/**
 * Annoy.rb is a Ruby binding for the Annoy (Approximate Nearest Neighbors Oh Yeah).
 *
 * Copyright (c) 2020 Atsushi Tatsuma
 *
 * 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.
 */

#ifndef ANNOYEXT_HPP
#define ANNOYEXT_HPP 1

#include <typeinfo>

#include <ruby.h>
#include <annoylib.h>
#include <kissrandom.h>

#ifdef ANNOYLIB_MULTITHREADED_BUILD
  typedef AnnoyIndexMultiThreadedBuildPolicy AnnoyIndexThreadedBuildPolicy;
#else
  typedef AnnoyIndexSingleThreadedBuildPolicy AnnoyIndexThreadedBuildPolicy;
#endif

typedef AnnoyIndex<int, double, Angular, Kiss64Random, AnnoyIndexThreadedBuildPolicy> AnnoyIndexAngular;
typedef AnnoyIndex<int, double, DotProduct, Kiss64Random, AnnoyIndexThreadedBuildPolicy> AnnoyIndexDotProduct;
typedef AnnoyIndex<int, uint64_t, Hamming, Kiss64Random, AnnoyIndexThreadedBuildPolicy> AnnoyIndexHamming;
typedef AnnoyIndex<int, double, Euclidean, Kiss64Random, AnnoyIndexThreadedBuildPolicy> AnnoyIndexEuclidean;
typedef AnnoyIndex<int, double, Manhattan, Kiss64Random, AnnoyIndexThreadedBuildPolicy> AnnoyIndexManhattan;

template<class T, typename F> class RbAnnoyIndex
{
  public:
    static VALUE annoy_index_alloc(VALUE self) {
      T* ptr = (T*)ruby_xmalloc(sizeof(T));
      return TypedData_Wrap_Struct(self, &annoy_index_type, ptr);
    };

    static void annoy_index_free(void* ptr) {
      ((T*)ptr)->~AnnoyIndex();
      ruby_xfree(ptr);
    };

    static size_t annoy_index_size(const void* ptr) {
      return sizeof(*((T*)ptr));
    };

    static T* get_annoy_index(VALUE self) {
      T* ptr;
      TypedData_Get_Struct(self, T, &annoy_index_type, ptr);
      return ptr;
    };

    static VALUE define_class(VALUE rb_mAnnoy, const char* class_name) {
      VALUE rb_cAnnoyIndex = rb_define_class_under(rb_mAnnoy, class_name, rb_cObject);
      rb_define_alloc_func(rb_cAnnoyIndex, annoy_index_alloc);
      rb_define_method(rb_cAnnoyIndex, "initialize", RUBY_METHOD_FUNC(_annoy_index_init), 1);
      rb_define_method(rb_cAnnoyIndex, "add_item", RUBY_METHOD_FUNC(_annoy_index_add_item), 2);
      rb_define_method(rb_cAnnoyIndex, "build", RUBY_METHOD_FUNC(_annoy_index_build), 2);
      rb_define_method(rb_cAnnoyIndex, "save", RUBY_METHOD_FUNC(_annoy_index_save), 2);
      rb_define_method(rb_cAnnoyIndex, "load", RUBY_METHOD_FUNC(_annoy_index_load), 2);
      rb_define_method(rb_cAnnoyIndex, "unload", RUBY_METHOD_FUNC(_annoy_index_unload), 0);
      rb_define_method(rb_cAnnoyIndex, "get_nns_by_item", RUBY_METHOD_FUNC(_annoy_index_get_nns_by_item), 4);
      rb_define_method(rb_cAnnoyIndex, "get_nns_by_vector", RUBY_METHOD_FUNC(_annoy_index_get_nns_by_vector), 4);
      rb_define_method(rb_cAnnoyIndex, "get_item", RUBY_METHOD_FUNC(_annoy_index_get_item), 1);
      rb_define_method(rb_cAnnoyIndex, "get_distance", RUBY_METHOD_FUNC(_annoy_index_get_distance), 2);
      rb_define_method(rb_cAnnoyIndex, "get_n_items", RUBY_METHOD_FUNC(_annoy_index_get_n_items), 0);
      rb_define_method(rb_cAnnoyIndex, "get_n_trees", RUBY_METHOD_FUNC(_annoy_index_get_n_trees), 0);
      rb_define_method(rb_cAnnoyIndex, "on_disk_build", RUBY_METHOD_FUNC(_annoy_index_on_disk_build), 1);
      rb_define_method(rb_cAnnoyIndex, "set_seed", RUBY_METHOD_FUNC(_annoy_index_set_seed), 1);
      rb_define_method(rb_cAnnoyIndex, "verbose", RUBY_METHOD_FUNC(_annoy_index_verbose), 1);
      rb_define_method(rb_cAnnoyIndex, "get_f", RUBY_METHOD_FUNC(_annoy_index_get_f), 0);
      return rb_cAnnoyIndex;
    };

  private:
    static const rb_data_type_t annoy_index_type;

    static VALUE _annoy_index_init(VALUE self, VALUE _n_dims) {
      const int n_dims = NUM2INT(_n_dims);
      T* ptr = get_annoy_index(self);
      new (ptr) T(n_dims);
      return Qnil;
    };

    static VALUE _annoy_index_add_item(VALUE self, VALUE _idx, VALUE arr) {
      const int idx = NUM2INT(_idx);
      const int n_dims = get_annoy_index(self)->get_f();

      if (!RB_TYPE_P(arr, T_ARRAY)) {
        rb_raise(rb_eArgError, "Expect item vector to be Array.");
        return Qfalse;
      }

      if (n_dims != RARRAY_LEN(arr)) {
        rb_raise(rb_eArgError, "Array size does not match to index dimensionality.");
        return Qfalse;
      }

      F* vec = (F*)ruby_xmalloc(n_dims * sizeof(F));
      for (int i = 0; i < n_dims; i++) {
        vec[i] = typeid(F) == typeid(double) ? NUM2DBL(rb_ary_entry(arr, i)) : NUM2UINT(rb_ary_entry(arr, i));
      }

      char* error;
      if (!get_annoy_index(self)->add_item(idx, vec, &error)) {
        VALUE error_str = rb_str_new_cstr(error);
        free(error);
        ruby_xfree(vec);
        rb_raise(rb_eRuntimeError, "%s", StringValuePtr(error_str));
        return Qfalse;
      }

      ruby_xfree(vec);
      return Qtrue;
    };

    static VALUE _annoy_index_build(VALUE self, VALUE _n_trees, VALUE _n_jobs) {
      const int n_trees = NUM2INT(_n_trees);
      const int n_jobs = NUM2INT(_n_jobs);
      char* error;
      if (!get_annoy_index(self)->build(n_trees, n_jobs, &error)) {
        VALUE error_str = rb_str_new_cstr(error);
        free(error);
        rb_raise(rb_eRuntimeError, "%s", StringValuePtr(error_str));
        return Qfalse;
      }
      return Qtrue;
    };

    static VALUE _annoy_index_save(VALUE self, VALUE _filename, VALUE _prefault) {
      const char* filename = StringValuePtr(_filename);
      const bool prefault = _prefault == Qtrue ? true : false;
      char* error;
      if (!get_annoy_index(self)->save(filename, prefault, &error)) {
        VALUE error_str = rb_str_new_cstr(error);
        free(error);
        rb_raise(rb_eRuntimeError, "%s", StringValuePtr(error_str));
        return Qfalse;
      }
      RB_GC_GUARD(_filename);
      return Qtrue;
    };

    static VALUE _annoy_index_load(VALUE self, VALUE _filename, VALUE _prefault) {
      const char* filename = StringValuePtr(_filename);
      const bool prefault = _prefault == Qtrue ? true : false;
      char* error;
      if (!get_annoy_index(self)->load(filename, prefault, &error)) {
        VALUE error_str = rb_str_new_cstr(error);
        free(error);
        rb_raise(rb_eRuntimeError, "%s", StringValuePtr(error_str));
        return Qfalse;
      }
      RB_GC_GUARD(_filename);
      return Qtrue;
    };

    static VALUE _annoy_index_unload(VALUE self) {
      get_annoy_index(self)->unload();
      return Qnil;
    };

    static VALUE _annoy_index_get_nns_by_item(VALUE self, VALUE _idx, VALUE _n_neighbors, VALUE _search_k, VALUE _include_distances) {
      const int idx = NUM2INT(_idx);
      const int n_neighbors = NUM2INT(_n_neighbors);
      const int search_k = NUM2INT(_search_k);
      const bool include_distances = _include_distances == Qtrue ? true : false;
      std::vector<int> neighbors;
      std::vector<F> distances;

      get_annoy_index(self)->get_nns_by_item(idx, n_neighbors, search_k, &neighbors, include_distances ? &distances : NULL);

      const int sz_neighbors = neighbors.size();
      VALUE neighbors_arr = rb_ary_new2(sz_neighbors);

      for (int i = 0; i < sz_neighbors; i++) {
        rb_ary_store(neighbors_arr, i, INT2NUM(neighbors[i]));
      }

      if (include_distances) {
        const int sz_distances = distances.size();
        VALUE distances_arr = rb_ary_new2(sz_distances);
        for (int i = 0; i < sz_distances; i++) {
          rb_ary_store(distances_arr, i, typeid(F) == typeid(double) ? DBL2NUM(distances[i]) : UINT2NUM(distances[i]));
        }
        VALUE res = rb_ary_new2(2);
        rb_ary_store(res, 0, neighbors_arr);
        rb_ary_store(res, 1, distances_arr);
        return res;
      }

      return neighbors_arr;
    };

    static VALUE _annoy_index_get_nns_by_vector(VALUE self, VALUE _vec, VALUE _n_neighbors, VALUE _search_k, VALUE _include_distances) {
      const int n_dims = get_annoy_index(self)->get_f();

      if (!RB_TYPE_P(_vec, T_ARRAY)) {
        rb_raise(rb_eArgError, "Expect item vector to be Array.");
        return Qfalse;
      }

      if (n_dims != RARRAY_LEN(_vec)) {
        rb_raise(rb_eArgError, "Array size does not match to index dimensionality.");
        return Qfalse;
      }

      F* vec = (F*)ruby_xmalloc(n_dims * sizeof(F));
      for (int i = 0; i < n_dims; i++) {
        vec[i] = typeid(F) == typeid(double) ? NUM2DBL(rb_ary_entry(_vec, i)) : NUM2UINT(rb_ary_entry(_vec, i));
      }

      const int n_neighbors = NUM2INT(_n_neighbors);
      const int search_k = NUM2INT(_search_k);
      const bool include_distances = _include_distances == Qtrue ? true : false;
      std::vector<int> neighbors;
      std::vector<F> distances;

      get_annoy_index(self)->get_nns_by_vector(vec, n_neighbors, search_k, &neighbors, include_distances ? &distances : NULL);

      ruby_xfree(vec);

      const int sz_neighbors = neighbors.size();
      VALUE neighbors_arr = rb_ary_new2(sz_neighbors);

      for (int i = 0; i < sz_neighbors; i++) {
        rb_ary_store(neighbors_arr, i, INT2NUM(neighbors[i]));
      }

      if (include_distances) {
        const int sz_distances = distances.size();
        VALUE distances_arr = rb_ary_new2(sz_distances);
        for (int i = 0; i < sz_distances; i++) {
          rb_ary_store(distances_arr, i, typeid(F) == typeid(double) ? DBL2NUM(distances[i]) : UINT2NUM(distances[i]));
        }
        VALUE res = rb_ary_new2(2);
        rb_ary_store(res, 0, neighbors_arr);
        rb_ary_store(res, 1, distances_arr);
        return res;
      }

      return neighbors_arr;
    };

    static VALUE _annoy_index_get_item(VALUE self, VALUE _idx) {
      const int idx = NUM2INT(_idx);
      const int n_dims = get_annoy_index(self)->get_f();
      F* vec = (F*)ruby_xmalloc(n_dims * sizeof(F));
      VALUE arr = rb_ary_new2(n_dims);

      get_annoy_index(self)->get_item(idx, vec);

      for (int i = 0; i < n_dims; i++) {
        rb_ary_store(arr, i, typeid(F) == typeid(double) ? DBL2NUM(vec[i]) : UINT2NUM(vec[i]));
      }

      ruby_xfree(vec);
      return arr;
    };

    static VALUE _annoy_index_get_distance(VALUE self, VALUE _i, VALUE _j) {
      const int i = NUM2INT(_i);
      const int j = NUM2INT(_j);
      const F dist = get_annoy_index(self)->get_distance(i, j);
      return typeid(F) == typeid(double) ? DBL2NUM(dist) : UINT2NUM(dist);
    };

    static VALUE _annoy_index_get_n_items(VALUE self) {
      const int32_t n_items = get_annoy_index(self)->get_n_items();
      return INT2NUM(n_items);
    };

    static VALUE _annoy_index_get_n_trees(VALUE self) {
      const int32_t n_trees = get_annoy_index(self)->get_n_trees();
      return INT2NUM(n_trees);
    };

    static VALUE _annoy_index_on_disk_build(VALUE self, VALUE _filename) {
      const char* filename = StringValuePtr(_filename);
      char* error;
      if (!get_annoy_index(self)->on_disk_build(filename, &error)) {
        VALUE error_str = rb_str_new_cstr(error);
        free(error);
        rb_raise(rb_eRuntimeError, "%s", StringValuePtr(error_str));
        return Qfalse;
      }
      RB_GC_GUARD(_filename);
      return Qtrue;
    };

    static VALUE _annoy_index_set_seed(VALUE self, VALUE _seed) {
      const int seed = NUM2INT(_seed);
      get_annoy_index(self)->set_seed(seed);
      return Qnil;
    };

    static VALUE _annoy_index_verbose(VALUE self, VALUE _flag) {
      const bool flag = _flag == Qtrue ? true : false;
      get_annoy_index(self)->verbose(flag);
      return Qnil;
    };

    static VALUE _annoy_index_get_f(VALUE self) {
      const int32_t f = get_annoy_index(self)->get_f();
      return INT2NUM(f);
    };
};

template<class T, typename F>
const rb_data_type_t RbAnnoyIndex<T, F>::annoy_index_type = {
  "RbAnnoyIndex",
  {
    NULL,
    RbAnnoyIndex::annoy_index_free,
    RbAnnoyIndex::annoy_index_size
  },
  NULL,
  NULL,
  RUBY_TYPED_FREE_IMMEDIATELY
};

#endif /* ANNOYEXT_HPP */