/*
 * Copyright 2022-present MongoDB, Inc.
 *
 * 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 MC_RANGE_EDGE_GENERATION_PRIVATE_H
#define MC_RANGE_EDGE_GENERATION_PRIVATE_H

#include "mc-dec128.h"
#include "mc-optional-private.h"
#include "mongocrypt-status-private.h"
#include <mlib/int128.h>
#include <stddef.h> // size_t
#include <stdint.h>

// mc_edges_t represents a list of edges.
typedef struct _mc_edges_t mc_edges_t;

// mc_edges_get returns edge at an index.
// Returns NULL if `index` is out of range.
const char *mc_edges_get(mc_edges_t *edges, size_t index);

// mc_edges_len returns the number of represented edges.
size_t mc_edges_len(mc_edges_t *edges);

// mc_edges_destroys frees `edges`.
void mc_edges_destroy(mc_edges_t *edges);

typedef struct {
    int32_t value;
    mc_optional_int32_t min;
    mc_optional_int32_t max;
    size_t sparsity;
} mc_getEdgesInt32_args_t;

// mc_getEdgesInt32 implements the Edge Generation algorithm described in
// SERVER-67751 for int32_t.
mc_edges_t *mc_getEdgesInt32(mc_getEdgesInt32_args_t args, mongocrypt_status_t *status);

typedef struct {
    int64_t value;
    mc_optional_int64_t min;
    mc_optional_int64_t max;
    size_t sparsity;
} mc_getEdgesInt64_args_t;

// mc_getEdgesInt64 implements the Edge Generation algorithm described in
// SERVER-67751 for int64_t.
mc_edges_t *mc_getEdgesInt64(mc_getEdgesInt64_args_t args, mongocrypt_status_t *status);

typedef struct {
    double value;
    size_t sparsity;
    mc_optional_double_t min;
    mc_optional_double_t max;
    mc_optional_uint32_t precision;
} mc_getEdgesDouble_args_t;

// mc_getEdgesDouble implements the Edge Generation algorithm described in
// SERVER-67751 for double.
mc_edges_t *mc_getEdgesDouble(mc_getEdgesDouble_args_t args, mongocrypt_status_t *status);

#if MONGOCRYPT_HAVE_DECIMAL128_SUPPORT
typedef struct {
    mc_dec128 value;
    size_t sparsity;
    mc_optional_dec128_t min, max;
    mc_optional_uint32_t precision;
} mc_getEdgesDecimal128_args_t;

mc_edges_t *mc_getEdgesDecimal128(mc_getEdgesDecimal128_args_t args, mongocrypt_status_t *status);
#endif // MONGOCRYPT_HAVE_DECIMAL128_SUPPORT

BSON_STATIC_ASSERT2(ull_is_u64, sizeof(uint64_t) == sizeof(unsigned long long));

// count_leading_zeros_u64 returns the number of leading 0 bits of `in`.
static inline size_t mc_count_leading_zeros_u64(uint64_t in) {
#ifdef __has_builtin
#if __has_builtin(__builtin_clzll)
    unsigned long long ull = in;
    return (size_t)(in ? __builtin_clzll(ull) : 64);
#endif
#endif
    uint64_t bit = UINT64_C(1) << 63;
    size_t count = 0;
    while ((bit & in) == 0 && bit > 0) {
        bit >>= 1;
        ++count;
    }
    return count;
}

// count_leading_zeros_u32 returns the number of leading 0 bits of `in`.
static inline size_t mc_count_leading_zeros_u32(uint32_t in) {
#ifdef __has_builtin
#if __has_builtin(__builtin_clz)
    // Pointer-cast to ensure we are speaking the right type
    unsigned int *p = &in;
    return (size_t)(in ? __builtin_clz(*p) : 32);
#endif
#endif
    uint32_t bit = UINT32_C(1) << 31;
    int count = 0;
    while ((bit & in) == 0 && bit > 0) {
        bit >>= 1;
        ++count;
    }
    return (size_t)count;
}

static inline size_t mc_count_leading_zeros_u128(mlib_int128 in) {
    size_t hi = mc_count_leading_zeros_u64(mlib_int128_to_u64(mlib_int128_rshift(in, 64)));
    size_t lo = mc_count_leading_zeros_u64(mlib_int128_to_u64(in));
    return hi + ((hi == 64 ? 1u : 0u) * lo);
}

typedef struct mc_bitstring {
    char str[129];
} mc_bitstring;

// mc_convert_to_bitstring_u64 returns a 64 character string of 1's and 0's
// representing the bits of `in`
mc_bitstring mc_convert_to_bitstring_u64(uint64_t in);

// mc_convert_to_bitstring_u32 returns a 32 character string of 1's and 0's
// representing the bits of `in`.
mc_bitstring mc_convert_to_bitstring_u32(uint32_t in);

mc_bitstring mc_convert_to_bitstring_u128(mlib_int128 i);

#endif /* MC_RANGE_EDGE_GENERATION_PRIVATE_H */