feat: harden search ranking and deduplication

internal/isphere/contacts.go

@@ -30,24 +30,32 @@ func SearchContactsFromMessages(messages []Message, query SearchContactsQuery) S
 		addMessageContact(unique, message.ReceiverID)
 	}
 
-	queryText := strings.ToLower(strings.TrimSpace(query.Query))
-	ids := make([]string, 0, len(unique))
-	for id := range unique {
-		if queryText == "" || strings.Contains(strings.ToLower(id), queryText) || strings.Contains(strings.ToLower(unique[id].DisplayName), queryText) {
-			ids = append(ids, id)
+	queryText := normalizedSearchText(query.Query)
+	contacts := make([]Contact, 0, len(unique))
+	for _, contact := range unique {
+		if contactMatchesQuery(contact, queryText) {
+			contacts = append(contacts, contact)
 		}
 	}
-	sort.Strings(ids)
+	sort.Slice(contacts, func(i, j int) bool {
+		leftRank := contactSearchRank(contacts[i], queryText)
+		rightRank := contactSearchRank(contacts[j], queryText)
+		if leftRank != rightRank {
+			return leftRank < rightRank
+		}
+		leftID := strings.ToLower(contacts[i].ContactID)
+		rightID := strings.ToLower(contacts[j].ContactID)
+		if leftID != rightID {
+			return leftID < rightID
+		}
+		return contacts[i].ContactID < contacts[j].ContactID
+	})
 
 	limit := query.Limit
-	if limit <= 0 || limit > len(ids) {
-		limit = len(ids)
+	if limit <= 0 || limit > len(contacts) {
+		limit = len(contacts)
 	}
-	contacts := make([]Contact, 0, limit)
-	for _, id := range ids[:limit] {
-		contacts = append(contacts, unique[id])
-	}
-	return SearchContactsResult{Contacts: contacts}
+	return SearchContactsResult{Contacts: contacts[:limit]}
 }
 
 func addMessageContact(unique map[string]Contact, id string) {
@@ -55,10 +63,11 @@ func addMessageContact(unique map[string]Contact, id string) {
 	if trimmed == "" {
 		return
 	}
-	if _, exists := unique[trimmed]; exists {
+	key := strings.ToLower(trimmed)
+	if _, exists := unique[key]; exists {
 		return
 	}
-	unique[trimmed] = Contact{
+	unique[key] = Contact{
 		ContactID:   trimmed,
 		DisplayName: trimmed,
 		Account:     trimmed,
@@ -67,3 +76,38 @@ func addMessageContact(unique map[string]Contact, id string) {
 		RawRef:      "message_jid",
 	}
 }
+
+func normalizedSearchText(value string) string {
+	return strings.ToLower(strings.TrimSpace(value))
+}
+
+func contactMatchesQuery(contact Contact, queryText string) bool {
+	if queryText == "" {
+		return true
+	}
+	return strings.Contains(strings.ToLower(contact.ContactID), queryText) ||
+		strings.Contains(strings.ToLower(contact.DisplayName), queryText) ||
+		strings.Contains(strings.ToLower(contact.Account), queryText)
+}
+
+func contactSearchRank(contact Contact, queryText string) int {
+	if queryText == "" {
+		return 0
+	}
+	values := []string{
+		strings.ToLower(contact.ContactID),
+		strings.ToLower(contact.DisplayName),
+		strings.ToLower(contact.Account),
+	}
+	for _, value := range values {
+		if value == queryText {
+			return 0
+		}
+	}
+	for _, value := range values {
+		if strings.HasPrefix(value, queryText) {
+			return 1
+		}
+	}
+	return 2
+}