/*
**  L2 - OSSP Logging Library
**  Copyright (c) 2001 The OSSP Project (http://www.ossp.org/)
**  Copyright (c) 2001 Cable & Wireless Deutschland (http://www.cw.com/de/)
**
**  This file is part of OSSP L2, a flexible logging library which
**  can be found at http://www.ossp.org/pkg/l2/.
**
**  Permission to use, copy, modify, and distribute this software for
**  any purpose with or without fee is hereby granted, provided that
**  the above copyright notice and this permission notice appear in all
**  copies.
**
**  THIS SOFTWARE IS PROVIDED ``AS IS'' AND ANY EXPRESSED OR IMPLIED
**  WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE IMPLIED WARRANTIES OF
**  MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE ARE DISCLAIMED.
**  IN NO EVENT SHALL THE AUTHORS AND COPYRIGHT HOLDERS AND THEIR
**  CONTRIBUTORS BE LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL,
**  SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT
**  LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS OF
**  USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND
**  ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY,
**  OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT
**  OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF
**  SUCH DAMAGE.
**
**  l2_ch_buffer.c: buffering channel implementation
*/

#include "l2.h"

#include <string.h>

/* declare private channel configuration */
typedef struct {
    char  *buf;
    int    bufpos;
    int    bufsize;
} l2_ch_buffer_t;

/* create channel */
static l2_result_t hook_create(l2_context_t *ctx, l2_channel_t *ch)
{
    l2_ch_buffer_t *cfg;

    /* allocate private channel configuration */
    if ((cfg = (l2_ch_buffer_t *)malloc(sizeof(l2_ch_buffer_t))) == NULL)
        return L2_ERROR;

    /* initialize configuration with reasonable defaults */
    cfg->buf     = NULL;
    cfg->bufpos  = 0;
    cfg->bufsize = 4096;

    /* link private channel configuration into channel context */
    ctx->vp = cfg;

    return L2_OK;
}

/* configure channel */
static l2_result_t hook_configure(l2_context_t *ctx, l2_channel_t *ch, const char *fmt, va_list ap)
{
    l2_ch_buffer_t *cfg;
    l2_param_t pa[2];
    l2_result_t rv;

    /* parameter checks */
    if ((cfg = (l2_ch_buffer_t *)ctx->vp) == NULL)
        return L2_ERROR;

    /* feed and call generic parameter parsing engine */
    L2_PARAM_SET(pa[0], size, INT, &cfg->bufsize);
    L2_PARAM_END(pa[1]);
    rv = l2_util_setparams(pa, fmt, ap);
    if (cfg->bufsize < 0) 
        return L2_ERROR;
    return rv;
}

/* open channel */
static l2_result_t hook_open(l2_context_t *ctx, l2_channel_t *ch)
{
    l2_ch_buffer_t *cfg;
    l2_channel_t *downstream;

    /* parameter checks */
    if ((cfg = (l2_ch_buffer_t *)ctx->vp) == NULL)
        return L2_ERROR;

    /* open channel buffer */
    if (cfg->bufsize > 0) {
        if ((cfg->buf = malloc(cfg->bufsize)) == NULL)
            return L2_ERROR;
        cfg->bufpos = 0;
    }

    /* optionally open downstream channel, too */
    if ((downstream = l2_channel_downstream(ch)) != NULL)
        if (l2_channel_open(downstream) == L2_ERROR)
            return L2_ERROR;

    return L2_OK;
}

/* write to channel */
static l2_result_t hook_write(l2_context_t *ctx, l2_channel_t *ch, 
                      const char *buf, size_t bufsize)
{
    l2_channel_t *downstream = l2_channel_downstream(ch);
    l2_ch_buffer_t *cfg;
    l2_result_t rv;

    /* parameter checks */
    if ((cfg = (l2_ch_buffer_t *)ctx->vp) == NULL)
        return L2_ERROR;

    if (bufsize > (cfg->bufsize - cfg->bufpos)) {
        /* flush buffer if necessary */
        if (cfg->bufpos > 0) {
            if ((rv = l2_channel_write(downstream, cfg->buf, cfg->bufpos)) != L2_OK)
                return rv;
            cfg->bufpos = 0;
        }
        /* pass through immediately to downstream if still too large */
        if (bufsize > cfg->bufsize)
            return l2_channel_write(downstream, buf, bufsize);
    }

    /* write message to channel buffer */
    memcpy(cfg->buf+cfg->bufpos, buf, bufsize);
    cfg->bufpos += bufsize;

    return L2_OK;
}

/* flush channel */
static l2_result_t hook_flush(l2_context_t *ctx, l2_channel_t *ch)
{
    l2_ch_buffer_t *cfg;
    l2_channel_t *downstream;

    /* parameter checks */
    if ((cfg = (l2_ch_buffer_t *)ctx->vp) == NULL)
        return L2_ERROR;

    /* write the buffer contents downstream */
    if (cfg->bufpos > 0) {
        if ((downstream = l2_channel_downstream(ch)) != NULL)
            if (l2_channel_write(downstream, cfg->buf, cfg->bufpos) == L2_ERROR)
                return L2_ERROR;
        cfg->bufpos = 0;
    }

    /* optionally flush downstream channel, too */
    if ((downstream = l2_channel_downstream(ch)) != NULL)
        if (l2_channel_flush(downstream) == L2_ERROR)
            return L2_ERROR;

    return L2_OK;
}

/* close channel */
static l2_result_t hook_close(l2_context_t *ctx, l2_channel_t *ch)
{
    l2_ch_buffer_t *cfg;
    l2_channel_t *downstream;

    /* parameter checks */
    if ((cfg = (l2_ch_buffer_t *)ctx->vp) == NULL)
        return L2_ERROR;

    /* write stale data before closing down */
    if (cfg->bufpos > 0) {
        if ((downstream = l2_channel_downstream(ch)) != NULL)
            if (l2_channel_write(downstream, cfg->buf, cfg->bufpos) == L2_ERROR)
                return L2_ERROR;
        cfg->bufpos = 0;
    }

    /* optionally close downstream channel, too */
    if ((downstream = l2_channel_downstream(ch)) != NULL)
        if (l2_channel_close(downstream) == L2_ERROR)
            return L2_ERROR;

    /* close channel buffer */
    if (cfg->buf != NULL) {
        free(cfg->buf);
        cfg->buf = NULL;
    }

    return L2_OK;
}

/* destroy channel */
static l2_result_t hook_destroy(l2_context_t *ctx, l2_channel_t *ch)
{
    l2_ch_buffer_t *cfg;

    /* parameter checks */
    if ((cfg = (l2_ch_buffer_t *)ctx->vp) == NULL)
        return L2_ERROR;

    /* if not already closed, close channel buffer now */
    if (cfg->buf != NULL) {
        free(cfg->buf);
        cfg->buf = NULL;
    }

    /* destroy channel configuration */
    free(cfg);

    return L2_OK;
}

/* exported channel handler structure */
l2_handler_t l2_handler_buffer = {
    L2_CHANNEL_FILTER,
    hook_create,
    hook_configure,
    hook_open,
    hook_write,
    hook_flush,
    hook_close,
    hook_destroy
};