/*
**  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_prefix.c: prefixing channel implementation
*/

#include <time.h>
#include <sys/types.h>
#include <unistd.h>

#include "l2.h"

/* declare private channel configuration */
typedef struct {
    char *prefix;
    char *timezone;
} l2_ch_prefix_t;

/* create channel */
static l2_result_t hook_create(l2_context_t *ctx, l2_channel_t *ch)
{
    l2_ch_prefix_t *cfg;

    /* allocate private channel configuration */
    if ((cfg = (l2_ch_prefix_t *)malloc(sizeof(l2_ch_prefix_t))) == NULL)
        return L2_ERR_MEM;

    /* initialize configuration with reasonable defaults */
    cfg->prefix   = NULL;
    cfg->timezone = strdup("local");

    /* 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_prefix_t *cfg = (l2_ch_prefix_t *)ctx->vp;
    l2_param_t pa[3]; 
    l2_result_t rv;

    /* feed and call generic parameter parsing engine */
    L2_PARAM_SET(pa[0], prefix,  STRING, &cfg->prefix);
    L2_PARAM_SET(pa[1], timezone, STRING, &cfg->timezone);
    L2_PARAM_END(pa[2]);
    rv = l2_util_setparams(pa, fmt, ap);

    /* argument consistency check */
    if (rv == L2_OK) {
        if (cfg->timezone == NULL)
            return L2_ERR_ARG;
        if (!(   strcmp(cfg->timezone, "local") == 0 
              || strcmp(cfg->timezone, "utc")   == 0))
            return L2_ERR_ARG;
    }

    return rv;
}

static l2_result_t expand_specials(char *buf, size_t bufsize, l2_level_t level)
{
    char *cpSC;
    char *cpSE;
    char *cpBE;
    char caBuf[128];
    size_t nBuf;
    l2_level_t rv;
    int bSubst;

    cpSC = buf;             /* string current pointer */
    cpSE = buf+strlen(buf); /* string end pointer     */
    cpBE = buf+bufsize;     /* buffer end pointer     */
    while (cpSC < cpSE) {
        if ((cpSC+1) < cpSE && *cpSC == '%') {
            bSubst = FALSE;
            switch (*(cpSC+1)) {
                case 'L': {
                    if ((rv = l2_util_l2s(caBuf, sizeof(caBuf), '\0', level)) != L2_OK)
                        return rv;
                    bSubst = TRUE;
                    break;
                }
                case 'P': {
                    sprintf(caBuf, "%lu", (unsigned long)getpid());
                    bSubst = TRUE;
                    break;
                }
            }
            if (bSubst) {
                nBuf = strlen(caBuf);
                if ((cpBE-cpSE)+2 < nBuf)
                    return L2_ERR_MEM;
                memmove(cpSC+nBuf, cpSC+2, cpSE-(cpSC+2)+1);
                memmove(cpSC, caBuf, nBuf);
                cpSC += nBuf;
                cpSE += (-2+nBuf);
                continue;
            }
        }
        cpSC++;
    }

    return L2_OK;
}

/* write to channel */
static l2_result_t hook_write(l2_context_t *ctx, l2_channel_t *ch,
                              l2_level_t level, const char *buf, size_t buf_size)
{
    l2_ch_prefix_t *cfg = (l2_ch_prefix_t *)ctx->vp;
    l2_channel_t *downstream = l2_channel_downstream(ch);
    time_t t;
    struct tm *tm;
    size_t n;
    l2_result_t rv;
    char buf1[1024];
    char buf2[1024];

    /* optionally provide prefix */
    if (cfg->prefix != NULL) {
        if (strlen(cfg->prefix) >= sizeof(buf1))
            return L2_ERR_MEM;
        strcpy(buf1, cfg->prefix);
        if ((rv = expand_specials(buf1, sizeof(buf1), level)) != L2_OK)
            return rv;
        t = time(NULL);
        if (strcmp(cfg->timezone, "local") == 0)
            tm = localtime(&t);
        else if (strcmp(cfg->timezone, "utc") == 0)
            tm = gmtime(&t);
        else
            return L2_ERR_ARG;
        if ((n = strftime(buf2, sizeof(buf2), buf1, tm)) == 0)
            return L2_ERR_SYS;
        if ((rv = l2_channel_write(downstream, level, buf2, n)) != L2_OK)
            return rv;
    }

    /* write to downstream channel */
    if ((rv = l2_channel_write(downstream, level, buf, buf_size)) != L2_OK)
        return rv;

    return L2_OK;
}

/* destroy channel */
static l2_result_t hook_destroy(l2_context_t *ctx, l2_channel_t *ch)
{
    l2_ch_prefix_t *cfg = (l2_ch_prefix_t *)ctx->vp;
    l2_channel_t *downstream = l2_channel_downstream(ch);
    l2_result_t rv;

    /* free prefix structure */
    if (cfg->prefix != NULL)
        free(cfg->prefix);
    if (cfg->timezone != NULL)
        free(cfg->timezone);
    free(cfg);

    /* optionally destroy downstream channel, too */
    if ((rv = l2_channel_destroy(downstream)) != L2_OK)
        return rv;

    return L2_OK;
}

/* exported channel handler structure */
l2_handler_t l2_handler_prefix = {
    L2_CHANNEL_FILTER,
    hook_create,
    hook_configure,
    NULL,
    hook_write,
    NULL,
    NULL,
    hook_destroy
};