Save per-terminal-mode theme settings

At this point, termshark doesn't insist that a theme has to support
every typical terminal color mode - 16-colors, 256-colors,
truecolor. Most of the current themes are for 256-colors, and will also
work in truecolor mode. If the user has theme dracula set in 256-colors
mode, then runs termshark in a cut-down terminal on the same
machine (e.g. an xterm with 16 colors), then the theme won't
load. Rather than having that silently fail, I'm now saving a theme
setting per terminal mode, under toml keys theme-16, theme-256 and
theme-truecolor. When the theme is set, a message is displayed to make
it clear the theme is set for this color mode only. It's still not
completely obvious though - if the user set a theme in one terminal
emulator, the user might still wonder why it doesn't load up in the
cut-down terminal emulator. I'm not displaying a message - I don't want
to make the user click it away. Maybe it would help to have a more
obvious message buffer for short messages of interest to the user that
will disappear on their own...

cmd/termshark/termshark.go

@@ -1022,15 +1022,21 @@ Loop:
 			// Need to do that here because the app won't know how many colors the screen
 			// has (and therefore which variant of the theme to load) until the screen is
 			// activated.
-			themeName := termshark.ConfString("main.theme", "default")
-			err = theme.Load(themeName, app)
-			if err != nil {
-				log.Warnf("Theme %s could not be loaded: %v", themeName, err)
-				if themeName != "default" {
-					err = theme.Load("default", app)
-					if err != nil {
-						log.Warnf("Theme %s could not be loaded: %v", themeName, err)
-					}
+			mode := theme.Mode(app.GetColorMode()).String() // more concise
+			themeName := termshark.ConfString(fmt.Sprintf("main.theme-%s", mode), "default")
+			loaded := false
+			if themeName != "" {
+				err = theme.Load(themeName, app)
+				if err != nil {
+					log.Warnf("Theme %s could not be loaded: %v", themeName, err)
+				} else {
+					loaded = true
+				}
+			}
+			if !loaded && themeName != "default" {
+				err = theme.Load("default", app)
+				if err != nil {
+					log.Warnf("Theme %s could not be loaded: %v", themeName, err)
 				}
 			}
 

theme/utils.go

@@ -64,6 +64,27 @@ func MakeColorSafe(s string, l Layer) (gowid.Color, error) {
 	return gowid.MakeColorSafe(s)
 }
 
+type Mode gowid.ColorMode
+
+func (m Mode) String() string {
+	switch gowid.ColorMode(m) {
+	case gowid.Mode256Colors:
+		return "256"
+	case gowid.Mode88Colors:
+		return "88"
+	case gowid.Mode16Colors:
+		return "16"
+	case gowid.Mode8Colors:
+		return "8"
+	case gowid.ModeMonochrome:
+		return "mono"
+	case gowid.Mode24BitColors:
+		return "truecolor"
+	default:
+		return "unknown"
+	}
+}
+
 // Load will set the package-level theme object to a viper object representing the
 // toml file either (a) read from disk, or failing that (b) built-in to termshark.
 // Disk themes are prefered and take precedence.
@@ -81,21 +102,15 @@ func Load(name string, app gowid.IApp) error {
 	stdConf := configdir.New("", "termshark")
 	dirs := stdConf.QueryFolders(configdir.Global)
 
-	var mode string
-	switch app.GetColorMode() {
-	case gowid.Mode24BitColors:
-		mode = "truecolor"
-	case gowid.Mode256Colors:
-		mode = "256"
-	default:
-		mode = "16"
-	}
+	mode := Mode(app.GetColorMode()).String()
+
+	log.Infof("Loading theme %s in terminal mode %v", name, app.GetColorMode())
 
 	// If there's not a truecolor theme, we assume the user wants the best alternative to be loaded,
 	// and if a terminal has truecolor support, it'll surely have 256-color support.
 	modes := []string{mode}
 	if mode == "truecolor" {
-		modes = append(modes, "256")
+		modes = append(modes, Mode(gowid.Mode256Colors).String())
 	}
 
 	for _, m := range modes {

ui/lastline.go

@@ -542,9 +542,11 @@ func (d themeCommand) Run(app gowid.IApp, args ...string) error {
 	if len(args) != 2 {
 		err = invalidThemeCommandErr
 	} else {
-		termshark.SetConf("main.theme", args[1])
+		mode := theme.Mode(app.GetColorMode()).String() // more concise
+		termshark.SetConf(fmt.Sprintf("main.theme-%s", mode), args[1])
 		theme.Load(args[1], app)
 		SetupColors()
+		OpenMessage(fmt.Sprintf("Set %s theme for terminal mode %v.", args[1], app.GetColorMode()), appView, app)
 	}
 
 	if err != nil {

ui/ui.go

@@ -1019,10 +1019,12 @@ func lastLineMode(app gowid.IApp) {
 		return nil
 	}))
 
-	MiniBuffer.Register("no-theme", minibufferFn(func(gowid.IApp, ...string) error {
-		termshark.DeleteConf("main.theme")
+	MiniBuffer.Register("no-theme", minibufferFn(func(app gowid.IApp, s ...string) error {
+		mode := theme.Mode(app.GetColorMode()).String() // more concise
+		termshark.DeleteConf(fmt.Sprintf("main.theme-%s", mode))
 		theme.Load("default", app)
 		SetupColors()
+		OpenMessage(fmt.Sprintf("Cleared theme for terminal mode %v.", app.GetColorMode()), appView, app)
 		return nil
 	}))