package main

import (
	"context"
	"fmt"
	"log"
	"os"
	"os/exec"
	"os/signal"
	"strings"
	"syscall"
)

func main() {
	ctx, cancel := context.WithCancel(context.TODO())

	cmdStr := strings.Join(os.Args[1:], "")

	cmd := exec.CommandContext(ctx, "bash", "-c", cmdStr)

	exitCh := make(chan int)
	go runJob(cmd, cancel, exitCh)

	var exitCode = 0
	select {
	case exitCode = <-exitCh:
		log.Println("Exit Code: ", exitCode)
	}

	// If pid is negative, but not -1, sig shall be sent to all processes (excluding an unspecified set of system processes)
	// whose process group ID is equal to the absolute value of pid, and for which the process has permission to send a signal.
	err := syscall.Kill(-cmd.Process.Pid, syscall.SIGKILL)
	if err != nil {
		fmt.Println("Warning sending SIGKILL to customer processes group, err: ", err.Error())
	}

	os.Exit(exitCode)
}

func runJob(cmd *exec.Cmd, cancel context.CancelFunc, exitCh chan<- int) {
	defer func() {
		if r := recover(); r != nil {
			// Recovered from panic. This is just a safe net.
			log.Println("Panic when running job! ", r)
		}
		cancel()
	}()

	cmd.SysProcAttr = &syscall.SysProcAttr{Setpgid: true}
	cmd.Stderr = os.Stderr
	cmd.Stdout = os.Stdout

	go signalDeamon(cmd)

	if err := cmd.Run(); err != nil {
		log.Println("Run cmd error:", err.Error())
	}

	success := cmd.ProcessState != nil && cmd.ProcessState.Success()
	defer func(ok bool) {
		var exitCode = 0
		w := cmd.ProcessState.Sys().(syscall.WaitStatus)
		if w.Exited() {
			exitCode = w.ExitStatus()
		} else if w.Signaled() {
			exitCode = int(w.Signal())
		} else {
			exitCode = 1
		}

		exitCh <- exitCode
	}(success)

}

func signalDeamon(cmd *exec.Cmd) {
	c := make(chan os.Signal, 1)
	signal.Notify(c, syscall.SIGHUP, syscall.SIGINT, syscall.SIGTERM)
	s := <-c

	_ = cmd.Process.Signal(s)
}

c := make(chan os.Signal, 1)
signal.Notify(c, syscall.SIGHUP, syscall.SIGINT, syscall.SIGTERM)
go func() { <- c }

	go runJob(cmd, cancel, exitCh)

	var exitCode = 0
	select {
	case exitCode = <-exitCh:
		log.Println("Exit Code: ", exitCode)
	}

exitCode := runJob(cmd, cancel)