package sync

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

// CopyFile copies the file at src to dest, creating any missing parent
// directories. After a successful write the destination mtime is set to
// srcModTime so that subsequent sync passes do not treat the file as changed.
func CopyFile(src, dest string, srcModTime time.Time) error {
	if err := os.MkdirAll(filepath.Dir(dest), 0o755); err != nil {
		return err
	}

	in, err := os.Open(src)
	if err != nil {
		return err
	}
	defer in.Close()

	out, err := os.Create(dest)
	if err != nil {
		return err
	}

	if _, err := io.Copy(out, in); err != nil {
		out.Close()
		return err
	}
	if err := out.Close(); err != nil {
		return err
	}

	return os.Chtimes(dest, srcModTime, srcModTime)
}