content: /*
   * Copyright (c) 1997 - 2022
   * Idorsia Pharmaceuticals Ltd.
   * Hegenheimermattweg 91
   * CH-4123 Allschwil, Switzerland
   *
   * All rights reserved.
   *
   * Redistribution and use in source and binary forms, with or without
   * modification, are permitted provided that the following conditions are met:
   *
   * 1. Redistributions of source code must retain the above copyright notice, this
   *    list of conditions and the following disclaimer.
   * 2. Redistributions in binary form must reproduce the above copyright notice,
   *    this list of conditions and the following disclaimer in the documentation
   *    and/or other materials provided with the distribution.
   * 3. Neither the name of the copyright holder nor the
   *    names of its contributors may be used to endorse or promote products
   *    derived from this software without specific prior written permission.
   *
   * THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS "AS IS" AND
   * ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE IMPLIED
   * WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE ARE
   * DISCLAIMED. IN NO EVENT SHALL THE COPYRIGHT OWNER OR CONTRIBUTORS BE LIABLE FOR
   * ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES
   * (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES;
   * LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND
   * ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT
   * (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE OF THIS
   * SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.
   *
   * @author Modest v. Korff
   */
  
  package com.actelion.research.chem.descriptor.flexophore;
  
  import java.util.ArrayList;
  import java.util.List;
  
  public class MDHIndexTables {
  	
  	
  	private static MDHIndexTables INSTANCE = null;
  	
  	private static final int MAX_SIZE = 50;
  	
  	private List<int [][]> liArrAtPairsBonds;
  	
  	private List<int [][]> liConnectionTable;
  	
  	private MDHIndexTables() {
  		init();
  	}
  	
  	public static MDHIndexTables getInstance(){
  		if(INSTANCE==null)
  			INSTANCE=new MDHIndexTables();
  		
  		return INSTANCE;
  	}
  	
  	private void init(){
  		
  		liArrAtPairsBonds = new ArrayList<int[][]>();
  		liArrAtPairsBonds.add(0, null);
  		liArrAtPairsBonds.add(1, null);
  		for (int i = 2; i < MAX_SIZE+1; i++) {
  			liArrAtPairsBonds.add(i, createBondTable(i));
  		}
  		
  		liConnectionTable = new ArrayList<int[][]>();
  		liConnectionTable.add(0, null);
  		liConnectionTable.add(1, null);
  		for (int i = 2; i < MAX_SIZE+1; i++) {
  			liConnectionTable.add(i, createConnectionTable(i));
  		}
  	}
  	
  	private int [][] createBondTable(int nodes){
  		
  		int bonds = ((nodes * nodes)-nodes) / 2;
  		
  		int [][] arrAtPairsBonds = new int [2][bonds];
  		int cc=0;
  		for (int i = 0; i < nodes; i++) {
  			for (int j = i+1; j < nodes; j++) {
  				arrAtPairsBonds[0][cc]=i;
  				arrAtPairsBonds[1][cc]=j;
  				cc++;
  			}
  		}
  		
  		return arrAtPairsBonds;
  	}
  	
  	private int [][] createConnectionTable(int nodes){
  		
  		int [][] arrAtPairsBonds = liArrAtPairsBonds.get(nodes);
  		
  		int bonds = ((nodes * nodes)-nodes) / 2;
  		int [][] arrConnBond = new int [nodes][nodes-1];
  		int [] arrNumBonds = new int [nodes];
  		for(int bnd=0; bnd< bonds; bnd++) {
  			int at1 = arrAtPairsBonds[0][bnd];
  			int at2 = arrAtPairsBonds[1][bnd];
  			
  			arrConnBond[at1][arrNumBonds[at1]++]=bnd;
  			arrConnBond[at2][arrNumBonds[at2]++]=bnd;
  			
  		}
  		return arrConnBond;
  	}
  	
  	public int [][] getAtomPairsBondsTable(int nodes){
  		return liArrAtPairsBonds.get(nodes);
  	}
  	
  	public int [][] getConnectionTable(int nodes){
  		return liConnectionTable.get(nodes);
  	}
  
  }
  