// Copyright IBM Corp. 2014, 2026
// SPDX-License-Identifier: BUSL-1.1

package configload

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

// copyDir copies the src directory contents into dst. Both directories
// should already exist.
func copyDir(dst, src string) error {
	src, err := filepath.EvalSymlinks(src)
	if err != nil {
		return err
	}

	walkFn := func(path string, info os.FileInfo, err error) error {
		if err != nil {
			return err
		}

		if path == src {
			return nil
		}

		// The "path" has the src prefixed to it. We need to join our
		// destination with the path without the src on it.
		dstPath := filepath.Join(dst, path[len(src):])

		// Call os.Stat on dstPath to obtain os.FileInfo since os.SameFile
		// requires FileInfo objects for comparison.
		dstInfo, err := os.Stat(dstPath)
		if err != nil {
			if !os.IsNotExist(err) {
				return err
			}
		} else if os.SameFile(info, dstInfo) {
			// The destination file exists and is the same as the source file;
			// skip copying.
			return nil
		}

		// If we have a directory, make that subdirectory, then continue
		// the walk.
		if info.IsDir() {
			if path == filepath.Join(src, dst) {
				// dst is in src; don't walk it.
				return nil
			}

			if err := os.MkdirAll(dstPath, 0755); err != nil {
				return err
			}

			return nil
		}

		// If the current path is a symlink, recreate the symlink relative to
		// the dst directory
		if info.Mode()&os.ModeSymlink == os.ModeSymlink {
			target, err := os.Readlink(path)
			if err != nil {
				return err
			}

			return os.Symlink(target, dstPath)
		}

		// If we have a file, copy the contents.
		srcF, err := os.Open(path)
		if err != nil {
			return err
		}
		defer srcF.Close()

		dstF, err := os.Create(dstPath)
		if err != nil {
			return err
		}
		defer dstF.Close()

		if _, err := io.Copy(dstF, srcF); err != nil {
			return err
		}

		// Chmod it
		return os.Chmod(dstPath, info.Mode())
	}

	return filepath.Walk(src, walkFn)
}