/*
 * 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
 *
 *   https://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.accumulo.core.iteratorsImpl.system;

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

import org.apache.accumulo.core.conf.AccumuloConfiguration;
import org.apache.accumulo.core.conf.Property;
import org.apache.accumulo.core.data.ByteSequence;
import org.apache.accumulo.core.data.Key;
import org.apache.accumulo.core.data.PartialKey;
import org.apache.accumulo.core.data.Range;
import org.apache.accumulo.core.data.Value;
import org.apache.accumulo.core.iterators.IteratorEnvironment;
import org.apache.accumulo.core.iterators.IteratorUtil;
import org.apache.accumulo.core.iterators.ServerWrappingIterator;
import org.apache.accumulo.core.iterators.SortedKeyValueIterator;

public class DeletingIterator extends ServerWrappingIterator {
  private final boolean propagateDeletes;
  private final Key workKey = new Key();

  public enum Behavior {
    PROCESS, FAIL
  }

  @Override
  public DeletingIterator deepCopy(IteratorEnvironment env) {
    return new DeletingIterator(this, env);
  }

  private DeletingIterator(DeletingIterator other, IteratorEnvironment env) {
    super(other.source.deepCopy(env));
    propagateDeletes = other.propagateDeletes;
  }

  private DeletingIterator(SortedKeyValueIterator<Key,Value> iterator, boolean propagateDeletes) {
    super(iterator);
    this.propagateDeletes = propagateDeletes;
  }

  @Override
  public void next() throws IOException {
    if (source.getTopKey().isDeleted()) {
      skipRowColumn();
    } else {
      source.next();
    }
    findTop();
  }

  @Override
  public void seek(Range range, Collection<ByteSequence> columnFamilies, boolean inclusive)
      throws IOException {
    // do not want to seek to the middle of a row
    Range seekRange = IteratorUtil.maximizeStartKeyTimeStamp(range);

    source.seek(seekRange, columnFamilies, inclusive);
    findTop();

    if (range.getStartKey() != null) {
      while (source.hasTop() && source.getTopKey().compareTo(range.getStartKey(),
          PartialKey.ROW_COLFAM_COLQUAL_COLVIS_TIME) < 0) {
        next();
      }

      while (hasTop() && range.beforeStartKey(getTopKey())) {
        next();
      }
    }
  }

  private void findTop() throws IOException {
    if (!propagateDeletes) {
      while (source.hasTop() && source.getTopKey().isDeleted()) {
        skipRowColumn();
      }
    }
  }

  private void skipRowColumn() throws IOException {
    workKey.set(source.getTopKey());

    Key keyToSkip = workKey;
    source.next();

    while (source.hasTop()
        && source.getTopKey().equals(keyToSkip, PartialKey.ROW_COLFAM_COLQUAL_COLVIS)) {
      source.next();
    }
  }

  @Override
  public void init(SortedKeyValueIterator<Key,Value> source, Map<String,String> options,
      IteratorEnvironment env) {
    throw new UnsupportedOperationException();
  }

  public static SortedKeyValueIterator<Key,Value> wrap(SortedKeyValueIterator<Key,Value> source,
      boolean propagateDeletes, Behavior behavior) {
    return switch (behavior) {
      case PROCESS -> new DeletingIterator(source, propagateDeletes);
      case FAIL -> new ServerWrappingIterator(source) {
        @Override
        public Key getTopKey() {
          Key top = source.getTopKey();
          if (top.isDeleted()) {
            throw new IllegalStateException("Saw unexpected delete " + top);
          }
          return top;
        }
      };
    };
  }

  public static Behavior getBehavior(AccumuloConfiguration conf) {
    return DeletingIterator.Behavior
        .valueOf(conf.get(Property.TABLE_DELETE_BEHAVIOR).toUpperCase());
  }
}
