/*

 * Copyright (c) 2016-present, Yann Collet, Facebook, Inc.

 * All rights reserved.

 *

 * This source code is licensed under both the BSD-style license (found in the

 * LICENSE file in the root directory of this source tree) and the GPLv2 (found

 * in the COPYING file in the root directory of this source tree).

 * You may select, at your option, one of the above-listed licenses.

 */

#ifndef DICTBUILDER_H_001

#define DICTBUILDER_H_001

#if defined (__cplusplus)

extern "C" {

#endif

/*======  Dependencies  ======*/

#include <stddef.h>  /* size_t */

/* =====   ZDICTLIB_API : control library symbols visibility   ===== */

#ifndef ZDICTLIB_VISIBILITY

#  if defined(__GNUC__) && (__GNUC__ >= 4)

#    define ZDICTLIB_VISIBILITY __attribute__ ((visibility ("default")))

#  else

#    define ZDICTLIB_VISIBILITY

#  endif

#endif

#if defined(ZSTD_DLL_EXPORT) && (ZSTD_DLL_EXPORT==1)

#  define ZDICTLIB_API __declspec(dllexport) ZDICTLIB_VISIBILITY

#elif defined(ZSTD_DLL_IMPORT) && (ZSTD_DLL_IMPORT==1)

#  define ZDICTLIB_API __declspec(dllimport) ZDICTLIB_VISIBILITY /* It isn't required but allows to generate better code, saving a function pointer load from the IAT and an indirect jump.*/

#else

#  define ZDICTLIB_API ZDICTLIB_VISIBILITY

#endif

/*! ZDICT_trainFromBuffer():

 *  Train a dictionary from an array of samples.

 *  Redirect towards ZDICT_optimizeTrainFromBuffer_fastCover() single-threaded, with d=8, steps=4,

 *  f=20, and accel=1.

 *  Samples must be stored concatenated in a single flat buffer `samplesBuffer`,

 *  supplied with an array of sizes `samplesSizes`, providing the size of each sample, in order.

 *  The resulting dictionary will be saved into `dictBuffer`.

 * @return: size of dictionary stored into `dictBuffer` (<= `dictBufferCapacity`)

 *          or an error code, which can be tested with ZDICT_isError().

 *  Note:  Dictionary training will fail if there are not enough samples to construct a

 *         dictionary, or if most of the samples are too small (< 8 bytes being the lower limit).

 *         If dictionary training fails, you should use zstd without a dictionary, as the dictionary

 *         would've been ineffective anyways. If you believe your samples would benefit from a dictionary

 *         please open an issue with details, and we can look into it.

 *  Note: ZDICT_trainFromBuffer()'s memory usage is about 6 MB.

 *  Tips: In general, a reasonable dictionary has a size of ~ 100 KB.

 *        It's possible to select smaller or larger size, just by specifying `dictBufferCapacity`.

 *        In general, it's recommended to provide a few thousands samples, though this can vary a lot.

 *        It's recommended that total size of all samples be about ~x100 times the target size of dictionary.

 */

ZDICTLIB_API size_t ZDICT_trainFromBuffer(void* dictBuffer, size_t dictBufferCapacity,

                                    const void* samplesBuffer,

                                    const size_t* samplesSizes, unsigned nbSamples);

/*======   Helper functions   ======*/

ZDICTLIB_API unsigned ZDICT_getDictID(const void* dictBuffer, size_t dictSize);  /**< extracts dictID; @return zero if error (not a valid dictionary) */

ZDICTLIB_API unsigned ZDICT_isError(size_t errorCode);

ZDICTLIB_API const char* ZDICT_getErrorName(size_t errorCode);

#ifdef ZDICT_STATIC_LINKING_ONLY

/* ====================================================================================

 * The definitions in this section are considered experimental.

 * They should never be used with a dynamic library, as they may change in the future.

 * They are provided for advanced usages.

 * Use them only in association with static linking.

 * ==================================================================================== */

typedef struct {

    int      compressionLevel;   /* optimize for a specific zstd compression level; 0 means default */

    unsigned notificationLevel;  /* Write log to stderr; 0 = none (default); 1 = errors; 2 = progression; 3 = details; 4 = debug; */

    unsigned dictID;             /* force dictID value; 0 means auto mode (32-bits random value) */

} ZDICT_params_t;

/*! ZDICT_cover_params_t:

 *  k and d are the only required parameters.

 *  For others, value 0 means default.

 */

typedef struct {

    unsigned k;                  /* Segment size : constraint: 0 < k : Reasonable range [16, 2048+] */

    unsigned d;                  /* dmer size : constraint: 0 < d <= k : Reasonable range [6, 16] */

    unsigned steps;              /* Number of steps : Only used for optimization : 0 means default (40) : Higher means more parameters checked */

    unsigned nbThreads;          /* Number of threads : constraint: 0 < nbThreads : 1 means single-threaded : Only used for optimization : Ignored if ZSTD_MULTITHREAD is not defined */

    double splitPoint;           /* Percentage of samples used for training: Only used for optimization : the first nbSamples * splitPoint samples will be used to training, the last nbSamples * (1 - splitPoint) samples will be used for testing, 0 means default (1.0), 1.0 when all samples are used for both training and testing */

    unsigned shrinkDict;         /* Train dictionaries to shrink in size starting from the minimum size and selects the smallest dictionary that is shrinkDictMaxRegression% worse than the largest dictionary. 0 means no shrinking and 1 means shrinking  */

    unsigned shrinkDictMaxRegression; /* Sets shrinkDictMaxRegression so that a smaller dictionary can be at worse shrinkDictMaxRegression% worse than the max dict size dictionary. */

    ZDICT_params_t zParams;

} ZDICT_cover_params_t;

typedef struct {

    unsigned k;                  /* Segment size : constraint: 0 < k : Reasonable range [16, 2048+] */

    unsigned d;                  /* dmer size : constraint: 0 < d <= k : Reasonable range [6, 16] */

    unsigned f;                  /* log of size of frequency array : constraint: 0 < f <= 31 : 1 means default(20)*/

    unsigned steps;              /* Number of steps : Only used for optimization : 0 means default (40) : Higher means more parameters checked */

    unsigned nbThreads;          /* Number of threads : constraint: 0 < nbThreads : 1 means single-threaded : Only used for optimization : Ignored if ZSTD_MULTITHREAD is not defined */

    double splitPoint;           /* Percentage of samples used for training: Only used for optimization : the first nbSamples * splitPoint samples will be used to training, the last nbSamples * (1 - splitPoint) samples will be used for testing, 0 means default (0.75), 1.0 when all samples are used for both training and testing */

    unsigned accel;              /* Acceleration level: constraint: 0 < accel <= 10, higher means faster and less accurate, 0 means default(1) */

    unsigned shrinkDict;         /* Train dictionaries to shrink in size starting from the minimum size and selects the smallest dictionary that is shrinkDictMaxRegression% worse than the largest dictionary. 0 means no shrinking and 1 means shrinking  */

    unsigned shrinkDictMaxRegression; /* Sets shrinkDictMaxRegression so that a smaller dictionary can be at worse shrinkDictMaxRegression% worse than the max dict size dictionary. */

    ZDICT_params_t zParams;

} ZDICT_fastCover_params_t;

/*! ZDICT_trainFromBuffer_cover():

 *  Train a dictionary from an array of samples using the COVER algorithm.

 *  Samples must be stored concatenated in a single flat buffer `samplesBuffer`,

 *  supplied with an array of sizes `samplesSizes`, providing the size of each sample, in order.

 *  The resulting dictionary will be saved into `dictBuffer`.

 * @return: size of dictionary stored into `dictBuffer` (<= `dictBufferCapacity`)

 *          or an error code, which can be tested with ZDICT_isError().

 *          See ZDICT_trainFromBuffer() for details on failure modes.

 *  Note: ZDICT_trainFromBuffer_cover() requires about 9 bytes of memory for each input byte.

 *  Tips: In general, a reasonable dictionary has a size of ~ 100 KB.

 *        It's possible to select smaller or larger size, just by specifying `dictBufferCapacity`.

 *        In general, it's recommended to provide a few thousands samples, though this can vary a lot.

 *        It's recommended that total size of all samples be about ~x100 times the target size of dictionary.

 */

ZDICTLIB_API size_t ZDICT_trainFromBuffer_cover(

          void *dictBuffer, size_t dictBufferCapacity,

    const void *samplesBuffer, const size_t *samplesSizes, unsigned nbSamples,

          ZDICT_cover_params_t parameters);

/*! ZDICT_optimizeTrainFromBuffer_cover():

 * The same requirements as above hold for all the parameters except `parameters`.

 * This function tries many parameter combinations and picks the best parameters.

 * `*parameters` is filled with the best parameters found,

 * dictionary constructed with those parameters is stored in `dictBuffer`.

 *

 * All of the parameters d, k, steps are optional.

 * If d is non-zero then we don't check multiple values of d, otherwise we check d = {6, 8}.

 * if steps is zero it defaults to its default value.

 * If k is non-zero then we don't check multiple values of k, otherwise we check steps values in [50, 2000].

 *

 * @return: size of dictionary stored into `dictBuffer` (<= `dictBufferCapacity`)

 *          or an error code, which can be tested with ZDICT_isError().

 *          On success `*parameters` contains the parameters selected.

 *          See ZDICT_trainFromBuffer() for details on failure modes.

 * Note: ZDICT_optimizeTrainFromBuffer_cover() requires about 8 bytes of memory for each input byte and additionally another 5 bytes of memory for each byte of memory for each thread.

 */

ZDICTLIB_API size_t ZDICT_optimizeTrainFromBuffer_cover(

          void* dictBuffer, size_t dictBufferCapacity,

    const void* samplesBuffer, const size_t* samplesSizes, unsigned nbSamples,

          ZDICT_cover_params_t* parameters);

/*! ZDICT_trainFromBuffer_fastCover():

 *  Train a dictionary from an array of samples using a modified version of COVER algorithm.

 *  Samples must be stored concatenated in a single flat buffer `samplesBuffer`,

 *  supplied with an array of sizes `samplesSizes`, providing the size of each sample, in order.

 *  d and k are required.

 *  All other parameters are optional, will use default values if not provided

 *  The resulting dictionary will be saved into `dictBuffer`.

 * @return: size of dictionary stored into `dictBuffer` (<= `dictBufferCapacity`)

 *          or an error code, which can be tested with ZDICT_isError().

 *          See ZDICT_trainFromBuffer() for details on failure modes.

 *  Note: ZDICT_trainFromBuffer_fastCover() requires 6 * 2^f bytes of memory.

 *  Tips: In general, a reasonable dictionary has a size of ~ 100 KB.

 *        It's possible to select smaller or larger size, just by specifying `dictBufferCapacity`.

 *        In general, it's recommended to provide a few thousands samples, though this can vary a lot.

 *        It's recommended that total size of all samples be about ~x100 times the target size of dictionary.

 */

ZDICTLIB_API size_t ZDICT_trainFromBuffer_fastCover(void *dictBuffer,

                    size_t dictBufferCapacity, const void *samplesBuffer,

                    const size_t *samplesSizes, unsigned nbSamples,

                    ZDICT_fastCover_params_t parameters);

/*! ZDICT_optimizeTrainFromBuffer_fastCover():

 * The same requirements as above hold for all the parameters except `parameters`.

 * This function tries many parameter combinations (specifically, k and d combinations)

 * and picks the best parameters. `*parameters` is filled with the best parameters found,

 * dictionary constructed with those parameters is stored in `dictBuffer`.

 * All of the parameters d, k, steps, f, and accel are optional.

 * If d is non-zero then we don't check multiple values of d, otherwise we check d = {6, 8}.

 * if steps is zero it defaults to its default value.

 * If k is non-zero then we don't check multiple values of k, otherwise we check steps values in [50, 2000].

 * If f is zero, default value of 20 is used.

 * If accel is zero, default value of 1 is used.

 *

 * @return: size of dictionary stored into `dictBuffer` (<= `dictBufferCapacity`)

 *          or an error code, which can be tested with ZDICT_isError().

 *          On success `*parameters` contains the parameters selected.

 *          See ZDICT_trainFromBuffer() for details on failure modes.

 * Note: ZDICT_optimizeTrainFromBuffer_fastCover() requires about 6 * 2^f bytes of memory for each thread.

 */

ZDICTLIB_API size_t ZDICT_optimizeTrainFromBuffer_fastCover(void* dictBuffer,

                    size_t dictBufferCapacity, const void* samplesBuffer,

                    const size_t* samplesSizes, unsigned nbSamples,

                    ZDICT_fastCover_params_t* parameters);

/*! ZDICT_finalizeDictionary():

 * Given a custom content as a basis for dictionary, and a set of samples,

 * finalize dictionary by adding headers and statistics.

 *

 * Samples must be stored concatenated in a flat buffer `samplesBuffer`,

 * supplied with an array of sizes `samplesSizes`, providing the size of each sample in order.

 *

 * dictContentSize must be >= ZDICT_CONTENTSIZE_MIN bytes.

 * maxDictSize must be >= dictContentSize, and must be >= ZDICT_DICTSIZE_MIN bytes.

 *

 * @return: size of dictionary stored into `dictBuffer` (<= `dictBufferCapacity`),

 *          or an error code, which can be tested by ZDICT_isError().

 * Note: ZDICT_finalizeDictionary() will push notifications into stderr if instructed to, using notificationLevel>0.

 * Note 2: dictBuffer and dictContent can overlap

 */

#define ZDICT_CONTENTSIZE_MIN 128

#define ZDICT_DICTSIZE_MIN    256

ZDICTLIB_API size_t ZDICT_finalizeDictionary(void* dictBuffer, size_t dictBufferCapacity,

                                const void* dictContent, size_t dictContentSize,

                                const void* samplesBuffer, const size_t* samplesSizes, unsigned nbSamples,

                                ZDICT_params_t parameters);

typedef struct {

    unsigned selectivityLevel;   /* 0 means default; larger => select more => larger dictionary */

    ZDICT_params_t zParams;

} ZDICT_legacy_params_t;

/*! ZDICT_trainFromBuffer_legacy():

 *  Train a dictionary from an array of samples.

 *  Samples must be stored concatenated in a single flat buffer `samplesBuffer`,

 *  supplied with an array of sizes `samplesSizes`, providing the size of each sample, in order.

 *  The resulting dictionary will be saved into `dictBuffer`.

 * `parameters` is optional and can be provided with values set to 0 to mean "default".

 * @return: size of dictionary stored into `dictBuffer` (<= `dictBufferCapacity`)

 *          or an error code, which can be tested with ZDICT_isError().

 *          See ZDICT_trainFromBuffer() for details on failure modes.

 *  Tips: In general, a reasonable dictionary has a size of ~ 100 KB.

 *        It's possible to select smaller or larger size, just by specifying `dictBufferCapacity`.

 *        In general, it's recommended to provide a few thousands samples, though this can vary a lot.

 *        It's recommended that total size of all samples be about ~x100 times the target size of dictionary.

 *  Note: ZDICT_trainFromBuffer_legacy() will send notifications into stderr if instructed to, using notificationLevel>0.

 */

ZDICTLIB_API size_t ZDICT_trainFromBuffer_legacy(

    void *dictBuffer, size_t dictBufferCapacity,

    const void *samplesBuffer, const size_t *samplesSizes, unsigned nbSamples,

    ZDICT_legacy_params_t parameters);

/* Deprecation warnings */

/* It is generally possible to disable deprecation warnings from compiler,

   for example with -Wno-deprecated-declarations for gcc

   or _CRT_SECURE_NO_WARNINGS in Visual.

   Otherwise, it's also possible to manually define ZDICT_DISABLE_DEPRECATE_WARNINGS */

#ifdef ZDICT_DISABLE_DEPRECATE_WARNINGS

#  define ZDICT_DEPRECATED(message) ZDICTLIB_API   /* disable deprecation warnings */

#else

#  define ZDICT_GCC_VERSION (__GNUC__ * 100 + __GNUC_MINOR__)

#  if defined (__cplusplus) && (__cplusplus >= 201402) /* C++14 or greater */

#    define ZDICT_DEPRECATED(message) [[deprecated(message)]] ZDICTLIB_API

#  elif (ZDICT_GCC_VERSION >= 405) || defined(__clang__)

#    define ZDICT_DEPRECATED(message) ZDICTLIB_API __attribute__((deprecated(message)))

#  elif (ZDICT_GCC_VERSION >= 301)

#    define ZDICT_DEPRECATED(message) ZDICTLIB_API __attribute__((deprecated))

#  elif defined(_MSC_VER)

#    define ZDICT_DEPRECATED(message) ZDICTLIB_API __declspec(deprecated(message))

#  else

#    pragma message("WARNING: You need to implement ZDICT_DEPRECATED for this compiler")

#    define ZDICT_DEPRECATED(message) ZDICTLIB_API

#  endif

#endif /* ZDICT_DISABLE_DEPRECATE_WARNINGS */

ZDICT_DEPRECATED("use ZDICT_finalizeDictionary() instead")

size_t ZDICT_addEntropyTablesFromBuffer(void* dictBuffer, size_t dictContentSize, size_t dictBufferCapacity,

                                  const void* samplesBuffer, const size_t* samplesSizes, unsigned nbSamples);

#endif   /* ZDICT_STATIC_LINKING_ONLY */

#if defined (__cplusplus)

}

#endif

#endif   /* DICTBUILDER_H_001 */