/*
 * This file Copyright (C) 2014 Mnemosyne LLC
 *
 * It may be used under the GNU GPL versions 2 or 3
 * or any future license endorsed by Mnemosyne LLC.
 *
 * $Id$
 */

#include <iostream>

#include <QApplication>
#include <QHostAddress>
#include <QNetworkAccessManager>
#include <QNetworkReply>
#include <QNetworkRequest>

#include <event2/buffer.h>

#include <libtransmission/transmission.h>
#include <libtransmission/rpcimpl.h>
#include <libtransmission/utils.h> // tr_free
#include <libtransmission/version.h> // LONG_VERSION_STRING

#include "rpc-client.h"

// #define DEBUG_HTTP

#define REQUEST_DATA_PROPERTY_KEY "requestData"

RpcClient::RpcClient (QObject * parent):
  QObject (parent),
  mySession (nullptr),
  myNAM (nullptr)
{
  connect (this, SIGNAL (responseReceived (QByteArray)),
           this, SLOT (parseResponse (QByteArray)));
}

void
RpcClient::stop ()
{
  mySession = nullptr;
  mySessionId.clear ();
  myUrl.clear ();

  if (myNAM != nullptr)
    {
      myNAM->deleteLater ();
      myNAM = nullptr;
    }
}

void
RpcClient::start (tr_session * session)
{
  mySession = session;
}

void
RpcClient::start (const QUrl& url)
{
  myUrl = url;
}

bool
RpcClient::isLocal () const
{
  if (mySession != 0)
    return true;

#if QT_VERSION < QT_VERSION_CHECK(5, 0, 0)
  if (myUrl.host () == "127.0.0.1" ||
      myUrl.host ().compare ("localhost", Qt::CaseInsensitive) == 0)
    return true;
#else
  if (QHostAddress (myUrl.host ()).isLoopback ())
    return true;
#endif

  return false;
}

const QUrl&
RpcClient::url () const
{
  return myUrl;
}

void
RpcClient::exec (tr_quark method, tr_variant * args, int64_t tag)
{
  exec (tr_quark_get_string (method, nullptr), args, tag);
}

void
RpcClient::exec (const char* method, tr_variant * args, int64_t tag)
{
  tr_variant top;
  tr_variantInitDict (&top, 3);
  tr_variantDictAddStr (&top, TR_KEY_method, method);
  if (tag >= 0)
    tr_variantDictAddInt (&top, TR_KEY_tag, tag);
  if (args != nullptr)
    tr_variantDictSteal (&top, TR_KEY_arguments, args);

  int length;
  char * str = tr_variantToStr (&top, TR_VARIANT_FMT_JSON_LEAN, &length);
  sendRequest (QByteArray (str, length));
  tr_free (str);

  tr_variantFree (&top);
}

void
RpcClient::sendRequest (const QByteArray& json)
{
  if (mySession != nullptr)
    {
      tr_rpc_request_exec_json (mySession, json.constData (), json.size (), localSessionCallback, this);
    }
  else if (!myUrl.isEmpty ())
    {
      QNetworkRequest request;
      request.setUrl (myUrl);
      request.setRawHeader ("User-Agent", (qApp->applicationName () + "/" + LONG_VERSION_STRING).toUtf8 ());
      request.setRawHeader ("Content-Type", "application/json; charset=UTF-8");

      if (!mySessionId.isEmpty ())
        request.setRawHeader (TR_RPC_SESSION_ID_HEADER, mySessionId.toUtf8 ());

      QNetworkReply * reply = networkAccessManager ()->post (request, json);
      reply->setProperty (REQUEST_DATA_PROPERTY_KEY, json);
      connect (reply, SIGNAL (downloadProgress (qint64, qint64)), this, SIGNAL (dataReadProgress ()));
      connect (reply, SIGNAL (uploadProgress (qint64, qint64)), this, SIGNAL (dataSendProgress ()));
      connect (reply, SIGNAL (error (QNetworkReply::NetworkError)), this, SIGNAL (error (QNetworkReply::NetworkError)));

#ifdef DEBUG_HTTP
      std::cerr << "sending " << "POST " << qPrintable (myUrl.path ()) << std::endl;
      foreach (const QByteArray& b, request.rawHeaderList ())
        std::cerr << b.constData ()
                  << ": "
                  << request.rawHeader (b).constData ()
                  << std::endl;
      std::cerr << "Body:\n" << json.constData () << std::endl;
#endif
    }
}

QNetworkAccessManager *
RpcClient::networkAccessManager ()
{
  if (myNAM == 0)
    {
      myNAM = new QNetworkAccessManager ();

      connect (myNAM, SIGNAL (finished (QNetworkReply *)),
               this, SLOT (onFinished (QNetworkReply *)));

      connect (myNAM, SIGNAL (authenticationRequired (QNetworkReply *,QAuthenticator *)),
               this, SIGNAL (httpAuthenticationRequired ()));
    }

  return myNAM;
}

void
RpcClient::localSessionCallback (tr_session * s, evbuffer * json, void * vself)
{
  Q_UNUSED (s);

  RpcClient * self = static_cast<RpcClient*> (vself);

  // this callback is invoked in the libtransmission thread, so we don't want
  // to process the response here... let's push it over to the Qt thread.
  self->responseReceived (QByteArray (reinterpret_cast<const char*> (evbuffer_pullup (json, -1)),
                                      static_cast<int> (evbuffer_get_length (json))).trimmed ());
}

void
RpcClient::onFinished (QNetworkReply * reply)
{
#ifdef DEBUG_HTTP
  std::cerr << "http response header: " << std::endl;
  foreach (const QByteArray& b, reply->rawHeaderList ())
    std::cerr << b.constData ()
              << ": "
              << reply->rawHeader (b).constData ()
              << std::endl;
  std::cerr << "json:\n" << reply->peek (reply->bytesAvailable ()).constData () << std::endl;
#endif

  if (reply->attribute (QNetworkRequest::HttpStatusCodeAttribute).toInt () == 409 &&
      reply->hasRawHeader (TR_RPC_SESSION_ID_HEADER))
    {
      // we got a 409 telling us our session id has expired.
      // update it and resubmit the request.
      mySessionId = QString::fromUtf8 (reply->rawHeader (TR_RPC_SESSION_ID_HEADER));
      sendRequest (reply->property (REQUEST_DATA_PROPERTY_KEY).toByteArray ());
    }
  else if (reply->error () != QNetworkReply::NoError)
    {
      emit errorMessage (reply->errorString ());
    }
  else
    {
      parseResponse (reply->readAll ().trimmed ());
      emit error (QNetworkReply::NoError);
    }

  reply->deleteLater ();
}

void
RpcClient::parseResponse (const QByteArray& json)
{
  tr_variant top;
  if (tr_variantFromJson (&top, json.constData (), json.size ()) != 0)
    return;

  int64_t tag;
  if (!tr_variantDictFindInt (&top, TR_KEY_tag, &tag))
    tag = -1;

  const char * result;
  if (!tr_variantDictFindStr (&top, TR_KEY_result, &result, nullptr))
    result = nullptr;

  tr_variant * args;
  if (!tr_variantDictFindDict (&top, TR_KEY_arguments, &args))
    args = nullptr;

  emit executed (tag, result == nullptr ? QString () : QString::fromUtf8 (result), args);

  tr_variantFree (&top);
}