#include <errno.h>
#include <stdlib.h>
#include <string.h>
#include "ucore/htable.h"

int uc_htable_init(struct UHTable *table, size_t buckets)
{
    if (buckets == 0) {
        return EINVAL;
    }

    table->buckets = calloc(buckets, sizeof *table->buckets);
    if (table->buckets == NULL) {
        return ENOMEM; 
    }

    table->cnt_buckets = buckets;
    table->cnt_elements = 0;

    return 0;
}

void uc_htable_destroy(struct UHTable *table)
{
    free(table->buckets);
    table->buckets = NULL;
    table->cnt_elements = table->cnt_buckets = -1;
}

struct UHNode *uc_htable_first_hash(const struct UHTable *table, size_t hash)
{
    size_t bucket = uc_htable_bucket(table, hash);
    struct UHNode *it = table->buckets[bucket];

    while (it && it->hash != hash) {
        it = it->next;
    }

    return it;
}

//given a node, find the next one in the chain with the given hash
struct UHNode *uc_htable_next_hash_hlp(struct UHNode *next, size_t hash)
{
    while (next && next->hash != hash) {
        next = next->next;
    }

    return next;
}

//find a node, starting at bucket
struct UHNode *uc_htable_iter_hlp(struct UHTable *table, size_t start_bucket)
{
    size_t i;
    struct UHNode *found = NULL;

    //search through buckets until a node is found
    for (i = start_bucket; i < table->cnt_buckets; i++) {
        found = uc_htable_first_bucket(table, i);
        if (found != NULL) {
            break;
        }
    }
    return found;
}

struct UHNode *uc_htable_next(struct UHTable *table, struct UHNode *node)
{
    struct UHNode *found;
    
    found = uc_htable_next_in_bucket(node);
    if (found == NULL) {
        size_t current_bucket = uc_htable_bucket(table, node->hash);
        found = uc_htable_iter_hlp(table, current_bucket + 1);
    }

    return found;
}

void uc_htable_swap(struct UHTable *a, struct UHTable *b)
{
    struct UHTable tmp;
    
    tmp = *a;
    *a = *b;
    *b = tmp;
}

int uc_htable_has_node(struct UHTable *table, struct UHNode *node)
{
    struct UHNode *iter;

    UC_HTABLE_FOREACH_BUCKET(table, iter, node->hash) {
        if (node == iter) {
            return 1;
        }
    }

    return 0;
}

void uc_htable_clear(struct UHTable *table)
{
    memset(table->buckets, 0 , sizeof *table->buckets * table->cnt_buckets);
    table->cnt_elements = 0;
}

void uc_htable_insert(struct UHTable *table, struct UHNode *node, size_t hash)
{
    size_t bucket = uc_htable_bucket(table, hash);

    node->next = table->buckets[bucket];
    table->buckets[bucket] = node;
    node->hash = hash;

    table->cnt_elements++;
}

void uc_htable_remove(struct UHTable *table, struct UHNode *node)
{
    struct UHNode **it = &table->buckets[uc_htable_bucket(table, node->hash)];
    
    while (*it) {

        if (*it == node) {
            *it = (*it)->next;
            table->cnt_elements--;
            break;
        }

        it = &(*it)->next;
    }
}

int uc_htable_resize(struct UHTable *table, size_t buckets)
{
    struct UHTable tmp_table;
    int rc;
    size_t h;

    if (buckets == 0) {
        return EINVAL;
    }

    //create new temp table
    rc = uc_htable_init(&tmp_table, buckets);
    if (rc != 0) {
        return rc;
    }

    
    //move all the nodes to the new temp table
    for (h = 0; h < table->cnt_buckets; h++) {
        struct UHNode *next;
        struct UHNode *node;

        for (node = uc_htable_first_bucket(table, h);
                    node != NULL;
                    node = next) {
            next = node->next;
            uc_htable_insert(&tmp_table, node, node->hash);
        }
    }

    //replace the existing table with the resized temp table
    uc_htable_swap(&tmp_table, table);
    uc_htable_destroy(&tmp_table);

    return 0;
}