package ifs

import (
	"io/fs"
	"os"
	"runtime"
)

type FS interface {
	Mkdir(name string, perm fs.FileMode) error
	MkdirAll(name string, perm fs.FileMode) error
	Open(name string) (fs.File, error)
	OpenFile(name string, flag int, perm fs.FileMode) (File, error)
	Remove(name string) error
	RemoveAll(name string) error
}

func DirFS(dir string) FS {
	return dirFS(dir)
}

type File interface {
	Stat() (fs.FileInfo, error)
	Read([]byte) (int, error)
	Write([]byte) (int, error)
	Close() error
}

type dirFS string

func (dir dirFS) validPath(name, op string) error {
	if !fs.ValidPath(name) || runtime.GOOS == "windows" && containsAny(name, `\:`) {
		return &os.PathError{Op: op, Path: name, Err: os.ErrInvalid}
	}
	return nil
}

func (dir dirFS) Mkdir(name string, perm fs.FileMode) error {
	if err := dir.validPath(name, "mkdir"); err != nil {
		return err
	}
	return os.Mkdir(string(dir)+"/"+name, perm)
}

func (dir dirFS) MkdirAll(name string, perm fs.FileMode) error {
	if err := dir.validPath(name, "mkdirAll"); err != nil {
		return err
	}
	return os.MkdirAll(string(dir)+"/"+name, perm)
}

func (dir dirFS) Open(name string) (fs.File, error) {
	if err := dir.validPath(name, "open"); err != nil {
		return nil, err
	}
	return os.Open(string(dir) + "/" + name)
}

func (dir dirFS) OpenFile(name string, flag int, perm fs.FileMode) (File, error) {
	if err := dir.validPath(name, "openFile"); err != nil {
		return nil, err
	}
	f, err := os.OpenFile(string(dir)+"/"+name, flag, perm)
	if err != nil {
		return nil, err
	}
	return f, nil
}

func (dir dirFS) Remove(name string) error {
	if err := dir.validPath(name, "remove"); err != nil {
		return err
	}
	return os.Remove(string(dir) + "/" + name)
}

func (dir dirFS) RemoveAll(name string) error {
	if err := dir.validPath(name, "removeAll"); err != nil {
		return err
	}
	return os.RemoveAll(string(dir) + "/" + name)
}

func (dir dirFS) Stat(name string) (fs.FileInfo, error) {
	if err := dir.validPath(name, "stat"); err != nil {
		return nil, err
	}
	f, err := os.Stat(string(dir) + "/" + name)
	if err != nil {
		return nil, err
	}
	return f, nil
}

func containsAny(s, chars string) bool {
	for i := 0; i < len(s); i++ {
		for j := 0; j < len(chars); j++ {
			if s[i] == chars[j] {
				return true
			}
		}
	}
	return false
}