////////////////////////////////////////////////////////////////////////////////
/// DISCLAIMER
///
/// Copyright 2014-2016 ArangoDB GmbH, Cologne, Germany
/// Copyright 2004-2014 triAGENS GmbH, Cologne, Germany
///
/// Licensed 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.
///
/// Copyright holder is ArangoDB GmbH, Cologne, Germany
///
/// @author Jan Steemann
////////////////////////////////////////////////////////////////////////////////

#include "Aggregator.h"

using namespace triagens::basics;
using namespace triagens::aql;
    
Aggregator* Aggregator::fromTypeString(triagens::arango::AqlTransaction* trx, std::string const& type) {
  if (type == "LENGTH") {
    return new AggregatorLength(trx);
  }
  if (type == "MIN") {
    return new AggregatorMin(trx);
  }
  if (type == "MAX") {
    return new AggregatorMax(trx);
  }
  if (type == "SUM") {
    return new AggregatorSum(trx);
  }
  if (type == "AVERAGE") {
    return new AggregatorAverage(trx);
  }

  // aggregator function name should have been validated before
  TRI_ASSERT(false);
  return nullptr;
}

Aggregator* Aggregator::fromJson(triagens::arango::AqlTransaction* trx,
                                 triagens::basics::Json const& json,  
                                 char const* variableName) {
  triagens::basics::Json variableJson = json.get(variableName);

  if (variableJson.isString()) {
    std::string const type(variableJson.json()->_value._string.data, variableJson.json()->_value._string.length - 1);
    return fromTypeString(trx, type);
  }

  THROW_ARANGO_EXCEPTION_MESSAGE(TRI_ERROR_INTERNAL, "invalid aggregate function"); 
}

bool Aggregator::isSupported(std::string const& type) {
  return (type == "LENGTH" ||
      type == "MIN" ||
      type == "MAX" ||
      type == "SUM" ||
      type == "AVERAGE");
}

  
void AggregatorLength::reset() {
  count = 0;
}

void AggregatorLength::reduce(AqlValue const&, TRI_document_collection_t const*) {
  ++count;
}
  
AqlValue AggregatorLength::stealValue() {
  uint64_t copy = count;
  count = 0; 
  return AqlValue(new Json(static_cast<double>(copy)));
}

AggregatorMin::~AggregatorMin() {
  value.destroy();
}

void AggregatorMin::reset() {
  value.destroy();
}

void AggregatorMin::reduce(AqlValue const& cmpValue,
                           TRI_document_collection_t const* cmpColl) {
  if (value.isEmpty() || 
      AqlValue::Compare(trx, value, coll, cmpValue, cmpColl, true) > 0) {
    value.destroy();
    value = cmpValue.clone();
    coll = cmpColl;
  }
}
  
AqlValue AggregatorMin::stealValue() {
  AqlValue copy = value;
  value.erase();
  return copy;
}

AggregatorMax::~AggregatorMax() {
  value.destroy();
}

void AggregatorMax::reset() {
  value.destroy();
}

void AggregatorMax::reduce(AqlValue const& cmpValue,
                           TRI_document_collection_t const* cmpColl) {
  if (value.isEmpty() || 
      AqlValue::Compare(trx, value, coll, cmpValue, cmpColl, true) < 0) {
    value.destroy();
    value = cmpValue.clone();
    coll = cmpColl;
  }
}

AqlValue AggregatorMax::stealValue() {
  AqlValue copy = value;
  value.erase();
  return copy;
}

AggregatorSum::~AggregatorSum() {
}

void AggregatorSum::reset() {
  sum = 0.0;
  invalid = false;
}

void AggregatorSum::reduce(AqlValue const& cmpValue,
                           TRI_document_collection_t const*) {
  if (!invalid && cmpValue.isNumber()) {
    bool failed = false;
    double number = cmpValue.toNumber(failed);
    if (! failed && !std::isnan(number) && number != HUGE_VAL && number != -HUGE_VAL) {
      sum += number;
      return;
    }
  }

  invalid = true;
}

AqlValue AggregatorSum::stealValue() {
  if (invalid || std::isnan(sum) || sum == HUGE_VAL || sum == -HUGE_VAL) {
    return AqlValue(new triagens::basics::Json(triagens::basics::Json::Null));
  }

  return AqlValue(new triagens::basics::Json(sum));
}

AggregatorAverage::~AggregatorAverage() {
}

void AggregatorAverage::reset() {
  count = 0;
  sum = 0.0;
  invalid = false;
}

void AggregatorAverage::reduce(AqlValue const& cmpValue,
                               TRI_document_collection_t const*) {
  if (!invalid && cmpValue.isNumber()) {
    bool failed = false;
    double number = cmpValue.toNumber(failed);
    if (! failed && !std::isnan(number) && number != HUGE_VAL && number != -HUGE_VAL) {
      sum += number;
      ++count;
      return;
    }
  }

  invalid = true;
}

AqlValue AggregatorAverage::stealValue() {
  if (invalid || count == 0 || std::isnan(sum) || sum == HUGE_VAL || sum == -HUGE_VAL) {
    return AqlValue(new triagens::basics::Json(triagens::basics::Json::Null));
  }

  TRI_ASSERT(count > 0);

  return AqlValue(new triagens::basics::Json(sum / static_cast<double>(count)));
}