using System;

using System.Runtime.CompilerServices;

using System.Text;

public class Program

{

    public static void Main()

    {

        var logger = new Logger();

        logger.LogMessage(LogLevel.Critical, "Critical messsage");

        Console.WriteLine("");

        logger.LogMessage(LogLevel.Critical, $"Critical messsage {DateTime.Now}");

        Console.WriteLine("");

        logger.LogMessage(LogLevel.Information, $"Information messsage {DateTime.Now}");

    }

}

​

public enum LogLevel

{

    Off,

    Critical,

    Error,

    Warning,

    Information,

    Trace

}

​

public class Logger

{

    public LogLevel EnabledLevel { get; init; } = LogLevel.Error;

​

    public void LogMessage(LogLevel level, string msg)

    {

        Console.WriteLine("LogMessage string version");

        if (EnabledLevel < level) return;

        Console.WriteLine(msg);

    }

    public void LogMessage(LogLevel level, [InterpolatedStringHandlerArgument("", "level")]LogInterpolatedStringHandler builder)

    {

        Console.WriteLine("LogMessage interpolated string version");

        if (EnabledLevel < level) return;

        Console.WriteLine(builder.GetFormattedText());

    }

}

​

[InterpolatedStringHandler]

public struct LogInterpolatedStringHandler

{

    StringBuilder builder;

    private readonly bool enabled;

    public LogInterpolatedStringHandler(int literalLength, int formattedCount, Logger logger, LogLevel logLevel) 

    {

        enabled = logger.EnabledLevel >= logLevel;

        builder = new StringBuilder(literalLength);         

    }

    public void AppendLiteral(string s) 

    {

        if(!enabled) return;

        Console.WriteLine($"Append Literal {s}");

        builder.Append(s);

    }

    public void AppendFormatted<T>(T t)

    {

        if(!enabled) return;

        Console.WriteLine($"Append Formatted {t}");

        builder.Append(t.ToString());

    }

    internal string GetFormattedText() => builder.ToString();

}