/* Copyright 2002-2004 Justin Erenkrantz and Greg Stein
 *
 * Licensed under the Apache License, Version 2.0 (the "License");
 * you may not use this file except in compliance with the License.
 * You may obtain a copy of the License at
 *
 *     http://www.apache.org/licenses/LICENSE-2.0
 *
 * Unless required by applicable law or agreed to in writing, software
 * distributed under the License is distributed on an "AS IS" BASIS,
 * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
 * See the License for the specific language governing permissions and
 * limitations under the License.
 */

#include <stdlib.h>  /* for abort() */

#include <apr_pools.h>

#include "serf.h"
#include "serf_bucket_util.h"


SERF_DECLARE(serf_bucket_t *) serf_bucket_create(
    const serf_bucket_type_t *type,
    serf_bucket_alloc_t *allocator,
    void *data)
{
    serf_bucket_t *bkt = serf_bucket_mem_alloc(allocator, sizeof(*bkt));

    bkt->type = type;
    bkt->data = data;
    bkt->allocator = allocator;

    return bkt;
}

SERF_DECLARE(apr_status_t) serf_default_read_iovec(
    serf_bucket_t *bucket,
    apr_size_t requested,
    int vecs_size,
    struct iovec *vecs,
    int *vecs_used)
{
    const char *data;
    apr_size_t len;

    /* Read some data from the bucket.
     *
     * Because we're an internal 'helper' to the bucket, we can't call the
     * normal serf_bucket_read() call because the debug allocator tracker will
     * end up marking the bucket as read *twice* - once for us and once for
     * our caller - which is reading the same bucket.  This leads to premature
     * abort()s if we ever see EAGAIN.  Instead, we'll go directly to the
     * vtable and bypass the debug tracker.
     */
    apr_status_t status = bucket->type->read(bucket, requested, &data, &len);

    /* assert that vecs_size >= 1 ? */

    /* Return that data as a single iovec. */
    if (len) {
        vecs[0].iov_base = (void *)data; /* loses the 'const' */
        vecs[0].iov_len = len;
        *vecs_used = 1;
    }
    else {
        *vecs_used = 0;
    }

    return status;
}

SERF_DECLARE(apr_status_t) serf_default_read_for_sendfile(
    serf_bucket_t *bucket,
    apr_size_t requested,
    apr_hdtr_t *hdtr,
    apr_file_t **file,
    apr_off_t *offset,
    apr_size_t *len)
{
    /* Read a bunch of stuff into the headers.
     *
     * See serf_default_read_iovec as to why we call into the vtable
     * directly.
     */
    apr_status_t status = bucket->type->read_iovec(bucket, requested,
                                                   hdtr->numheaders,
                                                   hdtr->headers,
                                                   &hdtr->numheaders);

    /* There isn't a file, and there are no trailers. */
    *file = NULL;
    hdtr->numtrailers = 0;

    return status;
}

SERF_DECLARE(serf_bucket_t *) serf_default_read_bucket(
    serf_bucket_t *bucket,
    const serf_bucket_type_t *type)
{
    return NULL;
}

SERF_DECLARE(void) serf_default_destroy(serf_bucket_t *bucket)
{
#ifdef SERF_DEBUG_BUCKET_USE
    serf_debug__bucket_destroy(bucket);
#endif

    serf_bucket_mem_free(bucket->allocator, bucket);
}

SERF_DECLARE(void) serf_default_destroy_and_data(serf_bucket_t *bucket)
{
    serf_bucket_mem_free(bucket->allocator, bucket->data);
    serf_default_destroy(bucket);
}


/* ==================================================================== */


SERF_DECLARE(char *) serf_bstrmemdup(serf_bucket_alloc_t *allocator,
                                     const char *str, apr_size_t size)
{
    char *newstr = serf_bucket_mem_alloc(allocator, size + 1);
    memcpy(newstr, str, size);
    newstr[size] = '\0';
    return newstr;
}

SERF_DECLARE(void *) serf_bmemdup(serf_bucket_alloc_t *allocator,
                                  const void *mem,
                                  apr_size_t size)
{
    void *newmem = serf_bucket_mem_alloc(allocator, size);
    memcpy(newmem, mem, size);
    return newmem;
}

SERF_DECLARE(char *) serf_bstrdup(serf_bucket_alloc_t *allocator,
                                  const char *str)
{
    apr_size_t size = strlen(str) + 1;
    char *newstr = serf_bucket_mem_alloc(allocator, size);
    memcpy(newstr, str, size);
    return newstr;
}


/* ==================================================================== */


static void find_crlf(const char **data, apr_size_t *len, int *found)
{
    const char *start = *data;
    const char *end = start + *len;

    while (start < end) {
        const char *cr = memchr(start, '\r', *len);

        if (cr == NULL) {
            break;
        }
        ++cr;

        if (cr < end && cr[0] == '\n') {
            *len -= cr + 1 - start;
            *data = cr + 1;
            *found = SERF_NEWLINE_CRLF;
            return;
        }
        if (cr == end) {
            *len = 0;
            *data = end;
            *found = SERF_NEWLINE_CRLF_SPLIT;
            return;
        }

        /* It was a bare CR without an LF. Just move past it. */
        *len -= cr - start;
        start = cr;
    }

    *data = start + *len;
    *len -= *data - start;
    *found = SERF_NEWLINE_NONE;
}

SERF_DECLARE(void) serf_util_readline(const char **data, apr_size_t *len,
                                      int acceptable, int *found)
{
    const char *start;
    const char *cr;
    const char *lf;
    int want_cr;
    int want_crlf;
    int want_lf;

    /* If _only_ CRLF is acceptable, then the scanning needs a loop to
     * skip false hits on CR characters. Use a separate function.
     */
    if (acceptable == SERF_NEWLINE_CRLF) {
        find_crlf(data, len, found);
        return;
    }

    start = *data;
    cr = lf = NULL;
    want_cr = acceptable & SERF_NEWLINE_CR;
    want_crlf = acceptable & SERF_NEWLINE_CRLF;
    want_lf = acceptable & SERF_NEWLINE_LF;

    if (want_cr || want_crlf) {
        cr = memchr(start, '\r', *len);
    }
    if (want_lf) {
        lf = memchr(start, '\n', *len);
    }

    if (cr != NULL) {
        if (lf != NULL) {
            if (cr + 1 == lf)
                *found = want_crlf ? SERF_NEWLINE_CRLF : SERF_NEWLINE_CR;
            else if (want_cr && cr < lf)
                *found = SERF_NEWLINE_CR;
            else
                *found = SERF_NEWLINE_LF;
        }
        else if (cr == start + *len - 1) {
            /* the CR occurred in the last byte of the buffer. this could be
             * a CRLF split across the data boundary.
             * ### FIX THIS LOGIC? does caller need to detect?
             */
            *found = want_crlf ? SERF_NEWLINE_CRLF_SPLIT : SERF_NEWLINE_CR;
        }
        else if (want_cr)
            *found = SERF_NEWLINE_CR;
        else /* want_crlf */
            *found = SERF_NEWLINE_NONE;
    }
    else if (lf != NULL)
        *found = SERF_NEWLINE_LF;
    else
        *found = SERF_NEWLINE_NONE;

    switch (*found) {
      case SERF_NEWLINE_LF:
        *data = lf + 1;
        break;
      case SERF_NEWLINE_CR:
      case SERF_NEWLINE_CRLF:
      case SERF_NEWLINE_CRLF_SPLIT:
        *data = cr + 1 + (*found == SERF_NEWLINE_CRLF);
        break;
      case SERF_NEWLINE_NONE:
        *data += *len;
        break;
      default:
        /* Not reachable */
        return;
    }

    *len -= *data - start;
}


/* ==================================================================== */


SERF_DECLARE(void) serf_databuf_init(serf_databuf_t *databuf)
{
    /* nothing is sitting in the buffer */
    databuf->remaining = 0;

    /* avoid thinking we have hit EOF */
    databuf->status = APR_SUCCESS;
}

/* Ensure the buffer is prepared for reading. Will return APR_SUCCESS,
 * APR_EOF, or some failure code. *len is only set for EOF. */
static apr_status_t common_databuf_prep(serf_databuf_t *databuf,
                                        apr_size_t *len)
{
    apr_size_t readlen;
    apr_status_t status;

    /* if there is data in the buffer, then we're happy. */
    if (databuf->remaining > 0)
        return APR_SUCCESS;

    /* if we already hit EOF, then keep returning that. */
    if (APR_STATUS_IS_EOF(databuf->status)) {
        /* *data = NULL;   ?? */
        *len = 0;
        return APR_EOF;
    }

    /* refill the buffer */
    status = (*databuf->read)(databuf->read_baton, sizeof(databuf->buf),
                              databuf->buf, &readlen);
    if (SERF_BUCKET_READ_ERROR(status)) {
        return status;
    }

    databuf->current = databuf->buf;
    databuf->remaining = readlen;
    databuf->status = status;

    return APR_SUCCESS;
}

SERF_DECLARE(apr_status_t) serf_databuf_read(serf_databuf_t *databuf,
                                             apr_size_t requested,
                                             const char **data,
                                             apr_size_t *len)
{
    apr_status_t status = common_databuf_prep(databuf, len);
    if (status)
        return status;

    /* peg the requested amount to what we have remaining */
    if (requested == SERF_READ_ALL_AVAIL || requested > databuf->remaining)
        requested = databuf->remaining;

    /* return the values */
    *data = databuf->current;
    *len = requested;

    /* adjust our internal state to note we've consumed some data */
    databuf->current += requested;
    databuf->remaining -= requested;

    /* If we read everything, then we need to return whatever the data
     * read returned to us. This is going to be APR_EOF or APR_EGAIN.
     * If we have NOT read everything, then return APR_SUCCESS to indicate
     * that we're ready to return some more if asked.
     */
    return databuf->remaining ? APR_SUCCESS : databuf->status;
}

SERF_DECLARE(apr_status_t) serf_databuf_readline(serf_databuf_t *databuf,
                                                 int acceptable, int *found,
                                                 const char **data,
                                                 apr_size_t *len)
{
    apr_status_t status = common_databuf_prep(databuf, len);
    if (status)
        return status;

    /* the returned line will start at the current position. */
    *data = databuf->current;

    /* read a line from the buffer, and adjust the various pointers. */
    serf_util_readline(&databuf->current, &databuf->remaining, acceptable,
                       found);

    /* the length matches the amount consumed by the readline */
    *len = databuf->current - *data;

    /* see serf_databuf_read's return condition */
    return databuf->remaining ? APR_SUCCESS : databuf->status;
}

SERF_DECLARE(apr_status_t) serf_databuf_peek(serf_databuf_t *databuf,
                                             const char **data,
                                             apr_size_t *len)
{
    apr_status_t status = common_databuf_prep(databuf, len);
    if (status)
        return status;

    /* return everything we have */
    *data = databuf->current;
    *len = databuf->remaining;

    /* If the last read returned EOF, then the peek should return the same.
     * The other possibility in databuf->status is APR_EAGAIN, which we
     * should never return. Thus, just return APR_SUCCESS for non-EOF cases.
     */
    if (APR_STATUS_IS_EOF(databuf->status))
        return APR_EOF;
    return APR_SUCCESS;
}


/* ==================================================================== */


SERF_DECLARE(void) serf_linebuf_init(serf_linebuf_t *linebuf)
{
    linebuf->state = SERF_LINEBUF_EMPTY;
    linebuf->used = 0;
}

SERF_DECLARE(apr_status_t) serf_linebuf_fetch(
    serf_linebuf_t *linebuf,
    serf_bucket_t *bucket,
    int acceptable)
{
    /* If we had a complete line, then assume the caller has used it, so
     * we can now reset the state.
     */
    if (linebuf->state == SERF_LINEBUF_READY) {
        linebuf->state = SERF_LINEBUF_EMPTY;

        /* Reset the line_used, too, so we don't have to test the state
         * before using this value.
         */
        linebuf->used = 0;
    }

    while (1) {
        apr_status_t status;
        const char *data;
        apr_size_t len;

        if (linebuf->state == SERF_LINEBUF_CRLF_SPLIT) {
            /* On the previous read, we received just a CR. The LF might
             * be present, but the bucket couldn't see it. We need to
             * examine a single character to determine how to handle the
             * split CRLF.
             */

            status = serf_bucket_peek(bucket, &data, &len);
            if (SERF_BUCKET_READ_ERROR(status))
                return status;

            if (len > 0) {
                if (*data == '\n') {
                    /* We saw the second part of CRLF. We don't need to
                     * save that character, so do an actual read to suck
                     * up that character.
                     */
                    /* ### check status */
                    (void) serf_bucket_read(bucket, 1, &data, &len);
                }
                /* else:
                 *   We saw the first character of the next line. Thus,
                 *   the current line is terminated by the CR. Just
                 *   ignore whatever we peeked at. The next reader will
                 *   see it and handle it as appropriate.
                 */

                /* Whatever was read, the line is now ready for use. */
                linebuf->state = SERF_LINEBUF_READY;
            }
            /* ### we need data. gotta check this char. bail if zero?! */
            /* else len == 0 */

            /* ### status */
        }
        else {
            int found;

            status = serf_bucket_readline(bucket, acceptable, &found,
                                          &data, &len);
            if (SERF_BUCKET_READ_ERROR(status)) {
                return status;
            }
            if (linebuf->used + len > sizeof(linebuf->line)) {
                /* ### need a "line too long" error */
                return APR_EGENERAL;
            }

            /* Note: our logic doesn't change for SERF_LINEBUF_PARTIAL. That
             * only affects how we fill the buffer. It is a communication to
             * our caller on whether the line is ready or not.
             */

            /* If we didn't see a newline, then we should mark the line
             * buffer as partially complete.
             */
            if (found == SERF_NEWLINE_NONE) {
                linebuf->state = SERF_LINEBUF_PARTIAL;
            }
            else if (found == SERF_NEWLINE_CRLF_SPLIT) {
                linebuf->state = SERF_LINEBUF_CRLF_SPLIT;

                /* Toss the partial CR. We won't ever need it. */
                --len;
            }
            else {
                /* We got a newline (of some form). We don't need it
                 * in the line buffer, so back up the length. Then
                 * mark the line as ready.
                 */
                len -= 1 + (found == SERF_NEWLINE_CRLF);

                linebuf->state = SERF_LINEBUF_READY;
            }

            /* ### it would be nice to avoid this copy if at all possible,
               ### and just return the a data/len pair to the caller. we're
               ### keeping it simple for now. */
            memcpy(&linebuf->line[linebuf->used], data, len);
            linebuf->used += len;
        }

        /* If we saw anything besides "success. please read again", then
         * we should return that status. If the line was completed, then
         * we should also return.
         */
        if (status || linebuf->state == SERF_LINEBUF_READY)
            return status;

        /* We got APR_SUCCESS and the line buffer is not complete. Let's
         * loop to read some more data.
         */
    }
    /* NOTREACHED */
}