/*
 * Copyright (C) 2017 Open Source Robotics Foundation
 *
 * Licensed under the Apache License, Version 2.0 (the "License");
 * you may not use this file except in compliance with the License.
 * You may obtain a copy of the License at
 *
 *     http://www.apache.org/licenses/LICENSE-2.0
 *
 * Unless required by applicable law or agreed to in writing, software
 * distributed under the License is distributed on an "AS IS" BASIS,
 * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
 * See the License for the specific language governing permissions and
 * limitations under the License.
 *
 */
#ifndef IGNITION_GUI_PLUGIN_HH_
#define IGNITION_GUI_PLUGIN_HH_

#include <tinyxml2.h>
#include <memory>
#include <string>

#include "ignition/gui/qt.h"
#include "ignition/gui/Export.hh"

namespace ignition
{
  namespace gui
  {
    class PluginPrivate;

    /// \brief Base class for Ignition GUI plugins.
    ///
    /// When inheriting from this plugin, the following are assumed:
    ///
    /// * The derived class' name is the same as the generated shared library
    ///   (i.e. if the Publisher class extends Plugin, the library file is
    ///   libPublisher.so)
    ///
    /// * There is a QML file with the same name as the plugin's shared library
    ///   name.
    ///   (i.e. there must be a Publisher.qml)
    ///
    /// * The QML file is prefixed by the library's name in the QRC file
    ///   (i.e. the file's resource is found at ':/Publisher/Publisher.qml')
    class IGNITION_GUI_VISIBLE Plugin : public QObject
    {
      Q_OBJECT

      /// \brief Constructor
      public: Plugin();

      /// \brief Destructor
      public: virtual ~Plugin();

      /// \brief Load the plugin with a configuration file.
      /// This loads the default parameters and then calls LoadConfig(), which
      /// should be overridden to load custom parameters.
      ///
      /// Called when a plugin is first created.
      /// This function should not be blocking.
      ///
      /// \sa Load
      /// \param[in] _pluginElem Element containing configuration
      public: void Load(const tinyxml2::XMLElement *_pluginElem);

      /// \brief Get the configuration XML as a string
      /// \return Config element
      public: virtual std::string ConfigStr();

      /// \brief Get the card item which contains this plugin. The item is
      /// generated the first time this function is run.
      /// \return Pointer to card item.
      public: QQuickItem *CardItem() const;

      /// \brief Get the plugin item.
      /// \return Pointer to plugin item.
      public: QQuickItem *PluginItem() const;

      /// \brief Get the QML context where the plugin was created.
      /// \return Pointer context.
      public: QQmlContext *Context() const;

      /// \brief Apply changes which should come after the plugin already
      /// has a parent.
      public: void PostParentChanges();

      /// \brief Load the plugin with a configuration file. Override this
      /// on custom plugins to handle custom configurations.
      ///
      /// Called when a plugin is first created.
      /// This function should not be blocking.
      ///
      /// \sa Load
      /// \param[in] _pluginElem Element containing configuration
      protected: virtual void LoadConfig(
          const tinyxml2::XMLElement * /*_pluginElem*/) {}

      /// \brief Get title
      /// \return Plugin title.
      public: virtual std::string Title() const {return this->title;}

      /// \brief Get the value of the the `delete_later` element from the
      /// configuration file, which defaults to false.
      /// \return The value of `delete_later`.
      public: bool DeleteLaterRequested() const;

      /// \brief Wait until the plugin has a parent, then close and delete the
      /// parent.
      protected: void DeleteLater();

      /// \brief Title to be displayed on top of plugin.
      protected: std::string title = "";

      /// \brief XML configuration
      protected: std::string configStr;

      /// \brief Load configuration which is common to all plugins and handled
      /// by Ignition GUI.
      /// \details Called when a plugin is first created.
      /// \sa LoadConfig
      /// \param[in] _ignGuiElem <ignition-gui> element within the <plugin>.
      /// Will be nullptr if not present in the SDF.
      private: virtual void LoadCommonConfig(
          const tinyxml2::XMLElement *_ignGuiElem);

      /// \brief Apply any anchors which may have been specified on the config
      /// through the <anchor> tag and any state properties.
      private: void ApplyAnchors();

      /// \internal
      /// \brief Pointer to private data
      private: std::unique_ptr<PluginPrivate> dataPtr;
    };
  }
}

#endif
