// Licensed to the LF AI & Data foundation under one
// or more contributor license agreements. See the NOTICE file
// distributed with this work for additional information
// regarding copyright ownership. The ASF licenses this file
// to you 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.

#pragma once

#include <stdint.h>
#include <memory>
#include <vector>

#include "common/BitsetView.h"
#include "common/OpContext.h"
#include "common/QueryInfo.h"
#include "common/QueryResult.h"
#include "common/Tracer.h"
#include "common/TypeTraits.h"
#include "common/Types.h"
#include "index/IndexInfo.h"
#include "index/IndexStats.h"
#include "index/VectorIndex.h"
#include "knowhere/config.h"
#include "knowhere/expected.h"
#include "knowhere/index/index.h"
#include "knowhere/index/index_node.h"
#include "knowhere/object.h"
#include "knowhere/sparse_utils.h"
#include "storage/FileManager.h"
#include "storage/MemFileManagerImpl.h"

namespace milvus::index {
// TODO : growing index should be isolated from VectorMemIndex
// For general index, it should not suppport AddWithDataset etc.
// For growing index, it should suppport AddWithDataset etc.
template <typename T>
class VectorMemIndex : public VectorIndex {
 public:
    explicit VectorMemIndex(
        DataType elem_type /* used for embedding list only */,
        const IndexType& index_type,
        const MetricType& metric_type,
        const IndexVersion& version,
        bool use_knowhere_build_pool = true,
        const storage::FileManagerContext& file_manager_context =
            storage::FileManagerContext());

    // knowhere data view index special constucter for intermin index, no need to hold file_manager_ to upload or download files
    VectorMemIndex(DataType elem_type /* used for embedding list only */,
                   const IndexType& index_type,
                   const MetricType& metric_type,
                   const IndexVersion& version,
                   const knowhere::ViewDataOp view_data,
                   bool use_knowhere_build_pool = true);

    BinarySet
    Serialize(const Config& config) override;

    void
    Load(const BinarySet& binary_set, const Config& config = {}) override;

    void
    Load(milvus::tracer::TraceContext ctx, const Config& config = {}) override;

    void
    BuildWithDataset(const DatasetPtr& dataset,
                     const Config& config = {}) override;

    void
    Build(const Config& config = {}) override;

    void
    AddWithDataset(const DatasetPtr& dataset, const Config& config) override;

    int64_t
    Count() override {
        const auto& offset_mapping = GetOffsetMapping();
        if (offset_mapping.IsEnabled() && offset_mapping.GetValidCount() == 0) {
            return 0;
        }
        if (IsEmptyEmbListIndex()) {
            return 0;
        }
        return index_.Count();
    }

    void
    Query(const DatasetPtr dataset,
          const SearchInfo& search_info,
          const BitsetView& bitset,
          milvus::OpContext* op_context,
          SearchResult& search_result) const override;

    const bool
    HasRawData() const override;

    bool
    IsIndexRefineEnabled() const override;

    std::vector<uint8_t>
    GetVector(const DatasetPtr dataset) const override;

    std::pair<std::vector<uint8_t>, std::vector<size_t>>
    GetEmbListByIds(const DatasetPtr dataset,
                    const std::string& metric_type) const override;

    std::unique_ptr<const knowhere::sparse::SparseRow<SparseValueType>[]>
    GetSparseVector(const DatasetPtr dataset) const override;

    IndexStatsPtr
    Upload(const Config& config = {}) override;

    knowhere::expected<std::vector<knowhere::IndexNode::IteratorPtr>>
    VectorIterators(const DatasetPtr dataset,
                    const knowhere::Json& json,
                    const BitsetView& bitset,
                    milvus::OpContext* op_context = nullptr) const override;

    knowhere::expected<knowhere::DataSetPtr>
    CalcDistByIDs(const knowhere::DataSetPtr query_dataset,
                  const BitsetView& bitset,
                  const int64_t* labels,
                  size_t labels_len,
                  bool is_cosine,
                  milvus::OpContext* op_context = nullptr) const override;

 protected:
    virtual void
    LoadWithoutAssemble(const BinarySet& binary_set, const Config& config);

 private:
    void
    LoadFromFile(const Config& config);

    bool
    IsEmptyEmbListIndex() const {
        return elem_type_ != DataType::NONE && !empty_emb_list_offsets_.empty();
    }

 protected:
    Config config_;
    knowhere::Index<knowhere::IndexNode> index_;
    std::shared_ptr<storage::MemFileManagerImpl> file_manager_;
    // used for embedding list only
    DataType elem_type_;

    CreateIndexInfo create_index_info_;
    bool use_knowhere_build_pool_;
    std::vector<size_t> empty_emb_list_offsets_;
};

template <typename T>
using VectorMemIndexPtr = std::unique_ptr<VectorMemIndex<T>>;
}  // namespace milvus::index
