/*
 * 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.accumulo.testing.continuous;

import static com.google.common.util.concurrent.Uninterruptibles.sleepUninterruptibly;
import static java.nio.charset.StandardCharsets.UTF_8;

import java.util.Iterator;
import java.util.Map.Entry;
import java.util.Random;
import java.util.concurrent.TimeUnit;

import org.apache.accumulo.core.client.AccumuloClient;
import org.apache.accumulo.core.client.Scanner;
import org.apache.accumulo.core.data.Key;
import org.apache.accumulo.core.data.Range;
import org.apache.accumulo.core.data.Value;
import org.apache.accumulo.core.security.Authorizations;
import org.apache.accumulo.testing.TestProps;
import org.apache.hadoop.io.Text;
import org.slf4j.Logger;
import org.slf4j.LoggerFactory;

public class ContinuousScanner {
  private static final Logger log = LoggerFactory.getLogger(ContinuousScanner.class);

  public static void main(String[] args) throws Exception {

    try (ContinuousEnv env = new ContinuousEnv(args)) {

      Random r = new Random();

      long distance = 1000000000000l;

      AccumuloClient client = env.getAccumuloClient();
      Authorizations auths = env.getRandomAuthorizations();
      Scanner scanner = ContinuousUtil.createScanner(client, env.getAccumuloTableName(), auths);

      int numToScan = Integer.parseInt(env.getTestProperty(TestProps.CI_SCANNER_ENTRIES));
      int scannerSleepMs = Integer.parseInt(env.getTestProperty(TestProps.CI_SCANNER_SLEEP_MS));

      double delta = Math.min(.05, .05 / (numToScan / 1000.0));

      while (true) {
        long startRow = ContinuousIngest.genLong(env.getRowMin(), env.getRowMax() - distance, r);
        byte[] scanStart = ContinuousIngest.genRow(startRow);
        byte[] scanStop = ContinuousIngest.genRow(startRow + distance);

        scanner.setRange(new Range(new Text(scanStart), new Text(scanStop)));

        int count = 0;
        Iterator<Entry<Key,Value>> iter = scanner.iterator();

        long t1 = System.currentTimeMillis();

        while (iter.hasNext()) {
          Entry<Key,Value> entry = iter.next();
          ContinuousWalk.validate(entry.getKey(), entry.getValue());
          count++;
        }

        long t2 = System.currentTimeMillis();

        if (count < (1 - delta) * numToScan || count > (1 + delta) * numToScan) {
          if (count == 0) {
            distance = distance * 10;
            if (distance < 0)
              distance = 1000000000000l;
          } else {
            double ratio = (double) numToScan / count;
            // move ratio closer to 1 to make change slower
            ratio = ratio - (ratio - 1.0) * (2.0 / 3.0);
            distance = (long) (ratio * distance);
          }
        }

        log.debug("SCN {} {} {} {}", t1, new String(scanStart, UTF_8), (t2 - t1), count);

        if (scannerSleepMs > 0) {
          sleepUninterruptibly(scannerSleepMs, TimeUnit.MILLISECONDS);
        }
      }
    }
  }
}