package vfs

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

	"github.com/spf13/afero"
)

// CopyDir represents a directory that is mimicked on hard drive.
type CopyDir interface {
	Fs() afero.Fs
	Retrieve(name string) (string, error)
	Path(name string) string
	Open(name string) (*os.File, error)
	Destroy() error
}

var _ CopyDir = &copyDir{}

type copyDir struct {
	fs   afero.Fs
	path string
}

func NewCopyDir(fs afero.Fs) (CopyDir, error) {
	dir, err := ioutil.TempDir("", "vfsCopy")
	if nil != err {
		return nil, err
	}
	return &copyDir{fs, dir}, nil
}

func (d *copyDir) Fs() afero.Fs { return d.fs }

func (d *copyDir) Retrieve(name string) (string, error) {
	var path = d.Path(name)
	if _, err := os.Stat(path); os.IsNotExist(err) {
		var dir = filepath.Dir(path)
		os.MkdirAll(dir, 0744)
		dst, err := os.Create(path)
		if nil != err {
			return path, err
		}
		defer dst.Close()
		src, err := d.fs.Open(name)
		if nil != err {
			return path, err
		}
		defer src.Close()
		_, err = io.Copy(dst, src)
		if nil != err {
			return path, err
		}
	}
	return path, nil
}

func (d *copyDir) Path(name string) string {
	return filepath.Join(d.path, name)
}

func (d *copyDir) Open(name string) (*os.File, error) {
	path, err := d.Retrieve(name)
	if nil != err {
		return nil, err
	}
	return os.Open(path)
}

func (d *copyDir) Destroy() error {
	return os.RemoveAll(d.path)
}