Refactor error handling

internalmain/main.go

@@ -7,6 +7,7 @@ import (
  "github.com/kkc/safari-books-downloader/safari"
 
  "github.com/kkc/safari-books-downloader/ebook"
+ "github.com/kkc/safari-books-downloader/utils"
 
  homedir "github.com/mitchellh/go-homedir"
  "github.com/spf13/cobra"
@@ -75,7 +76,8 @@ func DownloadSafariBook(cmd *cobra.Command, args []string) {
  password = viper.GetString("safari.password")
  }
  safari := safari.NewSafari()
- result := safari.FetchBookById(bookid, username, password)
+ result, err := safari.FetchBookById(bookid, username, password)
+ utils.StopOnErr(err)
  ebook := ebook.NewEbook(result)
  ebook.Save(output)
 }

safari/safari.go

@@ -11,6 +11,8 @@ import (
  "strings"
  "sync"
  "time"
+
+ logrus "github.com/Sirupsen/logrus"
 )
 
 type ChapterMeta struct {
@@ -203,14 +205,27 @@ func (s *Safari) adjustOrderByChapterNumber(chapters map[int]Chapter) ([]Chapter
  return chapters_slice, nil
 }
 
-func (s *Safari) FetchBookById(id string, username string, password string) []byte {
+// Get result by using book id
+func (s *Safari) FetchBookById(id string, username string, password string) ([]byte, error) {
  // check input format
 
- _ = s.authorizeUser(username, password)
- _ = s.fetchMeta(id)
+ err := s.authorizeUser(username, password)
+ if err != nil {
+ return nil, err
+ }
+ err = s.fetchMeta(id)
+ if err != nil {
+ return nil, err
+ }
  _ = s.fetchTOC(id)
- _ = s.fetchChapters(id)
- _ = s.fetchStylesheet(id)
+ err = s.fetchChapters(id)
+ if err != nil {
+ return nil, err
+ }
+ err = s.fetchStylesheet(id)
+ if err != nil {
+ return nil, err
+ }
 
  var author []string
  for _, a := range s.books[id].meta.Authors {
@@ -222,7 +237,10 @@ func (s *Safari) FetchBookById(id string, username string, password string) []by
  publisher = append(publisher, p.Name)
  }
 
- chapters, _ := s.adjustOrderByChapterNumber(s.books[id].chapters)
+ chapters, err := s.adjustOrderByChapterNumber(s.books[id].chapters)
+ if err != nil {
+ return nil, err
+ }
 
  response := &jsonBook{
  Title: s.books[id].meta.Title,
@@ -238,11 +256,9 @@ func (s *Safari) FetchBookById(id string, username string, password string) []by
 
  data, err := json.Marshal(response)
  if err != nil {
- fmt.Println("error:", err)
+ return nil, err
  }
- //d, _ := prettyprint(data)
- //fmt.Printf("%s", d)
- return data
+ return data, nil
 }
 
 type AuthResponse struct {
@@ -253,6 +269,7 @@ type AuthResponse struct {
  Scope string `json:"scope"`
 }
 
+// Login safari and get the access token
 func (s *Safari) authorizeUser(username string, password string) error {
  // http request
  uri := s.baseUrl + "/oauth2/access_token/"
@@ -265,47 +282,55 @@ func (s *Safari) authorizeUser(username string, password string) error {
  }
  resp, err := http.PostForm(uri, form)
  if err != nil {
- fmt.Println("errorination happened getting the response", err)
  return err
  }
- fmt.Println("login successfully")
  defer resp.Body.Close()
 
+ if resp.StatusCode != 200 {
+ return errors.New("Login fail, please double check your username and password")
+ }
+
+ logrus.Info("login successfully")
  body, err := ioutil.ReadAll(resp.Body)
+ if err != nil {
+ return err
+ }
 
  var stuff AuthResponse
  err = json.Unmarshal(body, &stuff)
  if err != nil {
- fmt.Println(err)
  return err
  }
 
  s.accessToken = stuff.AccessToken
  return nil
 }
 
+// Fetch safari resources by given url
 func (s *Safari) fetchResource(url string) (string, error) {
  uri := s.baseUrl + "/" + url
 
- fmt.Println("fetch uri " + uri + "with token " + s.accessToken)
+ logrus.Info("fetch uri " + uri + " with token " + s.accessToken)
  req, err := http.NewRequest("GET", uri, nil)
  if err != nil {
- fmt.Println("errorination happened getting the response", err)
- return "", err
+ return nil, err
  }
  req.Header.Set("Authorization", "Bearer "+s.accessToken)
  client := &http.Client{}
  resp, err := client.Do(req)
+ if err != nil {
+ return nil, err
+ }
  defer resp.Body.Close()
 
  if resp.StatusCode != 200 {
  err = errors.New("Error: status code != 200, actual status code '" + resp.Status + "'")
- return "", err
+ return nil, err
  }
 
  body, err := ioutil.ReadAll(resp.Body)
  if err != nil {
- return "", err
+ return nil, err
  }
 
  return string(body), nil

utils/utils.go

@@ -0,0 +1,20 @@
+package utils
+
+import (
+ "os"
+
+ logrus "github.com/Sirupsen/logrus"
+)
+
+// StopOnErr exits on any error after logging it.
+func StopOnErr(err error) {
+ if err == nil {
+ return
+ }
+ defer os.Exit(-1)
+
+ newMessage := err.Error()
+ if newMessage != "" {
+ logrus.Error(newMessage)
+ }
+}