doom-dm/Engine/src/EngineBuilder.cs

using Engine.Graphics;
using Engine.Input;
using Serilog;
using Serilog.Core;
using Serilog.Events;
using Serilog.Sinks.SystemConsole.Themes;

namespace Engine;

/// <summary>
/// Provides a builder for creating and configuring an instance of the <see cref="Engine"/> class.
/// </summary>
public sealed class EngineBuilder
{
  /// <summary>
  /// The title of the application window.
  /// </summary>
  private string _title = "";

  /// <summary>
  /// Indicates whether the engine should run in headless mode.
  /// </summary>
  private bool _headless;

  /// <summary>
  /// The width of the rendering window.
  /// </summary>
  private int _width = 1;

  /// <summary>
  /// The height of the rendering window.
  /// </summary>
  private int _height = 1;

  /// <summary>
  /// The path to the asset folder.
  /// </summary>
  private string _assetFolder = "./asset";

  /// <summary>
  /// The path to the data folder.
  /// </summary>
  private string _dataFolder = "./data";

  /// <summary>
  /// The input handler factory.
  /// </summary>
  private Func<Engine, IInputHandler>? _inputHandlerFunc;

  /// <summary>
  /// The presenter factory.
  /// </summary>
  private Func<Engine, IPresenter>? _presenterFunc;

  // Logging
  /// <summary>
  /// Indicates whether to log to the console.
  /// </summary>
  private bool _logToConsole;

  /// <summary>
  /// Indicates whether to log to a file.
  /// </summary>
  private bool _logToFile;

  /// <summary>
  /// The path to the log file.
  /// </summary>
  private string? _logFilePath;

  /// <summary>
  /// The log level.
  /// </summary>
  private LogEventLevel _logLevel = LogEventLevel.Information;

  /// <summary>
  /// Sets the title of the engine window.
  /// </summary>
  /// <param name="parTitle">The title to use for the engine window.</param>
  /// <returns>The current instance of <see cref="EngineBuilder"/> for chaining.</returns>
  public EngineBuilder Title(string parTitle)
  {
    _title = parTitle;
    return this;
  }

  /// <summary>
  /// Configures the engine to run in headless mode.
  /// </summary>
  /// <param name="parHeadless">Indicates whether to enable headless mode. Defaults to <c>true</c>.</param>
  /// <returns>The current instance of <see cref="EngineBuilder"/> for chaining.</returns>
  public EngineBuilder Headless(bool parHeadless = true)
  {
    _headless = parHeadless;
    return this;
  }

  /// <summary>
  /// Sets the width of the engine window.
  /// </summary>
  /// <param name="parWidth">The width in pixels. Must be greater than zero.</param>
  /// <returns>The current instance of <see cref="EngineBuilder"/> for chaining.</returns>
  public EngineBuilder Width(int parWidth)
  {
    ArgumentOutOfRangeException.ThrowIfNegativeOrZero(parWidth);

    _width = parWidth;
    return this;
  }

  /// <summary>
  /// Sets the height of the engine window.
  /// </summary>
  /// <param name="parHeight">The height in pixels. Must be greater than zero.</param>
  /// <returns>The current instance of <see cref="EngineBuilder"/> for chaining.</returns>
  public EngineBuilder Height(int parHeight)
  {
    ArgumentOutOfRangeException.ThrowIfNegativeOrZero(parHeight);

    _height = parHeight;
    return this;
  }

  /// <summary>
  /// Sets the folder path for assets used by the engine.
  /// </summary>
  /// <param name="parAssetFolder">The folder path containing asset files.</param>
  /// <returns>The current instance of <see cref="EngineBuilder"/> for chaining.</returns>
  public EngineBuilder AssetFolder(string parAssetFolder)
  {
    _assetFolder = parAssetFolder;
    return this;
  }

  /// <summary>
  /// Sets the folder path for data files used by the engine.
  /// </summary>
  /// <param name="parDataFolder">The folder path containing data files.</param>
  /// <returns>The current instance of <see cref="EngineBuilder"/> for chaining.</returns>
  public EngineBuilder DataFolder(string parDataFolder)
  {
    _dataFolder = parDataFolder;
    return this;
  }

  /// <summary>
  /// Specifies the input handler to be used by the engine.
  /// </summary>
  /// <param name="parInputHandlerFunc">A function that creates an input handler for the engine.</param>
  /// <returns>The current instance of <see cref="EngineBuilder"/> for chaining.</returns>
  public EngineBuilder InputHandler(Func<Engine, IInputHandler> parInputHandlerFunc)
  {
    _inputHandlerFunc = parInputHandlerFunc;
    return this;
  }

  /// <summary>
  /// Specifies the presenter to be used by the engine.
  /// </summary>
  /// <param name="parPresenterFunc">A function that creates a presenter for the engine.</param>
  /// <returns>The current instance of <see cref="EngineBuilder"/> for chaining.</returns>
  public EngineBuilder Presenter(Func<Engine, IPresenter> parPresenterFunc)
  {
    _presenterFunc = parPresenterFunc;
    return this;
  }

  /// <summary>
  /// Configures logging to output to the console.
  /// </summary>
  /// <param name="parLogToConsole">Indicates whether to enable console logging. Defaults to <c>true</c>.</param>
  /// <returns>The current instance of <see cref="EngineBuilder"/> for chaining.</returns>
  public EngineBuilder LogToConsole(bool parLogToConsole = true)
  {
    _logToConsole = parLogToConsole;
    return this;
  }

  /// <summary>
  /// Configures logging to output to a file.
  /// </summary>
  /// <param name="parLogToFile">Indicates whether to enable file logging. Defaults to <c>true</c>.</param>
  /// <param name="parLogFilePath">The path of the log file. Cannot be <c>null</c> if file logging is enabled.</param>
  /// <returns>The current instance of <see cref="EngineBuilder"/> for chaining.</returns>
  /// <exception cref="ArgumentNullException">Thrown if <paramref name="parLogFilePath"/> is <c>null</c> when <paramref name="parLogToFile"/> is <c>true</c>.</exception>
  public EngineBuilder LogToFile(bool parLogToFile = true, string? parLogFilePath = null)
  {
    if (parLogToFile && parLogFilePath == null)
    {
      throw new ArgumentNullException(nameof(parLogFilePath));
    }

    _logToFile = parLogToFile;
    _logFilePath = parLogFilePath;
    return this;
  }

  /// <summary>
  /// Sets the minimum log level for logging.
  /// </summary>
  /// <param name="parLogLevel">The minimum level of log events to capture.</param>
  /// <returns>The current instance of <see cref="EngineBuilder"/> for chaining.</returns>
  public EngineBuilder LogLevel(LogEventLevel parLogLevel)
  {
    _logLevel = parLogLevel;
    return this;
  }

  /// <summary>
  /// Builds and returns a new instance of the <see cref="Engine"/> class based on the configured settings.
  /// </summary>
  /// <returns>A fully configured instance of <see cref="Engine"/>.</returns>
  public Engine Build()
  {
    var logger = BuildLogger();
    var engine = new Engine(_width, _height, _headless, _title, _assetFolder, _dataFolder, logger);

    var presenter = _presenterFunc?.Invoke(engine);
    if (presenter != null)
    {
      engine.Presenter = presenter;
    }

    var inputHandler = _inputHandlerFunc?.Invoke(engine);
    if (inputHandler != null)
    {
      engine.InputHandler = inputHandler;
    }

    return engine;
  }

  /// <summary>
  /// Configures and builds a logger based on the current logging settings.
  /// </summary>
  /// <returns>A configured instance of <see cref="Logger"/>.</returns>
  private Logger BuildLogger()
  {
    const string template =
      "[{Timestamp:yyyy-MM-dd HH:mm:ss.fff}] [{Level:u3}] [{ThreadName,-15:l}:{ThreadId,-4:d4}] [{SourceContext:l}] {Message:lj}{NewLine}{Exception}";

    var loggerConfiguration = new LoggerConfiguration()
      .MinimumLevel.Is(_logLevel)
      .Enrich.WithThreadName()
      .Enrich.WithThreadId()
      .Enrich.FromLogContext();

    if (_logToConsole)
    {
      loggerConfiguration.WriteTo.Console(
        outputTemplate: template,
        theme: AnsiConsoleTheme.Literate
      );
    }

    if (_logToFile)
    {
      loggerConfiguration.WriteTo.File(
        _logFilePath!,
        outputTemplate: template
      );
    }

    return loggerConfiguration.CreateLogger();
  }
}