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

clip/totp.go

@@ -0,0 +1,65 @@
+package clip
+
+import (
+	"errors"
+	"strings"
+	"time"
+
+	"github.com/pquerna/otp"
+	"github.com/pquerna/otp/totp"
+)
+
+// GenTOTP generates a TOTP token from a secret (supports standard and Steam TOTP).
+func GenTOTP(secret string, time time.Time, forSteam bool) (string, error) {
+	var totpToken string
+	var err error
+
+	if forSteam {
+		totpToken, err = totp.GenerateCodeCustom(secret, time, totp.ValidateOpts{Period: 30, Digits: 5, Encoder: otp.EncoderSteam})
+	} else {
+		totpToken, err = totp.GenerateCode(secret, time)
+	}
+
+	if err != nil {
+		return "", errors.New("unable to generate TOTP token: " + err.Error())
+	}
+
+	return totpToken, nil
+}
+
+// TOTPCopier is meant to be run as a goroutine to keep
+// the clipboard up-to-date with the latest TOTP token.
+// Set oneTime to -1 for a one-time (non-continuous) TOTP copy.
+func TOTPCopier(secret string, oneTime int, errorChan chan<- error, done <-chan bool) {
+	var forSteam bool
+	if strings.HasPrefix(secret, "steam@") {
+		secret = secret[6:]
+		forSteam = true
+	}
+
+	for {
+		currentTime := time.Now()
+		token, err := GenTOTP(secret, currentTime, forSteam)
+		if err != nil {
+			errorChan <- err
+		}
+		err = CopyString(true, token)
+		if err != nil {
+			errorChan <- err
+		}
+		if oneTime != -1 {
+			errorChan <- nil
+			time.Sleep(time.Duration(30-(currentTime.Second()%30)) * time.Second)
+		} else {
+			return
+		}
+
+		// exit after sleep if indicated (will not update clipboard again)
+		select {
+		case <-done:
+			errorChan <- nil
+			return
+		default:
+		}
+	}
+}