qamp/Qrakhen.Qamp.Core/Logging/ILogger.cs

using System.Diagnostics;
using System.Runtime.CompilerServices;
using System.Xml.XPath;

namespace Qrakhen.Qamp.Core.Logging;

public interface ILogger
{
    LogLevel Level { get; set; }

    void Log(LogLevel level, params object?[] values);

    void Critical(params object?[] values);
    void Error(params object?[] values);
    void Warn(params object?[] values);
    void Info(params object?[] values);
    void Debug(params object?[] values);
    void Trace(params object?[] values);
    void Verbose(params object?[] values);
    void Method(object? value = null, string? caller = null);
}

[Flags]
public enum LogLevel
{
    Mute     = 0x00,
    Critical = 0x01,
    Error    = 0x02,
    Warn     = 0x04,
    Info     = 0x08,
    Debug    = 0x10,
    Trace    = 0x20,
    Verbose  = 0x40,
    All      = Critical | Error | Warn | Info | Debug | Trace | Verbose
}

public interface ILogFormatter
{
    string[] Format(object? value, int maxWidth = 80);
}

public interface ILoggerService
{
    ILogger Get<T>(string? name = null, LogLevel? level = null);
    ILogger Get(string name, LogLevel? level = null);
}

public class LoggerService
{
    private static readonly Dictionary<string, ILogger> _loggers = new Dictionary<string, ILogger>();

    public static LogLevel Default = LogLevel.All;

    public static ILogger Get<T>(string? name = null, LogLevel? level = null)
    {
        level ??= Default;
        string _name = nameof(T);
        if (!string.IsNullOrEmpty(name))
            _name = $"{_name}:{name}";
        return Get(_name, level);
    }

    public static ILogger Get(string name, LogLevel? level = null)
    {
        level ??= Default;
        ILogger? logger;
        if (_loggers.TryGetValue(name, out logger))
            return logger;
        logger = new Logger(name, level.Value);
        _loggers.Add(name, logger);
        return logger;
    }
}

public class Logger : ILogger, ILogFormatter
{
    public string Name { get; private set; }
    private LogLevel _level;
    public LogLevel Level { get => true ? LoggerService.Default : _level; set => _level = value; }

    private static Dictionary<LogLevel, (string First, string Extra)> headers = new() { 
        { LogLevel.Critical, (" !? ", " !? ") },
        { LogLevel.Error,    (" !! ", " !  ") },
        { LogLevel.Warn,     (" !> ", " !  ") },
        { LogLevel.Info,     (" :> ", " :  ") },
        { LogLevel.Debug,    ("  > ", "    ") },
        { LogLevel.Trace,    ("  > ", "    ") },
        { LogLevel.Verbose,  ("  > ", "    ") },
    };

    private static Dictionary<LogLevel, ConsoleColor> colors = new()
    {
        { LogLevel.Critical, ConsoleColor.DarkRed },
        { LogLevel.Error,    ConsoleColor.Red },
        { LogLevel.Warn,     ConsoleColor.Yellow },
        { LogLevel.Info,     ConsoleColor.White },
        { LogLevel.Debug,    ConsoleColor.Gray },
        { LogLevel.Trace,    ConsoleColor.DarkGray },
        { LogLevel.Verbose,  ConsoleColor.DarkGray },
    };

    public Logger(string name, LogLevel level)
    {
        Name = name;
        Level = level;
    }

    public string[] Format(object? value, int maxWidth = 80)
    {
        List<string> result = [];
        if (value == null)
            result.Add("null");
        else if (value is string str)
            result.AddRange(str.Split('\n'));
        else if (value is Exception e)
        {
            result.Add(e.Message);
            if (!string.IsNullOrEmpty(e.StackTrace))
                result.AddRange(e.StackTrace.Split('\n'));
        } else
            result.Add(value?.ToString() ?? "null");

        return result.ToArray();
    }

    public void Log(LogLevel level, params object?[] values)
    {
        if ((level & Level) != level)
            return;

        var header = headers[level];
        Console.ForegroundColor = colors[level];
        foreach (var value in values)
        {
            var lines = Format(value);
            for (int i = 0; i < lines.Length; i++)            
                Console.WriteLine($"{(i == 0 ? header.First : header.Extra)}{lines[i]}");
        }
        Console.ForegroundColor = ConsoleColor.White;
    }

    public void Critical(params object?[] values)   => Log(LogLevel.Critical, values);
    public void Error(params object?[] values)      => Log(LogLevel.Error, values);
    public void Warn(params object?[] values)       => Log(LogLevel.Warn, values);
    public void Info(params object?[] values)       => Log(LogLevel.Info, values);
    public void Debug(params object?[] values)      => Log(LogLevel.Debug, values);
    public void Trace(params object?[] values)      => Log(LogLevel.Trace, values);
    public void Verbose(params object?[] values)    => Log(LogLevel.Verbose, values);

    public void Method(object? value = null, [CallerMemberName] string? caller = null)
    {
        if (caller == null)
        {
            var st = new StackTrace();
            var previous = st.GetFrame(1)?.GetMethod();
            if (previous != null)
                caller = $"{previous.DeclaringType?.Name}.{previous.Name}";            
        }
        Log(LogLevel.Trace, [ $"[{caller}] {value}" ]);
    }
}