/*
 * This file Copyright (C) 2016 Mnemosyne LLC
 *
 * It may be used under the GNU GPL versions 2 or 3
 * or any future license endorsed by Mnemosyne LLC.
 *
 */

#include <cassert>

#include "RpcQueue.h"

RpcQueue::RpcQueue (QObject * parent):
  QObject (parent),
  myTolerateErrors (false)
{
  connect (&myFutureWatcher, SIGNAL (finished ()), SLOT (stepFinished ()));
}

RpcResponseFuture
RpcQueue::future ()
{
  return myPromise.future ();
}

void
RpcQueue::stepFinished ()
{
  RpcResponse result;

  if (myFutureWatcher.future ().isResultReadyAt (0))
    {
      result = myFutureWatcher.result ();
      RpcResponseFuture future = myFutureWatcher.future ();

      // we can't handle network errors, abort queue and pass the error upwards
      if (result.networkError != QNetworkReply::NoError)
        {
          assert (!result.success);

          myPromise.reportFinished (&result);
          deleteLater ();
          return;
        }

      // call user-handler for ordinary errors
      if (!result.success && myNextErrorHandler)
        {
          myNextErrorHandler (future);
        }

      // run next request, if we have one to run and there was no error (or if we tolerate errors)
      if ((result.success || myTolerateErrors) && !myQueue.isEmpty ())
        {
          runNext (future);
          return;
        }
    }
  else
    {
      assert (!myNextErrorHandler);
      assert (myQueue.isEmpty ());

      // one way or another, the last step returned nothing.
      // assume it is OK and ensure that we're not going to give an empty response object to any of the next steps.
      result.success = true;
    }

  myPromise.reportFinished (&result);
  deleteLater ();
}

void
RpcQueue::runNext (const RpcResponseFuture& response)
{
  assert (!myQueue.isEmpty ());

  auto next = myQueue.dequeue ();
  myNextErrorHandler = next.second;
  myFutureWatcher.setFuture ((next.first) (response));
}

void
RpcQueue::run ()
{
  runNext (RpcResponseFuture ());
}