//go:build !windows

package process

import (
	"errors"
	"os"
	"os/exec"
	"syscall"

	"golang.org/x/sys/unix"
)

type scope struct {
	cmd        *exec.Cmd
	terminal   int
	foreground int
}

func newScope(cmd *exec.Cmd) (*scope, error) {
	if cmd.SysProcAttr == nil {
		cmd.SysProcAttr = &syscall.SysProcAttr{}
	}
	cmd.SysProcAttr.Setpgid = true
	cmd.SysProcAttr.Pgid = 0
	s := &scope{cmd: cmd, terminal: -1}
	// A CLI tool that inherits our foreground terminal must be allowed to read
	// it (e.g. sudo). Web/TUI tools use null stdin and do not change the terminal.
	if input, ok := cmd.Stdin.(*os.File); ok {
		fd := int(input.Fd())
		if group, err := unix.IoctlGetInt(fd, unix.TIOCGPGRP); err == nil && group == unix.Getpgrp() {
			s.terminal, s.foreground = fd, group
			cmd.SysProcAttr.Foreground = true
			cmd.SysProcAttr.Ctty = fd
		}
	}
	return s, nil
}

func (s *scope) attach() error { return nil }
func (s *scope) resume() error { return nil }

func (s *scope) kill() error {
	if s.cmd.Process == nil {
		return nil
	}
	err := unix.Kill(-s.cmd.Process.Pid, unix.SIGKILL)
	if errors.Is(err, unix.ESRCH) {
		return nil
	}
	return err
}

func (s *scope) close() {
	if s.terminal >= 0 {
		_ = unix.IoctlSetPointerInt(s.terminal, unix.TIOCSPGRP, s.foreground)
	}
}