// This file is part of arduino-cli.
//
// Copyright 2020 ARDUINO SA (http://www.arduino.cc/)
//
// This software is released under the GNU General Public License version 3,
// which covers the main part of arduino-cli.
// The terms of this license can be found at:
// https://www.gnu.org/licenses/gpl-3.0.en.html
//
// You can be released from the requirements of the above licenses by purchasing
// a commercial license. Buying such a license is mandatory if you want to
// modify or otherwise use the software for commercial activities involving the
// Arduino software without disclosing the source code of your own applications.
// To purchase a commercial license, send an email to license@arduino.cc.

package gohasissues

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

func Walk(root string, walkFn filepath.WalkFunc) error {
	info, err := os.Stat(root)
	if err != nil {
		return walkFn(root, nil, err)
	}
	return walk(root, info, walkFn)
}

func walk(path string, info os.FileInfo, walkFn filepath.WalkFunc) error {
	err := walkFn(path, info, nil)
	if err != nil {
		if info.IsDir() && err == filepath.SkipDir {
			return nil
		}
		return err
	}

	if !info.IsDir() {
		return nil
	}

	names, err := readDirNames(path)
	if err != nil {
		return walkFn(path, info, err)
	}

	for _, name := range names {
		filename := filepath.Join(path, name)
		fileInfo, err := os.Stat(filename)
		if err != nil {
			if err := walkFn(filename, fileInfo, err); err != nil && err != filepath.SkipDir {
				return err
			}
		} else {
			err = walk(filename, fileInfo, walkFn)
			if err != nil {
				if !fileInfo.IsDir() || err != filepath.SkipDir {
					return err
				}
			}
		}
	}
	return nil
}

// readDirNames reads the directory named by dirname and returns
// a sorted list of directory entries.
func readDirNames(dirname string) ([]string, error) {
	f, err := os.Open(dirname)
	if err != nil {
		return nil, err
	}
	names, err := f.Readdirnames(-1)
	f.Close()
	if err != nil {
		return nil, err
	}
	sort.Strings(names)
	return names, nil
}

func ReadDir(dirname string) ([]os.FileInfo, error) {
	infos, err := ioutil.ReadDir(dirname)
	if err != nil {
		return nil, err
	}

	for idx, info := range infos {
		info, err := resolveSymlink(dirname, info)
		if err != nil {
			// unresolvable symlinks should be skipped silently
			continue
		}
		infos[idx] = info
	}

	return infos, nil
}

func resolveSymlink(parentFolder string, info os.FileInfo) (os.FileInfo, error) {
	if !isSymlink(info) {
		return info, nil
	}
	return os.Stat(filepath.Join(parentFolder, info.Name()))
}

func isSymlink(info os.FileInfo) bool {
	return info.Mode()&os.ModeSymlink != 0
}