Start work on porting themes kitten to Go

tools/cmd/themes/main.go

@@ -0,0 +1,62 @@
+// License: GPLv3 Copyright: 2023, Kovid Goyal, <kovid at kovidgoyal.net>
+
+package themes
+
+import (
+	"fmt"
+	"strings"
+	"time"
+
+	"kitty/tools/cli"
+	"kitty/tools/themes"
+	"kitty/tools/utils"
+)
+
+var _ = fmt.Print
+
+func complete_themes(completions *cli.Completions, word string, arg_num int) {
+	themes.CompleteThemes(completions, word, arg_num)
+}
+
+func non_interactive(opts *Options, theme_name string) (rc int, err error) {
+	themes, closer, err := themes.LoadThemes(time.Duration(opts.CacheAge * float64(time.Hour*24)))
+	if err != nil {
+		return 1, err
+	}
+	defer closer.Close()
+	theme := themes.ThemeByName(theme_name)
+	if theme == nil {
+		theme_name = strings.ReplaceAll(theme_name, `\`, ``)
+		theme = themes.ThemeByName(theme_name)
+		if theme == nil {
+			return 1, fmt.Errorf("No theme named: %s", theme_name)
+		}
+	}
+	if opts.DumpTheme {
+		code, err := theme.Code()
+		if err != nil {
+			return 1, err
+		}
+		fmt.Println(code)
+	} else {
+		err = theme.SaveInConf(utils.ConfigDir(), opts.ReloadIn, opts.ConfigFileName)
+		if err != nil {
+			return 1, err
+		}
+	}
+	return
+}
+
+func main(_ *cli.Command, opts *Options, args []string) (rc int, err error) {
+	if len(args) > 1 {
+		args = []string{strings.Join(args, ` `)}
+	}
+	if len(args) == 1 {
+		return non_interactive(opts, args[0])
+	}
+	return
+}
+
+func EntryPoint(parent *cli.Command) {
+	create_cmd(parent, main)
+}