#include <assert.h>

#define HASH_FUNCTION(keyptr, keylen, hashv) HASH_FUNCTION_OVERWRITE(keyptr, keylen, &hashv)
#define HASH_KEYCMP(a, b, len) HASH_KEYCMP_OVERWRITE(a, b, len)
#include "session_table.h"
#include "session_private.h"

struct session_table
{
    struct session *root;
    session_free_cb free_cb;
    void *arg;
    uint64_t count;

    struct session *oldest_ptr;
    struct session *newest_ptr;
};

/******************************************************************************
 * Private API
 ******************************************************************************/

static void HASH_FUNCTION_OVERWRITE(const struct session_key *key, unsigned int keylen, uint32_t *hashv)
{
    *hashv = session_key_hash(key);
}

static int HASH_KEYCMP_OVERWRITE(const void *key1, const void *key2, size_t len)
{
    struct session_key *sess_key1 = (struct session_key *)key1;
    struct session_key *sess_key2 = (struct session_key *)key2;

    if (session_key_cmp(sess_key1, sess_key2) == 0)
    {
        return 0;
    }

    struct session_key reverse_key;
    session_key_reverse(sess_key2, &reverse_key);
    if (session_key_cmp(sess_key1, &reverse_key) == 0)
    {
        return 0;
    }

    return -1;
}

static void session_table_add_session_to_linklist(struct session_table *table, struct session *sess)
{
    if (table == NULL || sess == NULL)
    {
        return;
    }

    if (table->newest_ptr == NULL)
    {
        table->oldest_ptr = sess;
        table->newest_ptr = sess;
        sess->prev_ptr = NULL;
        sess->next_ptr = NULL;
    }
    else
    {
        sess->next_ptr = table->newest_ptr;
        table->newest_ptr->prev_ptr = sess;
        sess->prev_ptr = NULL;
        table->newest_ptr = sess;
    }
}

static void session_table_del_session_from_linklist(struct session_table *table, struct session *sess)
{
    if (table == NULL || sess == NULL)
    {
        return;
    }

    if (sess->prev_ptr == NULL && sess->next_ptr == NULL)
    {
        table->oldest_ptr = NULL;
        table->newest_ptr = NULL;
    }
    else if (sess->prev_ptr == NULL && sess->next_ptr != NULL)
    {
        table->newest_ptr = sess->next_ptr;
        sess->next_ptr->prev_ptr = NULL;
    }
    else if (sess->prev_ptr != NULL && sess->next_ptr == NULL)
    {
        table->oldest_ptr = sess->prev_ptr;
        sess->prev_ptr->next_ptr = NULL;
    }
    else
    {
        sess->prev_ptr->next_ptr = sess->next_ptr;
        sess->next_ptr->prev_ptr = sess->prev_ptr;
    }
    sess->prev_ptr = NULL;
    sess->next_ptr = NULL;
}

/******************************************************************************
 * Public API
 ******************************************************************************/

struct session_table *session_table_create()
{
    struct session_table *table = (struct session_table *)calloc(1, sizeof(struct session_table));
    table->count = 0;
    table->oldest_ptr = NULL;
    table->newest_ptr = NULL;

    return table;
}

void session_table_destroy(struct session_table *table)
{
    if (table)
    {
        struct session *node = NULL;
        struct session *tmp = NULL;
        HASH_ITER(hh, table->root, node, tmp)
        {
            HASH_DELETE(hh, table->root, node);
            if (table->free_cb && node)
            {
                table->free_cb(node, table->arg);
            }
        }
        table->count--;

        free(table);
        table = NULL;
    }
}

uint64_t session_table_get_count(struct session_table *table)
{
    if (table == NULL)
    {
        return 0;
    }

    return table->count;
}

void session_table_set_freecb(struct session_table *table, session_free_cb free_cb, void *arg)
{
    if (table)
    {
        table->free_cb = free_cb;
        table->arg = arg;
    }
}

int session_table_add_session(struct session_table *table, const struct session_key *key, struct session *sess)
{
    if (table == NULL || sess == NULL)
    {
        return -1;
    }

    if (session_table_find_session(table, key))
    {
        return -1;
    }

    HASH_ADD(hh, table->root, key, sizeof(sess->key), sess);
    session_table_add_session_to_linklist(table, sess);
    table->count++;

    return 0;
}

void session_table_delete_session(struct session_table *table, const struct session_key *key)
{
    if (table == NULL)
    {
        return;
    }

    struct session *sess = session_table_find_session(table, key);
    if (sess == NULL)
    {
        return;
    }

    HASH_DELETE(hh, table->root, sess);
    if (table->free_cb && sess)
    {
        table->free_cb(sess, table->arg);
    }
    session_table_del_session_from_linklist(table, sess);
    table->count--;
}

struct session *session_table_find_session(struct session_table *table, const struct session_key *key)
{
    if (table == NULL)
    {
        return NULL;
    }

    struct session *sess = NULL;
    HASH_FIND(hh, table->root, key, sizeof(struct session_key), sess);

    return sess;
}

struct session *session_table_find_oldest_session(struct session_table *table)
{
    if (table == NULL)
    {
        return NULL;
    }

    return table->oldest_ptr;
}

struct session *session_table_find_newest_session(struct session_table *table)
{
    if (table == NULL)
    {
        return NULL;
    }

    return table->newest_ptr;
}