Use map instead of list as set

internal/transfer/provider_mbox.go

@@ -49,24 +49,24 @@ func (p *MBOXProvider) Mailboxes(includeEmpty, includeAllMail bool) ([]Mailbox,
 		return nil, err
 	}
 
-	mailboxNames := []string{}
+	mailboxNames := map[string]bool{}
 	for _, filePath := range filePaths {
 		fileName := filepath.Base(filePath)
 		mailboxName := strings.TrimSuffix(fileName, ".mbox")
-		mailboxNames = appendIfNew(mailboxNames, mailboxName)
+		mailboxNames[mailboxName] = true
 
 		labels, err := getGmailLabelsFromMboxFile(filepath.Join(p.root, filePath))
 		if err != nil {
 			log.WithError(err).Error("Failed to get gmail labels from mbox file")
 			continue
 		}
-		for _, label := range labels {
-			mailboxNames = appendIfNew(mailboxNames, label)
+		for label := range labels {
+			mailboxNames[label] = true
 		}
 	}
 
 	mailboxes := []Mailbox{}
-	for _, mailboxName := range mailboxNames {
+	for mailboxName := range mailboxNames {
 		mailboxes = append(mailboxes, Mailbox{
 			ID:          "",
 			Name:        mailboxName,

internal/transfer/provider_mbox_gmail_labels.go

@@ -25,9 +25,11 @@ import (
 	"strings"
 )
 
+type stringSet map[string]bool
+
 const xGmailLabelsHeader = "X-Gmail-Labels"
 
-func getGmailLabelsFromMboxFile(filePath string) ([]string, error) {
+func getGmailLabelsFromMboxFile(filePath string) (stringSet, error) {
 	f, err := os.Open(filePath) //nolint[gosec]
 	if err != nil {
 		return nil, err
@@ -35,8 +37,8 @@ func getGmailLabelsFromMboxFile(filePath string) ([]string, error) {
 	return getGmailLabelsFromMboxReader(f)
 }
 
-func getGmailLabelsFromMboxReader(f io.Reader) ([]string, error) {
-	allLabels := []string{}
+func getGmailLabelsFromMboxReader(f io.Reader) (stringSet, error) {
+	allLabels := map[string]bool{}
 
 	r := bufio.NewReader(f)
 	for {
@@ -57,8 +59,8 @@ func getGmailLabelsFromMboxReader(f io.Reader) ([]string, error) {
 			continue
 		}
 		if bytes.HasPrefix(b, []byte(xGmailLabelsHeader)) {
-			for _, label := range getGmailLabelsFromValue(string(b)) {
-				allLabels = appendIfNew(allLabels, label)
+			for label := range getGmailLabelsFromValue(string(b)) {
+				allLabels[label] = true
 			}
 		}
 	}
@@ -66,7 +68,7 @@ func getGmailLabelsFromMboxReader(f io.Reader) ([]string, error) {
 	return allLabels, nil
 }
 
-func getGmailLabelsFromMessage(body []byte) ([]string, error) {
+func getGmailLabelsFromMessage(body []byte) (stringSet, error) {
 	header, err := getMessageHeader(body)
 	if err != nil {
 		return nil, err
@@ -75,15 +77,15 @@ func getGmailLabelsFromMessage(body []byte) ([]string, error) {
 	return getGmailLabelsFromValue(labels), nil
 }
 
-func getGmailLabelsFromValue(value string) []string {
+func getGmailLabelsFromValue(value string) stringSet {
 	value = strings.TrimPrefix(value, xGmailLabelsHeader+":")
-	labels := []string{}
+	labels := map[string]bool{}
 	for _, label := range strings.Split(value, ",") {
 		label = strings.TrimSpace(label)
 		if label == "" {
 			continue
 		}
-		labels = appendIfNew(labels, label)
+		labels[label] = true
 	}
 	return labels
 }

internal/transfer/provider_mbox_gmail_labels_test.go

@@ -59,38 +59,38 @@ hello
 	mboxReader := strings.NewReader(mboxFile)
 	labels, err := getGmailLabelsFromMboxReader(mboxReader)
 	r.NoError(t, err)
-	r.Equal(t, []string{"Foo", "Bar", "Baz"}, labels)
+	r.Equal(t, toSet("Foo", "Bar", "Baz"), labels)
 }
 
 func TestGetGmailLabelsFromMessage(t *testing.T) {
 	tests := []struct {
 		body       string
-		wantLabels []string
+		wantLabels stringSet
 	}{
 		{`Subject: One
 X-Gmail-Labels: Foo,Bar
 
 Hello
-`, []string{"Foo", "Bar"}},
+`, toSet("Foo", "Bar")},
 		{`Subject: Two
 X-Gmail-Labels: Foo , Bar ,
 
 Hello
-`, []string{"Foo", "Bar"}},
+`, toSet("Foo", "Bar")},
 		{`Subject: Three
 X-Gmail-Labels: ,
 
 Hello
-`, []string{}},
+`, toSet()},
 		{`Subject: Four
 X-Gmail-Labels:
 
 Hello
-`, []string{}},
+`, toSet()},
 		{`Subject: Five
 
 Hello
-`, []string{}},
+`, toSet()},
 	}
 	for _, tc := range tests {
 		tc := tc
@@ -105,15 +105,15 @@ Hello
 func TestGetGmailLabelsFromValue(t *testing.T) {
 	tests := []struct {
 		value      string
-		wantLabels []string
+		wantLabels stringSet
 	}{
-		{"Foo,Bar", []string{"Foo", "Bar"}},
-		{" Foo , Bar ", []string{"Foo", "Bar"}},
-		{" Foo , Bar , ", []string{"Foo", "Bar"}},
-		{" Foo Bar ", []string{"Foo Bar"}},
-		{" , ", []string{}},
-		{" ", []string{}},
-		{"", []string{}},
+		{"Foo,Bar", toSet("Foo", "Bar")},
+		{" Foo , Bar ", toSet("Foo", "Bar")},
+		{" Foo , Bar , ", toSet("Foo", "Bar")},
+		{" Foo Bar ", toSet("Foo Bar")},
+		{" , ", toSet()},
+		{" ", toSet()},
+		{"", toSet()},
 	}
 	for _, tc := range tests {
 		tc := tc
@@ -123,3 +123,11 @@ func TestGetGmailLabelsFromValue(t *testing.T) {
 		})
 	}
 }
+
+func toSet(items ...string) stringSet {
+	set := map[string]bool{}
+	for _, item := range items {
+		set[item] = true
+	}
+	return set
+}

internal/transfer/provider_mbox_source.go

@@ -179,7 +179,7 @@ func (p *MBOXProvider) getMessageRules(rules transferRules, folderName, id strin
 	if err != nil {
 		log.WithError(err).Error("Failed to get gmail labels, ")
 	} else {
-		for _, label := range gmailLabels {
+		for label := range gmailLabels {
 			rule, err := rules.getRuleBySourceMailboxName(label)
 			if err != nil {
 				log.WithField("msg", id).WithField("source", label).Debug("Message skipped due to source")

internal/transfer/provider_mbox_test.go

@@ -58,7 +58,7 @@ func TestMBOXProviderMailboxes(t *testing.T) {
 		t.Run(fmt.Sprintf("%v", tc.includeEmpty), func(t *testing.T) {
 			mailboxes, err := tc.provider.Mailboxes(tc.includeEmpty, false)
 			r.NoError(t, err)
-			r.Equal(t, tc.wantMailboxes, mailboxes)
+			r.ElementsMatch(t, tc.wantMailboxes, mailboxes)
 		})
 	}
 }

internal/transfer/utils.go

@@ -160,13 +160,5 @@ func sanitizeFileName(fileName string) string {
 		}
 		return r
 	}, fileName)
-
-func appendIfNew(list []string, newItem string) []string {
-	for _, item := range list {
-		if item == newItem {
-			return list
-		}
-	}
-	return append(list, newItem)
 }