using System;

using System.Net.Http;

using System.Threading.Tasks;

using System.Linq;

using System.Collections.Generic;

public class Program

{

    public static void Main()

    {

        // Set symbol and date range for historical data

        string symbol = "2888.HK";//"BTC-USD";

        DateTime startDate = new DateTime(2020, 01, 01);

        DateTime endDate = DateTime.Now; //new DateTime(2022, 12, 31);

        int timestampOfStartDate = (int)(startDate.Subtract(new DateTime(1970, 1, 1))).TotalSeconds;

        int timestampOfEndDate = (int)(endDate.Subtract(new DateTime(1970, 1, 1))).TotalSeconds;

        string interval = "1d"; //intervals: 1m, 2m, 5m, 15m, 30m, 60m, 90m, 1h, 1d, 5d, 1wk, 1mo, 3mo

        bool includeAdjustedClose = true;

        int rsiPeriod = 14;

​

        // Set URL for API request

        string url = string.Format("https://query1.finance.yahoo.com/v7/finance/download/{0}?period1={1}&period2={2}&interval={3}&events=history&includeAdjustedClose={4}",

            symbol, timestampOfStartDate, timestampOfEndDate, interval, includeAdjustedClose);

        Console.WriteLine(url); 

        // Read response data

        var responseData = GetWebContentAsync(url);

        //Console.WriteLine(responseData.Result);

        // Split response data into lines

        string[] lines = responseData.Result.Split("\n", StringSplitOptions.RemoveEmptyEntries);

        Console.WriteLine("Lines: " + lines.Length.ToString()); 

        // Extract price data from lines

        float lastClose = 0;

        List<PriceData> myList = new();

        for (int i = 1; i < lines.Length; i++)

        {

            string[] fields = lines[i].Split(',');

            PriceData newData = new();

            try{newData.Date = DateTime.Parse(fields[0]);} catch{}

            try{newData.Open = float.Parse(fields[1]);} catch{}

            try{newData.High = float.Parse(fields[2]);} catch{}

            try{newData.Low = float.Parse(fields[3]);} catch{}

            try{newData.Close = float.Parse(fields[4]);} catch{}

            try{newData.AdjClose = float.Parse(fields[5]);} catch{}

            try{newData.Volume = float.Parse(fields[6]);} catch{}

​

            //Calculate direction

            newData.Direction = newData.Close > lastClose ? "up" : newData.Close < lastClose ? "down" : "flat";

            //Calculate change, gain and loss (needed for RSI) 

            newData.Change = newData.Close - lastClose;

            newData.Gain = newData.Close > lastClose ? newData.Change : 0;

            newData.Loss = newData.Close < lastClose ? newData.Change * -1 : 0;

            newData.AvgGain = 0;

            newData.AvgLoss = 0;

            myList.Add(newData);

            lastClose = newData.Close;

        }

        Console.WriteLine("List.Count: " + myList.Count().ToString());  

        //Calculate average gain and loss and RSI

        for(int i = 0; i < myList.Count; i++)

        {

            if(i <= rsiPeriod) continue;

            List<PriceData> mySelection = myList.GetRange(i - rsiPeriod, rsiPeriod);

            myList[i].AvgGain = mySelection.Sum(x => x.Gain);

            myList[i].AvgLoss = mySelection.Sum(x => x.Loss);

            myList[i].RSI = 100 - (100 / (1 + myList[i].AvgGain / myList[i].AvgLoss));

        }

        // Create output

        string content = lines[0] + ",Direction,RSI\n";

        foreach(PriceData pd in myList)

        {

            content += $"{pd.Date:yyyy-MM-dd},{pd.Open},{pd.High},{pd.Low},{pd.Close},{pd.AdjClose},{pd.Volume},{pd.Direction},{pd.RSI}\n"; 

        }

        Console.WriteLine(content);

    }

    internal static async Task<string> GetWebContentAsync(string url)

    {

        using var client = new HttpClient();

        var content = await client.GetStringAsync(url);

        return content;

    }

}

​

public class PriceData

{

    public DateTime Date { get; set; }

    public float Open { get; set; }

    public float High { get; set; }

    public float Low { get; set; }

    public float Close { get; set; }

    public float AdjClose { get; set; }

    public float Volume { get; set; }

    public string Direction { get; set; }

    public float Change { get; set; }

    public float Gain { get; set; }

    public float Loss { get; set; }

    public float AvgGain { get; set; }

    public float AvgLoss { get; set; }

    public float RSI { get; set; }

}