/*
 * Copyright (c) 2025 Eric Faurot <eric@faurot.net>
 *
 * Permission to use, copy, modify, and distribute this software for any
 * purpose with or without fee is hereby granted, provided that the above
 * copyright notice and this permission notice appear in all copies.
 *
 * THE SOFTWARE IS PROVIDED "AS IS" AND THE AUTHOR DISCLAIMS ALL WARRANTIES
 * WITH REGARD TO THIS SOFTWARE INCLUDING ALL IMPLIED WARRANTIES OF
 * MERCHANTABILITY AND FITNESS. IN NO EVENT SHALL THE AUTHOR BE LIABLE FOR
 * ANY SPECIAL, DIRECT, INDIRECT, OR CONSEQUENTIAL DAMAGES OR ANY DAMAGES
 * WHATSOEVER RESULTING FROM LOSS OF USE, DATA OR PROFITS, WHETHER IN AN
 * ACTION OF CONTRACT, NEGLIGENCE OR OTHER TORTIOUS ACTION, ARISING OUT OF
 * OR IN CONNECTION WITH THE USE OR PERFORMANCE OF THIS SOFTWARE.
 */

package storage

import (
	"io"
	"os"
	"path/filepath"
)

func WriteToFileAtomic(filename string, rd io.Reader) (int64, error) {
	return WriteToFileAtomicTempDir(filename, rd, filepath.Dir(filename))
}

func WriteToFileAtomicTempDir(filename string, rd io.Reader, tmpdir string) (int64, error) {
	f, err := os.CreateTemp(tmpdir, "tmp.")
	if err != nil {
		return 0, err
	}

	var nbytes int64
	if nbytes, err = io.Copy(f, rd); err != nil {
		f.Close()
		os.Remove(f.Name())
		return 0, err
	}

	if err = f.Close(); err != nil {
		os.Remove(f.Name())
		return 0, err
	}

	err = os.Rename(f.Name(), filename)
	if err != nil {
		os.Remove(f.Name())
		return 0, err
	}

	return nbytes, nil
}
