package main

import (
	"errors"
	"fmt"
	"os"
	"syscall"

	"github.com/alexflint/go-arg"
	common "source.heropunch.io/tomo/go-coreutils"
)

var BadSignalName = errors.New("bad signal name")

func selectSignal(signame string) (syscall.Signal, error) {
	switch signame {
	case "TERM":
		return syscall.SIGTERM, nil
	case "KILL":
		return syscall.SIGKILL, nil
	case "PIPE":
		return syscall.SIGPIPE, nil
	case "INT":
		return syscall.SIGINT, nil
	case "QUIT":
		return syscall.SIGQUIT, nil
	case "SEGV":
		return syscall.SIGSEGV, nil
	case "STOP":
		return syscall.SIGSTOP, nil
	case "CONT":
		return syscall.SIGCONT, nil
	case "0":
		return 0, nil
	case "ABRT":
		return syscall.SIGABRT, nil
	case "ALRM":
		return syscall.SIGALRM, nil
	case "BUS":
		return syscall.SIGBUS, nil
	case "CHLD":
		return syscall.SIGCHLD, nil
	case "FPE":
		return syscall.SIGFPE, nil
	case "HUP":
		return syscall.SIGHUP, nil
	case "ILL":
		return syscall.SIGILL, nil
	case "TSTP":
		return syscall.SIGTSTP, nil
	case "TTIN":
		return syscall.SIGTTIN, nil
	case "TTOU":
		return syscall.SIGTTOU, nil
	case "USR1":
		return syscall.SIGUSR1, nil
	case "USR2":
		return syscall.SIGUSR2, nil
	case "URG":
		return syscall.SIGURG, nil
	default:
		return -1, BadSignalName
	}
}

func main() {
	var args struct {
		SignalName string `arg:"-s"`
		List       int    `arg:"-l"`
		PIDs       []int  `arg:"positional"`
	}

	args.SignalName = "TERM"
	args.List = -1

	p := arg.MustParse(&args)
	if len(os.Args) == 1 {
		p.WriteUsage(os.Stderr)
		os.Exit(1)
	}

	sig, err := selectSignal(args.SignalName)
	common.ExitIfError(err)

	exitCode := 0
	if len(args.PIDs) > 0 {
		for _, pid := range args.PIDs {
			process, err := os.FindProcess(pid)
			if err != nil {
				common.PrintToStderr(fmt.Sprintf("error finding process %v: %v", pid, err))
				exitCode = 1
				continue
			}
			err = process.Signal(sig)
			if err != nil {
				common.PrintToStderr(fmt.Sprintf("kill %v: %v", pid, err))
				exitCode = 1
			}
		}
	}
	os.Exit(exitCode)
}