package core

import (
	"errors"
	"os"
	"syscall"
)

func AcquireLock(lockPath string) (func() error, error) {
	f, err := os.OpenFile(lockPath, os.O_CREATE|os.O_RDWR, 0644)
	if err != nil {
		return nil, err
	}

	if err := syscall.Flock(int(f.Fd()), syscall.LOCK_EX|syscall.LOCK_NB); err != nil {
		_ = f.Close()
		return nil, errors.New("another compose-sync is already running")
	}

	return func() error {
		if err := syscall.Flock(int(f.Fd()), syscall.LOCK_UN); err != nil {
			f.Close()
			return err
		}
		if err := f.Close(); err != nil {
			return err
		}
		return os.Remove(lockPath)
	}, nil
}