchange_rates", cancellationToken);
            resp.EnsureSuccessStatusCode();
            return JObject.Parse(await resp.Content.ReadAsStringAsync()).GetValue("rates").Children()
                .Where(token => ((JProperty)token).Name != "btc")
                .Select(token => new PairRate(new CurrencyPair("BTC", ((JProperty)token).Name.ToString()),
                    new BidAsk(((JProperty)token).Value["value"].Value<decimal>()))).ToArray();
        }

        private async Task<HttpResponseMessage> GetWithBackoffAsync(string request, CancellationToken cancellationToken)
        {
            TimeSpan retryWait = TimeSpan.FromSeconds(1);
retry:
            var resp = await Client.GetAsync(request, cancellationToken);
            if (resp.StatusCode == System.Net.HttpStatusCode.TooManyRequests)
            {
                resp.Dispose();
                if (retryWait < TimeSpan.FromSeconds(60))
                {
                    await Task.Delay(retryWait, cancellationToken);
                    retryWait = TimeSpan.FromSeconds(retryWait.TotalSeconds * 2);
                    goto retry;
                }
                resp.EnsureSuccessStatusCode();
            }
            return resp;
        }

        private async Task<PairRate[]> GetCoinGeckoExchangeSpecificRates(int page, CancellationToken cancellationToken)
        {
            using var resp = await GetWithBackoffAsync($"exchanges/{UnderlyingExchange}/tickers?page={page}", cancellationToken);

            resp.EnsureSuccessStatusCode();
            List<PairRate> result = JObject.Parse(await resp.Content.ReadAsStringAsync()).GetValue("tickers")
                .Select(token => new PairRate(new CurrencyPair(token.Value<string>("base"), token.Value<string>("target")),
                    new BidAsk(token.Value<decimal>("last")))).ToList();
            if (page == 1 && resp.Headers.TryGetValues("total", out var total) &&
                resp.Headers.TryGetValues("per-page", out var perPage))
            {
                var totalItems = int.Parse(total.First());
                var perPageItems = int.Parse(perPage.First());

                var totalPages = totalItems / perPageItems;
                if (totalItems % perPageItems != 0)
                {
                    totalPages++;
                }

                var tasks = new List<Task<PairRate[]>>();
                for (int i = 2; i <= totalPages; i++)
                {
                    tasks.Add(GetCoinGeckoExchangeSpecificRates(i, cancellationToken));
                }

                foreach (var t in (await Task.WhenAll(tasks)))
                {
                    result.AddRange(t);
                }
            }

            return result.ToArray();
        }
    }
}