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// 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)
}
}
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