//  Copyright (c) Meta Platforms, Inc. and affiliates.

//  This source code is licensed under both the GPLv2 (found in the

//  COPYING file in the root directory) and Apache 2.0 License

//  (found in the LICENSE.Apache file in the root directory).

#pragma once

#include "db/multi_cf_iterator_impl.h"

#include "rocksdb/attribute_groups.h"

namespace ROCKSDB_NAMESPACE {

class AttributeGroupIteratorImpl : public AttributeGroupIterator {

 public:

  AttributeGroupIteratorImpl(

      const ReadOptions& read_options, const Comparator* comparator,

      std::vector<std::pair<ColumnFamilyHandle*, std::unique_ptr<Iterator>>>&&

          cfh_iter_pairs)

      : impl_(read_options, comparator, std::move(cfh_iter_pairs),

              ResetFunc(this), PopulateFunc(this)) {}

  ~AttributeGroupIteratorImpl() override {}

  // No copy allowed

  AttributeGroupIteratorImpl(const AttributeGroupIteratorImpl&) = delete;

  AttributeGroupIteratorImpl& operator=(const AttributeGroupIteratorImpl&) =

      delete;

  bool Valid() const override { return impl_.Valid(); }

  void SeekToFirst() override { impl_.SeekToFirst(); }

  void SeekToLast() override { impl_.SeekToLast(); }

  void Seek(const Slice& target) override { impl_.Seek(target); }

  void SeekForPrev(const Slice& target) override { impl_.SeekForPrev(target); }

  void Next() override { impl_.Next(); }

  void Prev() override { impl_.Prev(); }

  Slice key() const override { return impl_.key(); }

  Status status() const override { return impl_.status(); }

  const IteratorAttributeGroups& attribute_groups() const override {

    assert(Valid());

    return attribute_groups_;

  }

  void Reset() { attribute_groups_.clear(); }

  bool PrepareValue() override { return impl_.PrepareValue(); }

 private:

  class ResetFunc {

   public:

    explicit ResetFunc(AttributeGroupIteratorImpl* iter) : iter_(iter) {}

    void operator()() const {

      assert(iter_);

      iter_->Reset();

    }

   private:

    AttributeGroupIteratorImpl* iter_;

  };

  class PopulateFunc {

   public:

    explicit PopulateFunc(AttributeGroupIteratorImpl* iter) : iter_(iter) {}

    void operator()(const autovector<MultiCfIteratorInfo>& items) const {

      assert(iter_);

      iter_->AddToAttributeGroups(items);

    }

   private:

    AttributeGroupIteratorImpl* iter_;

  };

  MultiCfIteratorImpl<ResetFunc, PopulateFunc> impl_;

  IteratorAttributeGroups attribute_groups_;

  void AddToAttributeGroups(const autovector<MultiCfIteratorInfo>& items);

};

class EmptyAttributeGroupIterator : public AttributeGroupIterator {

 public:

  explicit EmptyAttributeGroupIterator(const Status& s) : status_(s) {}

  bool Valid() const override { return false; }

  void Seek(const Slice& /*target*/) override {}

  void SeekForPrev(const Slice& /*target*/) override {}

  void SeekToFirst() override {}

  void SeekToLast() override {}

  void Next() override { assert(false); }

  void Prev() override { assert(false); }

  Slice key() const override {

    assert(false);

    return Slice();

  }

  Status status() const override { return status_; }

  const IteratorAttributeGroups& attribute_groups() const override {

    return kNoIteratorAttributeGroups;

  }

 private:

  Status status_;

};

inline std::unique_ptr<AttributeGroupIterator> NewAttributeGroupErrorIterator(

    const Status& status) {

  return std::make_unique<EmptyAttributeGroupIterator>(status);

}

}  // namespace ROCKSDB_NAMESPACE