////////////////////////////////////////////////////////////////////////////////
/// 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 Dr. Frank Celler
////////////////////////////////////////////////////////////////////////////////

#ifndef ARANGOD_INDEXES_PRIMARY_INDEX_H
#define ARANGOD_INDEXES_PRIMARY_INDEX_H 1

#include "Basics/Common.h"
#include "Basics/AssocUnique.h"
#include "Indexes/Index.h"
#include "Indexes/IndexIterator.h"
#include "VocBase/vocbase.h"
#include "VocBase/voc-types.h"

#include <velocypack/Iterator.h>
#include <velocypack/Slice.h>
#include <velocypack/velocypack-aliases.h>

namespace arangodb {

class PrimaryIndex;
class Transaction;
  
typedef arangodb::basics::AssocUnique<uint8_t, SimpleIndexElement> PrimaryIndexImpl;

class PrimaryIndexIterator final : public IndexIterator {
 public:
  PrimaryIndexIterator(LogicalCollection* collection,
                       arangodb::Transaction* trx, 
                       ManagedDocumentResult* mmdr,
                       PrimaryIndex const* index,
                       std::unique_ptr<VPackBuilder>& keys);

  ~PrimaryIndexIterator();
    
  char const* typeName() const override { return "primary-index-iterator"; }

  IndexLookupResult next() override;

  void reset() override;

 private:
  PrimaryIndex const* _index;
  std::unique_ptr<VPackBuilder> _keys;
  arangodb::velocypack::ArrayIterator _iterator;
};

class AllIndexIterator final : public IndexIterator {
 public:
  AllIndexIterator(LogicalCollection* collection,
                   arangodb::Transaction* trx, 
                   ManagedDocumentResult* mmdr,
                   PrimaryIndex const* index,
                   PrimaryIndexImpl const* indexImpl,
                   bool reverse);

  ~AllIndexIterator() {}
    
  char const* typeName() const override { return "all-index-iterator"; }

  IndexLookupResult next() override;
  
  void nextBabies(std::vector<IndexLookupResult>&, size_t) override;

  void reset() override;

 private:
  PrimaryIndexImpl const* _index;
  arangodb::basics::BucketPosition _position;
  bool const _reverse;
  uint64_t _total;
};

class AnyIndexIterator final : public IndexIterator {
 public:
  AnyIndexIterator(LogicalCollection* collection, arangodb::Transaction* trx, 
                   ManagedDocumentResult* mmdr,
                   PrimaryIndex const* index,
                   PrimaryIndexImpl const* indexImpl);

  ~AnyIndexIterator() {}
  
  char const* typeName() const override { return "any-index-iterator"; }

  IndexLookupResult next() override;

  void reset() override;

 private:
  PrimaryIndexImpl const* _index;
  arangodb::basics::BucketPosition _initial;
  arangodb::basics::BucketPosition _position;
  uint64_t _step;
  uint64_t _total;
};

class PrimaryIndex final : public Index {
  friend class PrimaryIndexIterator;

 public:
  PrimaryIndex() = delete;

  explicit PrimaryIndex(arangodb::LogicalCollection*);

  ~PrimaryIndex();

 public:
  IndexType type() const override {
    return Index::TRI_IDX_TYPE_PRIMARY_INDEX;
  }
  
  bool allowExpansion() const override { return false; }

  bool canBeDropped() const override { return false; }

  bool isSorted() const override { return false; }

  bool hasSelectivityEstimate() const override { return true; }

  double selectivityEstimate(arangodb::StringRef const* = nullptr) const override { return 1.0; }

  size_t size() const;

  size_t memory() const override;

  void toVelocyPack(VPackBuilder&, bool) const override;
  void toVelocyPackFigures(VPackBuilder&) const override;

  int insert(arangodb::Transaction*, TRI_voc_rid_t, arangodb::velocypack::Slice const&, bool isRollback) override;

  int remove(arangodb::Transaction*, TRI_voc_rid_t, arangodb::velocypack::Slice const&, bool isRollback) override;

  int unload() override;

  SimpleIndexElement lookupKey(arangodb::Transaction*, VPackSlice const&) const;
  SimpleIndexElement lookupKey(arangodb::Transaction*, VPackSlice const&, ManagedDocumentResult&) const;
  SimpleIndexElement* lookupKeyRef(arangodb::Transaction*, VPackSlice const&) const;
  SimpleIndexElement* lookupKeyRef(arangodb::Transaction*, VPackSlice const&, ManagedDocumentResult&) const;

  /// @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.
  ///        DEPRECATED
  SimpleIndexElement lookupSequential(arangodb::Transaction*,
                                      arangodb::basics::BucketPosition& position,
                                      uint64_t& total);

  /// @brief request an iterator over all elements in the index in
  ///        a sequential order.
  IndexIterator* allIterator(arangodb::Transaction*, ManagedDocumentResult*, bool reverse) const;

  /// @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* anyIterator(arangodb::Transaction*, ManagedDocumentResult*) const;

  /// @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.
  ///        DEPRECATED
  SimpleIndexElement lookupSequentialReverse(
      arangodb::Transaction*, arangodb::basics::BucketPosition& position);

  int insertKey(arangodb::Transaction*, TRI_voc_rid_t revisionId, arangodb::velocypack::Slice const&);
  int insertKey(arangodb::Transaction*, TRI_voc_rid_t revisionId, arangodb::velocypack::Slice const&, ManagedDocumentResult&);

  int removeKey(arangodb::Transaction*, TRI_voc_rid_t revisionId, arangodb::velocypack::Slice const&);
  int removeKey(arangodb::Transaction*, TRI_voc_rid_t revisionId, arangodb::velocypack::Slice const&, ManagedDocumentResult&);

  int resize(arangodb::Transaction*, size_t);

  void invokeOnAllElements(std::function<bool(SimpleIndexElement const&)>);
  void invokeOnAllElementsForRemoval(std::function<bool(SimpleIndexElement&)>);

  bool supportsFilterCondition(arangodb::aql::AstNode const*,
                               arangodb::aql::Variable const*, size_t, size_t&,
                               double&) const override;

  IndexIterator* iteratorForCondition(arangodb::Transaction*,
                                      ManagedDocumentResult*,
                                      arangodb::aql::AstNode const*,
                                      arangodb::aql::Variable const*,
                                      bool) const override;

  IndexIterator* iteratorForSlice(arangodb::Transaction*, 
                                  ManagedDocumentResult*,
                                  arangodb::velocypack::Slice const,
                                  bool) const override;

  arangodb::aql::AstNode* specializeCondition(
      arangodb::aql::AstNode*, arangodb::aql::Variable const*) const override;

 private:

  /// @brief create the iterator, for a single attribute, IN operator
  IndexIterator* createInIterator(
      arangodb::Transaction*, 
      ManagedDocumentResult*,
      arangodb::aql::AstNode const*,
      arangodb::aql::AstNode const*) const;

  /// @brief create the iterator, for a single attribute, EQ operator
  IndexIterator* createEqIterator(
      arangodb::Transaction*, 
      ManagedDocumentResult*,
      arangodb::aql::AstNode const*,
      arangodb::aql::AstNode const*) const;

  /// @brief add a single value node to the iterator's keys
  void handleValNode(arangodb::Transaction* trx,
                     VPackBuilder* keys,
                     arangodb::aql::AstNode const* valNode,
                     bool isId) const; 

  SimpleIndexElement buildKeyElement(TRI_voc_rid_t revisionId, arangodb::velocypack::Slice const&) const;

 private:
  /// @brief the actual index
  PrimaryIndexImpl* _primaryIndex;
};
}

#endif