/*
 * container_list_sl.c
 * $Id$
 *
 */
#include <net-snmp/net-snmp-config.h>
#include <net-snmp/net-snmp-features.h>

#include <stdio.h>
#ifdef HAVE_STDLIB_H
#include <stdlib.h>
#endif
#ifdef HAVE_MALLOC_H
#include <malloc.h>
#endif
#include <sys/types.h>
#ifdef HAVE_STRING_H
#include <string.h>
#else
#include <strings.h>
#endif

#include <net-snmp/net-snmp-includes.h>
#include <net-snmp/types.h>
#include <net-snmp/library/snmp_api.h>
#include <net-snmp/library/container.h>
#include <net-snmp/library/tools.h>
#include <net-snmp/library/snmp_assert.h>

#include <net-snmp/library/container_list_ssll.h>
#include "factory.h"

netsnmp_feature_child_of(container_linked_list, container_types);
netsnmp_feature_child_of(container_fifo, container_types);
netsnmp_feature_child_of(container_lifo, container_types);

/* this is a fancy way of cleaning up ifdefs */
#ifdef NETSNMP_FEATURE_REQUIRE_CONTAINER_FIFO
netsnmp_feature_require(container_linked_list);
#endif /* NETSNMP_FEATURE_REQUIRE_CONTAINER_FIFO */
#ifdef NETSNMP_FEATURE_REQUIRE_CONTAINER_LIFO
netsnmp_feature_require(container_linked_list);
#endif /* NETSNMP_FEATURE_REQUIRE_CONTAINER_LIFO */

#ifndef NETSNMP_FEATURE_REMOVE_CONTAINER_LINKED_LIST
typedef struct sl_node {
   void           *data;
   struct sl_node *next;
} sl_node;

typedef struct sl_container_s {
   netsnmp_container          c;
   
   size_t                     count;      /* Index of the next free entry */
   sl_node                   *head;       /* head of list */

   int                        unsorted;   /* unsorted list? */
   int                        fifo;       /* lifo or fifo? */

} sl_container;

typedef struct ssll_iterator_s {
    netsnmp_iterator base;
 
    sl_node         *pos;
    sl_node         *last;
} ssll_iterator;

static netsnmp_iterator *_ssll_iterator_get(netsnmp_container *c);


static void *
_get(netsnmp_container *c, const void *key, int return_next)
{
    sl_container *sl = (sl_container *)c;
    sl_node *curr = sl->head;
    int rc = 0;

    /* If the key is NULL, return the first item in the container. */
    if (!key)
        return curr ? curr->data : NULL;

    for ( ; curr; curr = curr->next) {
        rc = sl->c.compare(curr->data, key);
        if (rc < 0)
            continue;
        if (rc == 0) {
            if (return_next)
                curr = curr->next;
            break;
        }
        if (!sl->unsorted) {
            /* If sorted, we can stop. */
            if (!return_next)
                curr = NULL;
            break;
        }
    }

    return curr ? curr->data : NULL;
}

/**********************************************************************
 *
 *
 *
 **********************************************************************/
static int
_ssll_free(netsnmp_container *c)
{
    if(c) {
        free(c);
    }
    return 0;
}

static void *
_ssll_find(netsnmp_container *c, const void *data)
{
    if((NULL == c) || (NULL == data))
        return NULL;

    return _get(c, data, 0);
}

static void *
_ssll_find_next(netsnmp_container *c, const void *data)
{
    if(NULL == c)
        return NULL;

    return _get(c, data, 1);
}

static int
_ssll_insert(netsnmp_container *c, const void *data)
{
    sl_container *sl = (sl_container*)c;
    sl_node  *new_node, *curr;
    
    if (c == NULL)
        return -1;

    curr = sl->head;

    new_node = SNMP_MALLOC_TYPEDEF(sl_node);
    if (new_node == NULL)
        return -1;
    new_node->data = NETSNMP_REMOVE_CONST(void *, data);
    ++sl->count;
    ++c->sync;

    /*
     * first node?
     */
    if(NULL == sl->head) {
        sl->head = new_node;
        return 0;
    }

    /*
     * sorted or unsorted insert?
     */
    if (1 == sl->unsorted) {
        /*
         * unsorted: fifo, or lifo?
         */
        if (1 == sl->fifo) {
            /*
             * fifo: insert at tail
             */
            while(NULL != curr->next)
                curr = curr->next;
            curr->next = new_node;
        }
        else {
            /*
             * lifo: insert at head
             */
            new_node->next = sl->head;
            sl->head = new_node;
        }
    }
    else {
        /*
         * sorted
         */
        sl_node *last = NULL;
        for( ; curr; last = curr, curr = curr->next) {
            if(sl->c.compare(curr->data, data) > 0)
                break;
        }
        if(NULL == last) {
            new_node->next = sl->head;
            sl->head = new_node;
        }
        else {
            new_node->next = last->next;
            last->next = new_node;
        }
    }
    
    return 0;
}

static int
_ssll_remove(netsnmp_container *c, const void *data)
{
    sl_container *sl = (sl_container*)c;
    sl_node  *curr;
    
    if (c == NULL)
        return -1;

    curr = sl->head;
    if (curr == NULL)
        return -1;

    /*
     * special case for NULL data, act like stack
     */
    if ((NULL == data) ||
        (sl->c.compare(sl->head->data, data) == 0)) {
        curr = sl->head;
        sl->head = sl->head->next;
    }
    else {
        sl_node *last = sl->head;
        int rc;
        for(curr = sl->head->next ; curr; last = curr, curr = curr->next) {
            rc = sl->c.compare(curr->data, data);
            if (rc == 0) {
                last->next = curr->next;
                break;
            }
            else if ((rc > 0) && (0 == sl->unsorted)) {
                /*
                 * if sorted and rc > 0, didn't find entry
                 */
                curr = NULL;
                break;
            }
        }
    }

    if(NULL == curr)
        return -2;
    
    /*
     * free our node structure, but not the data
     */
    free(curr);
    --sl->count;
    ++c->sync;
    
    return 0;
}

static size_t
_ssll_size(netsnmp_container *c)
{
    sl_container *sl = (sl_container*)c;
    
    if(NULL == c)
        return 0;

    return sl->count;
}

static void
_ssll_for_each(netsnmp_container *c, netsnmp_container_obj_func *f,
             void *context)
{
    sl_container *sl = (sl_container*)c;
    sl_node  *curr;
    
    if(NULL == c)
        return;
    
    for(curr = sl->head; curr; curr = curr->next)
        (*f) ((void *)curr->data, context);
}

static void
_ssll_clear(netsnmp_container *c, netsnmp_container_obj_func *f,
             void *context)
{
    sl_container *sl = (sl_container*)c;
    sl_node  *curr, *next;
    
    if(NULL == c)
        return;
    
    for(curr = sl->head; curr; curr = next) {

        next = curr->next;

        if( NULL != f ) {
            curr->next = NULL;
            (*f) ((void *)curr->data, context);
        }

        /*
         * free our node structure, but not the data
         */
        free(curr);
    }
    sl->head = NULL;
    sl->count = 0;
    ++c->sync;
}

/**********************************************************************
 *
 *
 *
 **********************************************************************/
netsnmp_container *
netsnmp_container_get_ssll(void)
{
    /*
     * allocate memory
     */
    sl_container *sl = SNMP_MALLOC_TYPEDEF(sl_container);
    if (NULL==sl) {
        snmp_log(LOG_ERR, "couldn't allocate memory\n");
        return NULL;
    }

    netsnmp_init_container((netsnmp_container *)sl, NULL, _ssll_free,
                           _ssll_size, NULL, _ssll_insert, _ssll_remove,
                           _ssll_find);
    sl->c.find_next = _ssll_find_next;
    sl->c.get_subset = NULL;
    sl->c.get_iterator =_ssll_iterator_get;
    sl->c.for_each = _ssll_for_each;
    sl->c.clear = _ssll_clear;

    return &sl->c;
}

netsnmp_container *
netsnmp_container_get_usll(void)
{
    /*
     * allocate memory
     */
    sl_container *sl = (sl_container *)netsnmp_container_get_ssll();
    if (NULL==sl)
        return NULL; /* msg already logged */

    sl->unsorted = 1;

    return (netsnmp_container*)sl;
}

netsnmp_container *
netsnmp_container_get_singly_linked_list(int fifo)
{
    sl_container *sl = (sl_container *)netsnmp_container_get_usll();
    if (NULL == sl)
        return NULL; /* error already logged */

    sl->fifo = fifo;

    return (netsnmp_container *)sl;
}

netsnmp_container *
netsnmp_container_get_fifo(void)
{
    return netsnmp_container_get_singly_linked_list(1);
}

void
netsnmp_container_ssll_init(void)
{
    static netsnmp_factory ssll = {
        "sorted_singly_linked_list",
        netsnmp_container_get_ssll
    };
    static netsnmp_factory usll = {
        "unsorted_singly_linked_list-lifo",
        netsnmp_container_get_usll
    };
    static netsnmp_factory fifo = {
        "unsorted_singly_linked_list-fifo",
        netsnmp_container_get_fifo
    };

    netsnmp_container_register("sorted_singly_linked_list", &ssll);
    netsnmp_container_register("unsorted_singly_linked_list", &usll);
    netsnmp_container_register("lifo", &usll);
    netsnmp_container_register("fifo", &fifo);
}


/**********************************************************************
 *
 * iterator
 *
 */
NETSNMP_STATIC_INLINE sl_container *
_ssll_it2cont(ssll_iterator *it)
{
    if(NULL == it) {
        netsnmp_assert(NULL != it);
        return NULL;
    }

    if(NULL == it->base.container) {
        netsnmp_assert(NULL != it->base.container);
        return NULL;
    }

    if(it->base.container->sync != it->base.sync) {
        DEBUGMSGTL(("container:iterator", "out of sync\n"));
        return NULL;
    }

    return (sl_container *)it->base.container;
}

static void *
_ssll_iterator_curr(netsnmp_iterator *p)
{
    ssll_iterator *it = (void *)p;
    sl_container *t = _ssll_it2cont(it);
    if ((NULL == t) || (NULL == it->pos))
        return NULL;

    return it->pos->data;
}

static void *
_ssll_iterator_first(netsnmp_iterator *p)
{
    ssll_iterator *it = (void *)p;
    sl_container *t = _ssll_it2cont(it);
    if ((NULL == t) || (NULL == t->head))
        return NULL;

    return t->head->data;
}

static void *
_ssll_iterator_next(netsnmp_iterator *p)
{
    ssll_iterator *it = (void *)p;
    sl_container *t = _ssll_it2cont(it);
    if ((NULL == t) || (NULL == it->pos))
        return NULL;

    it->pos = it->pos->next;
    if (NULL == it->pos)
        return NULL;

    return it->pos->data;
}

static void *
_ssll_iterator_last(netsnmp_iterator *p)
{
    ssll_iterator *it = (void *)p;
    sl_node      *n;
    sl_container *t = _ssll_it2cont(it);
    if(NULL == t)
        return NULL;
    
    if (it->last)
        return it->last;

    n = it->pos ? it->pos : t->head;
    if (NULL == n)
        return NULL;

    while (n->next)
        n = n->next;

    it->last = n;

    return it->last->data;
}

static int
_ssll_iterator_reset(netsnmp_iterator *p)
{
    ssll_iterator *it = (void *)p;
    sl_container *t;

    /** can't use it2conf cuz we might be out of sync */
    if(NULL == it) {
        netsnmp_assert(NULL != it);
        return 0;
    }

    if(NULL == it->base.container) {
        netsnmp_assert(NULL != it->base.container);
        return 0;
    }
    t = (sl_container *)it->base.container;
    if(NULL == t)
        return -1;

    it->last = NULL;
    it->pos = t->head;

    /*
     * save sync count, to make sure container doesn't change while
     * iterator is in use.
     */
    it->base.sync = it->base.container->sync;

    return 0;
}

static int
_ssll_iterator_release(netsnmp_iterator *it)
{
    free(it);

    return 0;
}

static netsnmp_iterator *
_ssll_iterator_get(netsnmp_container *c)
{
    ssll_iterator* it;

    if(NULL == c)
        return NULL;

    it = SNMP_MALLOC_TYPEDEF(ssll_iterator);
    if(NULL == it)
        return NULL;

    it->base.container = c;
    
    it->base.first = _ssll_iterator_first;
    it->base.next = _ssll_iterator_next;
    it->base.curr = _ssll_iterator_curr;
    it->base.last = _ssll_iterator_last;
    it->base.reset = _ssll_iterator_reset;
    it->base.release = _ssll_iterator_release;

    (void)_ssll_iterator_reset(&it->base);

    return &it->base;
}
#else /* NETSNMP_FEATURE_REMOVE_CONTAINER_LINKED_LIST */
netsnmp_feature_unused(container_linked_list);
#endif /* NETSNMP_FEATURE_REMOVE_CONTAINER_LINKED_LIST */
