////////////////////////////////////////////////////////////////////////////////
/// 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
////////////////////////////////////////////////////////////////////////////////

#ifndef ARANGOD_UTILS_AQL_TRANSACTION_H
#define ARANGOD_UTILS_AQL_TRANSACTION_H 1

#include "Basics/Common.h"

#include "Aql/Collection.h"
#include "Cluster/ServerState.h"
#include "Utils/CollectionNameResolver.h"
#include "Utils/Transaction.h"
#include "Utils/StandaloneTransactionContext.h"
#include "VocBase/transaction.h"
#include "VocBase/vocbase.h"

namespace arangodb {

class AqlTransaction : public Transaction {
 public:
  //////////////////////////////////////////////////////////////////////////////
  /// @brief create the transaction and add all collections from the query
  /// context
  //////////////////////////////////////////////////////////////////////////////

  AqlTransaction(
      TransactionContext* transactionContext, TRI_vocbase_t* vocbase,
      std::map<std::string, arangodb::aql::Collection*> const* collections,
      bool isMainTransaction)
      : Transaction(transactionContext, vocbase, 0),
        _collections(*collections) {
    if (!isMainTransaction) {
      this->addHint(TRI_TRANSACTION_HINT_LOCK_NEVER, true);
    } else {
      this->addHint(TRI_TRANSACTION_HINT_LOCK_ENTIRELY, false);
    }

    for (auto it : *collections) {
      if (processCollection(it.second) != TRI_ERROR_NO_ERROR) {
        break;
      }
    }
  }

  //////////////////////////////////////////////////////////////////////////////
  /// @brief end the transaction
  //////////////////////////////////////////////////////////////////////////////

  ~AqlTransaction() {}

  //////////////////////////////////////////////////////////////////////////////
  /// @brief add a list of collections to the transaction
  //////////////////////////////////////////////////////////////////////////////

  int addCollectionList(
      std::map<std::string, arangodb::aql::Collection*>* collections) {
    int ret = TRI_ERROR_NO_ERROR;
    for (auto it : *collections) {
      ret = processCollection(it.second);
      if (ret != TRI_ERROR_NO_ERROR) {
        break;
      }
    }
    return ret;
  }

  //////////////////////////////////////////////////////////////////////////////
  /// @brief add a collection to the transaction
  //////////////////////////////////////////////////////////////////////////////

  int processCollection(arangodb::aql::Collection* collection) {
    int state = setupState();

    if (state != TRI_ERROR_NO_ERROR) {
      return state;
    }

    if (ServerState::instance()->isCoordinator()) {
      return processCollectionCoordinator(collection);
    }
    return processCollectionNormal(collection);
  }

  //////////////////////////////////////////////////////////////////////////////
  /// @brief add a coordinator collection to the transaction
  //////////////////////////////////////////////////////////////////////////////

  int processCollectionCoordinator(arangodb::aql::Collection* collection) {
    TRI_voc_cid_t cid =
        this->resolver()->getCollectionIdCluster(collection->getName());

    return this->addCollection(cid, collection->getName().c_str(),
                               collection->accessType);
  }

  //////////////////////////////////////////////////////////////////////////////
  /// @brief add a regular collection to the transaction
  //////////////////////////////////////////////////////////////////////////////

  int processCollectionNormal(arangodb::aql::Collection* collection) {
    TRI_vocbase_col_t const* col =
        this->resolver()->getCollectionStruct(collection->getName());
    TRI_voc_cid_t cid = 0;

    if (col != nullptr) {
      cid = col->_cid;
    }

    int res =
        this->addCollection(cid, collection->getName(), collection->accessType);

    if (res == TRI_ERROR_NO_ERROR && col != nullptr) {
      collection->setCollection(const_cast<TRI_vocbase_col_t*>(col));
    }

    return res;
  }

  //////////////////////////////////////////////////////////////////////////////
  /// @brief ditch
  //////////////////////////////////////////////////////////////////////////////

  arangodb::DocumentDitch* ditch(TRI_voc_cid_t cid) {
    TRI_transaction_collection_t* trxColl = this->trxCollection(cid);
    TRI_ASSERT(trxColl != nullptr);
    return trxColl->_ditch;
  }

  //////////////////////////////////////////////////////////////////////////////
  /// @brief documentCollection
  //////////////////////////////////////////////////////////////////////////////

  TRI_document_collection_t* documentCollection(TRI_voc_cid_t cid) {
    TRI_transaction_collection_t* trxColl = this->trxCollection(cid);
    TRI_ASSERT(trxColl != nullptr);
    return trxColl->_collection->_collection;
  }

  //////////////////////////////////////////////////////////////////////////////
  /// @brief clone, used to make daughter transactions for parts of a
  /// distributed
  /// AQL query running on the coordinator
  //////////////////////////////////////////////////////////////////////////////

  arangodb::AqlTransaction* clone() const {
    return new arangodb::AqlTransaction(
        new arangodb::StandaloneTransactionContext(), this->_vocbase,
        &_collections, false);
  }

  //////////////////////////////////////////////////////////////////////////////
  /// @brief lockCollections, this is needed in a corner case in AQL: we need
  /// to lock all shards in a controlled way when we set up a distributed
  /// execution engine. To this end, we prevent the standard mechanism to
  /// lock collections on the DBservers when we instantiate the query. Then,
  /// in a second round, we need to lock the shards in exactly the right
  /// order via an HTTP call. This method is used to implement that HTTP action.
  //////////////////////////////////////////////////////////////////////////////

  int lockCollections() {
    auto trx = getInternals();

    for (size_t i = 0; i < trx->_collections._length; i++) {
      auto trxCollection = static_cast<TRI_transaction_collection_t*>(
          TRI_AtVectorPointer(&trx->_collections, i));
      int res = TRI_LockCollectionTransaction(trxCollection,
                                              trxCollection->_accessType, 0);
      if (res != TRI_ERROR_NO_ERROR) {
        return res;
      }
    }
    return TRI_ERROR_NO_ERROR;
  }

  //////////////////////////////////////////////////////////////////////////////
  /// @brief keep a copy of the collections, this is needed for the clone
  /// operation
  //////////////////////////////////////////////////////////////////////////////

 private:
  std::map<std::string, arangodb::aql::Collection*> _collections;
};
}

#endif