/*
 * 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.pirk.querier.wideskies.decrypt;

import java.math.BigInteger;
import java.util.ArrayList;
import java.util.HashMap;
import java.util.List;
import java.util.Map;
import java.util.TreeMap;
import java.util.concurrent.Callable;

import org.apache.pirk.query.wideskies.QueryInfo;
import org.apache.pirk.query.wideskies.QueryUtils;
import org.apache.pirk.schema.query.QuerySchema;
import org.apache.pirk.schema.query.QuerySchemaRegistry;
import org.apache.pirk.schema.response.QueryResponseJSON;
import org.apache.pirk.utils.PIRException;
import org.slf4j.Logger;
import org.slf4j.LoggerFactory;

/**
 * Runnable class for multithreaded PIR decryption
 * <p>
 * NOTE: rElements and selectorMaskMap are joint access objects, for now
 *
 */
class DecryptResponseTask<V> implements Callable<Map<String,List<QueryResponseJSON>>>
{
  private static final Logger logger = LoggerFactory.getLogger(DecryptResponseTask.class);

  private final List<BigInteger> rElements;
  private final TreeMap<Integer,String> selectors;
  private final Map<String,BigInteger> selectorMaskMap;
  private final QueryInfo queryInfo;

  private final Map<Integer,String> embedSelectorMap;

  public DecryptResponseTask(List<BigInteger> rElementsInput, TreeMap<Integer,String> selectorsInput, Map<String,BigInteger> selectorMaskMapInput,
      QueryInfo queryInfoInput, Map<Integer,String> embedSelectorMapInput)
  {
    rElements = rElementsInput;
    selectors = selectorsInput;
    selectorMaskMap = selectorMaskMapInput;
    queryInfo = queryInfoInput;
    embedSelectorMap = embedSelectorMapInput;
  }

  @Override
  public Map<String,List<QueryResponseJSON>> call() throws PIRException
  {
    // Pull the necessary parameters
    int dataPartitionBitSize = queryInfo.getDataPartitionBitSize();
    int numPartitionsPerDataElement = queryInfo.getNumPartitionsPerDataElement();

    QuerySchema qSchema = QuerySchemaRegistry.get(queryInfo.getQueryType());
    String selectorName = qSchema.getSelectorName();

    // Result is a map of (selector -> List of hits).
    Map<String,List<QueryResponseJSON>> resultMap = new HashMap<>(selectors.size());
    for (String selector : selectors.values())
    {
      resultMap.put(selector, new ArrayList<QueryResponseJSON>());
    }

    // Pull the hits for each selector
    int maxHitsPerSelector = rElements.size() / numPartitionsPerDataElement; // Max number of data hits in the response elements for a given selector
    logger.debug("numResults = " + rElements.size() + " numPartitionsPerDataElement = " + numPartitionsPerDataElement + " maxHits = " + maxHitsPerSelector);

    for (int hits = 0; hits < maxHitsPerSelector; hits++)
    {
      int selectorIndex = selectors.firstKey();
      while (selectorIndex <= selectors.lastKey())
      {
        String selector = selectors.get(selectorIndex);
        logger.debug("selector = " + selector);

        List<BigInteger> parts = new ArrayList<>();
        boolean zeroElement = true;
        for (int partNum = 0; partNum < numPartitionsPerDataElement; partNum++)
        {
          BigInteger part = (rElements.get(hits * numPartitionsPerDataElement + partNum)).and(selectorMaskMap.get(selector)); // pull off the correct bits

          logger.debug("rElements.get(" + (hits * numPartitionsPerDataElement + partNum) + ") = "
              + rElements.get(hits * numPartitionsPerDataElement + partNum).toString(2) + " bitLength = "
              + rElements.get(hits * numPartitionsPerDataElement + partNum).bitLength() + " val = "
              + rElements.get(hits * numPartitionsPerDataElement + partNum));
          logger.debug("colNum = " + (hits * numPartitionsPerDataElement + partNum) + " partNum = " + partNum + " part = " + part);

          part = part.shiftRight(selectorIndex * dataPartitionBitSize);
          parts.add(part);

          logger.debug("partNum = " + partNum + " part = " + part.intValue());

          zeroElement = zeroElement && part.equals(BigInteger.ZERO);
        }

        logger.debug("parts.size() = " + parts.size());

        if (!zeroElement)
        {
          // Convert biHit to the appropriate QueryResponseJSON object, based on the queryType
          QueryResponseJSON qrJOSN = QueryUtils.extractQueryResponseJSON(queryInfo, qSchema, parts);
          qrJOSN.setMapping(selectorName, selector);
          logger.debug("selector = " + selector + " qrJOSN = " + qrJOSN.getJSONString());

          // Add the hit for this selector - if we are using embedded selectors, check to make sure
          // that the hit's embedded selector in the qrJOSN and the once in the embedSelectorMap match
          boolean addHit = true;
          if (queryInfo.getEmbedSelector())
          {
            if (!(embedSelectorMap.get(selectorIndex)).equals(qrJOSN.getValue(QueryResponseJSON.SELECTOR)))
            {
              addHit = false;
              logger.debug("qrJOSN embedded selector = " + qrJOSN.getValue(QueryResponseJSON.SELECTOR) + " != original embedded selector = "
                  + embedSelectorMap.get(selectorIndex));
            }
          }
          if (addHit)
          {
            List<QueryResponseJSON> selectorHitList = resultMap.get(selector);
            selectorHitList.add(qrJOSN);
            resultMap.put(selector, selectorHitList);

            // Add the selector into the wlJSONHit
            qrJOSN.setMapping(QueryResponseJSON.SELECTOR, selector);
          }
        }

        ++selectorIndex;
      }
    }

    return resultMap;
  }
}