Standardize isPostOnly

- a.k.a. MakerOnly or BookOrCancel or PendingOrCancelled
- most exchanges support this, but vary in the parameters needed to specify this

Author: vslee

src/ExchangeSharp/API/Exchanges/Aquanow/ExchangeAquanowAPI.cs

@@ -105,6 +105,7 @@ protected override async Task ProcessRequestAsync(IHttpWebRequest request, Dicti
 		// DONE
 		protected override async Task<ExchangeOrderResult> OnPlaceOrderAsync(ExchangeOrderRequest order)
 		{
+			if (order.IsPostOnly != null) throw new NotImplementedException("Post Only orders are not supported by this exchange or not implemented in ExchangeSharp. Please submit a PR if you are interested in this feature.");
 			// In Aquanow market order, when buying crypto the amount of crypto that is bought is the receiveQuantity
 			// and when selling the amount of crypto that is sold is the deliverQuantity
 			string amountParameter = order.IsBuy ? "receiveQuantity" : "deliverQuantity";

src/ExchangeSharp/API/Exchanges/BL3P/ExchangeBL3PAPI.cs

@@ -233,6 +233,7 @@ private string GetSignKey(IHttpWebRequest request, string formData)
 
 		protected override async Task<ExchangeOrderResult> OnPlaceOrderAsync(ExchangeOrderRequest order)
 		{
+			if (order.IsPostOnly != null) throw new NotImplementedException("Post Only orders are not supported by this exchange or not implemented in ExchangeSharp. Please submit a PR if you are interested in this feature.");
 			var roundedAmount = order.RoundAmount();
 			var amountInt = converterToEight.FromDecimal(roundedAmount);
 

src/ExchangeSharp/API/Exchanges/BTSE/ExchangeBTSEAPI.cs

@@ -165,6 +165,7 @@ protected override async Task<ExchangeOrderResult> OnPlaceOrderAsync(ExchangeOrd
 			dict.Add("size", request.Amount);
 			dict.Add("side", request.IsBuy ? "BUY" : "SELL");
 			dict.Add("symbol", request.MarketSymbol);
+			if (request.IsPostOnly != null) payload["postOnly"] = request.IsPostOnly;
 
 			switch (request.OrderType )
 			{

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

@@ -554,6 +554,11 @@ protected override async Task<ExchangeOrderResult> OnPlaceOrderAsync(ExchangeOrd
 			payload["side"] = order.IsBuy ? "BUY" : "SELL";
 			if (order.OrderType == OrderType.Stop)
 				payload["type"] = "STOP_LOSS";//if order type is stop loss/limit, then binance expect word 'STOP_LOSS' inestead of 'STOP'
+			else if (order.IsPostOnly == true)
+			{
+				if (order.OrderType == OrderType.Limit)	payload["type"] = "LIMIT_MAKER"; // LIMIT_MAKER are LIMIT orders that will be rejected if they would immediately match and trade as a taker.
+				else throw new NotImplementedException("PostOnly with non limit orders are not currently supported on Binance. Please submit a PR if you are interested in this feature");
+			}
 			else
 				payload["type"] = order.OrderType.ToStringUpperInvariant();
 

src/ExchangeSharp/API/Exchanges/BitBank/ExchangeBitBankAPI.cs

@@ -129,6 +129,8 @@ protected override async Task<ExchangeOrderResult> OnPlaceOrderAsync(ExchangeOrd
 			if (order.OrderType == OrderType.Stop)
 				throw new InvalidOperationException("Bitbank does not support stop order");
 			Dictionary<string, object> payload = await GetNoncePayloadAsync();
+			if (order.IsPostOnly != null)
+				payload["post_only"] = order.IsPostOnly;
 			payload.Add("pair", NormalizeMarketSymbol(order.MarketSymbol));
 			payload.Add("amount", order.Amount.ToStringInvariant());
 			payload.Add("side", order.IsBuy ? "buy" : "sell");

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

@@ -693,10 +693,10 @@ private void AddOrderToPayload(ExchangeOrderRequest order, Dictionary<string, ob
 			if(order.OrderType!=OrderType.Market)
 				payload["price"] = order.Price;
 
-			if (order.ExtraParameters.TryGetValue("execInst", out var execInst))
-			{
-				payload["execInst"] = execInst;
-			}
+			if (order.IsPostOnly == true)
+				payload["execInst"] = "ParticipateDoNotInitiate"; // Also known as a Post-Only order. If this order would have executed on placement, it will cancel instead. This is intended to protect you from the far touch moving towards you while the order is in transit. It is not intended for speculating on the far touch moving away after submission - we consider such behaviour abusive and monitor for it.
+
+			order.ExtraParameters.CopyTo(payload);
 		}
 
 		private ExchangePosition ParsePosition(JToken token)

src/ExchangeSharp/API/Exchanges/Bitfinex/ExchangeBitfinexAPI.cs

@@ -488,6 +488,7 @@ protected override async Task<ExchangeOrderResult> OnPlaceOrderAsync(ExchangeOrd
 			{
 				payload["price"] = "1";
 			}
+			if (order.IsPostOnly == true) payload["flags"] = "4096"; // The post-only limit order option ensures the limit order will be added to the order book and not match with a pre-existing order unless the pre-existing order is a hidden order.
 			order.ExtraParameters.CopyTo(payload);
 			JToken obj = await MakeJsonRequestAsync<JToken>("/order/new", BaseUrlV1, payload);
 			return ParseOrder(obj);

src/ExchangeSharp/API/Exchanges/Bitstamp/ExchangeBitstampAPI.cs

@@ -195,7 +195,8 @@ private static Dictionary<string, decimal> ExtractDictionary(JObject responseObj
 
         protected override async Task<ExchangeOrderResult> OnPlaceOrderAsync(ExchangeOrderRequest order)
         {
-            string action = order.IsBuy ? "buy" : "sell";
+			if (order.IsPostOnly != null) throw new NotImplementedException("Post Only orders are not supported by this exchange or not implemented in ExchangeSharp. Please submit a PR if you are interested in this feature.");
+			string action = order.IsBuy ? "buy" : "sell";
             string market = order.OrderType == OrderType.Market ? "/market" : "";
             string url = $"/{action}{market}/{order.MarketSymbol}/";
             Dictionary<string, object> payload = await GetNoncePayloadAsync();

src/ExchangeSharp/API/Exchanges/Bittrex/ExchangeBittrexAPI.cs

@@ -389,7 +389,8 @@ protected override async Task<ExchangeOrderResult> OnPlaceOrderAsync(ExchangeOrd
 			if (order.OrderType == ExchangeSharp.OrderType.Limit)
 			{
 				orderParams.Add("limit", orderPrice);
-				orderParams.Add("timeInForce", "GOOD_TIL_CANCELLED");
+				if (order.IsPostOnly == true) orderParams.Add("timeInForce", "POST_ONLY_GOOD_TIL_CANCELLED"); // This option allows market makers to ensure that their orders are making it to the order book instead of matching with a pre-existing order. Note: If the order is not a maker order, you will return an error and the order will be cancelled
+				else orderParams.Add("timeInForce", "GOOD_TIL_CANCELLED");
 			}
 
 			foreach (KeyValuePair<string, object> kv in order.ExtraParameters)

src/ExchangeSharp/API/Exchanges/Bybit/ExchangeBybitAPI.cs

@@ -816,6 +816,7 @@ protected override async Task<ExchangeOrderResult> OnPlaceOrderAsync(ExchangeOrd
 
 		public async Task<ExchangeOrderResult> OnAmendOrderAsync(ExchangeOrderRequest order)
 		{
+			if (order.IsPostOnly != null) throw new NotImplementedException("Post Only orders are not supported by this exchange or not implemented in ExchangeSharp. Please submit a PR if you are interested in this feature.");
 			var payload = new Dictionary<string, object>();
 			payload["symbol"] = order.MarketSymbol;
 			if(order.OrderId != null)