content: /*
   * This library is part of OpenCms -
   * the Open Source Content Management System
   *
   * Copyright (c) Alkacon Software GmbH & Co. KG (https://www.alkacon.com)
   *
   * This library is free software; you can redistribute it and/or
   * modify it under the terms of the GNU Lesser General Public
   * License as published by the Free Software Foundation; either
   * version 2.1 of the License, or (at your option) any later version.
   *
   * This library 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
   * Lesser General Public License for more details.
   *
   * For further information about Alkacon Software, please see the
   * company website: https://www.alkacon.com
   *
   * For further information about OpenCms, please see the
   * project website: https://www.opencms.org
   *
   * You should have received a copy of the GNU Lesser General Public
   * License along with this library; if not, write to the Free Software
   * Foundation, Inc., 59 Temple Place, Suite 330, Boston, MA  02111-1307  USA
   */
  
  package org.opencms.ade.editprovider.client;
  
  import org.opencms.gwt.client.util.CmsPositionBean;
  
  import java.util.ArrayList;
  import java.util.Collections;
  import java.util.Comparator;
  import java.util.HashMap;
  import java.util.List;
  import java.util.Map;
  
  /**
   * This class is used to calculate positions for a set of direct edit buttons so that
   * they don't overlap.<p>
   *
   * @since 8.0.0
   */
  public class CmsEditablePositionCalculator {
  
      /**
       * A comparator class which compares position beans by their left edge.<p>
       */
      protected class LeftComparator implements Comparator<CmsPositionBean> {
  
          /**
           * @see java.util.Comparator#compare(java.lang.Object, java.lang.Object)
           */
          public int compare(CmsPositionBean o1, CmsPositionBean o2) {
  
              int l1 = o1.getLeft();
              int l2 = o2.getLeft();
              if (l1 < l2) {
                  return -1;
              }
              if (l1 > l2) {
                  return +1;
              }
              return 0;
          }
      }
  
      /** A map of positions by element id. */
      private Map<String, CmsPositionBean> m_positionMap = new HashMap<String, CmsPositionBean>();
  
      /** The internal list of positions. */
      private List<CmsPositionBean> m_positions = new ArrayList<CmsPositionBean>();
  
      /** The assumed width of a direct edit button bar. */
      private static int WIDTH = 65;
  
      /** The assumed height of a direct edit button bar. */
      private static int HEIGHT = 24;
  
      /**
       * Creates a new instance.<p>
       *
       * @param positions the map of original positions by element id (will not be altered)
       */
      public CmsEditablePositionCalculator(Map<String, CmsPositionBean> positions) {
  
          for (Map.Entry<String, CmsPositionBean> entry : positions.entrySet()) {
              CmsPositionBean newPos = new CmsPositionBean(entry.getValue());
              m_positionMap.put(entry.getKey(), newPos);
              m_positions.add(newPos);
          }
      }
  
      /**
       * Calculates non-overlapping positions for the button bars and returns them in a map with
       * the element ids as keys.<p>
       *
       * @return the map of non-overlapping positions
       */
      public Map<String, CmsPositionBean> calculatePositions() {
  
          int maxCollisions = 500;
          // if there are more than 500 collisions, the style is probably messed up; give up.
          while (checkCollision() && (maxCollisions > 0)) {
              maxCollisions -= 1;
          }
          return m_positionMap;
      }
  
      /**
       * Checks whether a collision occurs and handle it if necessary.<p>
       *
       * @return true if a collision occured
       */
      protected boolean checkCollision() {
  
          // sort the positions by their left x coordinate, so we can easily exclude
          // pairs of positions which don't overlap horizontally
          sortByLeft();
          int i;
          for (i = 0; i < m_positions.size(); i++) {
              for (int j = i + 1; (j < m_positions.size())
                  && intersectsHorizontally(m_positions.get(i), m_positions.get(j)); j++) {
                  if (intersectsVertically(m_positions.get(i), m_positions.get(j))) {
                      handleCollision(m_positions.get(i), m_positions.get(j));
                      return true;
                  }
              }
          }
          return false;
      }
  
      /**
       * Handles a collision by moving the lower position down.<p>
       *
       * @param p1 the first position
       * @param p2 the second position
       */
      protected void handleCollision(CmsPositionBean p1, CmsPositionBean p2) {
  
          CmsPositionBean positionToChange = p1;
          if (p1.getTop() <= p2.getTop()) {
              positionToChange = p2;
          }
          positionToChange.setTop(positionToChange.getTop() + 25);
      }
  
      /**
       * Checks for intersection of two one-dimensional intervals.<p>
       *
       * @param a1 the left edge of the first interval
       * @param a2 the right edge of the first interval
       * @param b1 the left edge of the second interval
       * @param b2 the right edge of the second interval
       *
       * @return true if the intervals intersect
       */
      protected boolean intersectIntervals(int a1, int a2, int b1, int b2) {
  
          return !((a2 < b1) || (a1 > b2));
      }
  
      /**
       * Checks whether two positions intersect horizontally.<p>
       *
       * @param p1 the first position
       * @param p2 the second position
       *
       * @return true if the positions intersect horizontally
       */
      protected boolean intersectsHorizontally(CmsPositionBean p1, CmsPositionBean p2) {
  
          return intersectIntervals(p1.getLeft(), p1.getLeft() + WIDTH, p2.getLeft(), p2.getLeft() + WIDTH);
      }
  
      /**
       * Checks whether two positions intersect vertically.<p>
       *
       * @param p1 the first position
       * @param p2 the second position
       *
       * @return if the positions intersect vertically
       */
      protected boolean intersectsVertically(CmsPositionBean p1, CmsPositionBean p2) {
  
          return intersectIntervals(p1.getTop(), p1.getTop() + HEIGHT, p2.getTop(), p2.getTop() + HEIGHT);
      }
  
      /**
       * Sorts the internal list of positions by their left edge.<p>
       */
      protected void sortByLeft() {
  
          Collections.sort(m_positions, new LeftComparator());
      }
  
  }
  