//go:build go1.16 && finder

// +build go1.16,finder

package viper

import (

	"errors"

	"io/fs"

	"path"

)

type finder struct {

	paths      []string

	fileNames  []string

	extensions []string

	withoutExtension bool

}

func (f finder) Find(fsys fs.FS) (string, error) {

	for _, searchPath := range f.paths {

		for _, fileName := range f.fileNames {

			for _, extension := range f.extensions {

				filePath := path.Join(searchPath, fileName+"."+extension)

				ok, err := fileExists(fsys, filePath)

				if err != nil {

					return "", err

				}

				if ok {

					return filePath, nil

				}

			}

			if f.withoutExtension {

				filePath := path.Join(searchPath, fileName)

				ok, err := fileExists(fsys, filePath)

				if err != nil {

					return "", err

				}

				if ok {

					return filePath, nil

				}

			}

		}

	}

	return "", nil

}

func fileExists(fsys fs.FS, filePath string) (bool, error) {

	fileInfo, err := fs.Stat(fsys, filePath)

	if err == nil {

		return !fileInfo.IsDir(), nil

	}

	if errors.Is(err, fs.ErrNotExist) {

		return false, nil

	}

	return false, err

}