/**
  * Helper class for simple function topic request handling
  * $Id$
  * $HeadURL$
  * $Author$
  */

#pragma once

#ifdef REQUEST_HELPER_WITH_GUI
#include <LtsUtilsGuiDds/ltsutilsguidds_export.h>
#define LTSUTILSGUIDDS_INTERNAL_EXPORT LTSUTILSGUIDDS_EXPORT
#else
#include <LtsUtilsGuiDds/ltsutilsdds_export.h>
#define LTSUTILSGUIDDS_INTERNAL_EXPORT LTSUTILSDDS_EXPORT
#endif

#include <DDS/Core/function_reply_object.h>
#include <DDS/Core/core.hpp> // Core::FunctionReply (base reply)

#include <QObject>
#include <QVector>
#include <QPair>
#include <functional>


namespace LtsUtils
{

template<typename T>
dds::core::optional<T> toOptional(T inVal)
{
  return inVal != T() ? dds::core::optional<T>(inVal) : dds::core::optional<T>();
}

template<typename T>
dds::core::optional<T> optional()
{
  return dds::core::optional<T>();
}


class LTSUTILSGUIDDS_INTERNAL_EXPORT RequestHelper : public QObject // TODO: DOC !!!
{
  Q_OBJECT

public:
  static bool s_debug;

  explicit RequestHelper(QObject *parent = nullptr, bool quiet = false,
                         // for non-blocking
                         const std::function<void (void)> &success = [](){},
                         const std::function<void (void)> &failure = [](){});
  ~RequestHelper() = default;

  bool quiet() const { return m_quiet; }
  void setQuiet(bool quiet) { m_quiet = quiet; }
  void addRequest(const std::function<int64_t()> &requestFunction,
                  const std::function<void(const Core::FunctionReply &baseReply)> &baseReplyHandler = nullptr);
  bool startRequests(); // blocks!

  // do not throw a message if this method fails, as this method does this already  // blocks!
  bool startSingleRequest(const std::function<int64_t(void)> &requestFunction,
                          const std::function<void(const Core::FunctionReply &baseReply)> &baseReplyHandler = nullptr // for replies that return a custom FunctionReply, which has to be handled >>after successful execution<<
  );

  // non-blocking !
  /**
   * @brief startSingleBackgroundRequest   << you cannot reuse this request helper after using background requests! Only use if your REALLY need it.
   * @param requestFunction
   * @param baseReplyHandler
   */
  void startSingleBackgroundRequest(const std::function<int64_t()> &requestFunction,
                                    const std::function<void(const Core::FunctionReply &baseReply)> &baseReplyHandler = nullptr);
  /**
   * @brief startBackgroundRequests   << you cannot reuse this request helper after using background requests! Only use if your REALLY need it.
   */
  void startBackgroundRequests(); // non-blocking !

  bool requestReply(const Core::FunctionReply &baseReply); // if you have a custom FunctionReply, pass the base ptr
  bool requestReply(const Core::FunctionReplyObject &replyObject);

  /**
   * @brief hasRequests are requests is added?
   * @return True if a request is added, otherwise false
   */
  bool hasRequests() const { return !m_requestFunctions.isEmpty(); }


  /**
   * @brief getRepliedId returns the Return-ID of the ReplyObject you gave to the method 'requestReply' - which is mostly the ID for the new Table Entry (Unique ID)
   * @return the Return-ID or -1 on error (not set)
   */
  int getRepliedId() const { return m_repliedId; }

  /**
   * @brief getErrorString returns the error string set by an ftc reply
   * @return
   */
  QString getErrorString() const { return m_errorString; }

  /**
   * @brief setCustomWaitMessage changes the default 'Waiting for server reply ...' message with a custom one (NOTE: " ..." is automagically added to the custom text)
   * After a request was started, the custom wait message is immediately reset, so that the next call to start a request, shows the default message again
   * @param customWaitMessage the wait message to replace the default message with (note that " ..." is added to the text)
   */
  void setCustomWaitMessage(const QString &customWaitMessage);

  bool failed() const { return m_failed; }
  void failure();

private:
  using RequestFunctionContainer = QPair<std::function<int64_t()>, std::function<void(const Core::FunctionReply &)>>;

  QVector<RequestFunctionContainer> m_requestFunctions;
  bool m_failed;
  int m_repliedId;
  std::function<void(const Core::FunctionReply &)> m_singleRequestCustomFunctionReply;
  bool m_quiet;
  bool m_blockingCall;
  std::function<void (void)> m_successFn;
  std::function<void (void)> m_failureFn;
  QString m_errorString;
  QString m_customWaitMessage;

  void done();
  bool _requestReply(const Core::FunctionReplyObject &fro, const Core::FunctionReply *baseReply);

signals:
  void signalNextRequest();
  void signalQuitLoop();
  void signalSuccess();
  void signalFailed();

private slots:
  void slotNextRequest();

};

} // namespace LtsUtils