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/*
 * [New BSD License]
 * Copyright (c) 2011-2012, Brackit Project Team 
 * All rights reserved.
 *
 * Redistribution and use in source and binary forms, with or without
 * modification, are permitted provided that the following conditions are met:
 *     * Redistributions of source code must retain the above copyright
 *       notice, this list of conditions and the following disclaimer.
 *     * 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.
 *     * Neither the name of the Brackit Project Team 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 HOLDER 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.
 */
package io.brackit.query.sequence;

import java.util.Comparator;

import io.brackit.query.jdm.Item;
import io.brackit.query.jdm.Iter;
import io.brackit.query.jdm.Sequence;
import io.brackit.query.jdm.Stream;
import io.brackit.query.jdm.node.Node;
import io.brackit.query.util.sort.TupleSort;
import io.brackit.query.ErrorCode;
import io.brackit.query.QueryException;
import io.brackit.query.Tuple;

/**
 * @author Sebastian Baechle
 */
public class SortedNodeSequence extends LazySequence {
  private final Comparator cmp;
  private final Sequence in;
  private final boolean dedup;

  public SortedNodeSequence(Comparator cmp, Sequence in, boolean dedup) {
    this.cmp = cmp;
    this.in = in;
    this.dedup = dedup;
  }

  @Override
  public Iter iterate() {
    return new BaseIter() {
      // TODO -1 means no external sort
      final TupleSort sort = new TupleSort(cmp, -1);
      final Sequence source = in;

      Stream sorted;
      Node p;
      Node n;

      @Override
      public Item next() {
        if (sorted == null) {
          loadAndSort();
          sorted = sort.stream();
          n = (Node) sorted.next();
        }

        while (n != null) {
          if ((dedup) && (p != null) && (p.cmp(n) == 0)) {
            n = (Node) sorted.next();
          }
          Node deliver = n;
          p = n;
          n = (Node) sorted.next();
          return deliver;
        }
        return null;
      }

      @Override
      public void close() {
        if (sorted != null) {
          sorted.close();
        }
      }

      private void loadAndSort() {
        loadSorter(source, sort);
      }

      private void loadSorter(Sequence sequence, final TupleSort sort) {
        if (sequence instanceof Item) {
          if (!(sequence instanceof Node)) {
            throw new QueryException(ErrorCode.ERR_TYPE_INAPPROPRIATE_TYPE,
                                     "Illegal atomic item found in sequence: '%s'",
                                     sequence);
          }
          sort.add(sequence);
        } else {
          Item item;
          try (Iter it = sequence.iterate()) {
            while ((item = it.next()) != null) {
              if (!(item instanceof Node)) {
                throw new QueryException(ErrorCode.ERR_TYPE_INAPPROPRIATE_TYPE,
                                         "Illegal atomic item found in sequence: '%s'",
                                         item);
              }
              sort.add(item);
            }
          }
        }
        sort.sort();
      }
    };
  }
}