////////////////////////////////////////////////////////////////////////////////
/// 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 "Collection.h"
#include "Basics/StringUtils.h"
#include "Basics/Exceptions.h"
#include "Cluster/ClusterInfo.h"
#include "Cluster/ClusterMethods.h"
#include "Cluster/ServerState.h"
#include "VocBase/document-collection.h"
#include "VocBase/transaction.h"
#include "VocBase/vocbase.h"

#include <velocypack/Iterator.h>
#include <velocypack/velocypack-aliases.h>

using namespace arangodb::aql;

////////////////////////////////////////////////////////////////////////////////
/// @brief create a collection wrapper
////////////////////////////////////////////////////////////////////////////////

Collection::Collection(std::string const& name, TRI_vocbase_t* vocbase,
                       TRI_transaction_type_e accessType)
    : collection(nullptr),
      currentShard(),
      name(name),
      vocbase(vocbase),
      accessType(accessType),
      isReadWrite(false) {
  TRI_ASSERT(!name.empty());
  TRI_ASSERT(vocbase != nullptr);
}

////////////////////////////////////////////////////////////////////////////////
/// @brief destroy a collection wrapper
////////////////////////////////////////////////////////////////////////////////

Collection::~Collection() {}
  
////////////////////////////////////////////////////////////////////////////////
/// @brief get the pointer to the document collection
////////////////////////////////////////////////////////////////////////////////

TRI_document_collection_t* Collection::documentCollection() const {
  TRI_ASSERT(collection != nullptr);
  TRI_ASSERT(collection->_collection != nullptr);

  return collection->_collection;
}
  
////////////////////////////////////////////////////////////////////////////////
/// @brief count the number of documents in the collection
////////////////////////////////////////////////////////////////////////////////

size_t Collection::count() const {
  if (numDocuments == UNINITIALIZED) {
    if (arangodb::ServerState::instance()->isCoordinator()) {
      // cluster case
      uint64_t result;
      int res = arangodb::countOnCoordinator(vocbase->_name, name, result);
      if (res != TRI_ERROR_NO_ERROR) {
        THROW_ARANGO_EXCEPTION_MESSAGE(
            res, "could not determine number of documents in collection");
      }
      numDocuments = static_cast<int64_t>(result);
    } else {
      // local case
      auto document = documentCollection();
      // cache the result
      numDocuments = static_cast<int64_t>(document->size());
    }
  }

  return static_cast<size_t>(numDocuments);
}

////////////////////////////////////////////////////////////////////////////////
/// @brief returns the collection's plan id
////////////////////////////////////////////////////////////////////////////////

TRI_voc_cid_t Collection::getPlanId() const {
  auto clusterInfo = arangodb::ClusterInfo::instance();
  auto collectionInfo =
      clusterInfo->getCollection(std::string(vocbase->_name), name);

  if (collectionInfo.get() == nullptr) {
    THROW_ARANGO_EXCEPTION_FORMAT(TRI_ERROR_INTERNAL,
                                  "collection not found '%s' -> '%s'",
                                  vocbase->_name, name.c_str());
  }

  return collectionInfo.get()->id();
}

////////////////////////////////////////////////////////////////////////////////
/// @brief returns the shard ids of a collection
////////////////////////////////////////////////////////////////////////////////

std::shared_ptr<std::vector<std::string>> Collection::shardIds() const {
  auto clusterInfo = arangodb::ClusterInfo::instance();
  return clusterInfo->getShardList(
      arangodb::basics::StringUtils::itoa(getPlanId()));
}

////////////////////////////////////////////////////////////////////////////////
/// @brief returns the shard keys of a collection
////////////////////////////////////////////////////////////////////////////////

std::vector<std::string> Collection::shardKeys() const {
  auto clusterInfo = arangodb::ClusterInfo::instance();

  std::string id;
  if (arangodb::ServerState::instance()->isDBServer() &&
      documentCollection()->_info.planId() > 0) {
    id = std::to_string(documentCollection()->_info.planId());
  } else {
    id = name;
  }

  auto collectionInfo =
      clusterInfo->getCollection(std::string(vocbase->_name), id);
  if (collectionInfo.get() == nullptr) {
    THROW_ARANGO_EXCEPTION_FORMAT(TRI_ERROR_INTERNAL,
                                  "collection not found '%s' -> '%s'",
                                  vocbase->_name, name.c_str());
  }

  std::vector<std::string> keys;
  for (auto const& x : collectionInfo.get()->shardKeys()) {
    keys.emplace_back(x);
  }
  return keys;
}

////////////////////////////////////////////////////////////////////////////////
/// @brief whether or not the collection uses the default sharding
////////////////////////////////////////////////////////////////////////////////

bool Collection::usesDefaultSharding() const {
  // check if collection shard keys are only _key
  std::vector<std::string> sk(shardKeys());

  if (sk.size() != 1 || sk[0] != TRI_VOC_ATTRIBUTE_KEY) {
    return false;
  }
  return true;
}