fix mention extracting when no domain exists (usually when intra-instance mentions)

Signed-off-by: kim <grufwub@gmail.com>

internal/ap/extract.go

@@ -565,13 +565,10 @@ func ExtractMention(i Mentionable) (*gtsmodel.Mention, error) {
 	}
 
 	// just make sure the mention string is valid so we can handle it properly later on...
-	username, domain, err := util.ExtractMentionParts(mentionString)
+	_, _, err = util.ExtractMentionParts(mentionString)
 	if err != nil {
 		return nil, err
 	}
-	if username == "" || domain == "" {
-		return nil, errors.New("username or domain was empty")
-	}
 	mention.NameString = mentionString
 
 	// the href prop should be the AP URI of a user we know, eg https://example.org/users/whatever_user

internal/regexes/regexes.go

@@ -47,7 +47,7 @@ const (
 )
 
 var (
-	mentionName = `^@(\w+)(?:@([a-zA-Z0-9_\-\.:]+)?)$`
+	mentionName = `^@(\w+)(?:@([a-zA-Z0-9_\-\.:]+))?$`
 	// MentionName captures the username and domain part from a mention string
 	// such as @whatever_user@example.org, returning whatever_user and example.org (without the @ symbols)
 	MentionName = regexp.MustCompile(mentionName)

internal/util/statustools.go

@@ -68,13 +68,14 @@ func DeriveEmojisFromText(text string) []string {
 // If nothing is matched, it will return an error.
 func ExtractMentionParts(mention string) (username, domain string, err error) {
 	matches := regexes.MentionName.FindStringSubmatch(mention)
-	if matches == nil || len(matches) != 3 {
-		err = fmt.Errorf("could't match mention %s", mention)
-		return
+	switch len(matches) {
+	case 2:
+		return matches[1], "", nil
+	case 3:
+		return matches[1], matches[2], nil
+	default:
+		return "", "", fmt.Errorf("couldn't match mention %s", mention)
 	}
-	username = matches[1]
-	domain = matches[2]
-	return
 }
 
 // IsMention returns true if the passed string looks like @whatever@example.org