Validate colors from configuration file

cmd/command.go

@@ -100,5 +100,31 @@ func (c *Config) Validate() error {
 	if c.AccessToken == "" {
 		err = errors.New("access_token is not set")
 	}
+
+	if err = c.validateColors(); err != nil {
+		return err
+	}
+
+	return err
+}
+
+func (c *Config) validateColors() (err error) {
+	if len(c.Colors) > 0 {
+		for name, hsb := range c.Colors {
+			if len(hsb) != 3 {
+				return fmt.Errorf("color '%s' needs three values", name)
+			}
+			h, s, b := hsb[0], hsb[1], hsb[2]
+			if h < 0 || h > 360 {
+				return fmt.Errorf("color '%s' hue value must be between 0.0-360.0", name)
+			}
+			if s < 0 || b > 1 {
+				return fmt.Errorf("color '%s' saturation value must be between 0.0-1.0", name)
+			}
+			if b < 0 || b > 1 {
+				return fmt.Errorf("color '%s' brightness value must be between 0.0-1.0", name)
+			}
+		}
+	}
 	return err
 }