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

 *    Licensed to the Apache Software Foundation (ASF) under one

 *    or more contributor license agreements.  See the NOTICE file

 *    distributed with this work for additional information

 *    regarding copyright ownership.  The ASF licenses this file

 *    to you 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 <apr_strings.h>

#include "serf.h"

#include "serf_bucket_util.h"

typedef struct {

    serf_bucket_t *stream;

    enum {

        STATE_SIZE,     /* reading the chunk size */

        STATE_CHUNK,    /* reading the chunk */

        STATE_TERM,     /* reading the chunk terminator */

        STATE_DONE      /* body is done; we've returned EOF */

    } state;

    /* Buffer for accumulating a chunk size. */

    serf_linebuf_t linebuf;

    /* How much of the chunk, or the terminator, do we have left to read? */

    apr_int64_t body_left;

} dechunk_context_t;

serf_bucket_t *serf_bucket_dechunk_create(

    serf_bucket_t *stream,

    serf_bucket_alloc_t *allocator)

{

    dechunk_context_t *ctx;

    ctx = serf_bucket_mem_alloc(allocator, sizeof(*ctx));

    ctx->stream = stream;

    ctx->state = STATE_SIZE;

    serf_linebuf_init(&ctx->linebuf);

    return serf_bucket_create(&serf_bucket_type_dechunk, allocator, ctx);

}

static void serf_dechunk_destroy_and_data(serf_bucket_t *bucket)

{

    dechunk_context_t *ctx = bucket->data;

    serf_bucket_destroy(ctx->stream);

    serf_default_destroy_and_data(bucket);

}

static apr_status_t serf_dechunk_read(serf_bucket_t *bucket,

                                      apr_size_t requested,

                                      const char **data, apr_size_t *len)

{

    dechunk_context_t *ctx = bucket->data;

    apr_status_t status;

    while (1) {

        switch (ctx->state) {

        case STATE_SIZE:

            /* fetch a line terminated by CRLF */

            status = serf_linebuf_fetch(&ctx->linebuf, ctx->stream,

                                        SERF_NEWLINE_CRLF);

            if (SERF_BUCKET_READ_ERROR(status))

                return status;

            /* if a line was read, then parse it. */

            if (ctx->linebuf.state == SERF_LINEBUF_READY) {

                /* NUL-terminate the line. if it filled the entire buffer,

                   then just assume the thing is too large. */

                if (ctx->linebuf.used == sizeof(ctx->linebuf.line))

                    return APR_FROM_OS_ERROR(ERANGE);

                ctx->linebuf.line[ctx->linebuf.used] = '\0';

                /* convert from HEX digits. */

                ctx->body_left = apr_strtoi64(ctx->linebuf.line, NULL, 16);

                if (errno == ERANGE) {

                    return APR_FROM_OS_ERROR(ERANGE);

                }

                if (ctx->body_left == 0) {

                    /* Just read the last-chunk marker. We're DONE. */

                    ctx->state = STATE_DONE;

                    status = APR_EOF;

                }

                else {

                    /* Got a size, so we'll start reading the chunk now. */

                    ctx->state = STATE_CHUNK;

                }

                /* If we can read more, then go do so. */

                if (!status)

                    continue;

            }

            /* assert: status != 0 */

            /* Note that we didn't actually read anything, so our callers

             * don't get confused.

             */

            *len = 0;

            return status;

        case STATE_CHUNK:

            if (requested > ctx->body_left) {

                requested = ctx->body_left;

            }

            /* Delegate to the stream bucket to do the read. */

            status = serf_bucket_read(ctx->stream, requested, data, len);

            if (SERF_BUCKET_READ_ERROR(status))

                return status;

            /* Some data was read, so decrement the amount left and see

             * if we're done reading this chunk.

             */

            ctx->body_left -= *len;

            if (!ctx->body_left) {

                ctx->state = STATE_TERM;

                ctx->body_left = 2;     /* CRLF */

            }

            /* We need more data but there is no more available. */

            if (ctx->body_left && APR_STATUS_IS_EOF(status)) {

                return SERF_ERROR_TRUNCATED_HTTP_RESPONSE;

            }

            /* Return the data we just read. */

            return status;

        case STATE_TERM:

            /* Delegate to the stream bucket to do the read. */

            status = serf_bucket_read(ctx->stream, ctx->body_left, data, len);

            if (SERF_BUCKET_READ_ERROR(status))

                return status;

            /* Some data was read, so decrement the amount left and see

             * if we're done reading the chunk terminator.

             */

            ctx->body_left -= *len;

            /* We need more data but there is no more available. */

            if (ctx->body_left && APR_STATUS_IS_EOF(status))

                return SERF_ERROR_TRUNCATED_HTTP_RESPONSE;

            if (!ctx->body_left) {

                ctx->state = STATE_SIZE;

            }

            /* Don't return the CR of CRLF to the caller! */

            *len = 0;

            if (status)

                return status;

            break;

        case STATE_DONE:

            /* Just keep returning EOF */

            *len = 0;

            return APR_EOF;

        default:

            /* Not reachable */

            return APR_EGENERAL;

        }

    }

    /* NOTREACHED */

}

/* ### need to implement */

#define serf_dechunk_readline NULL

#define serf_dechunk_peek NULL

const serf_bucket_type_t serf_bucket_type_dechunk = {

    "DECHUNK",

    serf_dechunk_read,

    serf_dechunk_readline,

    serf_default_read_iovec,

    serf_default_read_for_sendfile,

    serf_default_read_bucket,

    serf_dechunk_peek,

    serf_dechunk_destroy_and_data,

};