/**
 * @RDE_HEADER@
 * plugin loader helper function
 * $Id$
 * $HeadURL$
 * $Author$
 *
 * Created by Christian Ehrlicher, SLSE, 2016-07-07
 */

#include "lts_plugin_loader.h"

#include <NGLLogger/NGLLoggerBootstrap.h>
#include <LtsAppDescriptor/lts_app_descriptor.h>

#include <QCoreApplication>
#include <QDirIterator>
#include <QFileInfo>
#include <QJsonObject>
#include <QPluginLoader>
#include <QMutableListIterator>

#include <QDebug>


namespace LtsPluginManager
{

struct LtsPluginLoaderHandler
{
  LtsPluginLoader ltsPluginLoader;
  static NGL::INGLLogger &logger() { return NGL::NGLLoggerBootstrap::getNGLRootLogger().getNGLLogger("LtsPluginLoader"); }
  static void cleanupPluginLoader();
};
Q_GLOBAL_STATIC(LtsPluginLoaderHandler, s_ltsPluginLoader)

void LtsPluginLoaderHandler::cleanupPluginLoader()
{
  if (s_ltsPluginLoader.exists())
    s_ltsPluginLoader->ltsPluginLoader.unloadAllPlugins();
}


LtsPluginLoader *LtsPluginLoader::getInstance()
{
  if (!s_ltsPluginLoader.exists())
    qAddPostRoutine(&LtsPluginLoaderHandler::cleanupPluginLoader);
  return &s_ltsPluginLoader->ltsPluginLoader;
}


LtsPluginLoader::~LtsPluginLoader()
{
  unloadAllPlugins();
}

void LtsPluginLoader::unloadAllPlugins()
{
  for (auto &pi : qAsConst(m_loadedPlugins))
  {
    QPluginLoader *pluginLoader = pi.pluginLoader;

    delete pluginLoader->instance();

    if (!pluginLoader->unload())
      qWarning() << "~LtsPluginLoader: could not unload" << pi.pluginName << pluginLoader->errorString();

    delete pluginLoader;
  }
  m_loadedPlugins.clear();
}


void LtsPluginLoader::checkPlugins(const QVector<LtsAppDescriptor::AppDescription> &appVector,
                                   QStringList &errors /* out */)
{
  NGL::INGLLogger &logger = LtsPluginLoaderHandler::logger();

  if (appVector.isEmpty())
  {
    errors += QStringLiteral("No Apps available");
    return;
  }


  QVector<PluginInstance> dataPlugins;
  QVector<PluginInstance> guiPlugins;
  auto addDataPluginFn = [&](const PluginInstance &pi)
  {
    dataPlugins.append(pi);
    return true;
  };
  auto addGuiPluginFn = [&](const PluginInstance &pi)
  {
    guiPlugins.append(pi);
    return true;
  };

  if (!loadPlugins(PluginType::DATA, addDataPluginFn))
  {
    errors += QStringLiteral("failed to load data plugins");
    return;
  }

  if (!loadPlugins(PluginType::GUI, addGuiPluginFn))
  {
    errors += QStringLiteral("failed to load gui plugins");
    return;
  }



  // check for duplicate iids per plugin type
  auto checkDuplicateIidsFn = [&](const QVector<PluginInstance> &plugins, const QString &pluginType)
  {
    typedef QMap<QString /*iid*/, QString /*filename*/> IidMap;
    IidMap iids;

    for (auto i3 = plugins.constBegin(); i3 != plugins.constEnd(); ++i3)
    {
      const PluginInstance &pin = *i3;
      auto iidFound = iids.constFind(pin.pluginName);

      if (iidFound != iids.constEnd())
        errors += QStringLiteral("Iid duplicate for %1 plugin '%2'").arg(pluginType, pin.pluginName);
      else
        iids.insert(pin.pluginName, pin.fullFileName);
    }
  };

  checkDuplicateIidsFn(dataPlugins, QStringLiteral("data"));
  checkDuplicateIidsFn(guiPlugins, QStringLiteral("gui"));



  QVector<PluginInstance> plugins(dataPlugins + guiPlugins);


  // check if all in apps.json requested plugins are available
  for (auto i1 = appVector.constBegin(); i1 != appVector.constEnd(); ++i1) // Apps
  {
    const LtsAppDescriptor::AppDescription &app = *i1;

    //WARNING_LOG(logger) << "Checking app '"<<app.appName<<"'";

    const QVector<LtsAppDescriptor::PluginInfo> &piVector = app.pluginInfos;

    for (auto i2 = piVector.constBegin(); i2 != piVector.constEnd(); i2++) // App's Required Plugins
    {
      const LtsAppDescriptor::PluginInfo &pi = *i2;
      bool found = false;

      for (auto i3 = plugins.constBegin(); i3 != plugins.constEnd(); ++i3) // Available Plugins
      {
        const PluginInstance &pin = *i3;

        if (pi.iid == pin.pluginName)
        {
          found = true;
          break;
        }
      }

      if (!found)
      {
        ERROR_LOG(logger) << "Plugin with iid '" << pi.iid << "' was requested but was not loaded!";
        errors += QStringLiteral("App '%1' requires plugin '%2' that could not be found.").arg(app.appName, pi.iid);
      }
    }
  }

  return;
}


bool LtsPluginLoader::loadPlugins(PluginType requestedPluginType,
                                  const std::function<bool(const PluginInstance &)> &loadPlugin,
                                  const QStringList &requiredPlugins,
                                  const QString &specialTopicTypeFilter,
                                  const QStringList &optionalPlugins)
{
  NGL::INGLLogger &logger = LtsPluginLoaderHandler::logger();
  Q_ASSERT(requestedPluginType != PluginType::UNKNOWN); // do not allow to look for unknown

  QStringList requiredPluginsList = requiredPlugins; // copy ...
  QStringList optionalPluginsList = optionalPlugins; // copy ...
  bool checkPluginsLists = (!requiredPluginsList.isEmpty()) || (!optionalPluginsList.isEmpty());

  if (checkPluginsLists && !m_loadedPlugins.isEmpty()) // only lookup of there is something to lookup   TODO: faster to NOT do that check?
  {
    {
      QMutableListIterator<QString> i1(requiredPluginsList); // delete all plugins from the to-load list that were cached

      while (i1.hasNext())
      {
        const QString pluginName = i1.next().toLower();

        QMap<PluginKey, PluginInstance>::iterator i2 = m_loadedPlugins.find(PluginKey(requestedPluginType, pluginName));

        if (i2 != m_loadedPlugins.end())
        {
          DEBUG_LOG(logger) << "Plugin " << pluginName << " already loaded, using that instance";

          if (loadPlugin)
            loadPlugin(i2.value());

          i1.remove();
        }
      }
    }


    {
      QMutableListIterator<QString> i1(optionalPluginsList); // delete all plugins from the to-load list that were cached

      while (i1.hasNext())
      {
        const QString pluginName = i1.next().toLower();

        QMap<PluginKey, PluginInstance>::iterator i2 = m_loadedPlugins.find(PluginKey(requestedPluginType, pluginName));

        if (i2 != m_loadedPlugins.end())
        {
          DEBUG_LOG(logger) << "Plugin " << pluginName << " already loaded, using that instance";

          if (loadPlugin)
            loadPlugin(i2.value());

          i1.remove();
        }
      }
    }
  }


  QFileInfo libPathInfo(QCoreApplication::applicationDirPath() + QStringLiteral("/../lib/"));
  QString libPath(libPathInfo.absolutePath());
  if (!libPathInfo.exists())
  {
    /* ~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
     * In case of windows systems all libs are located in application directory. But can't
     * use QCoreApplication::applicationDirPath here, because it points some times to the
     * wrong directory.
     *                                                                      2016/10/18 JT
     * ~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~ */
    libPathInfo.setFile(QCoreApplication::applicationFilePath());
    libPath = libPathInfo.absolutePath();
  }

#ifdef Q_OS_WIN
  const QStringList nameFilter = QStringList(QStringLiteral("*Plugin*.dll"));
#else
  const QStringList nameFilter = QStringList(QStringLiteral("*Plugin*.so"));
#endif

  static const QStringList pluginTypes({QStringLiteral("data"),
                                        QStringLiteral("gui"),
                                        QStringLiteral("topic_type"),
                                        QStringLiteral("project"),
                                        QStringLiteral("style"),
                                        QStringLiteral("special"),
                                        QStringLiteral("gui_element")}); // #warning TODO: recordreplay is a data plugin ?

  QDirIterator pluginDir(libPath, nameFilter, QDir::Files);
  while (pluginDir.hasNext())
  {
    pluginDir.next();
    const QString filename = pluginDir.fileName();
    if (filename.contains(QStringLiteral("PluginInterface"), Qt::CaseSensitive))
      continue;

    const QString absoluteFilePath = pluginDir.filePath();

    DEBUG_LOG(logger) << "File Path: " << absoluteFilePath;

    //    if (!filename.contains(type))
    //    {
    //      pluginInfo.resultType = ResultType::WRONG_TYPE;
    //      pluginInfos.append(pluginInfo);
    //      continue;
    //    }

    QScopedPointer<QPluginLoader> pluginLoader(new QPluginLoader);
    pluginLoader->setFileName(absoluteFilePath);

    const QJsonObject jObj = pluginLoader->metaData();
    QJsonObject::const_iterator iid = jObj.find(QStringLiteral("IID"));

    if (iid == jObj.end())
    {
      DEBUG_LOG(logger) << "Plugin '" << filename << "' has no IID !";
      continue;
    }

    const QString jsonIid = iid.value().toString().toLower(); // LOWERCASE ! (pun intended)
    const QVector<QStringRef> iidParameters = jsonIid.splitRef(QLatin1Char(':'));

    DEBUG_LOG(logger) << "Plugin " << absoluteFilePath << " provides iid '" << jsonIid;

    if (iidParameters.count() != 3)
    {
      WARNING_LOG(logger) << "Invalid iid "<<jsonIid<<" for plugin " << filename;
      continue;
    }

    bool ok = false;
    int pluginLoaderVersion = iidParameters.at(1).toInt(&ok);

    if (!ok || pluginLoaderVersion != PLUGIN_LOADER_VERSION)
    {
      WARNING_LOG(logger) << "Invalid plugin loader version" << pluginLoaderVersion << "for plugin:" << filename;
      continue;
    }

    PluginType pluginType = PluginType::UNKNOWN;

    const QString pluginName = iidParameters.at(2).toString();
    const QString pluginTypeString = iidParameters.at(0).toString();
    switch (pluginTypes.indexOf(pluginTypeString))
    {
    case 0: // data
      pluginType = PluginType::DATA;
      break;
    case 1: // gui
      pluginType = PluginType::GUI;
      break;
    case 2: // topic_type
      pluginType = PluginType::TOPIC_TYPE;
      break;
    case 3: // project
      pluginType = PluginType::PROJECT;
      break;
    case 4: // style
      pluginType = PluginType::STYLE;
      break;
    case 5: // special
      pluginType = PluginType::SPECIAL;
      break;
    case 6: // gui_element
      pluginType = PluginType::GUI_ELEMENT;
      break;
    default:
      break;
    }

    if (pluginType != requestedPluginType)
    {
      DEBUG_LOG(logger) << "Plugin provides not the requested type " << (int)requestedPluginType << " is: " << (int)pluginType;
      continue;
    }

    if (pluginType == PluginType::SPECIAL && !specialTopicTypeFilter.isEmpty())
    {
      if (!pluginName.startsWith(specialTopicTypeFilter))
      {
        DEBUG_LOG(logger) << "Special plugin, but filter does not match: " << pluginName << " - " << specialTopicTypeFilter;
        continue;
      }
    }

    if (checkPluginsLists)
    {
      bool found = false;

      {
        QMutableListIterator<QString> i (requiredPluginsList);

        while (i.hasNext())
        {
          const QString requiredPlugin = i.next().toLower();

          if (pluginName == requiredPlugin)
          {
            found = true;
            i.remove();
            break; // no need to look further, just a waste of time, like writing this long unnecessary explanation
          }
        }
      }


      if (!found)
      {
        for (auto i = optionalPluginsList.constBegin(); i != optionalPluginsList.constEnd(); i++)
        {
          const QString optionalPlugin = (*i).toLower();

          if (pluginName == optionalPlugin)
          {
            found = true;
            break; // no need to look further, just a waste of time, like writing this long unnecessary explanation
          }
        }
      }


      if (!found)
      {
        DEBUG_LOG(logger) << "Plugin " << pluginName << " was not requested";
        continue; // plugin was not requested to be loaded
      }
    }


    // before we create a new instance of a plugin, which is not needed as one instance is perfectly fine to use for many apps, look it up in the loaded plugins list

    if (loadPlugin && !m_loadedPlugins.isEmpty()) // only lookup if there is something to lookup   TODO: faster to NOT do that check?
    {
      QMap<PluginKey, PluginInstance>::iterator i = m_loadedPlugins.find(PluginKey(requestedPluginType, pluginName));

      if (i != m_loadedPlugins.end())
      {
        DEBUG_LOG(logger) << "Plugin " << pluginName << " already loaded, using that instance ("<<i.value().plugin->metaObject()->className()<<")";

        loadPlugin(i.value());
        continue; // found, next plugin!
      }
    }

    // plugin not already loaded:
    QObject *plugin = pluginLoader->instance();

    if (!plugin)
    {
      ERROR_LOG(logger) << "Failed to load " << filename << " - " << pluginLoader->errorString();
      continue;
    }

    PluginInstance pi;
    pi.pluginName = pluginName;
    pi.fileName = filename;
    pi.fullFileName = absoluteFilePath;
    pi.plugin = plugin;
    pi.pluginLoader = pluginLoader.data();

    if (loadPlugin && !loadPlugin(pi)) // does the dev want this plugin? if no, unload it!   TODO: really unload? or still cache it??
    {
      DEBUG_LOG(logger) << "Plugin " << pluginName << " unloaded";
      delete pluginLoader->instance();
      pluginLoader->unload();
      continue; // next plugin
    }
    pi.pluginLoader = pluginLoader.take();

    // the dev decided to use that plugin, so cache it
    m_loadedPlugins.insert(PluginKey(requestedPluginType, pluginName), pi);

//    if (m_loadedPlugins.count() > 100)
//      WARNING_LOG(logger) << "There are more than 100 plugins cached!";

    DEBUG_LOG(logger) << "Loaded " << jsonIid << " - File: " << filename;
  } // end of  >>  pluginDir.hasNext();


  if (checkPluginsLists && !requiredPluginsList.isEmpty())
  {
    WARNING_LOG(logger) << "These plugins could not be found for Plugin Type " << (int)requestedPluginType << ": " << requiredPluginsList.join(QStringLiteral(", "));
    return false;
  }

  return true;
}

} // namespace LtsPluginManager