/*
 * Copyright 2009 The Apache Software Foundation
 *
 * 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.hadoop.hbase.regionserver;

import org.apache.hadoop.hbase.regionserver.KeyValueScanner;
import org.apache.hadoop.hbase.KeyValue;

import java.util.ArrayList;
import java.util.Iterator;
import java.util.Collections;
import java.util.List;

/**
 * A fixture that implements and presents a KeyValueScanner.
 * It takes a list of key/values which is then sorted according
 * to the provided comparator, and then the whole thing pretends
 * to be a store file scanner.
 */
public class KeyValueScanFixture implements KeyValueScanner {
  ArrayList<KeyValue> data;
  Iterator<KeyValue> iter = null;
  KeyValue current = null;
  KeyValue.KVComparator comparator;

  public KeyValueScanFixture(KeyValue.KVComparator comparator,
                             KeyValue... incData) {
    this.comparator = comparator;

    data = new ArrayList<KeyValue>(incData.length);
    for( int i = 0; i < incData.length ; ++i) {
      data.add(incData[i]);
    }
    Collections.sort(data, this.comparator);
  }

  public static List<KeyValueScanner> scanFixture(KeyValue[] ... kvArrays) {
    ArrayList<KeyValueScanner> scanners = new ArrayList<KeyValueScanner>();
    for (KeyValue [] kvs : kvArrays) {
      scanners.add(new KeyValueScanFixture(KeyValue.COMPARATOR, kvs));
    }
    return scanners;
  }


  @Override
  public KeyValue peek() {
    return this.current;
  }

  @Override
  public KeyValue next() {
    KeyValue res = current;

    if (iter.hasNext())
      current = iter.next();
    else
      current = null;
    return res;
  }

  @Override
  public boolean seek(KeyValue key) {
    // start at beginning.
    iter = data.iterator();
      int cmp;
    KeyValue kv = null;
    do {
      if (!iter.hasNext()) {
        current = null;
        return false;
      }
      kv = iter.next();
      cmp = comparator.compare(key, kv);
    } while (cmp > 0);
    current = kv;
    return true;
  }

  @Override
  public boolean reseek(KeyValue key) {
    return seek(key);
  }

  @Override
  public void close() {
    // noop.
  }

  @Override
  public long getSequenceID() {
    return 0;
  }
}