/*
 * Licensed to the Apache Software Foundation (ASF) under one
 * or more contributor license agreements.  See the NOTICE file
 * distributed with this work for additional information
 * regarding copyright ownership.  The ASF licenses this file
 * to you 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.apache.uima.cas.impl;

import java.util.Arrays;
import java.util.Comparator;
import java.util.NoSuchElementException;

import org.apache.uima.cas.FSIndex;
import org.apache.uima.cas.FSIterator;
import org.apache.uima.cas.FeatureStructure;
import org.apache.uima.jcas.cas.TOP;

public class FsIterator_subtypes_snapshot<T extends FeatureStructure>
        implements LowLevelIterator<T>, Comparator<FeatureStructure> {

  // final private FsIndex_flat<T> flatIndex; // a newly created one, just for this iterator
  private final T[] snapshot; // local for ref speed
  private int pos = 0;
  /** support for alternative source iterating, where there is no order */
  private final boolean is_unordered;
  private final LowLevelIndex<T> indexForComparator;

  private final boolean isNotUimaIndexSource;

  private final Comparator<TOP> comparatorMaybeNoTypeWithoutId;

  // public FsIterator_subtypes_snapshot(FsIndex_flat<T> flatIndex) {
  // this(flatIndex, false);
  // }

  public FsIterator_subtypes_snapshot(FsIndex_flat<T> flatIndex,
          Comparator<TOP> comparatorMaybeNoTypeWithoutId) {
    indexForComparator = flatIndex;
    snapshot = (T[]) flatIndex.getFlatArray();
    is_unordered = flatIndex.getIndexingStrategy() != FSIndex.SORTED_INDEX;
    this.comparatorMaybeNoTypeWithoutId = comparatorMaybeNoTypeWithoutId;
    isNotUimaIndexSource = false;
  }

  /**
   * Alternative source iterator, 1st arg is different (not an "index", just an array) - altSources
   * are unordered, and NoType is ignored - also supports backwards iterators, these are ordered
   * (Maybe fix this in the future - this is not necessarily required)
   * 
   * 
   * @param snapshot
   *          -
   * @param index
   *          -
   * @param is_unordered
   *          - mark as unordered
   * @param comparatorMaybeNoTypeWithoutId
   *          -
   */
  public FsIterator_subtypes_snapshot(T[] snapshot, LowLevelIndex<T> index, boolean is_unordered,
          Comparator<TOP> comparatorMaybeNoTypeWithoutId) {
    indexForComparator = index;
    this.snapshot = snapshot;
    this.is_unordered = is_unordered;
    this.comparatorMaybeNoTypeWithoutId = comparatorMaybeNoTypeWithoutId;
    isNotUimaIndexSource = true;
  }

  /*
   * (non-Javadoc)
   * 
   * @see org.apache.uima.cas.FSIterator#isValid()
   */
  @Override
  public boolean isValid() {
    return (0 <= pos) && (pos < snapshot.length);
  }

  /*
   * (non-Javadoc)
   * 
   * @see org.apache.uima.cas.FSIterator#get()
   */
  @Override
  public T get() throws NoSuchElementException {
    if (isValid()) {
      return snapshot[pos];
    }
    throw new NoSuchElementException();
  }

  /*
   * (non-Javadoc)
   * 
   * @see org.apache.uima.cas.FSIterator#get()
   */
  @Override
  public T getNvc() {
    return snapshot[pos];
  }

  /*
   * (non-Javadoc)
   * 
   * @see org.apache.uima.cas.FSIterator#moveToNext()
   */
  @Override
  public void moveToNext() {
    if (isValid()) {
      pos++;
    }
  }

  @Override
  public void moveToNextNvc() {
    pos++;
  }

  /*
   * (non-Javadoc)
   * 
   * @see org.apache.uima.cas.FSIterator#moveToPrevious()
   */
  @Override
  public void moveToPrevious() {
    if (isValid()) {
      pos--;
    }
  }

  @Override
  public void moveToPreviousNvc() {
    pos--;
  }

  /*
   * (non-Javadoc)
   * 
   * @see org.apache.uima.cas.FSIterator#moveToFirst()
   */
  @Override
  public void moveToFirstNoReinit() {
    pos = 0;
  }

  /*
   * (non-Javadoc)
   * 
   * @see org.apache.uima.cas.FSIterator#moveToLast()
   */
  @Override
  public void moveToLastNoReinit() {
    pos = snapshot.length - 1;
  }

  /*
   * (non-Javadoc)
   * 
   * @see org.apache.uima.cas.FSIterator#moveTo(org.apache.uima.cas.FeatureStructure)
   */
  @Override
  public void moveToNoReinit(FeatureStructure fs) {
    if (is_unordered) {
      int i = 0;
      while ((i < snapshot.length) && compare(snapshot[i], fs) != 0) {
        i++;
      }
      pos = i;
    } else {
      int c = Arrays.binarySearch(snapshot, 0, snapshot.length, fs, this);
      if (c < 0) {
        // was not found, c is (-(insertion point) - 1)
        // insertion point c pos
        // 0 -1 0
        // 1 -2 1
        // size - 1 -(size - 1) - 1 size - 1
        // size -size - 1 size (invalid)
        pos = (-c) - 1;
      } else {
        // found an equal. need to move to leftmost
        c--;
        while ((c >= 0) && compare(snapshot[c], fs) == 0) {
          c--;
        }
        pos = c + 1;
      }
    }
  }

  // /* (non-Javadoc)
  // * @see org.apache.uima.cas.FSIterator#moveTo(org.apache.uima.cas.FeatureStructure)
  // */
  // @Override
  // public void moveToExactNoReinit(FeatureStructure fs) {
  //// if (is_unordered) {
  // int i = 0;
  // while ((i < snapshot.length) && snapshot[i] != fs) {
  // i++;
  // }
  // pos = i;
  //// } else {
  //// // next doesn't work, the snapshot is not sorted by the comparator
  ////// pos = Arrays.binarySearch(snapshot, fs);
  //// if ()
  //// }
  // }

  /*
   * (non-Javadoc)
   * 
   * @see org.apache.uima.cas.FSIterator#copy()
   */
  @Override
  public FSIterator<T> copy() {
    FsIterator_subtypes_snapshot<T> it = new FsIterator_subtypes_snapshot<>(snapshot,
            indexForComparator, is_unordered, comparatorMaybeNoTypeWithoutId);
    it.pos = pos;
    return it;
  }

  /*
   * (non-Javadoc)
   * 
   * @see org.apache.uima.cas.impl.LowLevelIterator#ll_indexSize()
   */
  @Override
  public int ll_indexSizeMaybeNotCurrent() {
    return snapshot.length;
  }

  @Override
  public int ll_maxAnnotSpan() {
    return indexForComparator.ll_maxAnnotSpan();
  }

  /*
   * (non-Javadoc)
   * 
   * @see org.apache.uima.cas.impl.LowLevelIterator#ll_getIndex()
   */
  @Override
  public LowLevelIndex<T> ll_getIndex() {
    return indexForComparator;
  }

  @Override
  public int compare(FeatureStructure fs1, FeatureStructure fs2) {
    return (null == comparatorMaybeNoTypeWithoutId) ? Integer.compare(fs1._id(), fs2._id())
            : comparatorMaybeNoTypeWithoutId.compare((TOP) fs1, (TOP) fs2);
  }

  /*
   * (non-Javadoc)
   * 
   * @see org.apache.uima.cas.impl.LowLevelIterator#isIndexesHaveBeenUpdated()
   */
  @Override
  public boolean isIndexesHaveBeenUpdated() {
    return false;
  }

  @Override
  public boolean maybeReinitIterator() {
    return false;
  }

  @Override
  public Comparator<TOP> getComparator() {
    return comparatorMaybeNoTypeWithoutId;
  }

  @Override
  public int size() {
    return snapshot.length;
  }
}
