/*
    * #%L
    * prolobjectlink-jpi-jtrolog
    * %%
    * Copyright (C) 2012 - 2018 WorkLogic Project
    * %%
    * This program 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 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 Lesser Public License for more details.
   * 
   * You should have received a copy of the GNU General Lesser Public
   * License along with this program.  If not, see
   * <http://www.gnu.org/licenses/lgpl-2.1.html>.
   * #L%
   */
  package jTrolog.engine;
  
  import jTrolog.terms.Struct;
  import jTrolog.terms.Term;
  import jTrolog.terms.Clause;
  
  import java.util.*;
  
  /**
   * Map for storing clauses in the LibraryAndTheoryManager
   * 
   * @author ivar.orstavik@hist.no
   */
  @SuppressWarnings({ "rawtypes", "unchecked","serial" })
  class ClauseDatabase extends LinkedHashMap {
  
  	public void addFirst(Object key, Object d) {
  		LinkedList family = (LinkedList) get(key);
  		if (family == null)
  			put(key, family = new LinkedList());
  		family.addFirst(d);
  	}
  
  	public void addLast(Object key, Object d) {
  		LinkedList family = (LinkedList) get(key);
  		if (family == null)
  			put(key, family = new LinkedList());
  		family.addLast(d);
  	}
  
  	public List getPredicates(Object key) {
  		LinkedList family = (LinkedList) get(key);
  		if (family == null)
  			return new LinkedList();
  		return family;
  	}
  
  	public List getPredicatesIterator(Object key) {
  		return (LinkedList) get(key);
  	}
  
  	public Object restore(Object s) {
  		return s;
  	}
  
  	public LinkedList abolish(Object key) {
  		return (LinkedList) remove(key);
  	}
  
  	public Iterator iterator() {
  		return new CompleteIterator(this);
  	}
  
  	public String toString() {
  		StringBuffer buffer = new StringBuffer();
  		for (Iterator dynamicClauses = iterator(); dynamicClauses.hasNext();) {
  			Struct d = ((Clause) dynamicClauses.next()).original;
  			buffer.append(d.getArg(0).toString());
  			if (d.getArg(1).equals(Term.TRUE))
  				buffer.append(".\n");
  			else
  				buffer.append(":-\n\t").append(d.getArg(1).toString()).append(".\n");
  		}
  		return buffer.toString();
  	}
  
  	private static class CompleteIterator implements Iterator {
  		Iterator values;
  		Iterator workingList;
  		ClauseDatabase cdb;
  
  		public CompleteIterator(ClauseDatabase clauseDatabase) {
  			cdb = clauseDatabase;
  			values = clauseDatabase.values().iterator();
  		}
  
  		public boolean hasNext() {
  			if (workingList != null && workingList.hasNext())
 				return true;
 			if (values.hasNext()) {
 				workingList = ((List) values.next()).iterator();
 				return hasNext(); // start again on next workingList
 			}
 			return false;
 		}
 
 		public Object next() {
 			Clause modified = (Clause) workingList.next();
 			return cdb.restore(modified);
 		}
 
 		public void remove() {
 			workingList.remove();
 		}
 	}
 }