main.go

// blink1-shutdown: a dead-man's switch driven by a blink(1) USB LED.
// See AGENTS.md for the behavior specification.
package main

import (
	"bufio"
	"flag"
	"fmt"
	"net"
	"os"
	"strings"
	"time"

	"github.com/functionally/blink1-shutdown/internal/config"
	"github.com/functionally/blink1-shutdown/internal/daemon"
)

func usage() {
	fmt.Fprintf(os.Stderr, `usage: %s <command> [flags]

commands:
  daemon    run the monitoring daemon (systemd service)
  arm       arm the switch (LED red; USB removal triggers shutdown)
  disarm    disarm the switch (LED blue; USB removal ignored)
  status    show the current state

flags (all commands):
  -config path   config/state YAML file (default %s)
daemon flags:
  -dry-run       log instead of powering off; don't broadcast wall messages
`, os.Args[0], config.DefaultPath)
	os.Exit(2)
}

func main() {
	if len(os.Args) < 2 {
		usage()
	}
	cmd, args := os.Args[1], os.Args[2:]

	fs := flag.NewFlagSet(cmd, flag.ExitOnError)
	cfgPath := fs.String("config", config.DefaultPath, "config/state YAML file")
	dryRun := fs.Bool("dry-run", false, "log instead of powering off")
	_ = fs.Parse(args)

	switch cmd {
	case "daemon":
		if err := daemon.Run(*cfgPath, *dryRun); err != nil {
			fmt.Fprintln(os.Stderr, "blink1-shutdown:", err)
			os.Exit(1)
		}
	case "arm", "disarm", "status":
		if err := client(*cfgPath, cmd); err != nil {
			fmt.Fprintln(os.Stderr, "blink1-shutdown:", err)
			os.Exit(1)
		}
	default:
		usage()
	}
}

func client(cfgPath, cmd string) error {
	cfg, _, err := config.Load(cfgPath)
	if err != nil {
		return err
	}
	conn, err := net.DialTimeout("unix", cfg.Socket, 5*time.Second)
	if err != nil {
		return fmt.Errorf("is the daemon running? %w", err)
	}
	defer conn.Close()
	_ = conn.SetDeadline(time.Now().Add(5 * time.Second))
	if _, err := fmt.Fprintln(conn, cmd); err != nil {
		return err
	}
	reply, err := bufio.NewReader(conn).ReadString('\n')
	if err != nil {
		return err
	}
	reply = strings.TrimSpace(reply)
	fmt.Println(reply)
	if strings.HasPrefix(reply, "error:") {
		os.Exit(1)
	}
	return nil
}