#include <iostream>
#include <pybind11/pybind11.h>
#include <pybind11/numpy.h>
#include <pybind11/stl.h>
#include "hnswlib.h"
#include <thread>
#include <atomic>
#include <stdlib.h>
#include <assert.h>

namespace py = pybind11;
using namespace pybind11::literals; // needed to bring in _a literal

/*
 * replacement for the openmp '#pragma omp parallel for' directive
 * only handles a subset of functionality (no reductions etc)
 * Process ids from start (inclusive) to end (EXCLUSIVE)
 *
 * The method is borrowed from nmslib
 */
template<class Function>
inline void ParallelFor(size_t start, size_t end, size_t numThreads, Function fn) {
    if (numThreads <= 0) {
        numThreads = std::thread::hardware_concurrency();
    }

    if (numThreads == 1) {
        for (size_t id = start; id < end; id++) {
            fn(id, 0);
        }
    } else {
        std::vector<std::thread> threads;
        std::atomic<size_t> current(start);

        // keep track of exceptions in threads
        // https://stackoverflow.com/a/32428427/1713196
        std::exception_ptr lastException = nullptr;
        std::mutex lastExceptMutex;

        for (size_t threadId = 0; threadId < numThreads; ++threadId) {
            threads.push_back(std::thread([&, threadId] {
                while (true) {
                    size_t id = current.fetch_add(1);

                    if ((id >= end)) {
                        break;
                    }

                    try {
                        fn(id, threadId);
                    } catch (...) {
                        std::unique_lock<std::mutex> lastExcepLock(lastExceptMutex);
                        lastException = std::current_exception();
                        /*
                         * This will work even when current is the largest value that
                         * size_t can fit, because fetch_add returns the previous value
                         * before the increment (what will result in overflow
                         * and produce 0 instead of current + 1).
                         */
                        current = end;
                        break;
                    }
                }
            }));
        }
        for (auto &thread : threads) {
            thread.join();
        }
        if (lastException) {
            std::rethrow_exception(lastException);
        }
    }
}


inline void assert_true(bool expr, const std::string & msg) {
    if (expr == false)
    throw std::runtime_error("Unpickle Error: "+msg);
    return;
}


template<typename dist_t, typename data_t=float>
class Index {
public:
  Index(const std::string &space_name, const int dim) :
  space_name(space_name), dim(dim) {
    normalize=false;
    if(space_name=="l2") {
      l2space = new hnswlib::L2Space(dim);
    }
    else if(space_name=="ip") {
      l2space = new hnswlib::InnerProductSpace(dim);
    }
    else if(space_name=="cosine") {
      l2space = new hnswlib::InnerProductSpace(dim);
      normalize=true;
    } else {
      throw new std::runtime_error("Space name must be one of l2, ip, or cosine.");
    }
    appr_alg = NULL;
    ep_added = true;
    index_inited = false;
    num_threads_default = std::thread::hardware_concurrency();

    default_ef=10;
  }

  static const int ser_version = 1; // serialization version

  std::string space_name;
  int dim;
  size_t seed;
  size_t default_ef;

  bool index_inited;
  bool ep_added;
  bool normalize;
  int num_threads_default;
  hnswlib::labeltype cur_l;
  hnswlib::HierarchicalNSW<dist_t> *appr_alg;
  hnswlib::SpaceInterface<float> *l2space;

  ~Index() {
      delete l2space;
      if (appr_alg)
          delete appr_alg;
  }

    void init_new_index(const size_t maxElements, const size_t M, const size_t efConstruction, const size_t random_seed) {
        if (appr_alg) {
            throw new std::runtime_error("The index is already initiated.");
        }
        cur_l = 0;
        appr_alg = new hnswlib::HierarchicalNSW<dist_t>(l2space, maxElements, M, efConstruction, random_seed);
        index_inited = true;
        ep_added = false;
        appr_alg->ef_ = default_ef;
        seed=random_seed;
    }

    void set_ef(size_t ef) {
      default_ef=ef;
      if (appr_alg)
        appr_alg->ef_ = ef;
    }

    void set_num_threads(int num_threads) {
        this->num_threads_default = num_threads;
    }

    void saveIndex(const std::string &path_to_index) {
        appr_alg->saveIndex(path_to_index);
    }

    void loadIndex(const std::string &path_to_index, size_t max_elements) {
      if (appr_alg) {
          std::cerr<<"Warning: Calling load_index for an already inited index. Old index is being deallocated.";
          delete appr_alg;
      }
      appr_alg = new hnswlib::HierarchicalNSW<dist_t>(l2space, path_to_index, false, max_elements);
      cur_l = appr_alg->cur_element_count;
      index_inited = true;
    }

    void normalize_vector(float *data, float *norm_array){
        float norm=0.0f;
        for(int i=0;i<dim;i++)
            norm+=data[i]*data[i];
        norm= 1.0f / (sqrtf(norm) + 1e-30f);
        for(int i=0;i<dim;i++)
            norm_array[i]=data[i]*norm;
    }

    void addItems(py::object input, py::object ids_ = py::none(), int num_threads = -1) {
        py::array_t < dist_t, py::array::c_style | py::array::forcecast > items(input);
        auto buffer = items.request();
        if (num_threads <= 0)
            num_threads = num_threads_default;

        size_t rows, features;

        if (buffer.ndim != 2 && buffer.ndim != 1) throw std::runtime_error("data must be a 1d/2d array");
        if (buffer.ndim == 2) {
            rows = buffer.shape[0];
            features = buffer.shape[1];
        }
        else{
            rows = 1;
            features = buffer.shape[0];
        }

        if (features != dim)
            throw std::runtime_error("wrong dimensionality of the vectors");

        // avoid using threads when the number of searches is small:
        if(rows<=num_threads*4){
            num_threads=1;
        }

        std::vector<size_t> ids;

        if (!ids_.is_none()) {
            py::array_t < size_t, py::array::c_style | py::array::forcecast > items(ids_);
            auto ids_numpy = items.request();
            if(ids_numpy.ndim == 1 && ids_numpy.shape[0] == rows) {
                std::vector<size_t> ids1(ids_numpy.shape[0]);
                for (size_t i = 0; i < ids1.size(); i++) {
                    ids1[i] = items.data()[i];
                }
                ids.swap(ids1);
            }
            else if(ids_numpy.ndim == 0 && rows == 1) {
                ids.push_back(*items.data());
            }
            else
                throw std::runtime_error("wrong dimensionality of the labels");
        }


        {

          int start = 0;
          if (!ep_added) {
            size_t id = ids.size() ? ids.at(0) : (cur_l);
            float *vector_data = (float *) items.data(0);
            std::vector<float> norm_array(dim);
            if(normalize){
              normalize_vector(vector_data, norm_array.data());
              vector_data = norm_array.data();
            }
            appr_alg->addPoint((void *) vector_data, (size_t) id);
            start = 1;
            ep_added = true;
          }

            py::gil_scoped_release l;
            if(normalize==false) {
                ParallelFor(start, rows, num_threads, [&](size_t row, size_t threadId) {
                    size_t id = ids.size() ? ids.at(row) : (cur_l+row);
                    appr_alg->addPoint((void *) items.data(row), (size_t) id);
                });
            } else{
                std::vector<float> norm_array(num_threads * dim);
                ParallelFor(start, rows, num_threads, [&](size_t row, size_t threadId) {
                    // normalize vector:
                    size_t start_idx = threadId * dim;
                    normalize_vector((float *) items.data(row), (norm_array.data()+start_idx));

                    size_t id = ids.size() ? ids.at(row) : (cur_l+row);
                    appr_alg->addPoint((void *) (norm_array.data()+start_idx), (size_t) id);
                });
            };
            cur_l+=rows;
        }
    }

    std::vector<std::vector<data_t>> getDataReturnList(py::object ids_ = py::none()) {
        std::vector<size_t> ids;
        if (!ids_.is_none()) {
            py::array_t < size_t, py::array::c_style | py::array::forcecast > items(ids_);
            auto ids_numpy = items.request();

            if (ids_numpy.ndim == 0) {
              throw std::invalid_argument("get_items accepts a list of indices and returns a list of vectors");
            } else {
              std::vector<size_t> ids1(ids_numpy.shape[0]);
              for (size_t i = 0; i < ids1.size(); i++) {
                  ids1[i] = items.data()[i];
              }
              ids.swap(ids1);
            }
        }

        std::vector<std::vector<data_t>> data;
        for (auto id : ids) {
            data.push_back(appr_alg->template getDataByLabel<data_t>(id));
        }
        return data;
    }

    std::vector<hnswlib::labeltype> getIdsList() {
        std::vector<hnswlib::labeltype> ids;

        for(auto kv : appr_alg->label_lookup_) {
            ids.push_back(kv.first);
        }
        return ids;
    }


    py::dict getAnnData() const { /* WARNING: Index::getAnnData is not thread-safe with Index::addItems */
      std::unique_lock <std::mutex> templock(appr_alg->global);

      size_t level0_npy_size = appr_alg->cur_element_count * appr_alg->size_data_per_element_;
      size_t link_npy_size = 0;
      std::vector<size_t> link_npy_offsets(appr_alg->cur_element_count);

      for (size_t i = 0; i < appr_alg->cur_element_count; i++){
        size_t linkListSize = appr_alg->element_levels_[i] > 0 ? appr_alg->size_links_per_element_ * appr_alg->element_levels_[i] : 0;
        link_npy_offsets[i]=link_npy_size;
        if (linkListSize)
          link_npy_size += linkListSize;
      }

      char* data_level0_npy = (char *) malloc(level0_npy_size);
      char* link_list_npy = (char *) malloc(link_npy_size);
      int* element_levels_npy = (int *) malloc(appr_alg->element_levels_.size()*sizeof(int));

      hnswlib::labeltype* label_lookup_key_npy = (hnswlib::labeltype *) malloc(appr_alg->label_lookup_.size()*sizeof(hnswlib::labeltype));
      hnswlib::tableint*  label_lookup_val_npy = (hnswlib::tableint *)  malloc(appr_alg->label_lookup_.size()*sizeof(hnswlib::tableint));

      memset(label_lookup_key_npy, -1, appr_alg->label_lookup_.size()*sizeof(hnswlib::labeltype));
      memset(label_lookup_val_npy, -1, appr_alg->label_lookup_.size()*sizeof(hnswlib::tableint));

      size_t idx=0;
      for ( auto it = appr_alg->label_lookup_.begin(); it != appr_alg->label_lookup_.end(); ++it ){
        label_lookup_key_npy[idx]= it->first;
        label_lookup_val_npy[idx]= it->second;
        idx++;
      }

      memset(link_list_npy, 0, link_npy_size);

      memcpy(data_level0_npy, appr_alg->data_level0_memory_, level0_npy_size);
      memcpy(element_levels_npy, appr_alg->element_levels_.data(), appr_alg->element_levels_.size() * sizeof(int));

      for (size_t i = 0; i < appr_alg->cur_element_count; i++){
        size_t linkListSize = appr_alg->element_levels_[i] > 0 ? appr_alg->size_links_per_element_ * appr_alg->element_levels_[i] : 0;
        if (linkListSize){
          memcpy(link_list_npy+link_npy_offsets[i], appr_alg->linkLists_[i], linkListSize);
        }
      }

      py::capsule free_when_done_l0(data_level0_npy, [](void *f) {
          delete[] f;
      });
      py::capsule free_when_done_lvl(element_levels_npy, [](void *f) {
          delete[] f;
      });
      py::capsule free_when_done_lb(label_lookup_key_npy, [](void *f) {
          delete[] f;
      });
      py::capsule free_when_done_id(label_lookup_val_npy, [](void *f) {
          delete[] f;
      });
      py::capsule free_when_done_ll(link_list_npy, [](void *f) {
          delete[] f;
      });

      /*  TODO: serialize state of random generators appr_alg->level_generator_ and appr_alg->update_probability_generator_  */
      /*        for full reproducibility / to avoid re-initializing generators inside Index::createFromParams         */

      return py::dict(
                      "offset_level0"_a=appr_alg->offsetLevel0_,
                      "max_elements"_a=appr_alg->max_elements_,
                      "cur_element_count"_a=appr_alg->cur_element_count,
                      "size_data_per_element"_a=appr_alg->size_data_per_element_,
                      "label_offset"_a=appr_alg->label_offset_,
                      "offset_data"_a=appr_alg->offsetData_,
                      "max_level"_a=appr_alg->maxlevel_,
                      "enterpoint_node"_a=appr_alg->enterpoint_node_,
                      "max_M"_a=appr_alg->maxM_,
                      "max_M0"_a=appr_alg->maxM0_,
                      "M"_a=appr_alg->M_,
                      "mult"_a=appr_alg->mult_,
                      "ef_construction"_a=appr_alg->ef_construction_,
                      "ef"_a=appr_alg->ef_,
                      "has_deletions"_a=(bool)appr_alg->num_deleted_,
                      "size_links_per_element"_a=appr_alg->size_links_per_element_,

                      "label_lookup_external"_a=py::array_t<hnswlib::labeltype>(
                              {appr_alg->label_lookup_.size()}, // shape
                              {sizeof(hnswlib::labeltype)}, // C-style contiguous strides for double
                              label_lookup_key_npy, // the data pointer
                              free_when_done_lb),

                      "label_lookup_internal"_a=py::array_t<hnswlib::tableint>(
                              {appr_alg->label_lookup_.size()}, // shape
                              {sizeof(hnswlib::tableint)}, // C-style contiguous strides for double
                              label_lookup_val_npy, // the data pointer
                              free_when_done_id),

                      "element_levels"_a=py::array_t<int>(
                              {appr_alg->element_levels_.size()}, // shape
                              {sizeof(int)}, // C-style contiguous strides for double
                              element_levels_npy, // the data pointer
                              free_when_done_lvl),

                              // linkLists_,element_levels_,data_level0_memory_
                      "data_level0"_a=py::array_t<char>(
                              {level0_npy_size}, // shape
                              {sizeof(char)}, // C-style contiguous strides for double
                              data_level0_npy, // the data pointer
                              free_when_done_l0),

                      "link_lists"_a=py::array_t<char>(
                              {link_npy_size}, // shape
                              {sizeof(char)}, // C-style contiguous strides for double
                              link_list_npy, // the data pointer
                              free_when_done_ll)
                    );
    }


    py::dict getIndexParams() const { /* WARNING: Index::getAnnData is not thread-safe with Index::addItems */
        auto params = py::dict(
                            "ser_version"_a=py::int_(Index<float>::ser_version), //serialization version
                            "space"_a=space_name,
                            "dim"_a=dim,
                            "index_inited"_a=index_inited,
                            "ep_added"_a=ep_added,
                            "normalize"_a=normalize,
                            "num_threads"_a=num_threads_default,
                            "seed"_a=seed
                            );

        if(index_inited == false)
            return py::dict( **params, "ef"_a=default_ef);

        auto ann_params = getAnnData();

        return py::dict(**params, **ann_params);
    }


    static Index<float> * createFromParams(const py::dict d) {
      // check serialization version
      assert_true(((int)py::int_(Index<float>::ser_version)) >= d["ser_version"].cast<int>(), "Invalid serialization version!");

      auto space_name_=d["space"].cast<std::string>();
      auto dim_=d["dim"].cast<int>();
      auto index_inited_=d["index_inited"].cast<bool>();

      Index<float> *new_index = new Index<float>(space_name_, dim_);

      /*  TODO: deserialize state of random generators into new_index->level_generator_ and new_index->update_probability_generator_  */
      /*        for full reproducibility / state of generators is serialized inside Index::getIndexParams                      */
      new_index->seed = d["seed"].cast<size_t>();

      if (index_inited_){
        new_index->appr_alg = new hnswlib::HierarchicalNSW<dist_t>(new_index->l2space, d["max_elements"].cast<size_t>(), d["M"].cast<size_t>(), d["ef_construction"].cast<size_t>(), new_index->seed);
        new_index->cur_l = d["cur_element_count"].cast<size_t>();
      }

      new_index->index_inited = index_inited_;
      new_index->ep_added=d["ep_added"].cast<bool>();
      new_index->num_threads_default=d["num_threads"].cast<int>();
      new_index->default_ef=d["ef"].cast<size_t>();

      if (index_inited_)
        new_index->setAnnData(d);

      return new_index;
    }

    static Index<float> * createFromIndex(const Index<float> & index) {
        return createFromParams(index.getIndexParams());
    }

    void setAnnData(const py::dict d) { /* WARNING: Index::setAnnData is not thread-safe with Index::addItems */
      std::unique_lock <std::mutex> templock(appr_alg->global);

      assert_true(appr_alg->offsetLevel0_ == d["offset_level0"].cast<size_t>(), "Invalid value of offsetLevel0_ ");
      assert_true(appr_alg->max_elements_ == d["max_elements"].cast<size_t>(), "Invalid value of max_elements_ ");

      appr_alg->cur_element_count = d["cur_element_count"].cast<size_t>();

      assert_true(appr_alg->size_data_per_element_ == d["size_data_per_element"].cast<size_t>(), "Invalid value of size_data_per_element_ ");
      assert_true(appr_alg->label_offset_ == d["label_offset"].cast<size_t>(), "Invalid value of label_offset_ ");
      assert_true(appr_alg->offsetData_ == d["offset_data"].cast<size_t>(), "Invalid value of offsetData_ ");

      appr_alg->maxlevel_ = d["max_level"].cast<int>();
      appr_alg->enterpoint_node_ = d["enterpoint_node"].cast<hnswlib::tableint>();

      assert_true(appr_alg->maxM_ == d["max_M"].cast<size_t>(), "Invalid value of maxM_ ");
      assert_true(appr_alg->maxM0_ == d["max_M0"].cast<size_t>(), "Invalid value of maxM0_ ");
      assert_true(appr_alg->M_ == d["M"].cast<size_t>(), "Invalid value of M_ ");
      assert_true(appr_alg->mult_ == d["mult"].cast<double>(), "Invalid value of mult_ ");
      assert_true(appr_alg->ef_construction_ == d["ef_construction"].cast<size_t>(), "Invalid value of ef_construction_ ");

      appr_alg->ef_ = d["ef"].cast<size_t>();

      assert_true(appr_alg->size_links_per_element_ == d["size_links_per_element"].cast<size_t>(), "Invalid value of size_links_per_element_ ");

      auto label_lookup_key_npy = d["label_lookup_external"].cast<py::array_t < hnswlib::labeltype, py::array::c_style | py::array::forcecast > >();
      auto label_lookup_val_npy = d["label_lookup_internal"].cast<py::array_t < hnswlib::tableint, py::array::c_style | py::array::forcecast > >();
      auto element_levels_npy = d["element_levels"].cast<py::array_t < int, py::array::c_style | py::array::forcecast > >();
      auto data_level0_npy = d["data_level0"].cast<py::array_t < char, py::array::c_style | py::array::forcecast > >();
      auto link_list_npy = d["link_lists"].cast<py::array_t < char, py::array::c_style | py::array::forcecast > >();

      for (size_t i = 0; i < appr_alg->cur_element_count; i++){
        if (label_lookup_val_npy.data()[i] < 0){
            throw std::runtime_error("internal id cannot be negative!");
          }
        else{
          appr_alg->label_lookup_.insert(std::make_pair(label_lookup_key_npy.data()[i], label_lookup_val_npy.data()[i]));
        }
      }

      memcpy(appr_alg->element_levels_.data(), element_levels_npy.data(), element_levels_npy.nbytes());

      size_t link_npy_size = 0;
      std::vector<size_t> link_npy_offsets(appr_alg->cur_element_count);

      for (size_t i = 0; i < appr_alg->cur_element_count; i++){
        size_t linkListSize = appr_alg->element_levels_[i] > 0 ? appr_alg->size_links_per_element_ * appr_alg->element_levels_[i] : 0;
        link_npy_offsets[i]=link_npy_size;
        if (linkListSize)
          link_npy_size += linkListSize;
      }

      memcpy(appr_alg->data_level0_memory_, data_level0_npy.data(), data_level0_npy.nbytes());

      for (size_t i = 0; i < appr_alg->max_elements_; i++) {
          size_t linkListSize = appr_alg->element_levels_[i] > 0 ? appr_alg->size_links_per_element_ * appr_alg->element_levels_[i] : 0;
          if (linkListSize == 0) {
              appr_alg->linkLists_[i] = nullptr;
          } else {
            appr_alg->linkLists_[i] = (char *) malloc(linkListSize);
            if (appr_alg->linkLists_[i] == nullptr)
                throw std::runtime_error("Not enough memory: loadIndex failed to allocate linklist");

            memcpy(appr_alg->linkLists_[i], link_list_npy.data()+link_npy_offsets[i], linkListSize);

          }
      }

      // set num_deleted
      appr_alg->num_deleted_ = 0;
      bool has_deletions = d["has_deletions"].cast<bool>();
      if (has_deletions)
      {
        for (size_t i = 0; i < appr_alg->cur_element_count; i++) {
          if(appr_alg->isMarkedDeleted(i))
            appr_alg->num_deleted_ += 1;
        }
      }
}

    py::object knnQuery_return_numpy(py::object input, size_t k = 1, int num_threads = -1) {
        py::array_t < dist_t, py::array::c_style | py::array::forcecast > items(input);
        auto buffer = items.request();
        hnswlib::labeltype *data_numpy_l;
        dist_t *data_numpy_d;
        size_t rows, features;

        if (num_threads <= 0)
            num_threads = num_threads_default;

        {
            py::gil_scoped_release l;

            if (buffer.ndim != 2 && buffer.ndim != 1) throw std::runtime_error("data must be a 1d/2d array");
            if (buffer.ndim == 2) {
                rows = buffer.shape[0];
                features = buffer.shape[1];
            }
            else{
                rows = 1;
                features = buffer.shape[0];
            }

            // avoid using threads when the number of searches is small:

            if(rows<=num_threads*4){
                num_threads=1;
            }

            data_numpy_l = new hnswlib::labeltype[rows * k];
            data_numpy_d = new dist_t[rows * k];

            if(normalize==false) {
                ParallelFor(0, rows, num_threads, [&](size_t row, size_t threadId) {
                                std::priority_queue<std::pair<dist_t, hnswlib::labeltype >> result = appr_alg->searchKnn(
                                        (void *) items.data(row), k);
                                if (result.size() != k)
                                    throw std::runtime_error(
                                            "Cannot return the results in a contigious 2D array. Probably ef or M is too small");
                                for (int i = k - 1; i >= 0; i--) {
                                    auto &result_tuple = result.top();
                                    data_numpy_d[row * k + i] = result_tuple.first;
                                    data_numpy_l[row * k + i] = result_tuple.second;
                                    result.pop();
                                }
                            }
                );
            }
            else{
                std::vector<float> norm_array(num_threads*features);
                ParallelFor(0, rows, num_threads, [&](size_t row, size_t threadId) {
                                float *data= (float *) items.data(row);

                                size_t start_idx = threadId * dim;
                                normalize_vector((float *) items.data(row), (norm_array.data()+start_idx));

                                std::priority_queue<std::pair<dist_t, hnswlib::labeltype >> result = appr_alg->searchKnn(
                                        (void *) (norm_array.data()+start_idx), k);
                                if (result.size() != k)
                                    throw std::runtime_error(
                                            "Cannot return the results in a contigious 2D array. Probably ef or M is too small");
                                for (int i = k - 1; i >= 0; i--) {
                                    auto &result_tuple = result.top();
                                    data_numpy_d[row * k + i] = result_tuple.first;
                                    data_numpy_l[row * k + i] = result_tuple.second;
                                    result.pop();
                                }
                            }
                );
            }
        }
        py::capsule free_when_done_l(data_numpy_l, [](void *f) {
            delete[] f;
        });
        py::capsule free_when_done_d(data_numpy_d, [](void *f) {
            delete[] f;
        });

        return py::make_tuple(
                py::array_t<hnswlib::labeltype>(
                        {rows, k}, // shape
                        {k * sizeof(hnswlib::labeltype),
                         sizeof(hnswlib::labeltype)}, // C-style contiguous strides for double
                        data_numpy_l, // the data pointer
                        free_when_done_l),
                py::array_t<dist_t>(
                        {rows, k}, // shape
                        {k * sizeof(dist_t), sizeof(dist_t)}, // C-style contiguous strides for double
                        data_numpy_d, // the data pointer
                        free_when_done_d));

    }

    void markDeleted(size_t label) {
        appr_alg->markDelete(label);
    }

    void unmarkDeleted(size_t label) {
        appr_alg->unmarkDelete(label);
    }

    void resizeIndex(size_t new_size) {
        appr_alg->resizeIndex(new_size);
    }

    size_t getMaxElements() const {
        return appr_alg->max_elements_;
    }

    size_t getCurrentCount() const {
        return appr_alg->cur_element_count;
    }
};

template<typename dist_t, typename data_t=float>
class BFIndex {
public:
    BFIndex(const std::string &space_name, const int dim) :
            space_name(space_name), dim(dim) {
        normalize=false;
        if(space_name=="l2") {
            space = new hnswlib::L2Space(dim);
        }
        else if(space_name=="ip") {
            space = new hnswlib::InnerProductSpace(dim);
        }
        else if(space_name=="cosine") {
            space = new hnswlib::InnerProductSpace(dim);
            normalize=true;
        } else {
            throw new std::runtime_error("Space name must be one of l2, ip, or cosine.");
        }
        alg = NULL;
        index_inited = false;
    }

    static const int ser_version = 1; // serialization version

    std::string space_name;
    int dim;
    bool index_inited;
    bool normalize;

    hnswlib::labeltype cur_l;
    hnswlib::BruteforceSearch<dist_t> *alg;
    hnswlib::SpaceInterface<float> *space;

    ~BFIndex() {
        delete space;
        if (alg)
            delete alg;
    }

    void init_new_index(const size_t maxElements) {
        if (alg) {
            throw new std::runtime_error("The index is already initiated.");
        }
        cur_l = 0;
        alg = new hnswlib::BruteforceSearch<dist_t>(space, maxElements);
        index_inited = true;
    }

    void normalize_vector(float *data, float *norm_array){
        float norm=0.0f;
        for(int i=0;i<dim;i++)
            norm+=data[i]*data[i];
        norm= 1.0f / (sqrtf(norm) + 1e-30f);
        for(int i=0;i<dim;i++)
            norm_array[i]=data[i]*norm;
    }

    void addItems(py::object input, py::object ids_ = py::none()) {
        py::array_t < dist_t, py::array::c_style | py::array::forcecast > items(input);
        auto buffer = items.request();
        size_t rows, features;

        if (buffer.ndim != 2 && buffer.ndim != 1) throw std::runtime_error("data must be a 1d/2d array");
        if (buffer.ndim == 2) {
            rows = buffer.shape[0];
            features = buffer.shape[1];
        } else {
            rows = 1;
            features = buffer.shape[0];
        }

        if (features != dim)
            throw std::runtime_error("wrong dimensionality of the vectors");

        std::vector<size_t> ids;

        if (!ids_.is_none()) {
            py::array_t < size_t, py::array::c_style | py::array::forcecast > items(ids_);
            auto ids_numpy = items.request();
            if (ids_numpy.ndim == 1 && ids_numpy.shape[0] == rows) {
                std::vector<size_t> ids1(ids_numpy.shape[0]);
                for (size_t i = 0; i < ids1.size(); i++) {
                    ids1[i] = items.data()[i];
                }
                ids.swap(ids1);
            } else if (ids_numpy.ndim == 0 && rows == 1) {
                ids.push_back(*items.data());
            } else
                throw std::runtime_error("wrong dimensionality of the labels");
        }
        {

            for (size_t row = 0; row < rows; row++) {
                size_t id = ids.size() ? ids.at(row) : cur_l + row;
                if (!normalize) {
                    alg->addPoint((void *) items.data(row), (size_t) id);
                } else {
                    std::vector<float> normalized_vector(dim);
                    normalize_vector((float *)items.data(row), normalized_vector.data());
                    alg->addPoint((void *) normalized_vector.data(), (size_t) id);
                }
            }
            cur_l+=rows;
        }
    }

    void deleteVector(size_t label) {
        alg->removePoint(label);
    }

    void saveIndex(const std::string &path_to_index) {
        alg->saveIndex(path_to_index);
    }

    void loadIndex(const std::string &path_to_index, size_t max_elements) {
        if (alg) {
            std::cerr<<"Warning: Calling load_index for an already inited index. Old index is being deallocated.";
            delete alg;
        }
        alg = new hnswlib::BruteforceSearch<dist_t>(space, path_to_index);
        cur_l = alg->cur_element_count;
        index_inited = true;
    }

    py::object knnQuery_return_numpy(py::object input, size_t k = 1) {

        py::array_t < dist_t, py::array::c_style | py::array::forcecast > items(input);
        auto buffer = items.request();
        hnswlib::labeltype *data_numpy_l;
        dist_t *data_numpy_d;
        size_t rows, features;
        {
            py::gil_scoped_release l;

            if (buffer.ndim != 2 && buffer.ndim != 1) throw std::runtime_error("data must be a 1d/2d array");
            if (buffer.ndim == 2) {
                rows = buffer.shape[0];
                features = buffer.shape[1];
            } else {
                rows = 1;
                features = buffer.shape[0];
            }

            data_numpy_l = new hnswlib::labeltype[rows * k];
            data_numpy_d = new dist_t[rows * k];

            for (size_t row = 0; row < rows; row++) {
                std::priority_queue<std::pair<dist_t, hnswlib::labeltype >> result = alg->searchKnn(
                        (void *) items.data(row), k);
                for (int i = k - 1; i >= 0; i--) {
                    auto &result_tuple = result.top();
                    data_numpy_d[row * k + i] = result_tuple.first;
                    data_numpy_l[row * k + i] = result_tuple.second;
                    result.pop();
                }
            }
        }

        py::capsule free_when_done_l(data_numpy_l, [](void *f) {
            delete[] f;
        });
        py::capsule free_when_done_d(data_numpy_d, [](void *f) {
            delete[] f;
        });


        return py::make_tuple(
                py::array_t<hnswlib::labeltype>(
                        {rows, k}, // shape
                        {k * sizeof(hnswlib::labeltype),
                         sizeof(hnswlib::labeltype)}, // C-style contiguous strides for double
                        data_numpy_l, // the data pointer
                        free_when_done_l),
                py::array_t<dist_t>(
                        {rows, k}, // shape
                        {k * sizeof(dist_t), sizeof(dist_t)}, // C-style contiguous strides for double
                        data_numpy_d, // the data pointer
                        free_when_done_d));

    }

};

PYBIND11_PLUGIN(hnswlib) {
        py::module m("hnswlib");

        py::class_<Index<float>>(m, "Index")
        .def(py::init(&Index<float>::createFromParams), py::arg("params"))
           /* WARNING: Index::createFromIndex is not thread-safe with Index::addItems */
        .def(py::init(&Index<float>::createFromIndex), py::arg("index"))
        .def(py::init<const std::string &, const int>(), py::arg("space"), py::arg("dim"))
        .def("init_index", &Index<float>::init_new_index, py::arg("max_elements"), py::arg("M")=16, py::arg("ef_construction")=200, py::arg("random_seed")=100)
        .def("knn_query", &Index<float>::knnQuery_return_numpy, py::arg("data"), py::arg("k")=1, py::arg("num_threads")=-1)
        .def("add_items", &Index<float>::addItems, py::arg("data"), py::arg("ids") = py::none(), py::arg("num_threads")=-1)
        .def("get_items", &Index<float, float>::getDataReturnList, py::arg("ids") = py::none())
        .def("get_ids_list", &Index<float>::getIdsList)
        .def("set_ef", &Index<float>::set_ef, py::arg("ef"))
        .def("set_num_threads", &Index<float>::set_num_threads, py::arg("num_threads"))
        .def("save_index", &Index<float>::saveIndex, py::arg("path_to_index"))
        .def("load_index", &Index<float>::loadIndex, py::arg("path_to_index"), py::arg("max_elements")=0)
        .def("mark_deleted", &Index<float>::markDeleted, py::arg("label"))
        .def("unmark_deleted", &Index<float>::unmarkDeleted, py::arg("label"))
        .def("resize_index", &Index<float>::resizeIndex, py::arg("new_size"))
        .def("get_max_elements", &Index<float>::getMaxElements)
        .def("get_current_count", &Index<float>::getCurrentCount)
        .def_readonly("space", &Index<float>::space_name)
        .def_readonly("dim", &Index<float>::dim)
        .def_readwrite("num_threads", &Index<float>::num_threads_default)
        .def_property("ef",
          [](const Index<float> & index) {
            return index.index_inited ? index.appr_alg->ef_ : index.default_ef;
          },
          [](Index<float> & index, const size_t ef_) {
            index.default_ef=ef_;
            if (index.appr_alg)
              index.appr_alg->ef_ = ef_;
        })
        .def_property_readonly("max_elements", [](const Index<float> & index) {
            return index.index_inited ? index.appr_alg->max_elements_ : 0;
        })
        .def_property_readonly("element_count", [](const Index<float> & index) {
            return index.index_inited ? index.appr_alg->cur_element_count : 0;
        })
        .def_property_readonly("ef_construction", [](const Index<float> & index) {
          return index.index_inited ? index.appr_alg->ef_construction_ : 0;
        })
        .def_property_readonly("M",  [](const Index<float> & index) {
          return index.index_inited ? index.appr_alg->M_ : 0;
        })

        .def(py::pickle(
            [](const Index<float> &ind) { // __getstate__
                return py::make_tuple(ind.getIndexParams()); /* Return dict (wrapped in a tuple) that fully encodes state of the Index object */
            },
            [](py::tuple t) { // __setstate__
                if (t.size() != 1)
                    throw std::runtime_error("Invalid state!");

                return Index<float>::createFromParams(t[0].cast<py::dict>());
            }
        ))

        .def("__repr__", [](const Index<float> &a) {
            return "<hnswlib.Index(space='" + a.space_name + "', dim="+std::to_string(a.dim)+")>";
        });

        py::class_<BFIndex<float>>(m, "BFIndex")
        .def(py::init<const std::string &, const int>(), py::arg("space"), py::arg("dim"))
        .def("init_index", &BFIndex<float>::init_new_index, py::arg("max_elements"))
        .def("knn_query", &BFIndex<float>::knnQuery_return_numpy, py::arg("data"), py::arg("k")=1)
        .def("add_items", &BFIndex<float>::addItems, py::arg("data"), py::arg("ids") = py::none())
        .def("delete_vector", &BFIndex<float>::deleteVector, py::arg("label"))
        .def("save_index", &BFIndex<float>::saveIndex, py::arg("path_to_index"))
        .def("load_index", &BFIndex<float>::loadIndex, py::arg("path_to_index"), py::arg("max_elements")=0)
        .def("__repr__", [](const BFIndex<float> &a) {
            return "<hnswlib.BFIndex(space='" + a.space_name + "', dim="+std::to_string(a.dim)+")>";
        });
        return m.ptr();
}
