////////////////////////////////////////////////////////////////////////////////
/// 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 "CollectionNameResolver.h"

#include "Basics/Common.h"
#include "Basics/NumberUtils.h"
#include "Basics/ReadLocker.h"
#include "Basics/StringUtils.h"
#include "Cluster/ClusterInfo.h"
#include "VocBase/LogicalCollection.h"
#include "VocBase/LogicalView.h"
#include "VocBase/vocbase.h"

using namespace arangodb;

//////////////////////////////////////////////////////////////////////////////
/// @brief look up a collection id for a collection name (local case),
/// use this if you know you are on a single server or on a DBserver
/// and need to look up a local collection name (or shard name).
//////////////////////////////////////////////////////////////////////////////

TRI_voc_cid_t CollectionNameResolver::getCollectionIdLocal(
    std::string const& name) const {
  if (name[0] >= '0' && name[0] <= '9') {
    // name is a numeric id
    return NumberUtils::atoi_zero<TRI_voc_cid_t>(name.data(), name.data() + name.size());
  }

  arangodb::LogicalCollection const* collection = getCollectionStruct(name);

  if (collection != nullptr) {
    return collection->cid();
  }

  auto view = _vocbase->lookupView(name);

  if (view) {
    return view->id();
  }

  return 0;
}

//////////////////////////////////////////////////////////////////////////////
/// @brief look up a cluster collection id for a cluster collection name,
/// only use this is in cluster mode on a coordinator or DBserver, in both
/// cases the name is resolved as a cluster wide collection name and the
/// cluster wide collection id is returned.
//////////////////////////////////////////////////////////////////////////////

TRI_voc_cid_t CollectionNameResolver::getCollectionIdCluster(
    std::string const& name) const {
  if (!ServerState::isRunningInCluster(_serverRole)) {
    return getCollectionIdLocal(name);
  }
  if (name[0] >= '0' && name[0] <= '9') {
    // name is a numeric id
    TRI_voc_cid_t cid = NumberUtils::atoi_zero<TRI_voc_cid_t>(name.data(), name.data() + name.size());
    // Now validate the cid
    TRI_col_type_e type = getCollectionTypeCluster(getCollectionNameCluster(cid));
    if (type == TRI_COL_TYPE_UNKNOWN) {
      return 0;
    }
    return cid;
  }

  try {
    // We have to look up the collection info:
    ClusterInfo* ci = ClusterInfo::instance();
    auto cinfo = ci->getCollection(_vocbase->name(), name);

    if (cinfo) {
      return cinfo->cid();
    }

    auto vinfo = ci->getView(_vocbase->name(), name);

    if (vinfo) {
      return vinfo->id();
    }
  } catch (...) {
  }

  return 0;
}

//////////////////////////////////////////////////////////////////////////////
/// @brief look up a collection id for a collection name, this is the
/// default one to use, which will usually do the right thing. On a
/// single server or DBserver it will use the local lookup and on a
/// coordinator it will use the cluster wide lookup.
//////////////////////////////////////////////////////////////////////////////

TRI_voc_cid_t CollectionNameResolver::getCollectionId(
    std::string const& name) const {
  if (!ServerState::isRunningInCluster(_serverRole) ||
      ServerState::isDBServer(_serverRole)) {
    return getCollectionIdLocal(name);
  }
  return getCollectionIdCluster(name);
}

//////////////////////////////////////////////////////////////////////////////
/// @brief look up a collection type for a collection name (local case)
//////////////////////////////////////////////////////////////////////////////

TRI_col_type_e CollectionNameResolver::getCollectionType(
    std::string const& name) const {
  if (name[0] >= '0' && name[0] <= '9') {
    // name is a numeric id
    return getCollectionType(getCollectionName(NumberUtils::atoi_zero<TRI_voc_cid_t>(name.data(), name.data() + name.size())));
  }

  arangodb::LogicalCollection const* collection = getCollectionStruct(name);

  if (collection != nullptr) {
    return collection->type();
  }
  return TRI_COL_TYPE_UNKNOWN;
}

//////////////////////////////////////////////////////////////////////////////
/// @brief look up a collection struct for a collection name
//////////////////////////////////////////////////////////////////////////////

arangodb::LogicalCollection const* CollectionNameResolver::getCollectionStruct(
    std::string const& name) const {
  auto it = _resolvedNames.find(name);

  if (it != _resolvedNames.end()) {
    return (*it).second;
  }

  arangodb::LogicalCollection const* collection = _vocbase->lookupCollection(name);

  if (collection != nullptr) {
    _resolvedNames.emplace(name, collection);
  }

  return collection;
}

//////////////////////////////////////////////////////////////////////////////
/// @brief look up a cluster collection type for a cluster collection name on
/// the
///        coordinator and for a shard name on the db server
//////////////////////////////////////////////////////////////////////////////

TRI_col_type_e CollectionNameResolver::getCollectionTypeCluster(
    std::string const& name) const {
  // This fires in Single server case as well
  if (!ServerState::isCoordinator(_serverRole)) {
    return getCollectionType(name);
  }
  if (name[0] >= '0' && name[0] <= '9') {
    // name is a numeric id
    return getCollectionTypeCluster(
        getCollectionName(NumberUtils::atoi_zero<TRI_voc_cid_t>(name.data(), name.data() + name.size())));
  }

  try {
    // We have to look up the collection info:
    ClusterInfo* ci = ClusterInfo::instance();
    auto cinfo = ci->getCollection(_vocbase->name(), name);
    TRI_ASSERT(cinfo != nullptr);
    return cinfo->type();
  } catch(...) {
  }
  return TRI_COL_TYPE_UNKNOWN;
}

//////////////////////////////////////////////////////////////////////////////
/// @brief look up a collection name for a collection id, this implements
/// some magic in the cluster case: a DBserver in a cluster will automatically
/// translate the local collection ID into a cluster wide collection name.
//////////////////////////////////////////////////////////////////////////////

std::string CollectionNameResolver::getCollectionName(TRI_voc_cid_t cid) const {
  auto it = _resolvedIds.find(cid);

  if (it != _resolvedIds.end()) {
    return (*it).second;
  }

  std::string name = localNameLookup(cid);
  _resolvedIds.emplace(cid, name);

  return name;
}

//////////////////////////////////////////////////////////////////////////////
/// @brief look up a cluster-wide collection name for a cluster-wide
/// collection id
//////////////////////////////////////////////////////////////////////////////

std::string CollectionNameResolver::getCollectionNameCluster(
    TRI_voc_cid_t cid) const {
  // First check the cache:
  auto it = _resolvedIds.find(cid);

  if (it != _resolvedIds.end()) {
    return (*it).second;
  }

  if (!ServerState::isClusterRole(_serverRole)) {
    // This handles the case of a standalone server
    return getCollectionName(cid);
  }

  std::string name;
  
  if (ServerState::isDBServer(_serverRole)) {
    // This might be a local system collection:
    name = localNameLookup(cid);
    if (name != "_unknown") {
      _resolvedIds.emplace(cid, name);
      return name;
    }
  }
 
  int tries = 0;

  while (tries++ < 2) {
    try {
      auto ci = ClusterInfo::instance()->getCollection(
          _vocbase->name(), arangodb::basics::StringUtils::itoa(cid));
    
      name = ci->name();
      _resolvedIds.emplace(cid, name);
      return name;
    } catch (...) {
      // most likely collection not found. now try again
      ClusterInfo::instance()->flush();
    }
  }

  LOG_TOPIC(ERR, arangodb::Logger::FIXME) << "CollectionNameResolver: was not able to resolve id " << cid;
  return "_unknown";
}

//////////////////////////////////////////////////////////////////////////////
/// @brief return collection name if given string is either the name or
/// a string with the (numerical) collection id, this returns the cluster
/// wide collection name in the DBserver case
//////////////////////////////////////////////////////////////////////////////

std::string CollectionNameResolver::getCollectionName(
    std::string const& nameOrId) const {
  if (!nameOrId.empty() &&
      (nameOrId[0] < '0' || nameOrId[0] > '9')) {
    return nameOrId;
  }
  return getCollectionName(NumberUtils::atoi_zero<TRI_voc_cid_t>(nameOrId.data(), nameOrId.data() + nameOrId.size()));
}

std::string CollectionNameResolver::localNameLookup(TRI_voc_cid_t cid) const {
  std::string name;

  if (ServerState::isDBServer(_serverRole)) {
    READ_LOCKER(readLocker, _vocbase->_dataSourceLock);
    auto it = _vocbase->_dataSourceById.find(cid);

    if (it != _vocbase->_dataSourceById.end()
        && std::dynamic_pointer_cast<LogicalCollection>(it->second)) {
      if (it->second->planId() == it->second->id()) {
        // DBserver local case
        name = (*it).second->name();
      } else {
        // DBserver case of a shard:
        name = arangodb::basics::StringUtils::itoa((*it).second->planId());
        std::shared_ptr<LogicalCollection> ci;
        try {
          ci = ClusterInfo::instance()->getCollection(
            std::dynamic_pointer_cast<LogicalCollection>(it->second)->dbName(),
            name
          );
        }
        catch (...) {
        }
        if (ci == nullptr) {
          name = ""; // collection unknown
        } else {
          name = ci->name();  // can be empty, if collection unknown
        }
      }
    }
  } else {
    // exactly as in the non-cluster case
    name = _vocbase->collectionName(cid);
  }

  if (name.empty()) {
    name = "_unknown";
  }
  return name;
}

std::shared_ptr<LogicalDataSource> CollectionNameResolver::getDataSource(
    TRI_voc_cid_t id
) const noexcept {
  // db server / standalone
  if (!ServerState::isRunningInCluster(_serverRole)
      || ServerState::isDBServer(_serverRole)) {
    return _vocbase ? _vocbase->lookupDataSource(id) : nullptr;
  }

  // cluster coordinator
  auto* ci = ClusterInfo::instance();

  if (!ci) {
    return nullptr;
  }

  try {
    auto name = std::to_string(id);
    auto cinfo = ci->getCollection(_vocbase->name(), name);

    if (cinfo) {
      return std::static_pointer_cast<LogicalDataSource>(cinfo);
    }

    return std::static_pointer_cast<LogicalDataSource>(
      ci->getView(_vocbase->name(), name)
    );
  } catch (...) {
    LOG_TOPIC(ERR, arangodb::Logger::FIXME)
      << "caught exception while resolving cluster data-source id: " << id;
  }

  return nullptr;
}

std::string CollectionNameResolver::getViewNameCluster(
    TRI_voc_cid_t cid
) const {
  if (!ServerState::isClusterRole(_serverRole)) {
    // This handles the case of a standalone server
    return _vocbase->viewName(cid);
  }

  // FIXME not supported
  return StaticStrings::Empty;
}

bool CollectionNameResolver::visitCollections(
    std::function<bool(TRI_voc_cid_t)> const& visitor, TRI_voc_cid_t cid
) const {
  if (!_vocbase) {
    return false; // no way to determine what to visit
  }

  auto* collection = _vocbase->lookupCollection(cid);

  if (collection) {
    // TODO resolve smart edge collection CIDs here
    return visitor(cid);
  }

  auto view = _vocbase->lookupView(cid);

  if (view) {
    // each CID in a view might need further resolution
    return view->visitCollections([this, &visitor, cid](TRI_voc_cid_t ccid)->bool {
      return ccid == cid ? visitor(ccid) : visitCollections(visitor, ccid);
    });
  }

  // no way to determine what to visit
  // emulate the original behaviour, assume 'cid' is for a regular collection and visit it as is
  return visitor(cid);
}