notifier/stdout: Stdout notifier maximbaz#31

Make it easier to use in scripts by having a stdout notifier that can
be ingested via. a pipe.

main.go

@@ -22,15 +22,18 @@ func main() {
 
 	envVerbose := truthyValues[strings.ToLower(os.Getenv("YUBIKEY_TOUCH_DETECTOR_VERBOSE"))]
 	envLibnotify := truthyValues[strings.ToLower(os.Getenv("YUBIKEY_TOUCH_DETECTOR_LIBNOTIFY"))]
+	envStdout := truthyValues[strings.ToLower(os.Getenv("YUBIKEY_TOUCH_DETECTOR_STDOUT"))]
 
 	var version bool
 	var verbose bool
 	var libnotify bool
+	var stdout bool
 	var gpgPubringPath string
 
 	flag.BoolVar(&version, "version", false, "print version and exit")
 	flag.BoolVar(&verbose, "v", envVerbose, "print verbose output")
 	flag.BoolVar(&libnotify, "libnotify", envLibnotify, "show desktop notifications using libnotify")
+	flag.BoolVar(&stdout, "stdout", envStdout, "Output notifications to stdout")
 	flag.Parse()
 
 	if version {
@@ -63,6 +66,9 @@ func main() {
 	if libnotify {
 		go notifier.SetupLibnotifyNotifier(notifiers)
 	}
+	if stdout {
+		go notifier.SetupStdoutNotifier(notifiers)
+	}
 
 	requestGPGCheck := make(chan bool)
 	go detector.CheckGPGOnRequest(requestGPGCheck, notifiers)

notifier/stdout.go

@@ -0,0 +1,18 @@
+package notifier
+
+import (
+	"os"
+	"sync"
+)
+
+// SetupStdoutNotifier configures a notifier to log to stdout
+func SetupStdoutNotifier(notifiers *sync.Map) {
+	touch := make(chan Message, 10)
+	notifiers.Store("notifier/stdout", touch)
+
+	for {
+		value := <-touch
+		os.Stdout.WriteString(string(value))
+		os.Stdout.WriteString("\n")
+	}
+}