////////////////////////////////////////////////////////////////////////////////
/// @brief primary index
///
/// @file
///
/// DISCLAIMER
///
/// Copyright 2014 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 Dr. Frank Celler
/// @author Copyright 2014, ArangoDB GmbH, Cologne, Germany
/// @author Copyright 2011-2013, triAGENS GmbH, Cologne, Germany
////////////////////////////////////////////////////////////////////////////////

#include "PrimaryIndex.h"
#include "Aql/AstNode.h"
#include "Aql/SortCondition.h"
#include "Basics/Exceptions.h"
#include "Basics/hashes.h"
#include "Basics/logging.h"
#include "Indexes/SimpleAttributeEqualityMatcher.h"
#include "Utils/CollectionNameResolver.h"
#include "VocBase/document-collection.h"
#include "VocBase/transaction.h"

using namespace triagens::arango;

// -----------------------------------------------------------------------------
// --SECTION--                                                 private functions
// -----------------------------------------------------------------------------

static inline uint64_t HashKey (char const* key) {
  return TRI_FnvHashString(key);
}

static inline uint64_t HashElement (TRI_doc_mptr_t const* element) {
  return element->_hash;
}

////////////////////////////////////////////////////////////////////////////////
/// @brief determines if a key corresponds to an element
////////////////////////////////////////////////////////////////////////////////

static bool IsEqualKeyElement (char const* key,
                               uint64_t const hash,
                               TRI_doc_mptr_t const* element) {

  return (hash == element->_hash &&
          strcmp(key, TRI_EXTRACT_MARKER_KEY(element)) == 0);
}

////////////////////////////////////////////////////////////////////////////////
/// @brief determines if two elements are equal
////////////////////////////////////////////////////////////////////////////////

static bool IsEqualElementElement (TRI_doc_mptr_t const* left,
                                   TRI_doc_mptr_t const* right) {
  return left->_hash == right->_hash
         && strcmp(TRI_EXTRACT_MARKER_KEY(left), TRI_EXTRACT_MARKER_KEY(right)) == 0;
}

// -----------------------------------------------------------------------------
// --SECTION--                                        class PrimaryIndexIterator
// -----------------------------------------------------------------------------

// -----------------------------------------------------------------------------
// --SECTION--                                                    public methods
// -----------------------------------------------------------------------------

TRI_doc_mptr_t* PrimaryIndexIterator::next () {
  while (true) {
    if (_position >= _keys.size()) {
      // we're at the end of the lookup values
      return nullptr;
    }

    auto result = _index->lookupKey(_keys[_position++]);

    if (result != nullptr) {
      // found a result
      return result;
    }

    // found no result. now go to next lookup value in _keys
  }
}

void PrimaryIndexIterator::reset () {
  _position = 0;
}

// -----------------------------------------------------------------------------
// --SECTION--                                                class PrimaryIndex
// -----------------------------------------------------------------------------
        
// -----------------------------------------------------------------------------
// --SECTION--                                      constructors and destructors
// -----------------------------------------------------------------------------

PrimaryIndex::PrimaryIndex (TRI_document_collection_t* collection) 
  : Index(0, collection, std::vector<std::vector<triagens::basics::AttributeName>>( { { { TRI_VOC_ATTRIBUTE_KEY, false } } } ), true, false),
    _primaryIndex(nullptr) {
  
  uint32_t indexBuckets = 1;

  if (collection != nullptr) {
    // document is a nullptr in the coordinator case
    indexBuckets = collection->_info._indexBuckets;
  }

  _primaryIndex = new TRI_PrimaryIndex_t(HashKey,
                                         HashElement,
                                         IsEqualKeyElement,
                                         IsEqualElementElement,
                                         IsEqualElementElement,
                                         indexBuckets,
                                         [] () -> std::string { return "primary"; }
  );
}

////////////////////////////////////////////////////////////////////////////////
/// @brief create an index stub with a hard-coded selectivity estimate
/// this is used in the cluster coordinator case
////////////////////////////////////////////////////////////////////////////////

PrimaryIndex::PrimaryIndex (TRI_json_t const* json)
  : Index(json),
    _primaryIndex(nullptr) {
}

PrimaryIndex::~PrimaryIndex () {
  delete _primaryIndex;
}

// -----------------------------------------------------------------------------
// --SECTION--                                                    public methods
// -----------------------------------------------------------------------------

////////////////////////////////////////////////////////////////////////////////
/// @brief return the number of documents from the index
////////////////////////////////////////////////////////////////////////////////
        
size_t PrimaryIndex::size () const {
  return _primaryIndex->size();
}

////////////////////////////////////////////////////////////////////////////////
/// @brief return the memory usage of the index
////////////////////////////////////////////////////////////////////////////////

size_t PrimaryIndex::memory () const {
  return _primaryIndex->memoryUsage();
}

////////////////////////////////////////////////////////////////////////////////
/// @brief return a JSON representation of the index
////////////////////////////////////////////////////////////////////////////////

triagens::basics::Json PrimaryIndex::toJson (TRI_memory_zone_t* zone,
                                             bool withFigures) const {
  auto json = Index::toJson(zone, withFigures);

  // hard-coded
  json("unique", triagens::basics::Json(true))
      ("sparse", triagens::basics::Json(false));

  return json;
}

////////////////////////////////////////////////////////////////////////////////
/// @brief return a JSON representation of the index figures
////////////////////////////////////////////////////////////////////////////////

triagens::basics::Json PrimaryIndex::toJsonFigures (TRI_memory_zone_t* zone) const {
  triagens::basics::Json json(zone, triagens::basics::Json::Object);
  
  json("memory", triagens::basics::Json(static_cast<double>(memory())));
  _primaryIndex->appendToJson(zone, json);

  return json;
}

int PrimaryIndex::insert (TRI_doc_mptr_t const*, 
                          bool) {
  THROW_ARANGO_EXCEPTION(TRI_ERROR_NOT_IMPLEMENTED);
}
         
int PrimaryIndex::remove (TRI_doc_mptr_t const*, 
                          bool) {
  THROW_ARANGO_EXCEPTION(TRI_ERROR_NOT_IMPLEMENTED);
}

////////////////////////////////////////////////////////////////////////////////
/// @brief looks up an element given a key
////////////////////////////////////////////////////////////////////////////////

TRI_doc_mptr_t* PrimaryIndex::lookupKey (char const* key) const {
  return _primaryIndex->findByKey(key);
}

////////////////////////////////////////////////////////////////////////////////
/// @brief looks up an element given a key
/// returns the index position into which a key would belong in the second
/// parameter. also returns the hash value for the object
////////////////////////////////////////////////////////////////////////////////

TRI_doc_mptr_t* PrimaryIndex::lookupKey (char const* key,
                                         triagens::basics::BucketPosition& position,
                                         uint64_t& hash) const {
  return _primaryIndex->findByKey(key, position, hash);
}

////////////////////////////////////////////////////////////////////////////////
/// @brief a method to iterate over all elements in the index in
///        a random order. 
///        Returns nullptr if all documents have been returned.
///        Convention: step === 0 indicates a new start.
////////////////////////////////////////////////////////////////////////////////

TRI_doc_mptr_t* PrimaryIndex::lookupRandom (triagens::basics::BucketPosition& initialPosition,
                                            triagens::basics::BucketPosition& position,
                                            uint64_t& step,
                                            uint64_t& total) {
  return _primaryIndex->findRandom(initialPosition, position, step, total);
}

////////////////////////////////////////////////////////////////////////////////
/// @brief a method to iterate over all elements in the index in
///        a sequential order. 
///        Returns nullptr if all documents have been returned.
///        Convention: position === 0 indicates a new start.
////////////////////////////////////////////////////////////////////////////////

TRI_doc_mptr_t* PrimaryIndex::lookupSequential (triagens::basics::BucketPosition& position,
                                                uint64_t& total) {
  return _primaryIndex->findSequential(position, total);
}

////////////////////////////////////////////////////////////////////////////////
/// @brief a method to iterate over all elements in the index in
///        reversed sequential order. 
///        Returns nullptr if all documents have been returned.
///        Convention: position === UINT64_MAX indicates a new start.
////////////////////////////////////////////////////////////////////////////////

TRI_doc_mptr_t* PrimaryIndex::lookupSequentialReverse (triagens::basics::BucketPosition& position) {
  return _primaryIndex->findSequentialReverse(position);
}

////////////////////////////////////////////////////////////////////////////////
/// @brief adds a key/element to the index
/// returns a status code, and *found will contain a found element (if any)
////////////////////////////////////////////////////////////////////////////////

int PrimaryIndex::insertKey (TRI_doc_mptr_t* header,
                             void const** found) {
  *found = nullptr;
  int res = _primaryIndex->insert(header);

  if (res == TRI_ERROR_ARANGO_UNIQUE_CONSTRAINT_VIOLATED) {
    *found = _primaryIndex->find(header);
  }

  return res;
}

////////////////////////////////////////////////////////////////////////////////
/// @brief adds a key/element to the index
/// this is a special, optimized version that receives the target slot index
/// from a previous lookupKey call
////////////////////////////////////////////////////////////////////////////////

int PrimaryIndex::insertKey (TRI_doc_mptr_t* header,
                             triagens::basics::BucketPosition const& position) {
  return _primaryIndex->insertAtPosition(header, position);
}

////////////////////////////////////////////////////////////////////////////////
/// @brief removes an key/element from the index
////////////////////////////////////////////////////////////////////////////////

TRI_doc_mptr_t* PrimaryIndex::removeKey (char const* key) {
  return _primaryIndex->removeByKey(key);
}

////////////////////////////////////////////////////////////////////////////////
/// @brief resizes the index
////////////////////////////////////////////////////////////////////////////////

int PrimaryIndex::resize (size_t targetSize) {
  return _primaryIndex->resize(targetSize);
}

uint64_t PrimaryIndex::calculateHash (char const* key) {
  return HashKey(key);
}

uint64_t PrimaryIndex::calculateHash (char const* key,
                                      size_t length) {
  return TRI_FnvHashPointer(static_cast<void const*>(key), length);
}

void PrimaryIndex::invokeOnAllElements (std::function<void(TRI_doc_mptr_t*)> work) {
  _primaryIndex->invokeOnAllElements(work);
}

////////////////////////////////////////////////////////////////////////////////
/// @brief checks whether the index supports the condition
////////////////////////////////////////////////////////////////////////////////

bool PrimaryIndex::supportsFilterCondition (triagens::aql::AstNode const* node,
                                            triagens::aql::Variable const* reference,
                                            size_t itemsInIndex,
                                            size_t& estimatedItems,
                                            double& estimatedCost) const {
  SimpleAttributeEqualityMatcher matcher({ 
    { triagens::basics::AttributeName(TRI_VOC_ATTRIBUTE_ID, false) },
    { triagens::basics::AttributeName(TRI_VOC_ATTRIBUTE_KEY, false) } 
  });

  return matcher.matchOne(this, node, reference, itemsInIndex, estimatedItems, estimatedCost);
}

////////////////////////////////////////////////////////////////////////////////
/// @brief creates an IndexIterator for the given Condition
////////////////////////////////////////////////////////////////////////////////

IndexIterator* PrimaryIndex::iteratorForCondition (IndexIteratorContext* context,
                                                   triagens::aql::Ast* ast,
                                                   triagens::aql::AstNode const* node,
                                                   triagens::aql::Variable const* reference,
                                                   bool reverse) const {
  TRI_ASSERT(node->type == aql::NODE_TYPE_OPERATOR_NARY_AND);

  SimpleAttributeEqualityMatcher matcher({ 
    { triagens::basics::AttributeName(TRI_VOC_ATTRIBUTE_ID, false) },
    { triagens::basics::AttributeName(TRI_VOC_ATTRIBUTE_KEY, false) } 
  });

  TRI_ASSERT(node->numMembers() == 1);

  auto comp = node->getMember(0);

  // assume a.b == value
  auto attrNode = comp->getMember(0);
  auto valNode  = comp->getMember(1);

  if (attrNode->type != aql::NODE_TYPE_ATTRIBUTE_ACCESS) {
    // value == a.b  ->  flip the two sides
    attrNode = comp->getMember(1);
    valNode  = comp->getMember(0);
  }
  TRI_ASSERT(attrNode->type == aql::NODE_TYPE_ATTRIBUTE_ACCESS); 
    
  if (comp->type == aql::NODE_TYPE_OPERATOR_BINARY_EQ) {
    // a.b == value
    return createIterator(context, attrNode, std::vector<triagens::aql::AstNode const*>({ valNode }));
  }
  else if (comp->type == aql::NODE_TYPE_OPERATOR_BINARY_IN) {
    // a.b IN values
    if (! valNode->isArray()) {
      return nullptr;
    }

    std::vector<triagens::aql::AstNode const*> valNodes;
    size_t const n = valNode->numMembers();
    valNodes.reserve(n);
    for (size_t i = 0; i < n; ++i) {
      valNodes.emplace_back(valNode->getMemberUnchecked(i));
      TRI_IF_FAILURE("PrimaryIndex::iteratorValNodes")  {
        THROW_ARANGO_EXCEPTION(TRI_ERROR_DEBUG);
      }
    }

    return createIterator(context, attrNode, valNodes);
  }

  // operator type unsupported
  return nullptr;
}

////////////////////////////////////////////////////////////////////////////////
/// @brief specializes the condition for use with the index
////////////////////////////////////////////////////////////////////////////////
        
triagens::aql::AstNode* PrimaryIndex::specializeCondition (triagens::aql::AstNode* node,
                                                           triagens::aql::Variable const* reference) const {
  SimpleAttributeEqualityMatcher matcher({ 
    { triagens::basics::AttributeName(TRI_VOC_ATTRIBUTE_ID, false) },
    { triagens::basics::AttributeName(TRI_VOC_ATTRIBUTE_KEY, false) } 
  });

  return matcher.specializeOne(this, node, reference);
}

// -----------------------------------------------------------------------------
// --SECTION--                                                   private methods
// -----------------------------------------------------------------------------

////////////////////////////////////////////////////////////////////////////////
/// @brief create the iterator
////////////////////////////////////////////////////////////////////////////////
    
IndexIterator* PrimaryIndex::createIterator (IndexIteratorContext* context,
                                             triagens::aql::AstNode const* attrNode,
                                             std::vector<triagens::aql::AstNode const*> const& valNodes) const {

  // _key or _id?
  bool const isId = (strcmp(attrNode->getStringValue(), TRI_VOC_ATTRIBUTE_ID) == 0);

  // only leave the valid elements in the vector
  size_t const n = valNodes.size();
  std::vector<char const*> keys;
  keys.reserve(n);

  for (size_t i = 0; i < n; ++i) {
    auto valNode = valNodes[i];

    if (! valNode->isStringValue()) {
      continue;
    }
    if (valNode->getStringLength() == 0) {
      continue;
    }

    if (isId) {
      // lookup by _id. now validate if the lookup is performed for the 
      // correct collection (i.e. _collection)
      TRI_voc_cid_t cid;
      char const* key;
      int res = context->resolveId(valNode->getStringValue(), cid, key);

      if (res != TRI_ERROR_NO_ERROR) {
        continue;
      }

      TRI_ASSERT(cid != 0);
      TRI_ASSERT(key != nullptr);

      if (! context->isCluster() && cid != _collection->_info._cid) {
        // only continue lookup if the id value is syntactically correct and
        // refers to "our" collection, using local collection id
        continue;
      }

      if (context->isCluster() && cid != _collection->_info._planId) {
        // only continue lookup if the id value is syntactically correct and
        // refers to "our" collection, using cluster collection id
        continue;
      }

      // use _key value from _id
      keys.push_back(key);
    }
    else {
      keys.push_back(valNode->getStringValue());
    }
  }

  if (keys.empty()) {
    // nothing to do
    return nullptr;
  }

  TRI_IF_FAILURE("PrimaryIndex::noIterator")  {
    THROW_ARANGO_EXCEPTION(TRI_ERROR_DEBUG);
  }
  return new PrimaryIndexIterator(this, keys);
}

// -----------------------------------------------------------------------------
// --SECTION--                                                       END-OF-FILE
// -----------------------------------------------------------------------------

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