Remove TCP entry point (#1007)

* Remove TCP entry point

Resolve #987

* Remove TCP entry point
  * Servers that do not support WebSocket will be marked as `Legacy`
  * Removal of TCP connection from the master will follow later.

* Tweaked error message

4 files changed, 161 insertions, 0 deletions

diff --git a/src/network/serverinfo.cpp b/src/network/serverinfo.cpp
new file mode 100644
index 00000000..1762866d
--- /dev/null
+++ b/src/network/serverinfo.cpp
@@ -0,0 +1,6 @@
+#include "serverinfo.h"
+
+QString ServerInfo::toString() const
+{
+  return QString("%1 (%2:%3)").arg(name.isEmpty() ? QStringLiteral("Unnamed Server") : name).arg(address).arg(port);
+}
diff --git a/src/network/serverinfo.h b/src/network/serverinfo.h
new file mode 100644
index 00000000..1f13e3e6
--- /dev/null
+++ b/src/network/serverinfo.h
@@ -0,0 +1,15 @@
+#pragma once
+
+#include <QString>
+
+class ServerInfo
+{
+public:
+  QString name;
+  QString description;
+  QString address;
+  quint16 port = 0;
+  bool legacy = false;
+
+  QString toString() const;
+};
diff --git a/src/network/websocketconnection.cpp b/src/network/websocketconnection.cpp
new file mode 100644
index 00000000..133eae1d
--- /dev/null
+++ b/src/network/websocketconnection.cpp
@@ -0,0 +1,97 @@
+#include "websocketconnection.h"
+
+#include "aoapplication.h"
+
+#include <QNetworkRequest>
+#include <QUrl>
+
+WebSocketConnection::WebSocketConnection(AOApplication *ao_app, QObject *parent)
+    : QObject(parent)
+    , ao_app(ao_app)
+    , m_socket(new QWebSocket(QString(), QWebSocketProtocol::VersionLatest, this))
+    , m_last_state(QAbstractSocket::UnconnectedState)
+{
+  connect(m_socket, QOverload<QAbstractSocket::SocketError>::of(&QWebSocket::error), this, &WebSocketConnection::onError);
+  connect(m_socket, &QWebSocket::stateChanged, this, &WebSocketConnection::onStateChanged);
+  connect(m_socket, &QWebSocket::textMessageReceived, this, &WebSocketConnection::onTextMessageReceived);
+}
+
+WebSocketConnection::~WebSocketConnection()
+{
+  m_socket->disconnect(this);
+  disconnectFromServer();
+}
+
+bool WebSocketConnection::isConnected()
+{
+  return m_last_state == QAbstractSocket::ConnectedState;
+}
+
+void WebSocketConnection::connectToServer(const ServerInfo &server)
+{
+  disconnectFromServer();
+
+  QUrl url;
+  url.setScheme("ws");
+  url.setHost(server.address);
+  url.setPort(server.port);
+
+  QNetworkRequest req(url);
+  req.setHeader(QNetworkRequest::UserAgentHeader, QStringLiteral("AttorneyOnline/%1 (Desktop)").arg(ao_app->get_version_string()));
+
+  m_socket->open(req);
+}
+
+void WebSocketConnection::disconnectFromServer()
+{
+  if (isConnected())
+  {
+    m_socket->close(QWebSocketProtocol::CloseCodeGoingAway);
+  }
+}
+
+void WebSocketConnection::sendPacket(AOPacket packet)
+{
+  m_socket->sendTextMessage(packet.toString(true));
+}
+
+void WebSocketConnection::onError()
+{
+  Q_EMIT errorOccurred(m_socket->errorString());
+}
+
+void WebSocketConnection::onStateChanged(QAbstractSocket::SocketState state)
+{
+  m_last_state = state;
+  switch (state)
+  {
+  default:
+    break;
+
+  case QAbstractSocket::ConnectedState:
+    Q_EMIT connectedToServer();
+    break;
+
+  case QAbstractSocket::UnconnectedState:
+    Q_EMIT disconnectedFromServer();
+    break;
+  }
+}
+
+void WebSocketConnection::onTextMessageReceived(QString message)
+{
+  if (!message.endsWith("#%"))
+  {
+    return;
+  }
+  message.chop(2);
+
+  QStringList raw_content = message.split('#');
+  const QString header = raw_content.takeFirst();
+  for (QString &data : raw_content)
+  {
+    data = AOPacket::decode(data);
+  }
+
+  Q_EMIT receivedPacket(AOPacket(header, raw_content));
+}
diff --git a/src/network/websocketconnection.h b/src/network/websocketconnection.h
new file mode 100644
index 00000000..9df9a49b
--- /dev/null
+++ b/src/network/websocketconnection.h
@@ -0,0 +1,43 @@
+#pragma once
+
+#include "aopacket.h"
+#include "serverinfo.h"
+
+#include <QObject>
+#include <QWebSocket>
+
+class AOApplication;
+
+class WebSocketConnection : public QObject
+{
+  Q_OBJECT
+
+public:
+  explicit WebSocketConnection(AOApplication *ao_app, QObject *parent = nullptr);
+  virtual ~WebSocketConnection();
+
+  bool isConnected();
+
+  void connectToServer(const ServerInfo &server);
+  void disconnectFromServer();
+
+  void sendPacket(AOPacket packet);
+
+Q_SIGNALS:
+  void connectedToServer();
+  void disconnectedFromServer();
+  void errorOccurred(QString error);
+
+  void receivedPacket(AOPacket packet);
+
+private:
+  AOApplication *ao_app;
+
+  QWebSocket *m_socket;
+  QAbstractSocket::SocketState m_last_state;
+
+private Q_SLOTS:
+  void onError();
+  void onStateChanged(QAbstractSocket::SocketState state);
+  void onTextMessageReceived(QString message);
+};