////////////////////////////////////////////////////////////////////////////////
/// 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"

namespace arangodb {

std::shared_ptr<LogicalCollection> CollectionNameResolver::getCollection(
  TRI_voc_cid_t id
) const noexcept {
  #ifdef ARANGODB_ENABLE_MAINTAINER_MODE
    return std::dynamic_pointer_cast<LogicalCollection>(getDataSource(id));
  #else
  auto dataSource = getDataSource(id);

  return dataSource->category() == LogicalCollection::category()
    ? std::static_pointer_cast<LogicalCollection>(dataSource) : nullptr;
  #endif
}

std::shared_ptr<LogicalCollection> CollectionNameResolver::getCollection(
  std::string const& nameOrId
) const noexcept {
  #ifdef ARANGODB_ENABLE_MAINTAINER_MODE
    return std::dynamic_pointer_cast<LogicalCollection>(getDataSource(nameOrId));
  #else
  auto dataSource = getDataSource(nameOrId);

  return dataSource->category() == LogicalCollection::category()
    ? std::static_pointer_cast<LogicalCollection>(dataSource) : nullptr;
  #endif
}

//////////////////////////////////////////////////////////////////////////////
/// @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->id();
  }

  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());
    auto collection = getCollection(cid);
    // Now validate the cid
    auto type = collection ? collection->type() : TRI_COL_TYPE_UNKNOWN;

    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->id();
    }

    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 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;
  }

  auto* collection = _vocbase->lookupCollection(name).get();

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

  return collection;
}

//////////////////////////////////////////////////////////////////////////////
/// @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()
        && LogicalCollection::category() == it->second->category()) {
      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(
            #ifdef ARANGODB_ENABLE_MAINTAINER_MODE
              dynamic_cast<LogicalCollection*>(it->second.get())->dbName(),
            #else
              static_cast<LogicalCollection*>(it->second.get())->dbName(),
            #endif
            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 {
  auto itr = _dataSourceById.find(id);

  if (itr != _dataSourceById.end()) {
    return itr->second;
  }

  std::shared_ptr<LogicalDataSource> ptr;

  // db server / standalone
  if (!ServerState::isCoordinator(_serverRole)) {
    ptr = _vocbase ? _vocbase->lookupDataSource(id) : nullptr;
  } else {
    ptr = getDataSource(std::to_string(id));
  }

  if (ptr) {
    _dataSourceById.emplace(id, ptr);
  }

  return ptr;
}

std::shared_ptr<LogicalDataSource> CollectionNameResolver::getDataSource(
  std::string const& nameOrId
) const noexcept {
  auto itr = _dataSourceByName.find(nameOrId);

  if (itr != _dataSourceByName.end()) {
    return itr->second;
  }

  std::shared_ptr<LogicalDataSource> ptr;

  // db server / standalone
  if (!ServerState::isCoordinator(_serverRole)) {
    ptr = _vocbase ? _vocbase->lookupDataSource(nameOrId) : nullptr;
  } else {
    // cluster coordinator
    auto* ci = ClusterInfo::instance();

    if (!ci) {
      return nullptr;
    }

    try {
      ptr = std::static_pointer_cast<LogicalDataSource>(
        ci->getCollection(_vocbase->name(), nameOrId)
      );

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

  if (ptr) {
    _dataSourceByName.emplace(nameOrId, ptr);
  }

  return ptr;
}

std::shared_ptr<LogicalView> CollectionNameResolver::getView(
  TRI_voc_cid_t id
) const noexcept {
  #ifdef ARANGODB_ENABLE_MAINTAINER_MODE
    return std::dynamic_pointer_cast<LogicalView>(getDataSource(id));
  #else
  auto dataSource = getDataSource(id);

  return dataSource->category() == LogicalView::category()
    ? std::static_pointer_cast<LogicalView>(dataSource) : nullptr;
  #endif
}

std::shared_ptr<LogicalView> CollectionNameResolver::getView(
  std::string const& nameOrId
) const noexcept {
  #ifdef ARANGODB_ENABLE_MAINTAINER_MODE
    return std::dynamic_pointer_cast<LogicalView>(getDataSource(nameOrId));
  #else
  auto dataSource = getDataSource(nameOrId);

  return dataSource->category() == LogicalView::category()
    ? std::static_pointer_cast<LogicalView>(dataSource) : nullptr;
  #endif
}

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(LogicalCollection&)> const& visitor,
    TRI_voc_cid_t id
) const {
  auto dataSource = getDataSource(id);

  if (!dataSource) {
    return false; // no way to determine what to visit
  }

  if (LogicalCollection::category() == dataSource->category()) {
    #ifdef ARANGODB_ENABLE_MAINTAINER_MODE
      auto collection = std::dynamic_pointer_cast<LogicalCollection>(dataSource);
      TRI_ASSERT(collection);
    #else
      auto collection = std::static_pointer_cast<LogicalCollection>(dataSource);
    #endif

    // TODO resolve smart edge collection CIDs here
    return visitor(*collection);
  }

  if (LogicalView::category() == dataSource->category()) {
    #ifdef ARANGODB_ENABLE_MAINTAINER_MODE
      auto view = std::dynamic_pointer_cast<LogicalView>(dataSource);
    #else
      auto view = std::static_pointer_cast<LogicalView>(dataSource);
    #endif

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

  return false; // no way to determine what to visit
}

} // namespace arangodb