generalise console color logic for reuse (#495)

4 files changed, 181 insertions, 0 deletions

diff --git a/src/SMAPI.Internal/ConsoleWriting/ColorfulConsoleWriter.cs b/src/SMAPI.Internal/ConsoleWriting/ColorfulConsoleWriter.cs
new file mode 100644
index 00000000..5f8fe271
--- /dev/null
+++ b/src/SMAPI.Internal/ConsoleWriting/ColorfulConsoleWriter.cs
@@ -0,0 +1,136 @@
+using System;
+using System.Collections.Generic;
+
+namespace StardewModdingAPI.Internal.ConsoleWriting
+{
+    /// <summary>Provides a wrapper for writing color-coded text to the console.</summary>
+    internal class ColorfulConsoleWriter
+    {
+        /*********
+        ** Properties
+        *********/
+        /// <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>
+        private readonly bool SupportsColor;
+
+
+        /*********
+        ** Public methods
+        *********/
+        /// <summary>Construct an instance.</summary>
+        /// <param name="platform">The target platform.</param>
+        /// <param name="colorScheme">The console color scheme to use.</param>
+        public ColorfulConsoleWriter(Platform platform, MonitorColorScheme colorScheme)
+        {
+            this.SupportsColor = this.TestColorSupport();
+            this.Colors = this.GetConsoleColorScheme(platform, colorScheme);
+        }
+
+        /// <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)
+                {
+                    Console.BackgroundColor = ConsoleColor.Red;
+                    Console.ForegroundColor = ConsoleColor.White;
+                    Console.WriteLine(message);
+                    Console.ResetColor();
+                }
+                else
+                {
+                    Console.ForegroundColor = this.Colors[level];
+                    Console.WriteLine(message);
+                    Console.ResetColor();
+                }
+            }
+            else
+                Console.WriteLine(message);
+        }
+
+
+        /*********
+        ** 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="colorScheme">The console color scheme to use.</param>
+        private IDictionary<ConsoleLogLevel, ConsoleColor> GetConsoleColorScheme(Platform platform, MonitorColorScheme colorScheme)
+        {
+            // auto detect color scheme
+            if (colorScheme == MonitorColorScheme.AutoDetect)
+            {
+                colorScheme = 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
+            switch (colorScheme)
+            {
+                case MonitorColorScheme.DarkBackground:
+                    return 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
+                    };
+
+                case MonitorColorScheme.LightBackground:
+                    return 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
+                    };
+
+                default:
+                    throw new NotSupportedException($"Unknown color scheme '{colorScheme}'.");
+            }
+        }
+
+        /// <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;
+            }
+        }
+    }
+}
diff --git a/src/SMAPI.Internal/ConsoleWriting/LogLevel.cs b/src/SMAPI.Internal/ConsoleWriting/LogLevel.cs
new file mode 100644
index 00000000..85e69f51
--- /dev/null
+++ b/src/SMAPI.Internal/ConsoleWriting/LogLevel.cs
@@ -0,0 +1,27 @@
+namespace StardewModdingAPI.Internal.ConsoleWriting
+{
+    /// <summary>The log severity levels.</summary>
+    internal enum ConsoleLogLevel
+    {
+        /// <summary>Tracing info intended for developers.</summary>
+        Trace,
+
+        /// <summary>Troubleshooting info that may be relevant to the player.</summary>
+        Debug,
+
+        /// <summary>Info relevant to the player. This should be used judiciously.</summary>
+        Info,
+
+        /// <summary>An issue the player should be aware of. This should be used rarely.</summary>
+        Warn,
+
+        /// <summary>A message indicating something went wrong.</summary>
+        Error,
+
+        /// <summary>Important information to highlight for the player when player action is needed (e.g. new version available). This should be used rarely to avoid alert fatigue.</summary>
+        Alert,
+
+        /// <summary>A critical issue that generally signals an immediate end to the application.</summary>
+        Critical
+    }
+}
diff --git a/src/SMAPI.Internal/ConsoleWriting/MonitorColorScheme.cs b/src/SMAPI.Internal/ConsoleWriting/MonitorColorScheme.cs
new file mode 100644
index 00000000..bccb56d7
--- /dev/null
+++ b/src/SMAPI.Internal/ConsoleWriting/MonitorColorScheme.cs
@@ -0,0 +1,15 @@
+namespace StardewModdingAPI.Internal.ConsoleWriting
+{
+    /// <summary>A monitor color scheme to use.</summary>
+    internal enum MonitorColorScheme
+    {
+        /// <summary>Choose a color scheme automatically.</summary>
+        AutoDetect,
+
+        /// <summary>Use lighter text colors that look better on a black or dark background.</summary>
+        DarkBackground,
+
+        /// <summary>Use darker text colors that look better on a white or light background.</summary>
+        LightBackground
+    }
+}
diff --git a/src/SMAPI.Internal/SMAPI.Internal.projitems b/src/SMAPI.Internal/SMAPI.Internal.projitems
index 764cb12e..dadae4b0 100644
--- a/src/SMAPI.Internal/SMAPI.Internal.projitems
+++ b/src/SMAPI.Internal/SMAPI.Internal.projitems
@@ -9,9 +9,12 @@
     <Import_RootNamespace>SMAPI.Internal</Import_RootNamespace>
   </PropertyGroup>
   <ItemGroup>
+    <Compile Include="$(MSBuildThisFileDirectory)ConsoleWriting\ColorfulConsoleWriter.cs" />
     <Compile Include="$(MSBuildThisFileDirectory)EnvironmentUtility.cs" />
+    <Compile Include="$(MSBuildThisFileDirectory)ConsoleWriting\LogLevel.cs" />
     <Compile Include="$(MSBuildThisFileDirectory)Models\ModInfoModel.cs" />
     <Compile Include="$(MSBuildThisFileDirectory)Models\ModSeachModel.cs" />
+    <Compile Include="$(MSBuildThisFileDirectory)ConsoleWriting\MonitorColorScheme.cs" />
     <Compile Include="$(MSBuildThisFileDirectory)Platform.cs" />
     <Compile Include="$(MSBuildThisFileDirectory)SemanticVersionImpl.cs" />
   </ItemGroup>