/**
 * Copyright 2014 National University of Ireland, Galway.
 *
 * This file is part of the SIREn project. Project and contact information:
 *
 *  https://github.com/rdelbru/SIREn
 *
 * 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 org.sindice.siren.search.node;

import java.io.IOException;
import java.util.Collection;

import org.apache.lucene.search.Weight;
import org.apache.lucene.util.IntsRef;
import org.sindice.siren.index.DocsAndNodesIterator;
import org.sindice.siren.util.NodeUtils;

/**
 * An extensions of {@link NodeConjunctionScorer} for conjunctions of an
 * ancestor {@link NodeScorer} and a set of descendant {@link NodeScorer}s.
 *
 * <p>
 *
 * The root node (ancestor node) is considered matching if its scorers and all
 * the descendant scorers match the same node.
 **/
class TwigConjunctionScorer extends NodeConjunctionScorer {

  private final NodeScorer root;
  private final NodeScorer[] descendants;

  public TwigConjunctionScorer(final Weight weight, final float coord,
                               final NodeScorer root,
                               final Collection<NodeScorer> scorers)
  throws IOException {
    this(weight, coord, root, scorers.toArray(new NodeScorer[scorers.size()]));
  }

  public TwigConjunctionScorer(final Weight weight, final float coord,
                               final NodeScorer root,
                               final NodeScorer ... scorers)
  throws IOException {
    super(weight, coord, append(scorers, root));
    this.root = root;
    this.descendants = scorers;
  }

  private static final NodeScorer[] append(final NodeScorer[] array, final NodeScorer element) {
    final NodeScorer[] newArray = new NodeScorer[array.length + 1];
    System.arraycopy(array, 0, newArray, 0, array.length);
    newArray[newArray.length - 1] = element;
    return newArray;
  }

  @Override
  public int doc() {
    // return root.doc();
    return lastDocument;
  }

  @Override
  public IntsRef node() {
    // return root.node();
    return lastNode;
  }

  @Override
  public boolean nextNode() throws IOException {
  root: // label statement for the beginning of the loop
    while (root.nextNode()) {
      for (int i = 0; i < descendants.length; i++) {
        int c;
        while ((c = NodeUtils.compareAncestor(root.node(), descendants[i].node())) > 0) {
          if (!descendants[i].nextNode()) {
            lastNode = DocsAndNodesIterator.NO_MORE_NOD;
            return false;
          }
        }
        if (c < 0) { // root node behind
          // continue to the label statement and move to the next root's node
          continue root;
        }
      }
      // all equals
      lastNode = root.node();
      return true;
    }
    lastNode = DocsAndNodesIterator.NO_MORE_NOD;
    return false;
  }

  @Override
  public String toString() {
    return "TwigConjunctionScorer(" + weight + "," + this.doc() + "," +
      this.node() + ")";
  }

}