Add package to control and monitor screensaver

screensaver/screensaver.go

@@ -0,0 +1,61 @@
+package screensaver
+
+import (
+	"os/exec"
+	"regexp"
+	"strings"
+)
+
+
+func IsActive() (bool, error) {
+	cmd := exec.Command("qdbus",
+		"org.kde.screensaver",
+		"/ScreenSaver",
+		"org.freedesktop.ScreenSaver.GetActive",
+	)
+	outputBytes, err := cmd.CombinedOutput()
+	if err != nil {
+		return false, err
+	}
+	output := string(outputBytes)
+
+	if strings.HasPrefix(output, "true") {
+		return true, nil
+	}
+	return false, nil
+}
+
+func Activate() error {
+	cmd := exec.Command("xset",
+		"dpms",
+		"force",
+		"suspend",
+	)
+	return cmd.Run()
+}
+
+func ShouldBeActive() (bool, error) {
+	cmd := exec.Command("xset", "q")
+	outputBytes, err := cmd.CombinedOutput()
+	if err != nil {
+		return false, err
+	}
+	return arbitrateXsetOutput(string(outputBytes)), nil
+}
+
+func arbitrateXsetOutput(output string) bool {
+	if ! strings.Contains(output, "Monitor") {
+		// after booting xset q is missing this line
+		// lacking better ideas assume display is on
+		return true
+	}
+
+	re := regexp.MustCompile(`Monitor is (\w+)`)
+	matches := re.FindStringSubmatch(output)
+	if len(matches) >= 2 {
+		if matches[1] == "On" {
+			return true
+		}
+	}
+	return false
+}