ColorfulConsoleWriter.cs

using System;
using System.Collections.Generic;
using System.Diagnostics.CodeAnalysis;
using StardewModdingAPI.Toolkit.Utilities;

namespace StardewModdingAPI.Internal.ConsoleWriting
{
    /// <summary>Writes color-coded text to the console.</summary>
    internal class ColorfulConsoleWriter : IConsoleWriter
    {
        /*********
        ** Fields
        *********/
        /// <summary>The console text color for each log level.</summary>
        private readonly IDictionary<ConsoleLogLevel, ConsoleColor>? Colors;

        /// <summary>Whether the current console supports color formatting.</summary>
        [MemberNotNullWhen(true, nameof(ColorfulConsoleWriter.Colors))]
        private bool SupportsColor { get; }


        /*********
        ** Public methods
        *********/
        /// <summary>Construct an instance.</summary>
        /// <param name="platform">The target platform.</param>
        public ColorfulConsoleWriter(Platform platform)
            : this(platform, ColorfulConsoleWriter.GetDefaultColorSchemeConfig(MonitorColorScheme.AutoDetect)) { }

        /// <summary>Construct an instance.</summary>
        /// <param name="platform">The target platform.</param>
        /// <param name="colorConfig">The colors to use for text written to the SMAPI console.</param>
        public ColorfulConsoleWriter(Platform platform, ColorSchemeConfig colorConfig)
        {
            if (colorConfig.UseScheme == MonitorColorScheme.None)
            {
                this.SupportsColor = false;
                this.Colors = null;
            }
            else
            {
                this.SupportsColor = this.TestColorSupport();
                this.Colors = this.GetConsoleColorScheme(platform, colorConfig);
            }
        }

        /// <summary>Write a message line to the log.</summary>
        /// <param name="message">The message to log.</param>
        /// <param name="level">The log level.</param>
        public void WriteLine(string message, ConsoleLogLevel level)
        {
            if (this.SupportsColor)
            {
                if (level == ConsoleLogLevel.Critical)
                {
                    this.WriteLineImpl(message, ConsoleColor.White, ConsoleColor.Red);
                }
                else
                {
                    this.WriteLineImpl(message, this.Colors[level], null);
                }
            }
            else
                this.WriteLineImpl(message, null, null);
        }

        /// <summary>Get the default color scheme config for cases where it's not configurable (e.g. the installer).</summary>
        /// <param name="useScheme">The default color scheme ID to use, or <see cref="MonitorColorScheme.AutoDetect"/> to select one automatically.</param>
        /// <remarks>The colors here should be kept in sync with the SMAPI config file.</remarks>
        public static ColorSchemeConfig GetDefaultColorSchemeConfig(MonitorColorScheme useScheme)
        {
            return new ColorSchemeConfig(
                useScheme: useScheme,
                schemes: new Dictionary<MonitorColorScheme, IDictionary<ConsoleLogLevel, ConsoleColor>>
                {
                    [MonitorColorScheme.DarkBackground] = new Dictionary<ConsoleLogLevel, ConsoleColor>
                    {
                        [ConsoleLogLevel.Trace] = ConsoleColor.DarkGray,
                        [ConsoleLogLevel.Debug] = ConsoleColor.DarkGray,
                        [ConsoleLogLevel.Info] = ConsoleColor.White,
                        [ConsoleLogLevel.Warn] = ConsoleColor.Yellow,
                        [ConsoleLogLevel.Error] = ConsoleColor.Red,
                        [ConsoleLogLevel.Alert] = ConsoleColor.Magenta,
                        [ConsoleLogLevel.Success] = ConsoleColor.DarkGreen
                    },
                    [MonitorColorScheme.LightBackground] = new Dictionary<ConsoleLogLevel, ConsoleColor>
                    {
                        [ConsoleLogLevel.Trace] = ConsoleColor.DarkGray,
                        [ConsoleLogLevel.Debug] = ConsoleColor.DarkGray,
                        [ConsoleLogLevel.Info] = ConsoleColor.Black,
                        [ConsoleLogLevel.Warn] = ConsoleColor.DarkYellow,
                        [ConsoleLogLevel.Error] = ConsoleColor.Red,
                        [ConsoleLogLevel.Alert] = ConsoleColor.DarkMagenta,
                        [ConsoleLogLevel.Success] = ConsoleColor.DarkGreen
                    }
                }
            );
        }


        /*********
        ** Private methods
        *********/
        /// <summary>
        /// Implementation of writing a line to the console, virtual to allow for other console implementations.
        /// </summary>
        /// <param name="message">The message to log.</param>
        /// <param name="foregroundColor">The foreground color to override the default with, if any.</param>
        /// <param name="backgroundColor">The background color to override the default with, if any.</param>
        protected virtual void WriteLineImpl(string message, ConsoleColor? foregroundColor, ConsoleColor? backgroundColor)
        {
            if (backgroundColor.HasValue)
                Console.BackgroundColor = backgroundColor.Value;
            if (foregroundColor.HasValue)
                Console.ForegroundColor = foregroundColor.Value;
            Console.WriteLine(message);
            Console.ResetColor();
        }

        /*********
        ** Private methods
        *********/
        /// <summary>Test whether the current console supports color formatting.</summary>
        private bool TestColorSupport()
        {
            try
            {
                Console.ForegroundColor = Console.ForegroundColor;
                return true;
            }
            catch (Exception)
            {
                return false; // Mono bug
            }
        }

        /// <summary>Get the color scheme to use for the current console.</summary>
        /// <param name="platform">The target platform.</param>
        /// <param name="colorConfig">The colors to use for text written to the SMAPI console.</param>
        private IDictionary<ConsoleLogLevel, ConsoleColor> GetConsoleColorScheme(Platform platform, ColorSchemeConfig colorConfig)
        {
            // get color scheme ID
            MonitorColorScheme schemeID = colorConfig.UseScheme;
            if (schemeID == MonitorColorScheme.AutoDetect)
            {
                schemeID = platform == Platform.Mac
                    ? MonitorColorScheme.LightBackground // macOS doesn't provide console background color info, but it's usually white.
                    : ColorfulConsoleWriter.IsDark(Console.BackgroundColor) ? MonitorColorScheme.DarkBackground : MonitorColorScheme.LightBackground;
            }

            // get colors for scheme
            return colorConfig.Schemes.TryGetValue(schemeID, out IDictionary<ConsoleLogLevel, ConsoleColor>? scheme)
                ? scheme
                : throw new NotSupportedException($"Unknown color scheme '{schemeID}'.");
        }

        /// <summary>Get whether a console color should be considered dark, which is subjectively defined as 'white looks better than black on this text'.</summary>
        /// <param name="color">The color to check.</param>
        private static bool IsDark(ConsoleColor color)
        {
            switch (color)
            {
                case ConsoleColor.Black:
                case ConsoleColor.Blue:
                case ConsoleColor.DarkBlue:
                case ConsoleColor.DarkMagenta: // PowerShell
                case ConsoleColor.DarkRed:
                case ConsoleColor.Red:
                    return true;

                default:
                    return false;
            }
        }
    }
}