acdream/src/AcDream.Bake/ConsoleErrorLogger.cs

using System;
using Microsoft.Extensions.Logging;

namespace AcDream.Bake;

/// <summary>
/// Minimal <see cref="ILogger"/> writing to stderr with a level prefix.
/// MeshExtractor logs failures via ILogger.LogError/LogWarning (dat-read
/// anomalies, malformed entries) — per the project's "logger injection for
/// silent catches" lesson, the bake tool must NOT wire a NullLogger here or
/// every per-id extraction failure goes silent. A tiny hand-rolled logger
/// avoids pulling in the Microsoft.Extensions.Logging.Console package
/// (not already a transitive dependency) for what is a one-line need.
/// </summary>
public sealed class ConsoleErrorLogger : ILogger {
    private readonly string _categoryName;

    public ConsoleErrorLogger(string categoryName) {
        _categoryName = categoryName;
    }

    public IDisposable? BeginScope<TState>(TState state) where TState : notnull => null;

    public bool IsEnabled(LogLevel logLevel) => logLevel >= LogLevel.Warning;

    public void Log<TState>(LogLevel logLevel, EventId eventId, TState state, Exception? exception, Func<TState, Exception?, string> formatter) {
        if (!IsEnabled(logLevel)) return;
        var message = formatter(state, exception);
        Console.Error.WriteLine($"[{logLevel}] {_categoryName}: {message}");
        if (exception is not null) Console.Error.WriteLine(exception);
    }
}

/// <summary>Factory producing <see cref="ConsoleErrorLogger"/> instances for any category/type.</summary>
public sealed class ConsoleErrorLoggerProvider : ILoggerProvider {
    public ILogger CreateLogger(string categoryName) => new ConsoleErrorLogger(categoryName);
    public void Dispose() { }
}