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

clip/copyUNIX.go

@@ -0,0 +1,44 @@
+//go:build !windows && !darwin && !android && !ios && !termux && !wsl
+
+package clip
+
+import (
+	"errors"
+	"os"
+	"os/exec"
+
+	"github.com/rwinkhart/go-boilerplate/back"
+)
+
+// CopyString copies a string to the clipboard.
+func CopyString(continuous bool, copySubject string) error {
+	// determine whether to use wl-copy (Wayland) or xclip (X11)
+	var envSet, isWayland bool // track whether environment variables are set
+	var cmdCopy *exec.Cmd
+	if _, envSet = os.LookupEnv("WAYLAND_DISPLAY"); envSet {
+		cmdCopy = exec.Command("wl-copy", "-t", "text/plain")
+		isWayland = true
+	} else if _, envSet = os.LookupEnv("DISPLAY"); envSet {
+		cmdCopy = exec.Command("xclip", "-sel", "c", "-t", "text/plain")
+	} else {
+		return errors.New("clipboard platform could not be determined")
+	}
+
+	_ = back.WriteToStdin(cmdCopy, copySubject)
+	err := cmdCopy.Run()
+	if err != nil {
+		return errors.New("unable to copy to clipboard: " + err.Error())
+	}
+	if !continuous {
+		LaunchClipClearProcess(copySubject, isWayland)
+	}
+	return nil
+}
+
+// getClipCommands returns the commands for pasting and clearing the clipboard contents.
+func getClipCommands() (*exec.Cmd, *exec.Cmd) {
+	if os.Args[2] == "true" { // wayland
+		return exec.Command("wl-paste"), exec.Command("wl-copy", "-c")
+	}
+	return exec.Command("xclip", "-o", "-sel", "c"), exec.Command("xclip", "-i", "/dev/null", "-sel", "c")
+}