Colourise Redirected Output

src/SeqCli/Cli/Commands/PrintCommand.cs

@@ -35,12 +35,13 @@ class PrintCommand : Command
         readonly InvalidDataHandlingFeature _invalidDataHandlingFeature;
 
         string _filter, _template = OutputFormatFeature.DefaultOutputTemplate;
-        bool _noColor;
+        bool _noColor, _forceColor;
 
         public PrintCommand(SeqCliOutputConfig outputConfig)
         {
             if (outputConfig == null) throw new ArgumentNullException(nameof(outputConfig));
             _noColor = outputConfig.DisableColor;
+            _forceColor = outputConfig.ForceColor;
 
             _fileInputFeature = Enable(new FileInputFeature("CLEF file to read", supportsWildcard: true));
 
@@ -55,17 +56,30 @@ public PrintCommand(SeqCliOutputConfig outputConfig)
             _invalidDataHandlingFeature = Enable<InvalidDataHandlingFeature>();
 
             Options.Add("no-color", "Don't colorize text output", v => _noColor = true);
+
+            Options.Add("force-color",
+                "Force redirected output to have ANSI color (unless `--no-color` is also specified)",
+                v => _forceColor = true);
         }
 
         protected override async Task<int> Run()
         {
+            var applyThemeToRedirectedOutput
+                = _noColor == false && _forceColor == true;
+
+            var theme
+                = _noColor                      ? ConsoleTheme.None
+                :  applyThemeToRedirectedOutput ? OutputFormatFeature.DefaultAnsiTheme
+                :                                 OutputFormatFeature.DefaultTheme;
+
             var outputConfiguration = new LoggerConfiguration()
                 .MinimumLevel.Is(LevelAlias.Minimum)
                 .Enrich.With<RedundantEventTypeRemovalEnricher>()
                 .Enrich.With<SurrogateLevelRemovalEnricher>()
                 .WriteTo.Console(
                     outputTemplate: _template,
-                    theme: _noColor ? ConsoleTheme.None : OutputFormatFeature.DefaultTheme);
+                    theme: theme,
+                    applyThemeToRedirectedOutput: applyThemeToRedirectedOutput);
 
             if (_filter != null)
                 outputConfiguration.Filter.ByIncludingOnly(_filter);

src/SeqCli/Cli/Features/OutputFormatFeature.cs

@@ -34,18 +34,25 @@ class OutputFormatFeature : CommandFeature
         public const string DefaultOutputTemplate =
             "[{Timestamp:o} {Level:u3}] {Message:lj} {Properties:j}{NewLine}{Exception}";
 
-        public static readonly ConsoleTheme DefaultTheme = SystemConsoleTheme.Literate;
+        public static readonly ConsoleTheme DefaultTheme     = SystemConsoleTheme.Literate;
+        public static readonly ConsoleTheme DefaultAnsiTheme = AnsiConsoleTheme.Code;
 
-        bool _json, _noColor;
+        bool _json, _noColor, _forceColor;
 
         public OutputFormatFeature(SeqCliOutputConfig outputConfig)
         {
             _noColor = outputConfig.DisableColor;
+            _forceColor = outputConfig.ForceColor;
         }
 
         public bool Json => _json;
 
-        ConsoleTheme Theme => _noColor ? ConsoleTheme.None : DefaultTheme;
+        bool ApplyThemeToRedirectedOutput => _noColor == false && _forceColor == true;
+
+        ConsoleTheme Theme
+            => _noColor                     ? ConsoleTheme.None
+            :  ApplyThemeToRedirectedOutput ? DefaultAnsiTheme
+            :                                 DefaultTheme;
 
         public override void Enable(OptionSet options)
         {
@@ -55,6 +62,10 @@ public override void Enable(OptionSet options)
                 v => _json = true);
 
             options.Add("no-color", "Don't colorize text output", v => _noColor = true);
+
+            options.Add("force-color",
+                "Force redirected output to have ANSI color (unless `--no-color` is also specified)",
+                v => _forceColor = true);
         }
 
         public Logger CreateOutputLogger()
@@ -72,7 +83,8 @@ public Logger CreateOutputLogger()
                 outputConfiguration.Enrich.With<SurrogateLevelRemovalEnricher>();
                 outputConfiguration.WriteTo.Console(
                     outputTemplate: DefaultOutputTemplate,
-                    theme: Theme);
+                    theme: Theme,
+                    applyThemeToRedirectedOutput: ApplyThemeToRedirectedOutput);
             }
 
             return outputConfiguration.CreateLogger();
@@ -115,7 +127,8 @@ public void WriteEntity(Entity entity)
                     .Enrich.With<StripStructureTypeEnricher>()
                     .WriteTo.Console(
                         outputTemplate: "{@Message:j}{NewLine}",
-                        theme: Theme)
+                        theme: Theme,
+                        applyThemeToRedirectedOutput: ApplyThemeToRedirectedOutput)
                     .CreateLogger();
                 writer.Information("{@Entity}", jo);
             }

src/SeqCli/Config/SeqCliOutputConfig.cs

@@ -17,5 +17,6 @@ namespace SeqCli.Config
     class SeqCliOutputConfig
     {
         public bool DisableColor { get; set; }
+        public bool ForceColor   { get; set; }
     }
 }