package services

import (
	"errors"
	"io"
	"os"
	"path/filepath"
	"sync"

	"github.com/rs/zerolog/log"
)

var (
	ErrFileCreation = errors.New("unexpected error occurred while creating book file")
	ErrFileCopy     = errors.New("unexpected error occurred while copying book file")
)

type IStore interface {
	Save(name string, content io.ReadCloser) error
}

var _ IStore = (*BookStore)(nil)

type BookStore struct {
	processing *sync.WaitGroup
	dir        string
}

func NewBookStore(dir string) *BookStore {
	if err := os.MkdirAll(dir, 0755); err != nil { //nolint
		log.Fatal().Err(err).Msg("unable to create store dir")
	}

	return &BookStore{
		processing: &sync.WaitGroup{},
		dir:        dir,
	}
}

func (bs *BookStore) Done() <-chan struct{} {
	chDone := make(chan struct{})
	go func() {
		bs.processing.Wait()
		chDone <- struct{}{}
		log.Info().Msg("book store processing done")
	}()
	return chDone
}

func (bs *BookStore) Save(name string, content io.ReadCloser) error {
	bs.processing.Add(1)
	defer bs.processing.Done()

	defer content.Close()

	dst, err := os.Create(filepath.Join(GetEnv().GetDir(), name))
	if err != nil {
		log.Err(err).Msg(ErrFileCreation.Error())
		return ErrFileCreation
	}
	defer dst.Close()

	if _, err := io.Copy(dst, content); err != nil {
		log.Err(err).Msg(ErrFileCopy.Error())
		return ErrFileCopy
	}

	return nil
}