/*
 * 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;

import com.google.gson.Gson;
import com.google.gson.JsonDeserializationContext;
import com.google.gson.JsonDeserializer;
import com.google.gson.JsonElement;
import com.google.gson.JsonObject;
import com.google.gson.JsonParseException;
import com.google.gson.reflect.TypeToken;
import org.apache.pirk.encryption.Paillier;
import org.apache.pirk.query.wideskies.Query;

import java.lang.reflect.Type;
import java.math.BigInteger;
import java.util.List;
import java.util.Map;

/**
 * Custom deserializer for Querier class for Gson.
 */
public class QuerierDeserializer implements JsonDeserializer<Querier>
{

  private static final Gson gson = new Gson();

  @Override
  public Querier deserialize(JsonElement jsonElement, Type type, JsonDeserializationContext jsonDeserializationContext) throws JsonParseException
  {
    JsonObject jsonObject = jsonElement.getAsJsonObject();
    // Check the version number.
    long querierVersion = jsonObject.get("querierVersion").getAsLong();
    if (querierVersion != Querier.querierSerialVersionUID)
    {
      throw new JsonParseException(
          "Attempt to deserialize unsupported query version. Supported: " + Querier.querierSerialVersionUID + "; Received: " + querierVersion);
    }
    // Then deserialize the Query Info
    Query query = gson.fromJson(jsonObject.get("query").toString(), Query.class);

    // Now Paillier
    Paillier paillier = deserializePaillier(jsonObject.get("paillier").getAsJsonObject());

    List<String> selectors = gson.fromJson(jsonObject.get("selectors").toString(), new TypeToken<List<String>>()
    {}.getType());
    Map<Integer,String> embedSelectorMap = gson.fromJson(jsonObject.get("embedSelectorMap").toString(), new TypeToken<Map<Integer,String>>()
    {}.getType());

    return new Querier(selectors, paillier, query, embedSelectorMap);
  }

  /**
   * Deserializes a Paillier JsonObject.
   *
   * @param paillier
   *          A JsonObject at the root of a serialied Paillier object.
   * @return A Paillier object of the deserialized Json.
   */
  private Paillier deserializePaillier(JsonObject paillier)
  {
    BigInteger p = new BigInteger(paillier.get("p").getAsString());
    BigInteger q = new BigInteger(paillier.get("q").getAsString());
    int bitLength = paillier.get("bitLength").getAsInt();
    return new Paillier(p, q, bitLength);
  }

}