/** BEGIN COPYRIGHT BLOCK
 * Copyright (C) 2001 Sun Microsystems, Inc. Used by permission.
 * Copyright (C) 2005 Red Hat, Inc.
 * All rights reserved.
 *
 * License: GPL (version 3 or any later version).
 * See LICENSE for details.
 * END COPYRIGHT BLOCK **/

#ifdef HAVE_CONFIG_H
#include <config.h>
#endif

/* ABAPI Broker */
/* Pete Rowley */

#include "stdio.h"
#include "slap.h"
#include "prlock.h"
#include "prerror.h"
#include "prcvar.h"
#include "prio.h"

static Slapi_Mutex *buffer_lock = 0;

/* circular api buffer */

typedef struct _THEABAPI
{
    char *guid;
    void **api;
    struct _THEABAPI *next;
    struct _THEABAPI *prev;
} ABAPI;

typedef struct _API_FEATURES
{
    int refcount;
    slapi_apib_callback_on_zero callback_on_zero;
    Slapi_Mutex *lock;
} APIB_FEATURES;

static ABAPI *head = NULL;

static ABAPI **ABAPIBroker_FindInterface(char *guid);
static void ***ABAPIBroker_FindInterface_All(char *guid);

int
slapi_apib_register(char *guid, void **api)
{
    int ret = -1;
    ABAPI *item;

    if (buffer_lock == 0) {
        if (0 == (buffer_lock = slapi_new_mutex())) /* we never free this mutex */
            /* badness */
            return -1;
    }

    /* simple - we don't check for duplicates */

    item = (ABAPI *)slapi_ch_malloc(sizeof(ABAPI));
    if (item) {
        item->guid = guid;
        item->api = api;

        slapi_lock_mutex(buffer_lock);
        if (head == NULL) {
            head = item;
            head->next = head;
            head->prev = head;
        } else {
            item->next = head;
            item->prev = head->prev;
            head->prev = item;
            item->prev->next = item;
        }
        slapi_unlock_mutex(buffer_lock);

        ret = 0;
    }

    return ret;
}

int
slapi_apib_unregister(char *guid)
{
    int ret = -1;
    ABAPI **api;

    if (buffer_lock == 0)
        return ret;

    if (buffer_lock == 0) {
        if (0 == (buffer_lock = slapi_new_mutex())) /* we never free this mutex */
            /* badness */
            return -1;
    }

    slapi_lock_mutex(buffer_lock);

    if ((api = ABAPIBroker_FindInterface(guid)) != NULL) {
        (*api)->prev->next = (*api)->next;
        (*api)->next->prev = (*api)->prev;

        if (*api == head) {
            head = (*api)->next;
        }

        if (*api == head) /* must be the last item, turn off the lights */
            head = 0;

        (*api)->guid = NULL;
        (*api)->api = NULL;
        slapi_ch_free((void **)api);
        *api = 0;
        ret = 0;
    }

    slapi_unlock_mutex(buffer_lock);

    return ret;
}

int
slapi_apib_get_interface(char *guid, void ***api)
{
    int ret = -1;
    ABAPI **theapi;

    if (buffer_lock == 0)
        return ret;

    if (buffer_lock == 0) {
        if (0 == (buffer_lock = slapi_new_mutex())) /* we never free this mutex */
            /* badness */
            return -1;
    }

    slapi_lock_mutex(buffer_lock);

    if ((theapi = ABAPIBroker_FindInterface(guid)) != NULL) {
        *api = (*theapi)->api;
        if ((*api)[0]) {
            slapi_apib_addref(*api);
        }

        ret = 0;
    }

    slapi_unlock_mutex(buffer_lock);

    return ret;
}

int
slapi_apib_get_interface_all(char *guid, void ****api)
{
    void ***retapi = NULL;
    int idx = 0;

    if (buffer_lock == 0)
        return -1;

    if (buffer_lock == 0) {
        if (0 == (buffer_lock = slapi_new_mutex())) /* we never free this mutex */
            /* badness */
            return -1;
    }

    slapi_lock_mutex(buffer_lock);

    retapi = ABAPIBroker_FindInterface_All(guid);
    for (idx = 0; retapi && retapi[idx]; ++idx) {
        void **theapi = retapi[idx];
        if (theapi[0]) {
            slapi_apib_addref(theapi);
        }
    }

    *api = retapi;

    slapi_unlock_mutex(buffer_lock);

    return 0;
}

int
slapi_apib_make_reference_counted(void **api, slapi_apib_callback_on_zero callback_on_zero)
{
    int ret = -1;

    if (api[0] == 0) {
        api[0] = slapi_ch_malloc(sizeof(APIB_FEATURES));
        if (api[0]) {
            ((APIB_FEATURES *)(api[0]))->lock = slapi_new_mutex();
            if (((APIB_FEATURES *)(api[0]))->lock) {
                ((APIB_FEATURES *)(api[0]))->refcount = 0; /* the ref count */
                ((APIB_FEATURES *)(api[0]))->callback_on_zero = callback_on_zero;
                ret = 0;
            } else
                slapi_ch_free(&(api[0]));
        }
    }

    return ret;
}

int
slapi_apib_addref(void **api)
{
    int ret;

    slapi_lock_mutex(((APIB_FEATURES *)(api[0]))->lock);

    ret = ++(((APIB_FEATURES *)(api[0]))->refcount);

    slapi_unlock_mutex(((APIB_FEATURES *)(api[0]))->lock);

    return ret;
}

int
slapi_apib_release(void **api)
{
    APIB_FEATURES *features = (APIB_FEATURES *)api[0];
    PRBool must_free = PR_FALSE;
    int ret;

    slapi_lock_mutex(features->lock);

    ret = --features->refcount;

    if (features->refcount == 0 && features->callback_on_zero &&
        features->callback_on_zero(api)) /* this should deregister the interface */
    {
        must_free = PR_TRUE;
    }
    slapi_unlock_mutex(features->lock);
    if (must_free) {
        slapi_destroy_mutex(features->lock);
        slapi_ch_free((void **)&features);
    }

    return ret;
}


static ABAPI **
ABAPIBroker_FindInterface(char *guid)
{
    static ABAPI *api = 0; /* simple gut feeling optimization for constant calls on same api */
    ABAPI *start_api = api;

    if (!api) {
        start_api = api = head;
    }

    if (api) {
        do {
            if (0 == strcmp(guid, api->guid)) {
                return &api;
            }

            api = api->next;
        } while (api != start_api);
    }

    return 0;
}

static void ***
ABAPIBroker_FindInterface_All(char *guid)
{
    ABAPI *api = NULL;
    ABAPI *start_api = head;
    void ***apilist = NULL;
    int idx = 0;

    api = start_api;
    if (!api) {
        return NULL;
    }

    do {
        if (0 == strcmp(guid, api->guid)) {
            apilist = (void ***)slapi_ch_realloc((char *)apilist, (idx + 2) * sizeof(void **));
            apilist[idx++] = api->api;
            apilist[idx] = NULL;
        }
        api = api->next;
    } while (api != start_api);

    return apilist;
}