Better modularize clipboard code (add "clip" package; break up TOTP code

clip/clipClearProcessGeneric.go

@@ -0,0 +1,51 @@
+//go:build (!android && !ios) || termux
+
+package clip
+
+import (
+	"errors"
+	"strings"
+	"time"
+
+	"github.com/rwinkhart/go-boilerplate/back"
+)
+
+// clipClearProcess clears the clipboard after 30 seconds if the clipboard contents have not changed.
+// assignedContents can be omitted to clear the clipboard immediately and unconditionally.
+func clipClearProcess(assignedContents string) error {
+	cmdPaste, cmdClear := getClipCommands()
+
+	clearClipboard := func() error {
+		err := cmdClear.Run()
+		if err != nil {
+			return errors.New("unable to clear clipboard")
+		}
+		back.Exit(0)
+		return nil
+	}
+
+	// if assignedContents is empty, clear the clipboard immediately and unconditionally
+	if assignedContents == "" {
+		err := clearClipboard()
+		if err != nil {
+			return err
+		}
+		return nil
+	}
+
+	// wait 30 seconds before checking clipboard contents
+	time.Sleep(30 * time.Second)
+
+	newContents, err := cmdPaste.Output()
+	if err != nil {
+		return errors.New("unable to read clipboard contents")
+	}
+
+	if assignedContents == strings.TrimRight(string(newContents), "\r\n") {
+		err := clearClipboard()
+		if err != nil {
+			return err
+		}
+	}
+	return nil
+}