// Copyright (C) 2019-2020 Zilliz. All rights reserved.
//
// 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.

#pragma once

#include <memory>
#include <string>
#include <vector>

#include "utils/Status.h"

namespace milvus {
namespace engine {

// TODO(linxj): replace with VecIndex::IndexType
enum class EngineType {
    INVALID = 0,
    FAISS_IDMAP = 1,
    FAISS_IVFFLAT,
    FAISS_IVFSQ8,
    NSG_MIX,
    FAISS_IVFSQ8H,
    FAISS_PQ,
    SPTAG_KDT,
    SPTAG_BKT,
    FAISS_BIN_IDMAP,
    FAISS_BIN_IVFFLAT,
    HNSW,
    MAX_VALUE = HNSW,
};

enum class MetricType {
    L2 = 1,        // Euclidean Distance
    IP = 2,        // Cosine Similarity
    HAMMING = 3,   // Hamming Distance
    JACCARD = 4,   // Jaccard Distance
    TANIMOTO = 5,  // Tanimoto Distance
    MAX_VALUE = TANIMOTO,
};

class ExecutionEngine {
 public:
    virtual Status
    AddWithIds(int64_t n, const float* xdata, const int64_t* xids) = 0;

    virtual Status
    AddWithIds(int64_t n, const uint8_t* xdata, const int64_t* xids) = 0;

    virtual size_t
    Count() const = 0;

    virtual size_t
    Size() const = 0;

    virtual size_t
    Dimension() const = 0;

    virtual size_t
    PhysicalSize() const = 0;

    virtual Status
    Serialize() = 0;

    virtual Status
    Load(bool to_cache = true) = 0;

    virtual Status
    CopyToGpu(uint64_t device_id, bool hybrid) = 0;

    virtual Status
    CopyToIndexFileToGpu(uint64_t device_id) = 0;

    virtual Status
    CopyToCpu() = 0;

    //    virtual std::shared_ptr<ExecutionEngine>
    //    Clone() = 0;

    //    virtual Status
    //    Merge(const std::string& location) = 0;

    virtual Status
    GetVectorByID(const int64_t& id, float* vector, bool hybrid) = 0;

    virtual Status
    GetVectorByID(const int64_t& id, uint8_t* vector, bool hybrid) = 0;

    virtual Status
    Search(int64_t n, const float* data, int64_t k, int64_t nprobe, float* distances, int64_t* labels, bool hybrid) = 0;

    virtual Status
    Search(int64_t n, const uint8_t* data, int64_t k, int64_t nprobe, float* distances, int64_t* labels,
           bool hybrid) = 0;

    virtual Status
    Search(int64_t n, const std::vector<int64_t>& ids, int64_t k, int64_t nprobe, float* distances, int64_t* labels,
           bool hybrid) = 0;

    virtual std::shared_ptr<ExecutionEngine>
    BuildIndex(const std::string& location, EngineType engine_type) = 0;

    virtual Status
    Cache() = 0;

    virtual Status
    GpuCache(uint64_t gpu_id) = 0;

    virtual Status
    Init() = 0;

    virtual EngineType
    IndexEngineType() const = 0;

    virtual MetricType
    IndexMetricType() const = 0;

    virtual std::string
    GetLocation() const = 0;
};

using ExecutionEnginePtr = std::shared_ptr<ExecutionEngine>;

}  // namespace engine
}  // namespace milvus