[Client] DeckSyncProfile + sidecar + DeckDiff with tests

cockatrice/src/interface/deck_sync/deck_sync_profile.cpp

@@ -0,0 +1,31 @@
+#include "deck_sync_profile.h"
+
+#include <QCryptographicHash>
+
+DeckSyncProfile::DeckSyncProfile(const QString &_host, int _port, const QString &_username)
+    : host(_host), port(_port), username(_username)
+{
+}
+
+bool DeckSyncProfile::isValid() const
+{
+    return !host.isEmpty() && port > 0 && !username.isEmpty();
+}
+
+QString DeckSyncProfile::key() const
+{
+    if (!isValid()) {
+        return {};
+    }
+    // NUL separators keep the triple injective: neither IPv6 hosts nor
+    // usernames containing ':' can collide two profiles into one file.
+    // Lowercasing is safe on both parts: DNS names are case-insensitive, and
+    // Servatrice usernames are unique under a case-insensitive collation
+    // (cockatrice_users uses utf8mb4_unicode_ci), so both spellings are one account.
+    QByteArray blob = host.trimmed().toLower().toUtf8();
+    blob.append('\0');
+    blob.append(QByteArray::number(port));
+    blob.append('\0');
+    blob.append(username.trimmed().toLower().toUtf8());
+    return QCryptographicHash::hash(blob, QCryptographicHash::Sha1).toHex();
+}