package file

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

	"gitlab.com/tozd/go/errors"
)

func Exists(path string) bool {
	stat, err := os.Stat(path)
	if err != nil && !errors.Is(err, fs.ErrNotExist) {
		panic("could not stat path " + path + ": " + err.Error())
	}

	return stat != nil
}

func Copy(src, dest string) error {
	stat, err := os.Stat(src)
	if err != nil {
		return errors.WithMessage(err, "could not stat source file")
	}

	sf, err := os.Open(src)
	if err != nil {
		return errors.WithMessage(err, "could not open source file for reading")
	}
	defer sf.Close()

	df, err := os.OpenFile(dest, os.O_RDWR|os.O_CREATE, stat.Mode())
	if err != nil {
		return errors.WithMessage(err, "could not open destination file for writing")
	}
	defer df.Close()

	if _, err := io.Copy(df, sf); err != nil {
		return errors.WithMessage(err, "could not copy")
	}

	err = df.Sync()
	if err != nil {
		return errors.WithMessage(err, "could not call fsync")
	}

	return nil
}

func CleanDir(dir string) (err error) {
	files, err := os.ReadDir(dir)
	if err != nil {
		return errors.WithMessage(err, "could not read directory")
	}

	for _, file := range files {
		err = errors.Join(err, os.Remove(filepath.Join(dir, file.Name())))
	}

	return err
}