/*
 * Copyright (c) Meta Platforms, Inc. and affiliates.
 *
 * This source code is licensed under the MIT license found in the
 * LICENSE file in the root directory of this source tree.
 */

// -*- c -*-

#ifndef FAISS_INDEX_FLAT_C_H
#define FAISS_INDEX_FLAT_C_H

#include "Index_c.h"
#include "faiss_c.h"

#ifdef __cplusplus
extern "C" {
#endif

// forward declaration
typedef enum FaissMetricType FaissMetricType;

/** Opaque type for IndexFlat */
FAISS_DECLARE_CLASS_INHERITED(IndexFlat, Index)

int faiss_IndexFlat_new(FaissIndexFlat** p_index);

int faiss_IndexFlat_new_with(
        FaissIndexFlat** p_index,
        idx_t d,
        FaissMetricType metric);

/** get a pointer to the index's internal data (the `xb` field). The outputs
 * become invalid after any data addition or removal operation.
 *
 * @param index   opaque pointer to index object
 * @param p_xb    output, the pointer to the beginning of `xb`.
 * @param p_size  output, the current size of `xb` in number of float values.
 */
void faiss_IndexFlat_xb(FaissIndexFlat* index, float** p_xb, size_t* p_size);

/** attempt a dynamic cast to a flat index, thus checking
 * check whether the underlying index type is `IndexFlat`.
 *
 * @param index opaque pointer to index object
 * @return the same pointer if the index is a flat index, NULL otherwise
 */
FAISS_DECLARE_INDEX_DOWNCAST(IndexFlat)

FAISS_DECLARE_DESTRUCTOR(IndexFlat)

/** compute distance with a subset of vectors
 *
 * @param index   opaque pointer to index object
 * @param x       query vectors, size n * d
 * @param labels  indices of the vectors that should be compared
 *                for each query vector, size n * k
 * @param distances
 *                corresponding output distances, size n * k
 */
int faiss_IndexFlat_compute_distance_subset(
        FaissIndex* index,
        idx_t n,
        const float* x,
        idx_t k,
        float* distances,
        const idx_t* labels);

/** Opaque type for IndexFlatIP */
FAISS_DECLARE_CLASS_INHERITED(IndexFlatIP, Index)

FAISS_DECLARE_INDEX_DOWNCAST(IndexFlatIP)
FAISS_DECLARE_DESTRUCTOR(IndexFlatIP)

int faiss_IndexFlatIP_new(FaissIndexFlatIP** p_index);

int faiss_IndexFlatIP_new_with(FaissIndexFlatIP** p_index, idx_t d);

/** Opaque type for IndexFlatL2 */
FAISS_DECLARE_CLASS_INHERITED(IndexFlatL2, Index)

FAISS_DECLARE_INDEX_DOWNCAST(IndexFlatL2)
FAISS_DECLARE_DESTRUCTOR(IndexFlatL2)

int faiss_IndexFlatL2_new(FaissIndexFlatL2** p_index);

int faiss_IndexFlatL2_new_with(FaissIndexFlatL2** p_index, idx_t d);

/** Opaque type for IndexRefineFlat
 *
 * Index that queries in a base_index (a fast one) and refines the
 * results with an exact search, hopefully improving the results.
 */
FAISS_DECLARE_CLASS_INHERITED(IndexRefineFlat, Index)

int faiss_IndexRefineFlat_new(
        FaissIndexRefineFlat** p_index,
        FaissIndex* base_index);

FAISS_DECLARE_DESTRUCTOR(IndexRefineFlat)
FAISS_DECLARE_INDEX_DOWNCAST(IndexRefineFlat)

FAISS_DECLARE_GETTER_SETTER(IndexRefineFlat, int, own_fields)

/// factor between k requested in search and the k requested from
/// the base_index (should be >= 1)
FAISS_DECLARE_GETTER_SETTER(IndexRefineFlat, float, k_factor)

/** Opaque type for IndexFlat1D
 *
 * optimized version for 1D "vectors"
 */
FAISS_DECLARE_CLASS_INHERITED(IndexFlat1D, Index)

FAISS_DECLARE_INDEX_DOWNCAST(IndexFlat1D)
FAISS_DECLARE_DESTRUCTOR(IndexFlat1D)

int faiss_IndexFlat1D_new(FaissIndexFlat1D** p_index);
int faiss_IndexFlat1D_new_with(
        FaissIndexFlat1D** p_index,
        int continuous_update);

int faiss_IndexFlat1D_update_permutation(FaissIndexFlat1D* index);

#ifdef __cplusplus
}
#endif

#endif
