/**
 * @license
 * Copyright 2013 Google Inc. All Rights Reserved.
 *
 * Licensed under the Apache License, Version 2.0 (the "License");
 * you may not use this file except in compliance with the License.
 * You may obtain a copy of the License at
 *
 *     http://www.apache.org/licenses/LICENSE-2.0
 *
 * Unless required by applicable law or agreed to in writing, software
 * distributed under the License is distributed on an "AS IS" BASIS,
 * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
 * See the License for the specific language governing permissions and
 * limitations under the License.
 */

package foam.dao;

import java.util.Comparator;
import java.util.Map;
import java.util.TreeMap;

import foam.core.Expression;
import foam.core.FObject;
import foam.core.Property;
import foam.core.PropertyComparator;
import foam.core.X;

public class TreeIndex implements Index {
  final Property prop_;
  
  public TreeIndex(Property p) {
    prop_ = p;
  }


  public Object put(Object state, FObject value) {
    if ( state == null ) state = new TreeMap(new PropertyComparator(prop_));

    ((Map) state).put(prop_.get(value), value);

    return state;
  }

  public Object remove(Object state, FObject value) {
    if ( state != null ) {
      ((Map) state).remove(prop_.get(value));

      if ( size(state) == 0 ) state = null;
    }

    return state;
  }
  
  public Plan plan(Object state, Sink sink, Expression<Boolean> p, Comparator c, long skip, long limit) {
    return new TreePlan();
  }

  public long size(Object state) {
    return state != null ? ((Map) state).size() : 0L;
  }

  class TreePlan implements Plan {
    public long cost() { return 1; }
    public String toString() { return "Tree Plan"; }
    public void execute(X x, Object state, Sink sink, Expression<Boolean> p, Comparator c, long skip, long limit)
        throws DAOException, DAOInternalException {
      if (state == null) return;


      TreeMap<Object, FObject> map = (TreeMap<Object, FObject>) state;
      if (sink instanceof MLang.CountSink && p == null) {
        ((MLang.CountSink) sink).setCount(Math.max((long) map.size() - skip, limit));
        return;
      }

      Iterable<FObject> i = IterableSelectHelper.decorate(map.values(), p, (Comparator<FObject>) c, skip, limit);
      for (FObject o : i) {
        sink.put(x, o);
      }
    }
  }
}