////////////////////////////////////////////////////////////////////////////////
/// 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 "RocksDBPrimaryMockIndex.h"
#include "Aql/AstNode.h"
#include "Basics/Exceptions.h"
#include "Basics/StaticStrings.h"
#include "Basics/VelocyPackHelper.h"
#include "Indexes/SimpleAttributeEqualityMatcher.h"
#include "Transaction/Context.h"
#include "Transaction/Helpers.h"
#include "Transaction/Methods.h"
#include "VocBase/LogicalCollection.h"

#include <velocypack/Builder.h>
#include <velocypack/Collection.h>
#include <velocypack/Slice.h>
#include <velocypack/velocypack-aliases.h>

using namespace arangodb;

/// @brief hard-coded vector of the index attributes
/// note that the attribute names must be hard-coded here to avoid an init-order
/// fiasco with StaticStrings::FromString etc.
static std::vector<std::vector<arangodb::basics::AttributeName>> const
    IndexAttributes{{arangodb::basics::AttributeName("_id", false)},
                    {arangodb::basics::AttributeName("_key", false)}};

RocksDBPrimaryMockIndexIterator::RocksDBPrimaryMockIndexIterator(
    LogicalCollection* collection, transaction::Methods* trx,
    ManagedDocumentResult* mmdr, RocksDBPrimaryMockIndex const* index,
    std::unique_ptr<VPackBuilder>& keys)
    : IndexIterator(collection, trx, mmdr, index),
      _index(index),
      _keys(keys.get()),
      _iterator(_keys->slice()) {
  keys.release();  // now we have ownership for _keys
  TRI_ASSERT(_keys->slice().isArray());
}

RocksDBPrimaryMockIndexIterator::~RocksDBPrimaryMockIndexIterator() {
  if (_keys != nullptr) {
    // return the VPackBuilder to the transaction context
    _trx->transactionContextPtr()->returnBuilder(_keys.release());
  }
}

bool RocksDBPrimaryMockIndexIterator::next(TokenCallback const& cb,
                                           size_t limit) {
  THROW_ARANGO_NOT_YET_IMPLEMENTED();
  return false;
}

void RocksDBPrimaryMockIndexIterator::reset() { _iterator.reset(); }

RocksDBAllIndexIterator::RocksDBAllIndexIterator(
    LogicalCollection* collection, transaction::Methods* trx,
    ManagedDocumentResult* mmdr, RocksDBPrimaryMockIndex const* index,
    bool reverse)
    : IndexIterator(collection, trx, mmdr, index),
      _reverse(reverse),
      _total(0) {}

bool RocksDBAllIndexIterator::next(TokenCallback const& cb, size_t limit) {
  // TODO
  return false;
}

void RocksDBAllIndexIterator::reset() {
  // TODO
}

RocksDBAnyIndexIterator::RocksDBAnyIndexIterator(
    LogicalCollection* collection, transaction::Methods* trx,
    ManagedDocumentResult* mmdr, RocksDBPrimaryMockIndex const* index)
    : IndexIterator(collection, trx, mmdr, index) {}

bool RocksDBAnyIndexIterator::next(TokenCallback const& cb, size_t limit) {
  THROW_ARANGO_NOT_YET_IMPLEMENTED();
  return true;
}

void RocksDBAnyIndexIterator::reset() { THROW_ARANGO_NOT_YET_IMPLEMENTED(); }

RocksDBPrimaryMockIndex::RocksDBPrimaryMockIndex(
    arangodb::LogicalCollection* collection, VPackSlice const& info)
    : Index(basics::VelocyPackHelper::stringUInt64(info, "objectId"),
            collection,
            std::vector<std::vector<arangodb::basics::AttributeName>>(
                {{arangodb::basics::AttributeName(StaticStrings::KeyString,
                                                  false)}}),
            true, false),
      _objectId(basics::VelocyPackHelper::stringUInt64(info, "objectId")) {}

RocksDBPrimaryMockIndex::~RocksDBPrimaryMockIndex() {}

/// @brief return the number of documents from the index
size_t RocksDBPrimaryMockIndex::size() const {
  // TODO
  return 0;
}

/// @brief return the memory usage of the index
size_t RocksDBPrimaryMockIndex::memory() const {
  return 0;  // TODO
}

/// @brief return a VelocyPack representation of the index
void RocksDBPrimaryMockIndex::toVelocyPack(VPackBuilder& builder,
                                           bool withFigures) const {
  Index::toVelocyPack(builder, withFigures);
  // hard-coded
  builder.add("unique", VPackValue(true));
  builder.add("sparse", VPackValue(false));
}

/// @brief return a VelocyPack representation of the index figures
void RocksDBPrimaryMockIndex::toVelocyPackFigures(VPackBuilder& builder) const {
  Index::toVelocyPackFigures(builder);
  // TODO: implement
}

RocksDBToken RocksDBPrimaryMockIndex::lookupKey(transaction::Methods* trx, arangodb::StringRef keyRef) {
  std::string key (keyRef.toString());
  std::lock_guard<std::mutex> lock(_keyRevMutex);
  LOG_TOPIC(ERR, Logger::FIXME) << "LOOKUP. THE KEY IS: " << key;
  auto it = _keyRevMap.find(key);
  if (it == _keyRevMap.end()) {
    return RocksDBToken();
  }
  return RocksDBToken((*it).second);
}

RocksDBToken RocksDBPrimaryMockIndex::lookupKey(transaction::Methods* trx,
                                                VPackSlice slice,
                                                ManagedDocumentResult& result) {
  std::string key = slice.copyString();
  std::lock_guard<std::mutex> lock(_keyRevMutex);
  LOG_TOPIC(ERR, Logger::FIXME) << "LOOKUP. THE KEY IS: " << key;
  auto it = _keyRevMap.find(key);
  if (it == _keyRevMap.end()) {
    return RocksDBToken();
  }
  return RocksDBToken((*it).second);
}

int RocksDBPrimaryMockIndex::insert(transaction::Methods*,
                                    TRI_voc_rid_t revisionId,
                                    VPackSlice const& slice, bool) {
  std::string key = slice.get("_key").copyString();
  std::lock_guard<std::mutex> lock(_keyRevMutex);
  LOG_TOPIC(ERR, Logger::FIXME) << "INSERT. THE KEY IS: " << key
                                << "; THE REVISION IS: " << revisionId;
  auto result = _keyRevMap.emplace(key, revisionId);
  if (result.second) {
    return TRI_ERROR_NO_ERROR;
  }
  return TRI_ERROR_INTERNAL;
}

int RocksDBPrimaryMockIndex::remove(transaction::Methods*,
                                    TRI_voc_rid_t revisionId,
                                    VPackSlice const& slice, bool) {
  std::string key = slice.get("_key").copyString();
  std::lock_guard<std::mutex> lock(_keyRevMutex);
  LOG_TOPIC(ERR, Logger::FIXME) << "REMOVE. THE KEY IS: " << key;
  auto result = _keyRevMap.erase(key);  // result number of deleted elements
  if (result) {
    return TRI_ERROR_NO_ERROR;
  }
  return TRI_ERROR_INTERNAL;
}

/// @brief unload the index data from memory
int RocksDBPrimaryMockIndex::unload() {
  // nothing to do
  return TRI_ERROR_NO_ERROR;
}

/// @brief checks whether the index supports the condition
bool RocksDBPrimaryMockIndex::supportsFilterCondition(
    arangodb::aql::AstNode const* node,
    arangodb::aql::Variable const* reference, size_t itemsInIndex,
    size_t& estimatedItems, double& estimatedCost) const {
  SimpleAttributeEqualityMatcher matcher(IndexAttributes);
  return matcher.matchOne(this, node, reference, itemsInIndex, estimatedItems,
                          estimatedCost);
}

/// @brief creates an IndexIterator for the given Condition
IndexIterator* RocksDBPrimaryMockIndex::iteratorForCondition(
    transaction::Methods* trx, ManagedDocumentResult* mmdr,
    arangodb::aql::AstNode const* node,
    arangodb::aql::Variable const* reference, bool reverse) const {
  THROW_ARANGO_NOT_YET_IMPLEMENTED();
  return nullptr;
}

/// @brief specializes the condition for use with the index
arangodb::aql::AstNode* RocksDBPrimaryMockIndex::specializeCondition(
    arangodb::aql::AstNode* node,
    arangodb::aql::Variable const* reference) const {
  SimpleAttributeEqualityMatcher matcher(IndexAttributes);
  return matcher.specializeOne(this, node, reference);
}

/// @brief request an iterator over all elements in the index in
///        a sequential order.
IndexIterator* RocksDBPrimaryMockIndex::allIterator(transaction::Methods* trx,
                                                    ManagedDocumentResult* mmdr,
                                                    bool reverse) const {
  return new RocksDBAllIndexIterator(_collection, trx, mmdr, this, reverse);
}

/// @brief request an iterator over all elements in the index in
///        a random order. It is guaranteed that each element is found
///        exactly once unless the collection is modified.
IndexIterator* RocksDBPrimaryMockIndex::anyIterator(
    transaction::Methods* trx, ManagedDocumentResult* mmdr) const {
  return new RocksDBAnyIndexIterator(_collection, trx, mmdr, this);
}