/*
 *  ircd-ratbox:  A slight useful ircd
 *  rawbuf.c: raw buffer (non-line oriented buffering)
 *
 *  Copyright (C) 2007 Aaron Sethman <androsyn@ratbox.org>
 *  Copyright (C) 2007 ircd-ratbox development team
 *
 *  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., 51 Franklin Street, Fifth Floor, Boston, MA  02110-1301
 *  USA
 *
 *  $Id$
 */
#include <libratbox_config.h>
#include <ratbox_lib.h>
#include <commio-int.h>
#define RAWBUF_SIZE 1024

struct _rawbuf {
    rb_dlink_node node;
    uint8_t data[RAWBUF_SIZE];
    int len;
    uint8_t flushing;
};

struct _rawbuf_head {
    rb_dlink_list list;
    int len;
    int written;
};

static rb_bh *rawbuf_heap;


static rawbuf_t *
rb_rawbuf_alloc(void)
{
    rawbuf_t *t;
    t = rb_bh_alloc(rawbuf_heap);
    return t;
}

static rawbuf_t *
rb_rawbuf_newbuf(rawbuf_head_t * rb)
{
    rawbuf_t *buf;
    buf = rb_rawbuf_alloc();
    rb_dlinkAddTail(buf, &buf->node, &rb->list);
    return buf;
}

static void
rb_rawbuf_done(rawbuf_head_t * rb, rawbuf_t * buf)
{
    rawbuf_t *ptr = buf;
    rb_dlinkDelete(&buf->node, &rb->list);
    rb_bh_free(rawbuf_heap, ptr);
}

static int
rb_rawbuf_flush_writev(rawbuf_head_t * rb, rb_fde_t *F)
{
    rb_dlink_node *ptr, *next;
    rawbuf_t *buf;
    int x = 0, y = 0;
    int xret, retval;
    struct rb_iovec vec[RB_UIO_MAXIOV];
    memset(vec, 0, sizeof(vec));

    if(rb->list.head == NULL) {
        errno = EAGAIN;
        return -1;
    }

    RB_DLINK_FOREACH(ptr, rb->list.head) {
        if(x >= RB_UIO_MAXIOV)
            break;

        buf = ptr->data;
        if(buf->flushing) {
            vec[x].iov_base = buf->data + rb->written;
            vec[x++].iov_len = buf->len - rb->written;
            continue;
        }
        vec[x].iov_base = buf->data;
        vec[x++].iov_len = buf->len;

    }

    if(x == 0) {
        errno = EAGAIN;
        return -1;
    }
    xret = retval = rb_writev(F, vec, x);
    if(retval <= 0)
        return retval;

    RB_DLINK_FOREACH_SAFE(ptr, next, rb->list.head) {
        buf = ptr->data;
        if(y++ >= x)
            break;
        if(buf->flushing) {
            if(xret >= buf->len - rb->written) {
                xret -= buf->len - rb->written;
                rb->len -= buf->len - rb->written;
                rb_rawbuf_done(rb, buf);
                continue;
            }
        }

        if(xret >= buf->len) {
            xret -= buf->len;
            rb->len -= buf->len;
            rb_rawbuf_done(rb, buf);
        } else {
            buf->flushing = 1;
            rb->written = xret;
            rb->len -= xret;
            break;
        }

    }
    return retval;
}

int
rb_rawbuf_flush(rawbuf_head_t * rb, rb_fde_t *F)
{
    rawbuf_t *buf;
    int retval;
    if(rb->list.head == NULL) {
        errno = EAGAIN;
        return -1;
    }

    if(!rb_fd_ssl(F))
        return rb_rawbuf_flush_writev(rb, F);

    buf = rb->list.head->data;
    if(!buf->flushing) {
        buf->flushing = 1;
        rb->written = 0;
    }

    retval = rb_write(F, buf->data + rb->written, buf->len - rb->written);
    if(retval <= 0)
        return retval;

    rb->written += retval;
    if(rb->written == buf->len) {
        rb->written = 0;
        rb_dlinkDelete(&buf->node, &rb->list);
        rb_bh_free(rawbuf_heap, buf);
    }
    rb->len -= retval;
    lrb_assert(rb->len >= 0);
    return retval;
}


void
rb_rawbuf_append(rawbuf_head_t * rb, void *data, int len)
{
    rawbuf_t *buf = NULL;
    int clen;
    void *ptr;
    if(rb->list.tail != NULL)
        buf = rb->list.tail->data;

    if(buf != NULL && buf->len < RAWBUF_SIZE && !buf->flushing) {
        buf = (rawbuf_t *) rb->list.tail->data;
        clen = RAWBUF_SIZE - buf->len;
        ptr = (void *)(buf->data + buf->len);
        if(len < clen)
            clen = len;

        memcpy(ptr, data, clen);
        buf->len += clen;
        rb->len += clen;
        len -= clen;
        if(len == 0)
            return;
        data = (char *)data + clen;

    }

    while(len > 0) {
        buf = rb_rawbuf_newbuf(rb);

        if(len >= RAWBUF_SIZE)
            clen = RAWBUF_SIZE;
        else
            clen = len;

        memcpy(buf->data, data, clen);
        buf->len += clen;
        len -= clen;
        data = (char *)data + clen;
        rb->len += clen;
    }
}


int
rb_rawbuf_get(rawbuf_head_t * rb, void *data, int len)
{
    rawbuf_t *buf;
    int cpylen;
    void *ptr;
    if(rb->list.head == NULL)
        return 0;

    buf = rb->list.head->data;

    if(buf->flushing)
        ptr = (void *)(buf->data + rb->written);
    else
        ptr = buf->data;

    if(len > buf->len)
        cpylen = buf->len;
    else
        cpylen = len;

    memcpy(data, ptr, cpylen);

    if(cpylen == buf->len) {
        rb->written = 0;
        rb_rawbuf_done(rb, buf);
        rb->len -= len;
        return cpylen;
    }

    buf->flushing = 1;
    buf->len -= cpylen;
    rb->len -= cpylen;
    rb->written += cpylen;
    return cpylen;
}

int
rb_rawbuf_length(rawbuf_head_t * rb)
{
    if(rb_dlink_list_length(&rb->list) == 0 && rb->len != 0)
        lrb_assert(1 == 0);
    return rb->len;
}

rawbuf_head_t *
rb_new_rawbuffer(void)
{
    return rb_malloc(sizeof(rawbuf_head_t));

}

void
rb_free_rawbuffer(rawbuf_head_t * rb)
{
    rb_dlink_node *ptr, *next;
    RB_DLINK_FOREACH_SAFE(ptr, next, rb->list.head) {
        rb_rawbuf_done(rb, ptr->data);
    }
    rb_free(rb);
}


void
rb_init_rawbuffers(int heap_size)
{
    if(rawbuf_heap == NULL)
        rawbuf_heap = rb_bh_create(sizeof(rawbuf_t), heap_size, "librb_rawbuf_heap");
}
