/***

  Olive - Non-Linear Video Editor
  Copyright (C) 2019 Olive Team

  This program is free software: you can redistribute it and/or modify
  it under the terms of the GNU General Public License as published by
  the Free Software Foundation, either version 3 of the License, or
  (at your option) any later version.

  This program is distributed in the hope that it will be useful,
  but WITHOUT ANY WARRANTY; without even the implied warranty of
  MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
  GNU General Public License for more details.

  You should have received a copy of the GNU General Public License
  along with this program.  If not, see <http://www.gnu.org/licenses/>.

***/

#ifndef NODEVIEWITEM_H
#define NODEVIEWITEM_H

#include <QFontMetrics>
#include <QGraphicsRectItem>
#include <QLinearGradient>
#include <QUndoCommand>
#include <QWidget>

#include "node/node.h"
#include "nodeviewedge.h"
#include "nodeviewitemwidgetproxy.h"

/**
 * @brief A visual widget representation of a Node object to be used in a NodeView
 *
 * This widget can be collapsed or expanded to show/hide the node's various parameters.
 *
 * To retrieve the NodeViewItem for a certain Node, use NodeView::NodeToUIObject().
 */
class NodeViewItem : public QGraphicsRectItem
{
public:
  NodeViewItem(QGraphicsItem* parent = nullptr);

  /**
   * @brief Set the Node to correspond to this widget
   */
  void SetNode(Node* n);

  /**
   * @brief Get currently attached noe
   */
  Node* node();

  /**
   * @brief Get expanded state
   */
  bool IsExpanded();

  /**
   * @brief Set expanded state
   */
  void SetExpanded(bool e);
  void ToggleExpanded();

  /**
   * @brief Get the rectangle of a specific parameter connector
   *
   * Useful for drawing parameter connectors (white squares where the Node edges attach) or determining whether a click
   * or drag occurred within one.
   *
   * @param index
   *
   * Index of the parameter of this node (see NodeParam::index()).
   */
  QRectF GetParameterConnectorRect(int index);
  QRectF GetParameterConnectorRect(NodeParam* index);

protected:
  virtual void paint(QPainter *painter, const QStyleOptionGraphicsItem *option, QWidget *widget = nullptr) override;

  virtual void mousePressEvent(QGraphicsSceneMouseEvent *event) override;
  virtual void mouseMoveEvent(QGraphicsSceneMouseEvent *event) override;
  virtual void mouseReleaseEvent(QGraphicsSceneMouseEvent *event) override;
  virtual void mouseDoubleClickEvent(QGraphicsSceneMouseEvent *event) override;

  virtual QVariant itemChange(QGraphicsItem::GraphicsItemChange change, const QVariant &value) override;

private:
  /**
   * @brief Get the relative position to draw text for a parameter at a certain index
   */
  QPointF GetParameterTextPoint(int index);

  /**
   * @brief Variable for the expand/collapse button rect (stored for clicking)
   */
  QRectF expand_hitbox_;

  /**
   * @brief Reference to attached Node
   */
  Node* node_;

  /**
   * @brief A QWidget that can receive CSS properties that NodeViewItem can use
   *
   * \see NodeViewItemWidget
   */
  NodeViewItemWidget css_proxy_;

  /**
   * @brief Rectangle of the Node's title bar (equal to rect() when collapsed)
   */
  QRectF title_bar_rect_;

  /**
   * @brief Rectangle of the Node's content (zero-size when collapsed, (rect() - title_bar_rect_) when expanded)
   */
  QRectF content_rect_;

  /// Used to determine certain padding/margin variables for high DPI support
  QFont font;
  QFontMetrics font_metrics;

  /// Edge dragging variables
  NodeViewEdge* dragging_edge_;
  QPointF dragging_edge_start_;
  NodeParam* drag_src_param_;
  NodeParam* drag_dest_param_;
  NodeViewItem* drag_source_;
  NodeViewItem* drag_expanded_item_;

  /// Sizing variables to use when drawing
  int node_connector_size_;
  int node_text_padding_;
  int node_icon_padding_;
  int node_border_width_;

  /**
   * @brief Expanded state
   */
  bool expanded_;

  /**
   * @brief Current click mode
   *
   * \see mousePressEvent()
   */
  bool standard_click_;

  /**
   * @brief QUndoCommand for creating and deleting edges by dragging
   *
   * \see mousePressEvent()
   * \see mouseReleaseEvent()
   */
  QUndoCommand* node_edge_change_command_;

};

#endif // NODEVIEWITEM_H