/******************************************************************************
 * The MIT License (MIT)
 *
 * Copyright (c) 2017 Baldur Karlsson
 *
 * Permission is hereby granted, free of charge, to any person obtaining a copy
 * of this software and associated documentation files (the "Software"), to deal
 * in the Software without restriction, including without limitation the rights
 * to use, copy, modify, merge, publish, distribute, sublicense, and/or sell
 * copies of the Software, and to permit persons to whom the Software is
 * furnished to do so, subject to the following conditions:
 *
 * The above copyright notice and this permission notice shall be included in
 * all copies or substantial portions of the Software.
 *
 * THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS OR
 * IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY,
 * FITNESS FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT. IN NO EVENT SHALL THE
 * AUTHORS OR COPYRIGHT HOLDERS BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER
 * LIABILITY, WHETHER IN AN ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING FROM,
 * OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS IN
 * THE SOFTWARE.
 ******************************************************************************/

#include "RDTreeView.h"
#include <QMouseEvent>
#include <QPainter>
#include <QProxyStyle>

RDTreeViewDelegate::RDTreeViewDelegate(RDTreeView *view) : QStyledItemDelegate(view), m_View(view)
{
}

QSize RDTreeViewDelegate::sizeHint(const QStyleOptionViewItem &option, const QModelIndex &index) const
{
  QSize ret = QStyledItemDelegate::sizeHint(option, index);

  // expand a pixel for the grid lines
  if(m_View->m_VisibleGridLines)
  {
    ret.setWidth(ret.width() + 1);
    ret.setHeight(ret.height() + 1);
  }

  // ensure we have at least the margin on top of font size. If the style applied more, don't add to
  // it.
  ret.setHeight(qMax(ret.height(), option.fontMetrics.height() + m_View->m_VertMargin));

  return ret;
}

RDTreeView::RDTreeView(QWidget *parent) : QTreeView(NULL)
{
  setMouseTracking(true);

  setItemDelegate(new RDTreeViewDelegate(this));
}

void RDTreeView::mouseMoveEvent(QMouseEvent *e)
{
  m_currentHoverIndex = indexAt(e->pos());
}

void RDTreeView::leaveEvent(QEvent *e)
{
  m_currentHoverIndex = QModelIndex();
}

void RDTreeView::rowsAboutToBeRemoved(const QModelIndex &parent, int start, int end)
{
  m_currentHoverIndex = QModelIndex();
}

void RDTreeView::drawRow(QPainter *painter, const QStyleOptionViewItem &options,
                         const QModelIndex &index) const
{
  QTreeView::drawRow(painter, options, index);

  if(m_VisibleGridLines)
  {
    QPen p = painter->pen();

    QColor back = options.palette.color(QPalette::Active, QPalette::Background);
    QColor fore = options.palette.color(QPalette::Active, QPalette::Foreground);

    // draw the grid lines with a colour half way between background and foreground
    painter->setPen(QPen(QColor::fromRgbF(back.redF() * 0.8 + fore.redF() * 0.2,
                                          back.greenF() * 0.8 + fore.greenF() * 0.2,
                                          back.blueF() * 0.8 + fore.blueF() * 0.2)));

    for(int i = 0, count = model()->columnCount(); i < count; i++)
    {
      QRect r = visualRect(model()->index(index.row(), i, index.parent()));
      r = r.intersected(options.rect);

      // draw bottom and right of the rect
      if(r.width() > 0 && r.height() > 0)
      {
        if(treePosition() == i)
        {
          int depth = 1;
          QModelIndex idx = index;
          while(idx.parent().isValid())
          {
            depth++;
            idx = idx.parent();
          }
          r.setLeft(r.left() - indentation() * depth);
        }

        painter->drawLine(r.bottomLeft(), r.bottomRight());
        painter->drawLine(r.topRight(), r.bottomRight());
      }
    }

    painter->setPen(p);
  }
}

void RDTreeView::fillBranchesRect(QPainter *painter, const QRect &rect, const QModelIndex &index) const
{
  QStyleOptionViewItem opt;
  opt.initFrom(this);
  if(selectionModel()->isSelected(index))
    opt.state |= QStyle::State_Selected;
  if(m_currentHoverIndex.row() == index.row() && m_currentHoverIndex.parent() == index.parent())
    opt.state |= QStyle::State_MouseOver;
  else
    opt.state &= ~QStyle::State_MouseOver;

  if(hasFocus())
    opt.state |= (QStyle::State_Active | QStyle::State_HasFocus);
  else
    opt.state &= ~(QStyle::State_Active | QStyle::State_HasFocus);

  int depth = 1;
  QModelIndex idx = index.parent();
  while(idx.isValid())
  {
    depth++;
    idx = idx.parent();
  }

  opt.rect = rect;
  opt.rect.setWidth(depth * indentation());
  opt.showDecorationSelected = true;
  style()->drawPrimitive(QStyle::PE_PanelItemViewItem, &opt, painter, this);
}

void RDTreeView::drawBranches(QPainter *painter, const QRect &rect, const QModelIndex &index) const
{
  if(m_fillBranchRect)
    fillBranchesRect(painter, rect, index);

  if(m_VisibleBranches)
  {
    QTreeView::drawBranches(painter, rect, index);
  }
  else
  {
    // draw only the expand item, not the branches
    QRect primitive(0, rect.top(), indentation(), rect.height());

    // if root isn't decorated, skip
    if(!rootIsDecorated() && !index.parent().isValid())
      return;

    // if no children, nothing to render
    if(model()->rowCount(index) == 0)
      return;

    QStyleOptionViewItem opt = viewOptions();

    opt.rect = primitive;

    // unfortunately QStyle::State_Children doesn't render ONLY the
    // open-toggle-button, but the vertical line upwards to a previous sibling.
    // For consistency, draw one downwards too.
    opt.state = QStyle::State_Children | QStyle::State_Sibling;
    if(isExpanded(index))
      opt.state |= QStyle::State_Open;

    style()->drawPrimitive(QStyle::PE_IndicatorBranch, &opt, painter, this);
  }
}