/*
 * Copyright (C) 1998,1999,2001  Ross Combs (rocombs@cs.nmsu.edu)
 *
 * This program is free software; you can redistribute it and/or
 * modify it under the terms of the GNU General Public License
 * as published by the Free Software Foundation; either version 2
 * of the License, or (at your option) any later version.
 *
 * This program is distributed in the hope that it will be useful,
 * but WITHOUT ANY WARRANTY; without even the implied warranty of
 * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
 * GNU General Public License for more details.
 *
 * You should have received a copy of the GNU General Public License
 * along with this program; if not, write to the Free Software
 * Foundation, Inc., 59 Temple Place - Suite 330, Boston, MA  02111-1307, USA.
 */
#define QUEUE_INTERNAL_ACCESS
#include "common/setup_before.h"
#ifdef HAVE_STDDEF_H
# include <stddef.h>
#else
# ifndef NULL
#  define NULL ((void *)0)
# endif
#endif
#ifdef STDC_HEADERS
# include <stdlib.h>
#else
# ifdef HAVE_MALLOC_H
#  include <malloc.h>
# endif
#endif
#ifdef HAVE_STRING_H
# include <string.h>
#else
# ifdef HAVE_STRINGS_H
#  include <strings.h>
# endif
# ifdef HAVE_MEMORY_H
#  include <memory.h>
# endif
#endif
#include "common/packet.h"
#include "common/eventlog.h"
#include "common/xalloc.h"
#include "common/queue.h"
#include "common/setup_after.h"

#define QUEUE_QUANTUM	10 /* allocate ring buffer slots for 10 packets at once */

extern t_packet * queue_pull_packet(t_queue * * queue)
{
    t_queue *  temp;
    t_packet * packet;

//    eventlog(eventlog_level_debug, __FUNCTION__, "entered: queue %p", queue);
    if (!queue)
    {
	eventlog(eventlog_level_error,__FUNCTION__,"got NULL queue pointer");
        return NULL;
    }

    temp = *queue;

    if (!temp || !temp->ulen)
        return NULL;

//    eventlog(eventlog_level_debug, __FUNCTION__, "getting element from tail (%d/%d head/tail %d/%d)", temp->alen, temp->ulen, temp->head, temp->tail);
    /* getting entry from tail and updating queue */
    packet = temp->ring[temp->tail];
    temp->tail = (temp->tail + 1) % temp->alen;
    temp->ulen--;
//    eventlog(eventlog_level_debug, __FUNCTION__, "read %p element from tail (%d/%d head/tail %d/%d)", packet, temp->alen, temp->ulen, temp->head, temp->tail);

    if (!packet)
    {
	eventlog(eventlog_level_error,__FUNCTION__,"NULL packet in queue");
        return NULL;
    }
    
    return packet;
}


extern t_packet * queue_peek_packet(t_queue const * const * queue)
{
    t_packet * packet;

//    eventlog(eventlog_level_debug, __FUNCTION__, "entered: queue %p", queue);
    if (!queue)
    {
	eventlog(eventlog_level_error,__FUNCTION__,"got NULL queue pointer");
        return NULL;
    }
    if (!*queue || !(*queue)->ulen)
        return NULL;

    packet = (*queue)->ring[(*queue)->tail];
    
    if (!packet)
    {
        eventlog(eventlog_level_error,__FUNCTION__,"NULL packet in queue");
        return NULL;
    }
    
    return packet;
}


extern void queue_push_packet(t_queue * * queue, t_packet * packet)
{
    t_queue * temp;
    void *ptr;

//    eventlog(eventlog_level_debug, __FUNCTION__, "entered: queue %p packet %p", queue, packet);
    if (!queue)
    {
	eventlog(eventlog_level_error,__FUNCTION__,"got NULL queue pointer");
        return;
    }
    if (!packet)
    {
	eventlog(eventlog_level_error,__FUNCTION__,"got NULL packet");
        return;
    }

    temp = *queue;

    if (!temp)
    {
//	eventlog(eventlog_level_debug, __FUNCTION__, "queue is NULL , initilizing");
        temp = xmalloc(sizeof(t_queue));
	temp->alen = temp->ulen = 0;
	temp->ring = NULL;
	temp->head = temp->tail = 0;
        *queue = temp;
    }

    if (temp->ulen == temp->alen) { /* ring queue is full, need to allocate some memory */
/* FIXME: find a solution
	if (temp->alen)
	    eventlog(eventlog_level_error, __FUNCTION__, "queue is full (resizing) (oldsize: %u)", temp->alen);
*/

	ptr = xrealloc(temp->ring, sizeof(t_packet *) * (temp->alen + QUEUE_QUANTUM));
	temp->ring = (t_packet **)ptr;
	temp->alen += QUEUE_QUANTUM;

//	eventlog(eventlog_level_debug, __FUNCTION__, "queue new size %d/%d head/tail %d/%d", temp->alen, temp->ulen, temp->head, temp->tail);
	if (temp->head) {
	    unsigned moved;

	    moved = (QUEUE_QUANTUM <= temp->head) ? QUEUE_QUANTUM : temp->head;
	    memmove(temp->ring + temp->ulen, temp->ring, sizeof(t_packet *) * moved);
	    if (temp->head > QUEUE_QUANTUM) {
		memmove(temp->ring, temp->ring + moved, sizeof(t_packet *) * (temp->head - moved));
		temp->head -= moved;
	    } else if (temp->head < QUEUE_QUANTUM)
		temp->head = temp->ulen + moved;
	    else temp->head = 0;
	} else temp->head = temp->ulen;

    }

    temp->ring[temp->head] = packet_add_ref(packet);

    temp->head = (temp->head + 1) % temp->alen;
    temp->ulen++;
//    eventlog(eventlog_level_debug, __FUNCTION__, "packet added (%d/%d head/tail %d/%d)", temp->alen, temp->ulen, temp->head, temp->tail);
}


extern int queue_get_length(t_queue const * const * queue)
{
//    eventlog(eventlog_level_debug, __FUNCTION__, "entered: queue %p", queue);
    if (!queue)
    {
	eventlog(eventlog_level_error,__FUNCTION__,"got NULL queue pointer");
	return 0;
    }

    if (*queue == NULL) return 0;

    return (*queue)->ulen;
}


extern void queue_clear(t_queue * * queue)
{
    t_packet * temp;

//    eventlog(eventlog_level_debug, __FUNCTION__, "entered: queue %p", queue);
    if (!queue)
    {
	eventlog(eventlog_level_error,__FUNCTION__,"got NULL queue pointer");
	return;
    }

    if (*queue) {
	while ((temp = queue_pull_packet(queue)))
	    packet_del_ref(temp);

	if ((*queue)->ring) xfree((void*)((*queue)->ring));
	xfree((void*)(*queue));
    }
}