/*
 * QUANTCONNECT.COM - Democratizing Finance, Empowering Individuals.
 * Lean Algorithmic Trading Engine v2.0. Copyright 2014 QuantConnect Corporation.
 *
 * Licensed under the Apache License, Version 2.0 (the "License");
 * you may not use this file except in compliance with the License.
 * You may obtain a copy of the License at http://www.apache.org/licenses/LICENSE-2.0
 *
 * Unless required by applicable law or agreed to in writing, software
 * distributed under the License is distributed on an "AS IS" BASIS,
 * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
 * See the License for the specific language governing permissions and
 * limitations under the License.
*/

using System;
using QuantConnect.Util;
using QuantConnect.Data;
using QuantConnect.Securities;
using QuantConnect.Orders.Fees;

namespace QuantConnect.Orders.Fills
{
    /// <summary>
    /// Represents the fill model used to simulate order fills for futures
    /// </summary>
    public class FutureFillModel : ImmediateFillModel
    {
        /// <summary>
        /// Default market fill model for the base security class. Fills at the last traded price.
        /// </summary>
        /// <param name="asset">Security asset we're filling</param>
        /// <param name="order">Order packet to model</param>
        /// <returns>Order fill information detailing the average price and quantity filled.</returns>
        public override OrderEvent MarketFill(Security asset, MarketOrder order)
        {
            //Default order event to return.
            var utcTime = asset.LocalTime.ConvertToUtc(asset.Exchange.TimeZone);
            var fill = new OrderEvent(order, utcTime, OrderFee.Zero);

            if (order.Status == OrderStatus.Canceled) return fill;

            // make sure the exchange is open on regular/extended market hours before filling
            if (!IsExchangeOpen(asset, true)) return fill;

            var prices = GetPricesCheckingPythonWrapper(asset, order.Direction);
            var pricesEndTimeUtc = prices.EndTime.ConvertToUtc(asset.Exchange.TimeZone);

            // if the order is filled on stale (fill-forward) data, set a warning message on the order event
            if (pricesEndTimeUtc.Add(Parameters.StalePriceTimeSpan) < order.Time)
            {
                fill.Message = Messages.FillModel.FilledAtStalePrice(asset, prices);
            }

            //Order [fill]price for a market order model is the current security price
            fill.FillPrice = prices.Current;
            fill.Status = OrderStatus.Filled;

            //Calculate the model slippage: e.g. 0.01c
            var slip = asset.SlippageModel.GetSlippageApproximation(asset, order);

            //Apply slippage
            switch (order.Direction)
            {
                case OrderDirection.Buy:
                    fill.FillPrice += slip;
                    break;
                case OrderDirection.Sell:
                    fill.FillPrice -= slip;
                    break;
            }

            // assume the order completely filled
            fill.FillQuantity = order.Quantity;

            return fill;
        }

        /// <summary>
        /// Stop fill model implementation for Future.
        /// </summary>
        /// <param name="asset">Security asset we're filling</param>
        /// <param name="order">Order packet to model</param>
        /// <returns>Order fill information detailing the average price and quantity filled.</returns>
        /// <remarks>
        /// A Stop order is an instruction to submit a buy or sell market order
        /// if and when the user-specified stop trigger price is attained or penetrated.
        ///
        /// A Sell Stop order is always placed below the current market price.
        /// We assume a fluid/continuous, high volume market. Therefore, it is filled at the stop trigger price
        /// if the current low price of trades is less than or equal to this price.
        ///
        /// A Buy Stop order is always placed above the current market price.
        /// We assume a fluid, high volume market. Therefore, it is filled at the stop trigger price
        /// if the current high price of trades is greater or equal than this price.
        ///
        /// The continuous market assumption is not valid if the market opens with an unfavorable gap.
        /// In this case, a new bar opens below/above the stop trigger price, and the order is filled with the opening price.
        /// <seealso cref="MarketFill(Security, MarketOrder)"/></remarks>
        public override OrderEvent StopMarketFill(Security asset, StopMarketOrder order)
        {
            //Default order event to return.
            var utcTime = asset.LocalTime.ConvertToUtc(asset.Exchange.TimeZone);
            var fill = new OrderEvent(order, utcTime, OrderFee.Zero);

            //If its cancelled don't need anymore checks:
            if (order.Status == OrderStatus.Canceled) return fill;

            // Fill only if open or extended
            // even though data from internal configurations are not sent to the algorithm.OnData they still drive security cache and data
            // this is specially relevant for the continuous contract underlying mapped contracts which are internal configurations
            if (!IsExchangeOpen(asset, Parameters.ConfigProvider.GetSubscriptionDataConfigs(asset.Symbol, includeInternalConfigs: true).IsExtendedMarketHours()))
            {
                return fill;
            }

            //Get the range of prices in the last bar:
            var prices = GetPricesCheckingPythonWrapper(asset, order.Direction);
            var pricesEndTime = prices.EndTime.ConvertToUtc(asset.Exchange.TimeZone);

            // do not fill on stale data
            if (pricesEndTime <= order.Time) return fill;

            //Calculate the model slippage: e.g. 0.01c
            var slip = asset.SlippageModel.GetSlippageApproximation(asset, order);

            //Check if the Stop Order was filled: opposite to a limit order
            switch (order.Direction)
            {
                case OrderDirection.Sell:
                    //-> 1.1 Sell Stop: If Price below setpoint, Sell:
                    if (prices.Low < order.StopPrice)
                    {
                        fill.Status = OrderStatus.Filled;
                        // Assuming worse case scenario fill - fill at lowest of the stop & asset price.
                        fill.FillPrice = Math.Min(order.StopPrice, prices.Current - slip);
                        // assume the order completely filled
                        fill.FillQuantity = order.Quantity;
                    }
                    break;

                case OrderDirection.Buy:
                    //-> 1.2 Buy Stop: If Price Above Setpoint, Buy:
                    if (prices.High > order.StopPrice)
                    {
                        fill.Status = OrderStatus.Filled;
                        // Assuming worse case scenario fill - fill at highest of the stop & asset price.
                        fill.FillPrice = Math.Max(order.StopPrice, prices.Current + slip);
                        // assume the order completely filled
                        fill.FillQuantity = order.Quantity;
                    }
                    break;
            }

            return fill;
        }
    }
}