Clean up code and strengthening (slack) (#519)

Changes include:
- Refactor of strings into package-wide constants.
- Predeclaration of regexps to be instantiated at package load time.
- Checking of unchecked errors.
- Structural changes:
  - Adding verifications to type-casting code.
  - Remove unnecessary 'len(X) > 0' checks before iterating over X.
  - Remove unnecessary 'else' clause after 'if' with 'return'.
  - Unexporting of public fields of Bridge struct.
- Formatting:
  - One-field-per-line struct definitions.

1 files changed, 72 insertions, 56 deletions

diff --git a/bridge/slack/handlers.go b/bridge/slack/handlers.go
index 1ef2d614..56fd7026 100644
--- a/bridge/slack/handlers.go
+++ b/bridge/slack/handlers.go
@@ -14,7 +14,7 @@ import (
 
 func (b *Bslack) handleSlack() {
 	messages := make(chan *config.Message)
-	if b.GetString("WebhookBindAddress") != "" {
+	if b.GetString(incomingWebhookConfig) != "" {
 		b.Log.Debugf("Choosing webhooks based receiving")
 		go b.handleMatterHook(messages)
 	} else {
@@ -43,7 +43,7 @@ func (b *Bslack) handleSlack() {
 
 func (b *Bslack) handleSlackClient(messages chan *config.Message) {
 	for msg := range b.rtm.IncomingEvents {
-		if msg.Type != "user_typing" && msg.Type != "latency_report" {
+		if msg.Type != sUserTyping && msg.Type != sLatencyReport {
 			b.Log.Debugf("== Receiving event %#v", msg.Data)
 		}
 		switch ev := msg.Data.(type) {
@@ -61,17 +61,25 @@ func (b *Bslack) handleSlackClient(messages chan *config.Message) {
 		case *slack.OutgoingErrorEvent:
 			b.Log.Debugf("%#v", ev.Error())
 		case *slack.ChannelJoinedEvent:
-			b.Users, _ = b.sc.GetUsers()
-			b.Usergroups, _ = b.sc.GetUserGroups()
+			var err error
+			b.users, err = b.sc.GetUsers()
+			if err != nil {
+				b.Log.Errorf("Could not reload users: %#v", err)
+			}
 		case *slack.ConnectedEvent:
 			var err error
-			b.channels, _, err = b.sc.GetConversations(&slack.GetConversationsParameters{Limit: 1000, Types: []string{"public_channel,private_channel,mpim,im"}})
+			b.channels, _, err = b.sc.GetConversations(&slack.GetConversationsParameters{
+				Limit: 1000,
+				Types: []string{"public_channel,private_channel,mpim,im"},
+			})
 			if err != nil {
 				b.Log.Errorf("Channel list failed: %#v", err)
 			}
 			b.si = ev.Info
-			b.Users, _ = b.sc.GetUsers()
-			b.Usergroups, _ = b.sc.GetUserGroups()
+			b.users, err = b.sc.GetUsers()
+			if err != nil {
+				b.Log.Errorf("Could not reload users: %#v", err)
+			}
 		case *slack.InvalidAuthEvent:
 			b.Log.Fatalf("Invalid Token %#v", ev)
 		case *slack.ConnectionErrorEvent:
@@ -88,16 +96,22 @@ func (b *Bslack) handleMatterHook(messages chan *config.Message) {
 		if message.UserName == "slackbot" {
 			continue
 		}
-		messages <- &config.Message{Username: message.UserName, Text: message.Text, Channel: message.ChannelName}
+		messages <- &config.Message{
+			Username: message.UserName,
+			Text:     message.Text,
+			Channel:  message.ChannelName,
+		}
 	}
 }
 
+var commentRE = regexp.MustCompile(`.*?commented: (.*)`)
+
 // handleDownloadFile handles file download
 func (b *Bslack) handleDownloadFile(rmsg *config.Message, file *slack.File) error {
 	// if we have a file attached, download it (in memory) and put a pointer to it in msg.Extra
 	// limit to 1MB for now
 	comment := ""
-	results := regexp.MustCompile(`.*?commented: (.*)`).FindAllStringSubmatch(rmsg.Text, -1)
+	results := commentRE.FindAllStringSubmatch(rmsg.Text, -1)
 	if len(results) > 0 {
 		comment = results[0][1]
 	}
@@ -106,7 +120,7 @@ func (b *Bslack) handleDownloadFile(rmsg *config.Message, file *slack.File) erro
 		return err
 	}
 	// actually download the file
-	data, err := helper.DownloadFileAuth(file.URLPrivateDownload, "Bearer "+b.GetString("Token"))
+	data, err := helper.DownloadFileAuth(file.URLPrivateDownload, "Bearer "+b.GetString(tokenConfig))
 	if err != nil {
 		return fmt.Errorf("download %s failed %#v", file.URLPrivateDownload, err)
 	}
@@ -116,7 +130,7 @@ func (b *Bslack) handleDownloadFile(rmsg *config.Message, file *slack.File) erro
 }
 
 // handleUploadFile handles native upload of files
-func (b *Bslack) handleUploadFile(msg *config.Message, channelID string) (string, error) {
+func (b *Bslack) handleUploadFile(msg *config.Message, channelID string) {
 	for _, f := range msg.Extra["file"] {
 		fi := f.(config.FileInfo)
 		if msg.Text == fi.Comment {
@@ -141,37 +155,46 @@ func (b *Bslack) handleUploadFile(msg *config.Message, channelID string) (string
 			b.Log.Errorf("uploadfile %#v", err)
 		}
 	}
-	return "", nil
 }
 
 // handleMessageEvent handles the message events
 func (b *Bslack) handleMessageEvent(ev *slack.MessageEvent) (*config.Message, error) {
+	var err error
+
 	// update the userlist on a channel_join
-	if ev.SubType == "channel_join" {
-		b.Users, _ = b.sc.GetUsers()
+	if ev.SubType == sChannelJoin {
+		if b.users, err = b.sc.GetUsers(); err != nil {
+			return nil, err
+		}
 	}
 
 	// Edit message
-	if !b.GetBool("EditDisable") && ev.SubMessage != nil && ev.SubMessage.ThreadTimestamp != ev.SubMessage.Timestamp {
+	if !b.GetBool(editDisableConfig) && ev.SubMessage != nil && ev.SubMessage.ThreadTimestamp != ev.SubMessage.Timestamp {
 		b.Log.Debugf("SubMessage %#v", ev.SubMessage)
 		ev.User = ev.SubMessage.User
-		ev.Text = ev.SubMessage.Text + b.GetString("EditSuffix")
+		ev.Text = ev.SubMessage.Text + b.GetString(editSuffixConfig)
 	}
 
 	// use our own func because rtm.GetChannelInfo doesn't work for private channels
-	channel, err := b.getChannelByID(ev.Channel)
+	channelInfo, err := b.getChannelByID(ev.Channel)
 	if err != nil {
 		return nil, err
 	}
 
-	rmsg := config.Message{Text: ev.Text, Channel: channel.Name, Account: b.Account, ID: "slack " + ev.Timestamp, Extra: make(map[string][]interface{})}
+	rmsg := config.Message{
+		Text:    ev.Text,
+		Channel: channelInfo.Name,
+		Account: b.Account,
+		ID:      "slack " + ev.Timestamp,
+		Extra:   map[string][]interface{}{},
+	}
 
-	if b.UseChannelID {
-		rmsg.Channel = "ID:" + channel.ID
+	if b.useChannelID {
+		rmsg.Channel = "ID:" + channelInfo.ID
 	}
 
 	// find the user id and name
-	if ev.User != "" && ev.SubType != messageDeleted && ev.SubType != "file_comment" {
+	if ev.User != "" && ev.SubType != sMessageDeleted && ev.SubType != sFileComment {
 		user, err := b.rtm.GetUserInfo(ev.User)
 		if err != nil {
 			return nil, err
@@ -198,7 +221,7 @@ func (b *Bslack) handleMessageEvent(ev *slack.MessageEvent) (*config.Message, er
 	}
 
 	// when using webhookURL we can't check if it's our webhook or not for now
-	if rmsg.Username == "" && ev.BotID != "" && b.GetString("WebhookURL") == "" {
+	if rmsg.Username == "" && ev.BotID != "" && b.GetString(outgoingWebhookConfig) == "" {
 		bot, err := b.rtm.GetBotInfo(ev.BotID)
 		if err != nil {
 			return nil, err
@@ -226,18 +249,18 @@ func (b *Bslack) handleMessageEvent(ev *slack.MessageEvent) (*config.Message, er
 	}
 
 	// file comments are set by the system (because there is no username given)
-	if ev.SubType == "file_comment" {
-		rmsg.Username = "system"
+	if ev.SubType == sFileComment {
+		rmsg.Username = sSystemUser
 	}
 
 	// do we have a /me action
-	if ev.SubType == "me_message" {
+	if ev.SubType == sMeMessage {
 		rmsg.Event = config.EVENT_USER_ACTION
 	}
 
 	// Handle join/leave
-	if ev.SubType == "channel_leave" || ev.SubType == "channel_join" {
-		rmsg.Username = "system"
+	if ev.SubType == sChannelLeave || ev.SubType == sChannelJoin {
+		rmsg.Username = sSystemUser
 		rmsg.Event = config.EVENT_JOIN_LEAVE
 	}
 
@@ -247,19 +270,19 @@ func (b *Bslack) handleMessageEvent(ev *slack.MessageEvent) (*config.Message, er
 	}
 
 	// deleted message event
-	if ev.SubType == messageDeleted {
+	if ev.SubType == sMessageDeleted {
 		rmsg.Text = config.EVENT_MSG_DELETE
 		rmsg.Event = config.EVENT_MSG_DELETE
 		rmsg.ID = "slack " + ev.DeletedTimestamp
 	}
 
 	// topic change event
-	if ev.SubType == "channel_topic" || ev.SubType == "channel_purpose" {
+	if ev.SubType == sChannelTopic || ev.SubType == sChannelPurpose {
 		rmsg.Event = config.EVENT_TOPIC_CHANGE
 	}
 
 	// Only deleted messages can have a empty username and text
-	if (rmsg.Text == "" || rmsg.Username == "") && ev.SubType != messageDeleted && len(ev.Files) == 0 {
+	if (rmsg.Text == "" || rmsg.Username == "") && ev.SubType != sMessageDeleted && len(ev.Files) == 0 {
 		// this is probably a webhook we couldn't resolve
 		if ev.BotID != "" {
 			return nil, fmt.Errorf("probably an incoming webhook we couldn't resolve (maybe ourselves)")
@@ -269,16 +292,14 @@ func (b *Bslack) handleMessageEvent(ev *slack.MessageEvent) (*config.Message, er
 
 	// save the attachments, so that we can send them to other slack (compatible) bridges
 	if len(ev.Attachments) > 0 {
-		rmsg.Extra["slack_attachment"] = append(rmsg.Extra["slack_attachment"], ev.Attachments)
+		rmsg.Extra[sSlackAttachment] = append(rmsg.Extra[sSlackAttachment], ev.Attachments)
 	}
 
 	// if we have a file attached, download it (in memory) and put a pointer to it in msg.Extra
-	if len(ev.Files) > 0 {
-		for _, f := range ev.Files {
-			err := b.handleDownloadFile(&rmsg, &f)
-			if err != nil {
-				b.Log.Errorf("download failed: %s", err)
-			}
+	for _, f := range ev.Files {
+		err := b.handleDownloadFile(&rmsg, &f)
+		if err != nil {
+			b.Log.Errorf("download failed: %s", err)
 		}
 	}
 
@@ -287,17 +308,17 @@ func (b *Bslack) handleMessageEvent(ev *slack.MessageEvent) (*config.Message, er
 
 // skipMessageEvent skips event that need to be skipped :-)
 func (b *Bslack) skipMessageEvent(ev *slack.MessageEvent) bool {
-	if ev.SubType == "channel_leave" || ev.SubType == "channel_join" {
-		return b.GetBool("nosendjoinpart")
+	if ev.SubType == sChannelLeave || ev.SubType == sChannelJoin {
+		return b.GetBool(noSendJoinConfig)
 	}
 
 	// ignore pinned items
-	if ev.SubType == "pinned_item" || ev.SubType == "unpinned_item" {
+	if ev.SubType == sPinnedItem || ev.SubType == sUnpinnedItem {
 		return true
 	}
 
 	// do not send messages from ourself
-	if b.GetString("WebhookURL") == "" && b.GetString("WebhookBindAddress") == "" && ev.Username == b.si.User.Name {
+	if b.GetString(outgoingWebhookConfig) == "" && b.GetString(incomingWebhookConfig) == "" && ev.Username == b.si.User.Name {
 		return true
 	}
 
@@ -308,7 +329,7 @@ func (b *Bslack) skipMessageEvent(ev *slack.MessageEvent) bool {
 		}
 	}
 
-	if !b.GetBool("EditDisable") && ev.SubMessage != nil && ev.SubMessage.ThreadTimestamp != ev.SubMessage.Timestamp {
+	if !b.GetBool(editDisableConfig) && ev.SubMessage != nil && ev.SubMessage.ThreadTimestamp != ev.SubMessage.Timestamp {
 		// it seems ev.SubMessage.Edited == nil when slack unfurls
 		// do not forward these messages #266
 		if ev.SubMessage.Edited == nil {
@@ -316,21 +337,16 @@ func (b *Bslack) skipMessageEvent(ev *slack.MessageEvent) bool {
 		}
 	}
 
-	if len(ev.Files) > 0 {
-		for _, f := range ev.Files {
-			// if the file is in the cache and isn't older then a minute, skip it
-			if ts, ok := b.cache.Get("file" + f.ID); ok && time.Since(ts.(time.Time)) < time.Minute {
-				b.Log.Debugf("Not downloading file id %s which we uploaded", f.ID)
-				return true
-			} else {
-				if ts, ok := b.cache.Get("filename" + f.Name); ok && time.Since(ts.(time.Time)) < time.Second*10 {
-					b.Log.Debugf("Not downloading file name %s which we uploaded", f.Name)
-					return true
-				} else {
-					b.Log.Debugf("Not skipping %s %s", f.Name, time.Now().String())
-				}
-			}
+	for _, f := range ev.Files {
+		// if the file is in the cache and isn't older then a minute, skip it
+		if ts, ok := b.cache.Get("file" + f.ID); ok && time.Since(ts.(time.Time)) < time.Minute {
+			b.Log.Debugf("Not downloading file id %s which we uploaded", f.ID)
+			return true
+		} else if ts, ok := b.cache.Get("filename" + f.Name); ok && time.Since(ts.(time.Time)) < 10*time.Second {
+			b.Log.Debugf("Not downloading file name %s which we uploaded", f.Name)
+			return true
 		}
+		b.Log.Debugf("Not skipping %s %s", f.Name, time.Now().String())
 	}
 
 	return false