package util

import (
	"context"
	"os/exec"
	"syscall"
	"time"
)

const killWaitDelay = time.Second

// KillableCommand builds a command whose cancellation actually stops it, and is
// the single place that plumbing lives — every context-aware external command
// goes through here.
//
// yt-dlp, ffmpeg and ffprobe spawn helpers that inherit the output pipe, and
// both Wait and Output block reading it until every holder exits. So killing
// only the direct child does not end the call; the group signal does, with
// WaitDelay as the backstop for whatever survives it.
func KillableCommand(ctx context.Context, path string, args ...string) *exec.Cmd {
	cmd := exec.CommandContext(ctx, path, args...)
	cmd.SysProcAttr = &syscall.SysProcAttr{Setpgid: true}
	cmd.Cancel = func() error {
		return syscall.Kill(-cmd.Process.Pid, syscall.SIGKILL)
	}
	cmd.WaitDelay = killWaitDelay
	return cmd
}