1 files changed, 92 insertions, 0 deletions
diff --git a/.config/waybar/modules/redshift.go b/.config/waybar/modules/redshift.go
new file mode 100644
index 0000000..43b623c
--- /dev/null
+++ b/.config/waybar/modules/redshift.go
@@ -0,0 +1,92 @@
+// usage:
+// go build -o waybar-redshift redshift.go
+package main
+
+import (
+	"encoding/json"
+	"fmt"
+	"os"
+	"os/exec"
+	"os/signal"
+	"strings"
+
+	. "syscall"
+)
+
+const (
+	ICON = ""
+)
+
+func main() {
+	var (
+		update = make(chan os.Signal, 1)
+		cancel = make(chan os.Signal, 1)
+	)
+	signal.Notify(update, SIGUSR1, SIGUSR2, SIGHUP)
+	signal.Notify(cancel, SIGTERM, SIGINT)
+
+	// could use golang.org/x/sys/unix.Prctl here
+	// but I want to avoid the dependency
+	if _, _, e := Syscall6(SYS_PRCTL,
+		uintptr(PR_SET_PDEATHSIG),
+		uintptr(SIGTERM),
+		0, 0, 0, 0); e != 0 {
+		os.Exit(1)
+	}
+	// if err := Prctl(PR_SET_PDEATHSIG,
+	// 		SIGTERM,
+	// 		0, 0, 0); err != nil {
+	// 	fmt.Fprintln(os.Stderr, err)
+	// 	os.Exit(1)
+	// }
+
+	lookup()
+	for {
+		select {
+		case sig := <-update:
+			switch sig {
+			case SIGUSR1:
+				// redshift off
+				printJson("day", "day", ICON)
+			case SIGUSR2:
+				// redshift on
+				printJson("night", "night", ICON)
+			case SIGHUP:
+				lookup()
+			}
+		case <-cancel:
+			fmt.Fprintln(os.Stderr, "bye")
+			os.Exit(0)
+		}
+	}
+}
+
+func printJson(class, tooltip, text string) {
+	_ = json.NewEncoder(os.Stdout).Encode(map[string]string{
+		"class":   class,
+		"tooltip": "redshift: " + tooltip,
+		"text":    text,
+	})
+}
+
+func lookup() {
+	b, err := exec.Command("redshift", "-p").Output()
+	if err != nil {
+		return
+	}
+	fds := strings.Fields(string(b))
+	for idx, f := range fds {
+		if f == "Period:" {
+			fds = fds[idx+1:]
+			break
+		}
+	}
+	switch fds[0] {
+	case "Night":
+		printJson("night", "night", ICON)
+	case "Transition":
+		printJson("night", "transition", ICON)
+	case "Day":
+		printJson("day", "day", ICON)
+	}
+}