added contact suggestion route, code refactor

database/auth.go

@@ -11,13 +11,13 @@ import (
 func CheckUserExists(db *sql.DB, username string) (bool, error) {
 	query := `SELECT COUNT(1) FROM accounts WHERE username = $1`
 
-	var exist bool
-	err := db.QueryRow(query, username).Scan(&exist)
-	if !errors.Is(err, sql.ErrNoRows) {
-		return false, helpers.NewError(helpers.ErrInternal, "Failed to check username", err)
+	var count int
+	err := db.QueryRow(query, username).Scan(&count)
+	if err != nil {
+		return false, helpers.NewError(helpers.ErrInternal, "Failed to check user existence", err)
 	}
 
-	return exist, nil
+	return count > 0, nil
 }
 
 func InsertUser(db *sql.DB, username string, passwordHash string) (string, error) {

database/contacts.go

@@ -7,6 +7,7 @@ import (
 	"github.com/google/uuid"
 	"relay-server/helpers"
 	"relay-server/model"
+	"strings"
 )
 
 func DeleteContact(db *sql.DB, userID uuid.UUID, conversationID uuid.UUID) error {
@@ -317,3 +318,31 @@ func GetContacts(db *sql.DB, userID uuid.UUID) ([]*model.Contact, error) {
 
 	return contacts, nil
 }
+
+func ContactSuggestion(db *sql.DB, contactUsername string) ([]string, error) {
+	query := `
+  	  SELECT username FROM accounts
+  	  WHERE LOWER(username) LIKE $1
+  	  LIMIT 5;
+  	`
+
+	rows, err := db.Query(query, "%"+strings.ToLower(contactUsername)+"%")
+
+	if err != nil && !errors.Is(err, sql.ErrNoRows) {
+		return nil, helpers.NewError(helpers.ErrInternal, "Failed to get contact suggestions", err)
+	}
+
+	var suggestions []string
+	for rows.Next() {
+		var suggestion string
+		err := rows.Scan(&suggestion)
+		if err != nil {
+			return nil, helpers.NewError(helpers.ErrInternal, "internal server error", err)
+		}
+		suggestions = append(suggestions, suggestion)
+	}
+	if err = rows.Err(); err != nil {
+		return nil, helpers.NewError(helpers.ErrInternal, "Error processing suggestions", err)
+	}
+	return suggestions, nil
+}