using System;
using System.Collections.Generic;
using System.Linq;
using System.Text;
using System.Drawing;
using System.Drawing.Drawing2D;
using System.Threading.Tasks;

namespace XTS.Base.Data.TI
{
    [IndicatorScaleAttribute(IndicatorScale.Custom, 0, 100)]
    [IndicatorAttribute("{95C1C6DA-9495-45DD-8266-33A1D9400107}", "RSI", "Relative Streangth Index", "SYMPH", IndicatorCategory = IndicatorCategoryType.Custom)]
    public class RSI : IndicatorBase
    {
        [Parameter("LengthPeriod", Description = "The length of the RSI", DefaultValue = 12)]
        private int _lengthPeriod = 12;
        [Parameter("UpperLimit", Description = "Over Bought Value", DefaultValue = 70)]
        private int _upperLimit = 70;
        [Parameter("LowerLimit", Description = "Over Sold Value", DefaultValue = 30)]
        private int _lowerLimit = 30;
        private double _lastUpwardPriceChangeSmooth = 0;
        private double _lastDownwardPriceChangeSmooth = 0;
        [Output("RSIValue", DefaultValue = double.NaN, LineColor = "Red")] 
        private DoubleSeries _rsiDoubleValueSeries = new DoubleSeries();
        [Output("UpperLimit", DefaultValue = double.NaN, LineColor = "Gray", LineStyle = DashStyle.DashDot)]
        private DoubleSeries _rsiUpperLimitDoubleValueSeries = new DoubleSeries();
        [Output("LowerLimit", DefaultValue = double.NaN, LineColor = "Gray", LineStyle = DashStyle.DashDot)]
        private DoubleSeries _rsiLowerLimitDoubleValueSeries = new DoubleSeries();
        public RSI(TimeDataSeries timeDataSeries, int lengthPeriod) : base(timeDataSeries){
            if (lengthPeriod <= 0)
                throw new ArgumentException("Invalid RSI length");
            _lengthPeriod = lengthPeriod;
        }
        public RSI() : base(null){}
        public RSI(TimeDataSeries timeDataSeries): base(timeDataSeries){}
        /// <summary>
        /// Calculates the Indicator Function value at the index.
        /// </summary>
        /// <param name="index">The index at which Indicator Function value need to be calculated.</param>
        /// <returns>
        /// The calculated Indicator function value at the index.
        /// </returns>
        protected override double Calculate(int index){
            double priceUpward = 0;
            double priceDownward = 0;
            int checkValue = _lengthPeriod;
            _rsiUpperLimitDoubleValueSeries[index] = _upperLimit;
            _rsiLowerLimitDoubleValueSeries[index] = _lowerLimit;
            if (index < checkValue)
                _rsiDoubleValueSeries[index] = double.NaN;
            else if (index == checkValue){
                int startIndex = Math.Max(index - _lengthPeriod, 1);
                double barPricePrevious = this.TimeDataSeries[startIndex].Close;
                for (int counter = startIndex + 1; counter <= index; counter++){
                    double barPriceCurrent = this.TimeDataSeries[counter].Close;
                    if (barPriceCurrent > barPricePrevious)  // Upward price movement
                        priceUpward += (barPriceCurrent - barPricePrevious);
                    else if (barPriceCurrent < barPricePrevious)  // Downward price movement
                        priceDownward += (barPricePrevious - barPriceCurrent);
                    barPricePrevious = barPriceCurrent;
                }
                _lastUpwardPriceChangeSmooth = priceUpward / _lengthPeriod;
                _lastDownwardPriceChangeSmooth = priceDownward / _lengthPeriod;
                double rsiValue = 100 - (100 / (1 + (_lastUpwardPriceChangeSmooth / _lastDownwardPriceChangeSmooth)));
                _rsiDoubleValueSeries[index] = Math.Round(rsiValue, 2);
            }else{
                double currentDownwardPriceChange;
                double currentUpwardPriceChange;
                double rsiValue = 0.0;
                currentUpwardPriceChange = this.TimeDataSeries[index].Close - this.TimeDataSeries[index - 1].Close;
                if (currentUpwardPriceChange >= 0)
                    currentDownwardPriceChange = 0;
                else{
                    currentDownwardPriceChange = -currentUpwardPriceChange;
                    currentUpwardPriceChange = 0;
                }
                _lastUpwardPriceChangeSmooth = ((_lengthPeriod - 1) * _lastUpwardPriceChangeSmooth + currentUpwardPriceChange) / _lengthPeriod;
                _lastDownwardPriceChangeSmooth = ((_lengthPeriod - 1) * _lastDownwardPriceChangeSmooth + currentDownwardPriceChange) / _lengthPeriod;
                if (_lastUpwardPriceChangeSmooth + _lastDownwardPriceChangeSmooth != 0)
                    rsiValue = 100 * _lastUpwardPriceChangeSmooth / (_lastUpwardPriceChangeSmooth + _lastDownwardPriceChangeSmooth);
                _rsiDoubleValueSeries[index] = Math.Round(rsiValue, 2);
            }
            return _rsiDoubleValueSeries[index];
        }
    }
}