Cleanup ExchangeMarketSymbolToGlobalMarketSymbolAsync overrides (#888)

* BinanceGroupCommon: Remove redundant ExchangeMarketSymbolToGlobalMarketSymbolAsync override

* MEXC: Remove redundant ExchangeMarketSymbolToGlobalMarketSymbolAsync override

* BitMEX: Override ExchangeMarketSymbolToGlobalMarketSymbolAsync

Adds an ExchangeMarketSymbolToGlobalMarketSymbolAsync override to convert
local ISO 4217-style symbols (e.g., XBT) to global market symbols (e.g., BTC).

Author: BZ-CO

src/ExchangeSharp/API/Exchanges/BinanceGroup/BinanceGroupCommon.cs

@@ -74,28 +74,6 @@ protected BinanceGroupCommon()
 			RateLimit = new RateGate(40, TimeSpan.FromSeconds(10));
 		}
 
-		protected virtual string[] NonThreeLetterQuoteCurrencies => new[] { "USDT", "USDC", "EURI" };
-
-		public override Task<string> ExchangeMarketSymbolToGlobalMarketSymbolAsync(
-				string marketSymbol
-		)
-		{
-			foreach (var quoteCurrency in NonThreeLetterQuoteCurrencies)
-			{
-				if (marketSymbol.EndsWith(quoteCurrency))
-				{
-					return ExchangeMarketSymbolToGlobalMarketSymbolWithSeparatorAsync(
-						marketSymbol.Substring(0, marketSymbol.Length - quoteCurrency.Length) +
-						GlobalMarketSymbolSeparator +
-						quoteCurrency);
-				}
-			}
-
-			return ExchangeMarketSymbolToGlobalMarketSymbolWithSeparatorAsync(
-				marketSymbol.Substring(0, marketSymbol.Length - 3) + GlobalMarketSymbolSeparator +
-				marketSymbol.Substring(marketSymbol.Length - 3));
-		}
-
 		/// <summary>
 		/// Get the details of all trades
 		/// </summary>

src/ExchangeSharp/API/Exchanges/BitMEX/ExchangeBitMEXAPI.cs

@@ -12,6 +12,7 @@ The above copyright notice and this permission notice shall be included in all c
 
 using System;
 using System.Collections.Generic;
+using System.IO;
 using System.Linq;
 using System.Net;
 using System.Text;
@@ -52,11 +53,32 @@ private ExchangeBitMEXAPI()
 			RateLimit = new RateGate(300, TimeSpan.FromMinutes(5));
 		}
 
-		public override Task<string> ExchangeMarketSymbolToGlobalMarketSymbolAsync(
+		public override async Task<string> ExchangeMarketSymbolToGlobalMarketSymbolAsync(
 				string marketSymbol
 		)
 		{
-			throw new NotImplementedException();
+			ExchangeMarket marketSymbolMetadata = await GetExchangeMarketFromCacheAsync(
+				marketSymbol
+			);
+			if (marketSymbolMetadata == null)
+			{
+				throw new InvalidDataException(
+					$"No market symbol metadata returned or unable to find symbol metadata for {marketSymbol}"
+				);
+			}
+
+			if (marketSymbolMetadata.BaseCurrency == "XBT")
+			{
+				marketSymbolMetadata.BaseCurrency = "BTC";
+			}
+
+			if (marketSymbolMetadata.QuoteCurrency == "XBT")
+			{
+				marketSymbolMetadata.QuoteCurrency = "BTC";
+			}
+
+			return await ExchangeMarketSymbolToGlobalMarketSymbolWithSeparatorAsync(
+				marketSymbolMetadata.BaseCurrency + GlobalMarketSymbolSeparator + marketSymbolMetadata.QuoteCurrency);
 		}
 
 		public override Task<string> GlobalMarketSymbolToExchangeMarketSymbolAsync(

src/ExchangeSharp/API/Exchanges/MEXC/ExchangeMEXCAPI.cs

@@ -26,24 +26,7 @@ private ExchangeMEXCAPI()
 			RateLimit = new RateGate(20, TimeSpan.FromSeconds(2));
 			WebSocketOrderBookType = WebSocketOrderBookType.FullBookFirstThenDeltas;
 		}
-
-		public override Task<string> ExchangeMarketSymbolToGlobalMarketSymbolAsync(string marketSymbol)
-		{
-			var quoteLength = 3;
-			if (marketSymbol.EndsWith("USDT") ||
-			    marketSymbol.EndsWith("USDC") ||
-			    marketSymbol.EndsWith("TUSD"))
-			{
-				quoteLength = 4;
-			}
-
-			var baseSymbol = marketSymbol.Substring(marketSymbol.Length - quoteLength);
-
-			return ExchangeMarketSymbolToGlobalMarketSymbolWithSeparatorAsync(
-				marketSymbol.Replace(baseSymbol, "")
-				+ GlobalMarketSymbolSeparator
-				+ baseSymbol);
-		}
+		
 
 		protected override async Task<IEnumerable<string>> OnGetMarketSymbolsAsync()
 		{