/**
 * Part of the Lccrt Project, under the Apache License v2.0
 * See http://www.apache.org/licenses/LICENSE-2.0.txt for license information.
 * SPDX-License-Identifier: Apache-2.0
 *
 * lccrt_hash.c - работа с хеш-таблицами.
 */

#include "internal/lccrt_ctx.h"

lccrt_check_type_define( lccrt_hash_entry_t);
lccrt_check_type_define( lccrt_hash_t);

/**
 * Запись.
 */
typedef struct lccrt_hash_entry_r
{
    uintptr_t key; /* значение ключа */
    uintptr_t data; /* пользовательские данные */
    int64_t bucket_ident; /* номер корзины */
    lccrt_hash_ptr table; /* исходная таблица */
    lccrt_hash_entry_ptr prev; /* список записей в корзине */
    lccrt_hash_entry_ptr next; /* список записей в корзине */
    lccrt_check_type_t type_check;
} lccrt_hash_entry_t;

/**
 * Таблица.
 */
typedef struct lccrt_hash_r
{
    lccrt_ctx_ptr ctx;
    lccrt_hash_key_type_t key_type; /* тип ключа, используемый в таблице */
    int64_t num_entries; /* общее количество всех записей */
    int64_t num_buckets; /* текущее количество корзин */
    lccrt_hash_entry_ptr *buckets; /* массив корзин */
    int64_t bucket_path_len; /* суммарный путь поиска по спискам */
    lccrt_check_type_t type_check;
} lccrt_hash_t;

#define LCCRT_HASH_IS_REDUCE( h) \
( \
  ((h)->num_entries < (h)->num_buckets/8) \
  && ((h)->num_buckets > 8) \
)

/**
 * Создание новой таблицы.
 */
lccrt_h_ptr
lccrt_hash_new( lccrt_ctx_ptr ctx, lccrt_hkt_t type)
{
    lccrt_h_ptr r = lccrt_ctx_malloc( ctx, lccrt_hash_t);

    memset( r, 0, sizeof( r[0]));
    lccrt_check_type_init( r, lccrt_hash_t);
    r->ctx = ctx;
    r->key_type = type;
    lccrt_assert( (0 <= type) && (type < LCCRT_HASH_KEY_LAST));

    return (r);
} /* lccrt_hash_new */

/**
 * Удаление данных записи.
 */
static void
lccrt_hash_entry_delete_internal( lccrt_hash_entry_ptr he)
{
    lccrt_hash_ptr h = he->table;
    lccrt_ctx_ptr ctx = h->ctx;

    lccrt_check_type_assert( he, lccrt_hash_entry_t);
    if ( (h->key_type == LCCRT_HASH_KEY_STRING) )
    {
        lccrt_ctx_free( ctx, (char *)he->key);
    } else
    {
        lccrt_assert( h->key_type == LCCRT_HASH_KEY_INTPTR);
    }

    lccrt_check_type_done( he, lccrt_hash_entry_t);
    lccrt_ctx_free( ctx, he);

    return;
} /* lccrt_hash_entry_delete_internal */

/**
 * Удаление таблицы.
 */
void
lccrt_hash_delete( lccrt_hash_ptr h)
{
    int64_t i;
    lccrt_ctx_ptr ctx = h->ctx;

    lccrt_check_type_assert( h, lccrt_hash_t);
    for ( i = 0; i < h->num_buckets; ++i )
    {
        lccrt_hash_entry_ptr he, he_next;

        he = h->buckets[i];
        while ( he )
        {
            he_next = he->next;
            lccrt_assert( i == he->bucket_ident);
            lccrt_hash_entry_delete_internal( he);
            he = he_next;
        }
    }

    lccrt_ctx_free( ctx, h->buckets);
    lccrt_check_type_done( h, lccrt_hash_t);
    lccrt_ctx_free( ctx, h);

    return;
} /* lccrt_hash_delete */

/**
 * Количество элементов в хеш-таблице.
 */
int64_t
lccrt_hash_length( lccrt_hash_ptr ht)
{
    int64_t r = ht->num_entries;

    return (r);
} /* lccrt_hash_length */

/**
 * Вычисление хеш-значения для ключа.
 */
static uint64_t
lccrt_hash_key_calc( lccrt_hash_key_type_t type, uintptr_t key)
{
    uint64_t r = 0;

    if ( (type == LCCRT_HASH_KEY_INTPTR) )
    {
        r = (uint64_t)key * 1103515245ULL;

    } else if ( (type == LCCRT_HASH_KEY_STRING) )
    {
        const char *p = (char *)key;

        while ( p[0] )
        {
            r = ((r << 7) | (r >> (64 - 7))) ^ (uint64_t)p[0];
            ++p;
        }
    } else
    {
        lccrt_assert( 0);
    }

    return (r);
} /* lccrt_hash_key_calc */

/**
 * Вычисление корзины для ключа.
 */
static int64_t
lccrt_hash_key_calc_pos( lccrt_hash_ptr h, uintptr_t key)
{
    int64_t r = -1;

    lccrt_check_type_assert( h, lccrt_hash_t);
    if ( (h->num_buckets > 0) )
    {
        r = lccrt_hash_key_calc( h->key_type, key) % h->num_buckets;
    }

    return (r);
} /* lccrt_hash_key_calc_pos */

/**
 * Сравнение двух ключей на равенство.
 */
static uintptr_t
lccrt_hash_key_copy( lccrt_ctx_ptr ctx, lccrt_hkt_t type, uintptr_t key)
{
    uintptr_t r = 0;

    if ( (type == LCCRT_HASH_KEY_STRING) )
    {
        r = (uintptr_t)lccrt_ctx_copy_str( ctx, (const char *)key);

    } else if ( (type == LCCRT_HASH_KEY_INTPTR) )
    {
        r = key;
    } else
    {
        lccrt_assert( 0);
    }

    return (r);
} /* lccrt_hash_key_copy */

/**
 * Сравнение двух ключей на равенство.
 */
static int
lccrt_hash_keys_equal( lccrt_hkt_t type, uintptr_t key1, uintptr_t key2)
{
    int r = 0;

    if ( (type == LCCRT_HASH_KEY_STRING) )
    {
        r = lccrt_str_eq( (const char *)key1, (const char *)key2);

    } else if ( (type == LCCRT_HASH_KEY_INTPTR) )
    {
        r = (key1 == key2);
    } else
    {
        lccrt_assert( 0);
    }

    return (r);
} /* lccrt_hash_keys_equal */

/**
 * Поиск в корзине записи с ключом заданного значения.
 */
static lccrt_hash_entry_ptr
lccrt_hash_bucket_find_key( lccrt_hash_entry_ptr he, uintptr_t key)
{
    lccrt_hash_entry_ptr r = 0;

    lccrt_check_type_assert( he, lccrt_hash_entry_t);
    if ( he )
    {
        int64_t i = 0;
        lccrt_hash_ptr h = he->table;
        lccrt_hash_key_type_t type = h->key_type;

        lccrt_check_type_assert( h, lccrt_hash_t);
        if ( (type == LCCRT_HASH_KEY_INTPTR) )
        {
            for ( ; he ; he = he->next, i++ )
            {
                if ( (key == he->key) )
                {
                    r = he;
                    break;
                }
            }
        } else if ( (type == LCCRT_HASH_KEY_STRING) )
        {
            for ( ; he ; he = he->next, i++ )
            {
                if ( lccrt_hash_keys_equal( type, key, he->key) )
                {
                    r = he;
                    break;
                }
            }
        } else
		{
			lccrt_assert( 0);
		}

        h->bucket_path_len += i;
    }

    return (r);
} /* lccrt_hash_bucket_find_key */

/**
 * Создать новую запись и вставить ее в список записей.
 */
static lccrt_hash_entry_ptr
lccrt_hash_entry_new( lccrt_hash_ptr h, uintptr_t key, uintptr_t data,
                      int64_t bucket_ident, lccrt_he_ptr prev, lccrt_he_ptr next)
{
    lccrt_ctx_ptr ctx = h->ctx;
    lccrt_hash_key_type_t type = h->key_type;
    lccrt_hash_entry_ptr r = lccrt_ctx_malloc( ctx, lccrt_hash_entry_t);

    lccrt_check_type_assert( h, lccrt_hash_t);
    memset( r, 0, sizeof( r[0]));
    lccrt_check_type_init( r, lccrt_hash_entry_t);
    r->table = h;
    r->bucket_ident = bucket_ident;
    r->key = lccrt_hash_key_copy( ctx, type, key);
    r->data = data;
    r->prev = prev;
    r->next = next;
    if ( next )
    {
        next->prev = r;
    }

    if ( prev )
    {
        prev->next = r;
    }

    return (r);
} /* lccrt_hash_entry_new */

/**
 * Увеличение/уменьшение количества корзин.
 */
static void
lccrt_hash_rebuild( lccrt_hash_ptr h, int is_increase)
{
    lccrt_ctx_ptr ctx = h->ctx;
    lccrt_hash_key_type_t type = h->key_type;

    lccrt_check_type_assert( h, lccrt_hash_t);
    h->bucket_path_len = 0;
    if ( (h->num_entries > 0) )
    {
        int64_t i;
        lccrt_hash_entry_ptr *buckets = h->buckets;
        int64_t num_buckets = h->num_buckets;

        h->num_buckets = is_increase ? 2*num_buckets : num_buckets/2;
        lccrt_assert( num_buckets > 0);
        h->buckets = lccrt_ctx_mallocn( ctx, lccrt_hash_entry_ptr, h->num_buckets);
        memset( h->buckets, 0, h->num_buckets*sizeof( h->buckets[0]));
        for ( i = 0; i < num_buckets; ++i )
        {
            lccrt_hash_entry_ptr e, e_next;

            for ( e = buckets[i]; e; e = e_next )
            {
                int64_t key_pos = lccrt_hash_key_calc_pos( h, e->key);

                e_next = e->next;
                h->buckets[key_pos] = lccrt_hash_entry_new( h, e->key, e->data, key_pos, 0, h->buckets[key_pos]);
                lccrt_hash_entry_delete_internal( e);
            }
        }

        lccrt_ctx_free( ctx, buckets);
    }

    return;
} /* lccrt_hash_rebuild */

/**
 * Добавить в таблицу запись с заданным ключом.
 */
lccrt_hash_entry_ptr
lccrt_hash_push( lccrt_hash_ptr h, uintptr_t key, int *is_new)
{
    lccrt_hash_entry_ptr r = 0;
    lccrt_ctx_ptr ctx = h->ctx;
    lccrt_hash_key_type_t type = h->key_type;
    int64_t key_pos = -1;
    lccrt_hash_entry_ptr he = 0;

    lccrt_check_type_assert( h, lccrt_hash_t);
    if ( (h->num_buckets == 0) )
    {
        lccrt_assert( h->num_entries == 0);
        h->num_buckets = 1;
        h->buckets = lccrt_ctx_mallocn( ctx, lccrt_hash_entry_ptr, 1);
        key_pos = 0;
        he = 0;
    } else
    {
        key_pos = lccrt_hash_key_calc_pos( h, key);
        he = h->buckets[key_pos];
        r = lccrt_hash_bucket_find_key( he, key);
    }

    if ( r )
    {
        lccrt_assign( is_new, 0);
    } else
    {
        lccrt_assign( is_new, 1);
        r = lccrt_hash_entry_new( h, key, 0, key_pos, 0, he);
        h->buckets[key_pos] = r;
        h->num_entries++;
    }

#if 0
    if ( (h->bucket_path_len >= h->num_entries) )
    {
        //lccrt_hash_rebuild( h);
    }
#endif

    if ( (h->num_entries > 0)
         && (h->num_entries >= 4*h->num_buckets) )
    {
        lccrt_hash_rebuild( h, 1);
        r = lccrt_hash_find( h, key);
    }

    return (r);
} /* lccrt_hash_push */

/**
 * Поиск записи.
 */
lccrt_hash_entry_ptr
lccrt_hash_find( lccrt_hash_ptr h, uintptr_t key)
{
    lccrt_hash_entry_ptr r = 0;

    lccrt_check_type_assert( h, lccrt_hash_t);
    if ( (h->num_entries > 0)
         && (h->num_entries >= 4*h->num_buckets) )
    {
        lccrt_assert( 0);
        //lccrt_hash_rebuild( h, 1);
    }

    if ( (h->num_entries > 0) )
    {
        int64_t key_pos = lccrt_hash_key_calc_pos( h, key);
        lccrt_hash_entry_ptr he = h->buckets[key_pos];

        r = lccrt_hash_bucket_find_key( he, key);
    }

    return (r);
} /* lccrt_hash_find */

/**
 * Поиск записи.
 */
uintptr_t
lccrt_hash_remove( lccrt_hash_entry_ptr he)
{
    lccrt_hash_entry_ptr r = 0;
    lccrt_hash_entry_ptr he_prev = he->prev;
    lccrt_hash_entry_ptr he_next = he->next;
    lccrt_hash_ptr h = he->table;

    lccrt_check_type_assert( he, lccrt_hash_entry_t);
    lccrt_check_type_assert( h, lccrt_hash_t);
    if ( he->next )
    {
        he_next->prev = he_prev;
    }

    if ( he_prev )
    {
        he_prev->next = he_next;
    } else
    {
        h->buckets[he->bucket_ident] = he_next;
    }

    lccrt_hash_entry_delete_internal( he);
    he = 0;

    h->num_entries--;
    if ( LCCRT_HASH_IS_REDUCE( h) )
    {
        lccrt_hash_rebuild( h, 0);
    }

    return (0);
} /* lccrt_hash_remove */

/**
 * Получить пользовательские данные.
 */
uintptr_t
lccrt_hash_get_key( lccrt_hash_entry_ptr he)
{
    uintptr_t r = he->key;

    lccrt_check_type_assert( he, lccrt_hash_entry_t);

    return (r);
} /* lccrt_hash_get_key */

/**
 * Получить пользовательские данные.
 */
uintptr_t
lccrt_hash_get( lccrt_hash_entry_ptr he)
{
    uintptr_t r = he->data;

    lccrt_check_type_assert( he, lccrt_hash_entry_t);

    return (r);
} /* lccrt_hash_get */

/**
 * Получить пользовательские данные.
 */
uintptr_t
lccrt_hash_set( lccrt_hash_entry_ptr he, uintptr_t data)
{
    uintptr_t r = lccrt_hash_get( he);

    he->data = data;

    return (r);
} /* lccrt_hash_set */

/**
 * Получить первую запись.
 */
lccrt_hash_entry_ptr
lccrt_hash_first( lccrt_hash_ptr h)
{
    int64_t i;
    lccrt_hash_entry_ptr r = 0;

    lccrt_check_type_assert( h, lccrt_hash_t);
    if ( (h->num_entries > 0) )
    {
        for ( i = 0; i < h->num_buckets; ++i )
        {
            if ( h->buckets[i] )
            {
                r = h->buckets[i];
                break;
            }
        }
    }

    return (r);
} /* lccrt_hash_first */

/**
 * Получить следующую запись.
 */
lccrt_hash_entry_ptr
lccrt_hash_next( lccrt_hash_entry_ptr he)
{
    lccrt_hash_entry_ptr r = 0;
    lccrt_hash_ptr h = he->table;

    lccrt_check_type_assert( he, lccrt_hash_entry_t);
    lccrt_check_type_assert( h, lccrt_hash_t);
    if ( he->next )
    {
        r = he->next;
    } else
    {
        int64_t i;

        for ( i = he->bucket_ident + 1; i < h->num_buckets; ++i )
        {
            if ( h->buckets[i] )
            {
                r = h->buckets[i];
                break;
            }
        }
    }

    return (r);
} /* lccrt_hash_next */