added implementation in GO lang

internal/app/config.go

@@ -0,0 +1,43 @@
+package app
+
+import (
+	"flag"
+	"os"
+)
+
+type Config struct {
+	WindowWidth  int
+	WindowHeight int
+	Fullscreen   bool
+}
+
+func ParseConfig() Config {
+	cfg := Config{
+		WindowWidth:  1280,
+		WindowHeight: 720,
+		Fullscreen:   envBool("KIDSKEYBOARD_FULLSCREEN"),
+	}
+
+	flag.IntVar(&cfg.WindowWidth, "width", cfg.WindowWidth, "window width")
+	flag.IntVar(&cfg.WindowHeight, "height", cfg.WindowHeight, "window height")
+	flag.BoolVar(&cfg.Fullscreen, "fullscreen", cfg.Fullscreen, "start in fullscreen mode")
+	flag.Bool("windowed", false, "force windowed mode")
+	flag.Parse()
+
+	if flag.Lookup("windowed") != nil {
+		if v := flag.Lookup("windowed").Value.String(); v == "true" {
+			cfg.Fullscreen = false
+		}
+	}
+
+	return cfg
+}
+
+func envBool(name string) bool {
+	switch os.Getenv(name) {
+	case "1", "true", "TRUE", "yes", "YES", "on", "ON":
+		return true
+	default:
+		return false
+	}
+}