Load the configured theme at startup

Termshark will now look in termshark.toml for a main.theme key. If set
to e.g. foobar, then termshark will attempt to load (1)
~/.config/termshark/themes/foobar.toml, and failing that (2) see if it
has a built-in theme called /themes/foobar.toml via its statik
filesystem. If it finds the toml, regardless of the contents, the theme
will be active and called foobar. Then when loading its color palette,
any config-file references to colors e.g. dark.progress-bar - will look
up a key dark.progress bar in the toml loaded from foobar.toml. If,
eventually, a value is found that can be parsed as a color, termshark
will use it for that UI element.

cmd/termshark/termshark.go

@@ -26,6 +26,7 @@ import (
 	"github.com/gcla/termshark/v2/pcap"
 	"github.com/gcla/termshark/v2/streams"
 	"github.com/gcla/termshark/v2/system"
+	"github.com/gcla/termshark/v2/theme"
 	"github.com/gcla/termshark/v2/tty"
 	"github.com/gcla/termshark/v2/ui"
 	"github.com/gcla/termshark/v2/widgets/filter"
@@ -675,6 +676,14 @@ func cmain() int {
 	ui.AutoScroll = termshark.ConfBool("main.auto-scroll", true)
 	ui.PacketColors = termshark.ConfBool("main.packet-colors", true)
 
+	themeName := termshark.ConfString("main.theme", "")
+	if themeName != "" {
+		err = theme.Load(themeName)
+		if err != nil {
+			log.Warnf("Theme %s could not be loaded: %v", themeName, err)
+		}
+	}
+
 	// Set them up here so they have access to any command-line flags that
 	// need to be passed to the tshark commands used
 	pdmlArgs := termshark.ConfStringSlice("main.pdml-args", []string{})

theme/utils.go

@@ -6,9 +6,17 @@
 package theme
 
 import (
+	"fmt"
+	"io"
+	"os"
+	"path/filepath"
+
 	"github.com/gcla/gowid"
-	"github.com/gcla/termshark/v2"
-	log "github.com/sirupsen/logrus"
+	"github.com/rakyll/statik/fs"
+	"github.com/shibukawa/configdir"
+	"github.com/spf13/viper"
+
+	_ "github.com/gcla/termshark/v2/assets/statik"
 )
 
 //======================================================================
@@ -20,39 +28,82 @@ const (
 	Background Layer = iota
 )
 
+var theme *viper.Viper
+
 // MakeColorSafe extends gowid's MakeColorSafe function, prefering to interpret
 // its string argument as a toml file config key lookup first; if this fails, then
 // fall back to gowid.MakeColorSafe, which will then read colors as urwid color names,
 // #-prefixed hex digits, grayscales, etc.
 func MakeColorSafe(s string, l Layer) (gowid.Color, error) {
 	loops := 10
 	cur := s
-	for {
-		next := termshark.ConfString(cur, "")
-		if next != "" {
-			cur = next
-		} else {
-			next := termshark.ConfStringSlice(cur, []string{})
-			if len(next) != 2 {
-				break
+	if theme != nil {
+		for {
+			next := theme.GetString(cur)
+			if next != "" {
+				cur = next
 			} else {
-				cur = next[l]
+				next := theme.GetStringSlice(cur)
+				if next == nil || len(next) != 2 {
+					break
+				} else {
+					cur = next[l]
+				}
+			}
+			loops -= 1
+			if loops == 0 {
+				break
 			}
-		}
-		loops -= 1
-		if loops == 0 {
-			break
 		}
 	}
 	col, err := gowid.MakeColorSafe(cur)
 	if err == nil {
 		return gowid.Color{IColor: col, Id: s}, nil
 	}
-	col, err = gowid.MakeColorSafe(s)
+	return gowid.MakeColorSafe(s)
+}
+
+// Clear resets the package-level theme object. Next time ui.SetupColors is called,
+// the theme-connected colors won't be found, and termshark will fall back to its
+// programmed default colors.
+func Clear() {
+	theme = nil
+}
+
+// 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.
+func Load(name string) error {
+	theme = viper.New()
+	theme.SetConfigType("toml")
+	stdConf := configdir.New("", "termshark")
+	dirs := stdConf.QueryFolders(configdir.Global)
+
+	// Prefer to load from disk
+	themeFileName := filepath.Join(dirs[0].Path, "themes", fmt.Sprintf("%s.toml", name))
+
+	var file io.ReadCloser
+	var err error
+
+	file, err = os.Open(themeFileName)
+	if err == nil {
+		defer file.Close()
+		return theme.ReadConfig(file)
+	}
+
+	// Fall back to built-in themes
+	statikFS, err := fs.New()
 	if err != nil {
-		log.Infof("Could not understand configured theme color '%s'", s)
+		return err
 	}
-	return col, err
+
+	file, err = statikFS.Open(filepath.Join("/themes", fmt.Sprintf("%s.toml", name)))
+	if err != nil {
+		return err
+	}
+	defer file.Close()
+
+	return theme.ReadConfig(file)
 }
 
 //======================================================================

ui/palette.go

@@ -9,8 +9,10 @@ import (
 	"fmt"
 
 	"github.com/gcla/gowid"
+	"github.com/gcla/termshark/v2"
 	"github.com/gcla/termshark/v2/theme"
 	"github.com/gcla/termshark/v2/theme/modeswap"
+	log "github.com/sirupsen/logrus"
 )
 
 //======================================================================
@@ -280,10 +282,19 @@ func lbg(key string, fb gowid.IColor) gowid.IColor {
 }
 
 func tomlCol(key string, layer theme.Layer, hue string, fb gowid.IColor) gowid.IColor {
-	col, err := theme.MakeColorSafe(fmt.Sprintf("themes.rules.%s.%s", hue, key), layer)
+	rule := fmt.Sprintf("%s.%s", hue, key)
+	col, err := theme.MakeColorSafe(rule, layer)
 	if err == nil {
 		return col
+	} else {
+		// Warn if the user has defined themes.rules.etcetc, but the resulting
+		// color can't be resolved. If no key is present, it means the user hasn't
+		// set up themes, so ignore.
+		if termshark.ConfString("main.theme", "") != "" {
+			log.Infof("Could not understand configured theme color '%s'", key)
+		}
 	}
+
 	return fb
 }