Migrate to idiomatic error handling in app/slackimport.go (#9694)

* MM-12610 Migrate to idiomatic error handling in the file  in the mattermost-server repo (#9686)

*  MM-12610 Migrate to idiomatic error handling in the file in the mattermost-server repo (mattermost#9686)

*  MM-12610 Migrate to idiomatic error handling in the file in the mattermost-server repo (#9686)

app/slackimport.go

@@ -10,6 +10,7 @@ import (
 	"fmt"
 	"io"
 	"mime/multipart"
+	"net/http"
 	"path/filepath"
 	"regexp"
 	"strconv"
@@ -17,8 +18,6 @@ import (
 	"time"
 	"unicode/utf8"
 
-	"net/http"
-
 	"github.com/mattermost/mattermost-server/mlog"
 	"github.com/mattermost/mattermost-server/model"
 	"github.com/mattermost/mattermost-server/utils"
@@ -97,9 +96,8 @@ func SlackConvertChannelName(channelName string, channelId string) string {
 
 	if isValidChannelNameCharacters(newName) {
 		return newName
-	} else {
-		return strings.ToLower(channelId)
 	}
+	return strings.ToLower(channelId)
 }
 
 func SlackParseChannels(data io.Reader) ([]SlackChannel, error) {
@@ -143,13 +141,12 @@ func (a *App) SlackAddUsers(teamId string, slackusers []SlackUser, importerLog *
 	addedUsers := make(map[string]*model.User)
 
 	// Need the team
-	var team *model.Team
+	result := <-a.Srv.Store.Team().Get(teamId)
-	if result := <-a.Srv.Store.Team().Get(teamId); result.Err != nil {
+	if result.Err != nil {
 		importerLog.WriteString(utils.T("api.slackimport.slack_import.team_fail"))
 		return addedUsers
-	} else {
-		team = result.Data.(*model.Team)
 	}
+	team := result.Data.(*model.Team)
 
 	for _, sUser := range slackusers {
 		firstName := sUser.Profile.FirstName
@@ -183,25 +180,25 @@ func (a *App) SlackAddUsers(teamId string, slackusers []SlackUser, importerLog *
 			Password:  password,
 		}
 
-		if mUser := a.OldImportUser(team, &newUser); mUser != nil {
+		mUser := a.OldImportUser(team, &newUser)
-			addedUsers[sUser.Id] = mUser
+		if mUser == nil {
-			importerLog.WriteString(utils.T("api.slackimport.slack_add_users.email_pwd", map[string]interface{}{"Email": newUser.Email, "Password": password}))
-		} else {
 			importerLog.WriteString(utils.T("api.slackimport.slack_add_users.unable_import", map[string]interface{}{"Username": sUser.Username}))
+			continue
 		}
+		addedUsers[sUser.Id] = mUser
+		importerLog.WriteString(utils.T("api.slackimport.slack_add_users.email_pwd", map[string]interface{}{"Email": newUser.Email, "Password": password}))
 	}
 
 	return addedUsers
 }
 
 func (a *App) SlackAddBotUser(teamId string, log *bytes.Buffer) *model.User {
-	var team *model.Team
+	result := <-a.Srv.Store.Team().Get(teamId)
-	if result := <-a.Srv.Store.Team().Get(teamId); result.Err != nil {
+	if result.Err != nil {
 		log.WriteString(utils.T("api.slackimport.slack_import.team_fail"))
 		return nil
-	} else {
-		team = result.Data.(*model.Team)
 	}
+	team := result.Data.(*model.Team)
 
 	password := model.NewId()
 	username := "slackimportuser_" + model.NewId()
@@ -215,13 +212,14 @@ func (a *App) SlackAddBotUser(teamId string, log *bytes.Buffer) *model.User {
 		Password:  password,
 	}
 
-	if mUser := a.OldImportUser(team, &botUser); mUser != nil {
+	mUser := a.OldImportUser(team, &botUser)
-		log.WriteString(utils.T("api.slackimport.slack_add_bot_user.email_pwd", map[string]interface{}{"Email": botUser.Email, "Password": password}))
+	if mUser == nil {
-		return mUser
-	} else {
 		log.WriteString(utils.T("api.slackimport.slack_add_bot_user.unable_import", map[string]interface{}{"Username": username}))
 		return nil
 	}
+
+	log.WriteString(utils.T("api.slackimport.slack_add_bot_user.email_pwd", map[string]interface{}{"Email": botUser.Email, "Password": password}))
+	return mUser
 }
 
 func (a *App) SlackAddPosts(teamId string, channel *model.Channel, posts []SlackPost, users map[string]*model.User, uploads map[string]*zip.File, botUser *model.User) {
@@ -231,7 +229,8 @@ func (a *App) SlackAddPosts(teamId string, channel *model.Channel, posts []Slack
 			if sPost.User == "" {
 				mlog.Debug("Slack Import: Unable to import the message as the user field is missing.")
 				continue
-			} else if users[sPost.User] == nil {
+			}
+			if users[sPost.User] == nil {
 				mlog.Debug(fmt.Sprintf("Slack Import: Unable to add the message as the Slack user %v does not exist in Mattermost.", sPost.User))
 				continue
 			}
@@ -258,10 +257,12 @@ func (a *App) SlackAddPosts(teamId string, channel *model.Channel, posts []Slack
 			if sPost.Comment == nil {
 				mlog.Debug("Slack Import: Unable to import the message as it has no comments.")
 				continue
-			} else if sPost.Comment.User == "" {
+			}
+			if sPost.Comment.User == "" {
 				mlog.Debug("Slack Import: Unable to import the message as the user field is missing.")
 				continue
-			} else if users[sPost.Comment.User] == nil {
+			}
+			if users[sPost.Comment.User] == nil {
 				mlog.Debug(fmt.Sprintf("Slack Import: Unable to add the message as the Slack user %v does not exist in Mattermost.", sPost.User))
 				continue
 			}
@@ -276,7 +277,8 @@ func (a *App) SlackAddPosts(teamId string, channel *model.Channel, posts []Slack
 			if botUser == nil {
 				mlog.Warn("Slack Import: Unable to import the bot message as the bot user does not exist.")
 				continue
-			} else if sPost.BotId == "" {
+			}
+			if sPost.BotId == "" {
 				mlog.Warn("Slack Import: Unable to import bot message as the BotId field is missing.")
 				continue
 			}
@@ -300,7 +302,8 @@ func (a *App) SlackAddPosts(teamId string, channel *model.Channel, posts []Slack
 			if sPost.User == "" {
 				mlog.Debug("Slack Import: Unable to import the message as the user field is missing.")
 				continue
-			} else if users[sPost.User] == nil {
+			}
+			if users[sPost.User] == nil {
 				mlog.Debug(fmt.Sprintf("Slack Import: Unable to add the message as the Slack user %v does not exist in Mattermost.", sPost.User))
 				continue
 			}
@@ -327,7 +330,8 @@ func (a *App) SlackAddPosts(teamId string, channel *model.Channel, posts []Slack
 			if sPost.User == "" {
 				mlog.Debug("Slack Import: Unable to import the message as the user field is missing.")
 				continue
-			} else if users[sPost.User] == nil {
+			}
+			if users[sPost.User] == nil {
 				mlog.Debug(fmt.Sprintf("Slack Import: Unable to add the message as the Slack user %v does not exist in Mattermost.", sPost.User))
 				continue
 			}
@@ -342,7 +346,8 @@ func (a *App) SlackAddPosts(teamId string, channel *model.Channel, posts []Slack
 			if sPost.User == "" {
 				mlog.Debug("Slack Import: Unable to import the message as the user field is missing.")
 				continue
-			} else if users[sPost.User] == nil {
+			}
+			if users[sPost.User] == nil {
 				mlog.Debug(fmt.Sprintf("Slack Import: Unable to add the message as the Slack user %v does not exist in Mattermost.", sPost.User))
 				continue
 			}
@@ -358,7 +363,8 @@ func (a *App) SlackAddPosts(teamId string, channel *model.Channel, posts []Slack
 			if sPost.User == "" {
 				mlog.Debug("Slack Import: Unable to import the message as the user field is missing.")
 				continue
-			} else if users[sPost.User] == nil {
+			}
+			if users[sPost.User] == nil {
 				mlog.Debug(fmt.Sprintf("Slack Import: Unable to add the message as the Slack user %v does not exist in Mattermost.", sPost.User))
 				continue
 			}
@@ -374,7 +380,8 @@ func (a *App) SlackAddPosts(teamId string, channel *model.Channel, posts []Slack
 			if sPost.User == "" {
 				mlog.Debug("Slack Import: Unable to import the message as the user field is missing.")
 				continue
-			} else if users[sPost.User] == nil {
+			}
+			if users[sPost.User] == nil {
 				mlog.Debug(fmt.Sprintf("Slack Import: Unable to add the message as the Slack user %v does not exist in Mattermost.", sPost.User))
 				continue
 			}
@@ -393,48 +400,47 @@ func (a *App) SlackAddPosts(teamId string, channel *model.Channel, posts []Slack
 }
 
 func (a *App) SlackUploadFile(sPost SlackPost, uploads map[string]*zip.File, teamId string, channelId string, userId string) (*model.FileInfo, bool) {
-	if sPost.File != nil {
+	if sPost.File == nil {
-		if file, ok := uploads[sPost.File.Id]; ok {
-			openFile, err := file.Open()
-			if err != nil {
-				mlog.Warn(fmt.Sprintf("Slack Import: Unable to open the file %v from the Slack export: %v.", sPost.File.Id, err.Error()))
-				return nil, false
-			}
-			defer openFile.Close()
-
-			timestamp := utils.TimeFromMillis(SlackConvertTimeStamp(sPost.TimeStamp))
-			uploadedFile, err := a.OldImportFile(timestamp, openFile, teamId, channelId, userId, filepath.Base(file.Name))
-			if err != nil {
-				mlog.Warn(fmt.Sprintf("Slack Import: An error occurred when uploading file %v: %v.", sPost.File.Id, err.Error()))
-				return nil, false
-			}
-
-			return uploadedFile, true
-		} else {
-			mlog.Warn(fmt.Sprintf("Slack Import: Unable to import file %v as the file is missing from the Slack export zip file.", sPost.File.Id))
-			return nil, false
-		}
-	} else {
 		mlog.Warn("Slack Import: Unable to attach the file to the post as the latter has no file section present in Slack export.")
 		return nil, false
 	}
+	file, ok := uploads[sPost.File.Id]
+	if !ok {
+		mlog.Warn(fmt.Sprintf("Slack Import: Unable to import file %v as the file is missing from the Slack export zip file.", sPost.File.Id))
+		return nil, false
+	}
+	openFile, err := file.Open()
+	if err != nil {
+		mlog.Warn(fmt.Sprintf("Slack Import: Unable to open the file %v from the Slack export: %v.", sPost.File.Id, err.Error()))
+		return nil, false
+	}
+	defer openFile.Close()
+
+	timestamp := utils.TimeFromMillis(SlackConvertTimeStamp(sPost.TimeStamp))
+	uploadedFile, err := a.OldImportFile(timestamp, openFile, teamId, channelId, userId, filepath.Base(file.Name))
+	if err != nil {
+		mlog.Warn(fmt.Sprintf("Slack Import: An error occurred when uploading file %v: %v.", sPost.File.Id, err.Error()))
+		return nil, false
+	}
+
+	return uploadedFile, true
 }
 
 func (a *App) deactivateSlackBotUser(user *model.User) {
-	_, err := a.UpdateActive(user, false)
+	if _, err := a.UpdateActive(user, false); err != nil {
-	if err != nil {
 		mlog.Warn("Slack Import: Unable to deactivate the user account used for the bot.")
 	}
 }
 
 func (a *App) addSlackUsersToChannel(members []string, users map[string]*model.User, channel *model.Channel, log *bytes.Buffer) {
 	for _, member := range members {
-		if user, ok := users[member]; !ok {
+		user, ok := users[member]
+		if !ok {
 			log.WriteString(utils.T("api.slackimport.slack_add_channels.failed_to_add_user", map[string]interface{}{"Username": "?"}))
-		} else {
+			continue
-			if _, err := a.AddUserToChannel(user, channel); err != nil {
+		}
-				log.WriteString(utils.T("api.slackimport.slack_add_channels.failed_to_add_user", map[string]interface{}{"Username": user.Username}))
+		if _, err := a.AddUserToChannel(user, channel); err != nil {
-			}
+			log.WriteString(utils.T("api.slackimport.slack_add_channels.failed_to_add_user", map[string]interface{}{"Username": user.Username}))
 		}
 	}
 }
@@ -733,32 +739,32 @@ func (a *App) OldImportUser(team *model.Team, user *model.User) *model.User {
 
 	user.Roles = model.SYSTEM_USER_ROLE_ID
 
-	if result := <-a.Srv.Store.User().Save(user); result.Err != nil {
+	result := <-a.Srv.Store.User().Save(user)
+	if result.Err != nil {
 		mlog.Error(fmt.Sprintf("Error saving user. err=%v", result.Err))
 		return nil
-	} else {
-		ruser := result.Data.(*model.User)
-
-		if cresult := <-a.Srv.Store.User().VerifyEmail(ruser.Id); cresult.Err != nil {
-			mlog.Error(fmt.Sprintf("Failed to set email verified err=%v", cresult.Err))
-		}
-
-		if err := a.JoinUserToTeam(team, user, ""); err != nil {
-			mlog.Error(fmt.Sprintf("Failed to join team when importing err=%v", err))
-		}
-
-		return ruser
 	}
+	ruser := result.Data.(*model.User)
+
+	if cresult := <-a.Srv.Store.User().VerifyEmail(ruser.Id); cresult.Err != nil {
+		mlog.Error(fmt.Sprintf("Failed to set email verified err=%v", cresult.Err))
+	}
+
+	if err := a.JoinUserToTeam(team, user, ""); err != nil {
+		mlog.Error(fmt.Sprintf("Failed to join team when importing err=%v", err))
+	}
+
+	return ruser
 }
 
 func (a *App) OldImportChannel(channel *model.Channel) *model.Channel {
-	if result := <-a.Srv.Store.Channel().Save(channel, *a.Config().TeamSettings.MaxChannelsPerTeam); result.Err != nil {
+	result := <-a.Srv.Store.Channel().Save(channel, *a.Config().TeamSettings.MaxChannelsPerTeam)
+	if result.Err != nil {
 		return nil
-	} else {
-		sc := result.Data.(*model.Channel)
-
-		return sc
 	}
+	sc := result.Data.(*model.Channel)
+
+	return sc
 }
 
 func (a *App) OldImportFile(timestamp time.Time, file io.Reader, teamId string, channelId string, userId string, fileName string) (*model.FileInfo, error) {