//go:build linux || darwin

package subprocess

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

type unixProcessTree struct {
	processGroupID int
}

func newOwnedProcessTree() (ownedProcessTree, error) {
	return &unixProcessTree{}, nil
}

func (tree *unixProcessTree) Start(cmd *exec.Cmd) error {
	cmd.SysProcAttr = &syscall.SysProcAttr{Setpgid: true}
	if err := cmd.Start(); err != nil {
		return err
	}
	tree.processGroupID = cmd.Process.Pid
	return nil
}

func (tree *unixProcessTree) TerminateGracefully() error {
	return tree.signal(syscall.SIGTERM)
}

func (tree *unixProcessTree) TerminateForcefully() error {
	return tree.signal(syscall.SIGKILL)
}

func (tree *unixProcessTree) Close() error {
	return nil
}

func (tree *unixProcessTree) signal(signal syscall.Signal) error {
	if tree.processGroupID <= 0 {
		return nil
	}
	err := syscall.Kill(-tree.processGroupID, signal)
	if errors.Is(err, syscall.ESRCH) || errors.Is(err, os.ErrProcessDone) {
		return nil
	}
	return err
}