Interview

Welcome

Thank you for cloning this project! This project is designed to conduct a technical interview for C# developers. Good luck! 🤞

How to Submit

You can submit your answers using one of the following methods:

1. Zip and send the code back to the HR contact.
2. Share the link to your forked project with HR.

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Background

Pricing System Overview

You are provided (no need to implement) a .NET Standard library that simulates a pricing system. The API mimics receiving prices from external services.

Here is a high-level diagram:

graph LR
    subgraph Current Application
        B[Trading API] -->|Event callback| C["Event handler - OnPricing()"]
    end
    A[External System] -->|Price streams| B

Loading

The library includes a class named TradingApi which implements the following interface:

public interface ITradingApi
{
    /// <summary>
    /// Get the full list of symbol definitions. Only two symbols are supported: "AUDUSD" and "CL-OIL".
    /// </summary>
    /// <returns>Symbols</returns>
    IEnumerable<Symbol> GetSymbols();

    /// <summary>
    /// If there is an incoming price and the symbol of the price is subscribed by SubscribeSymbol, 
    /// an event will fire, passing the pricing data as event data.
    /// </summary>
    event EventHandler<Price> OnPricing;

    /// <summary>
    /// Subscribe to a symbol to receive prices through the OnPricing event handler.
    /// </summary>
    /// <param name="symbolName">Name of a symbol</param>
    void SubscribeSymbol(string symbolName);
}

Supporting Data Structures

public struct Price
{
    public string Symbol { get; }
    public decimal Bid { get; }
    public decimal Ask { get; }
    public DateTime Time { get; }
}

public class Symbol
{
    public string Name { get; set; }
    public string BaseCurrency { get; set; }
    public int Digits { get; set; }
}

public class PriceStats
{
    public decimal Open { get; set; }
    public decimal Close { get; set; }
    public decimal Min { get; set; }
    public decimal Max { get; set; }
}

Extension Method for Time Rounding

You can use the following extension method to round down a DateTime to a specific interval:

public static DateTime RoundDown(this DateTime dateTime, TimeSpan interval)
{
    var delta = dateTime.Ticks % interval.Ticks;
    return new DateTime(dateTime.Ticks - delta, dateTime.Kind);
}

Example Usage:

DateTime now = DateTime.UtcNow;
TimeSpan interval = TimeSpan.FromMinutes(1);
DateTime roundedTime = now.RoundDown(interval);

Console.WriteLine($"Original: {now}");
Console.WriteLine($"Rounded: {roundedTime}");

Example Output:

Original: 2025-01-23 15:12:45
Rounded: 2025-01-23 15:12:00

Use this method to group prices into minute intervals for calculating the PriceStats.

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Tasks

Your task is to complete the controllers and services to fulfill the following requirements. The skeleton for the controllers and services is already provided in the project.

API Endpoints

1. GET /api/symbols

   • Return a list of all available symbols.

2. GET /api/symbols/{name}

   • Return a single Symbol object corresponding to the specified {name}.

3. GET /api/price/{symbol}

   • Return the latest Price for the specified {symbol}.

4. GET /api/price/{symbol}/stats

   • Return PriceStats containing the following details for the current minute (i.e., from the start of the current minute to now) for the specified {symbol}:
     • Open: The first Bid price in the minute.
     • Close: The last Bid price in the minute.
     • Low: The lowest Bid price in the minute.
     • High: The highest Bid price in the minute.

   Hint: Use the extension method above to round timestamps to the nearest minute and filter prices.

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Additional Notes

• You have full control over the project but do not modify the provided mock service or its interface.
• The mocked service provides live data when the project is built and run. The data updates every second, simulating real-time market conditions.
• Focus on code quality, performance, functionality, and solution design.
• The primary focus will be on your thought process and how you arrive at solutions.
• The estimated time to complete the tasks is 1 hour.

Good luck! 🚀