/*

 * Copyright (c) 2015,2016 Justin Zhu, DeNA Co., Ltd., Kazuho Oku

 *

 * Permission is hereby granted, free of charge, to any person obtaining a copy

 * of this software and associated documentation files (the "Software"), to

 * deal in the Software without restriction, including without limitation the

 * rights to use, copy, modify, merge, publish, distribute, sublicense, and/or

 * sell copies of the Software, and to permit persons to whom the Software is

 * furnished to do so, subject to the following conditions:

 *

 * The above copyright notice and this permission notice shall be included in

 * all copies or substantial portions of the Software.

 *

 * THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS OR

 * IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY,

 * FITNESS FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT. IN NO EVENT SHALL THE

 * AUTHORS OR COPYRIGHT HOLDERS BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER

 * LIABILITY, WHETHER IN AN ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING

 * FROM, OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS

 * IN THE SOFTWARE.

 */

#include <assert.h>

#include <stdlib.h>

#include "h2o.h"

#ifndef BUF_SIZE

#define BUF_SIZE 8192

#endif

struct st_compress_filter_t {

    h2o_filter_t super;

    h2o_compress_args_t args;

};

struct st_compress_encoder_t {

    h2o_ostream_t super;

    h2o_compress_context_t *compressor;

};

static void do_send(h2o_ostream_t *_self, h2o_req_t *req, h2o_sendvec_t *inbufs, size_t inbufcnt, h2o_send_state_t state)

{

    struct st_compress_encoder_t *self = (void *)_self;

    h2o_sendvec_t *outbufs;

    size_t outbufcnt;

    if (inbufcnt == 0 && h2o_send_state_is_in_progress(state)) {

        h2o_ostream_send_next(&self->super, req, inbufs, inbufcnt, state);

        return;

    }

    state = h2o_compress_transform(self->compressor, req, inbufs, inbufcnt, state, &outbufs, &outbufcnt);

    h2o_ostream_send_next(&self->super, req, outbufs, outbufcnt, state);

}

static void on_setup_ostream(h2o_filter_t *_self, h2o_req_t *req, h2o_ostream_t **slot)

{

    struct st_compress_filter_t *self = (void *)_self;

    struct st_compress_encoder_t *encoder;

    int compressible_types;

    int compressible_types_mask = H2O_COMPRESSIBLE_BROTLI | H2O_COMPRESSIBLE_GZIP | H2O_COMPRESSIBLE_ZSTD;

    h2o_compress_context_t *compressor;

    ssize_t i;

    if (req->version < 0x101)

        goto Next;

    if (req->res.status != 200)

        goto Next;

    if (h2o_memis(req->input.method.base, req->input.method.len, H2O_STRLIT("HEAD")))

        goto Next;

    switch (req->compress_hint) {

    case H2O_COMPRESS_HINT_DISABLE:

        /* compression was explicitly disabled, skip */

        goto Next;

    case H2O_COMPRESS_HINT_ENABLE:

        /* compression was explicitly enabled */

        break;

    case H2O_COMPRESS_HINT_ENABLE_BR:

        compressible_types_mask = H2O_COMPRESSIBLE_BROTLI;

        break;

    case H2O_COMPRESS_HINT_ENABLE_GZIP:

        compressible_types_mask = H2O_COMPRESSIBLE_GZIP;

        break;

    case H2O_COMPRESS_HINT_ENABLE_ZSTD:

        compressible_types_mask = H2O_COMPRESSIBLE_ZSTD;

        break;

    case H2O_COMPRESS_HINT_AUTO:

    default:

        /* no hint from the producer, decide whether to compress based

           on the configuration */

        if (req->res.mime_attr == NULL)

            h2o_req_fill_mime_attributes(req);

        if (!req->res.mime_attr->is_compressible)

            goto Next;

        if (req->res.content_length < self->args.min_size)

            goto Next;

    }

    /* skip if failed to gather the list of compressible types */

    compressible_types = h2o_get_compressible_types(&req->headers) & compressible_types_mask;

    if (compressible_types == 0)

        goto Next;

    /* skip if content-encoding header is being set (as well as obtain the location of accept-ranges moreover identify index of etag

     * to modified weaken) */

    size_t content_encoding_header_index = -1, accept_ranges_header_index = -1, etag_header_index = -1;

    for (i = 0; i != req->res.headers.size; ++i) {

        if (req->res.headers.entries[i].name == &H2O_TOKEN_CONTENT_ENCODING->buf)

            content_encoding_header_index = i;

        else if (req->res.headers.entries[i].name == &H2O_TOKEN_ACCEPT_RANGES->buf)

            accept_ranges_header_index = i;

        else if (req->res.headers.entries[i].name == &H2O_TOKEN_ETAG->buf)

            etag_header_index = i;

        else

            continue;

    }

    if (content_encoding_header_index != -1)

        goto Next;

/* open the compressor (TODO add support for zstd) */

#if H2O_USE_BROTLI

    if (self->args.brotli.quality != -1 && (compressible_types & H2O_COMPRESSIBLE_BROTLI) != 0) {

        compressor =

            h2o_compress_brotli_open(&req->pool, self->args.brotli.quality, req->res.content_length, req->preferred_chunk_size);

    } else

#endif

        if (self->args.gzip.quality != -1 && (compressible_types & H2O_COMPRESSIBLE_GZIP) != 0) {

        compressor = h2o_compress_gzip_open(&req->pool, self->args.gzip.quality);

    } else {

        /* let proxies know that we looked at accept-encoding when deciding not to compress */

        h2o_set_header_token(&req->pool, &req->res.headers, H2O_TOKEN_VARY, H2O_STRLIT("accept-encoding"));

        goto Next;

    }

    /* adjust the response headers */

    req->res.content_length = SIZE_MAX;

    h2o_add_header(&req->pool, &req->res.headers, H2O_TOKEN_CONTENT_ENCODING, NULL, compressor->name.base, compressor->name.len);

    h2o_set_header_token(&req->pool, &req->res.headers, H2O_TOKEN_VARY, H2O_STRLIT("accept-encoding"));

    if (etag_header_index != -1) {

        if (!(req->res.headers.entries[etag_header_index].value.len >= 2 &&

              h2o_memis(req->res.headers.entries[etag_header_index].value.base, 2, H2O_STRLIT("W/")))) {

            req->res.headers.entries[etag_header_index].value =

                h2o_concat(&req->pool, h2o_iovec_init(H2O_STRLIT("W/")), req->res.headers.entries[etag_header_index].value);

        }

    }

    if (accept_ranges_header_index != -1) {

        req->res.headers.entries[accept_ranges_header_index].value = h2o_iovec_init(H2O_STRLIT("none"));

    } else {

        h2o_add_header(&req->pool, &req->res.headers, H2O_TOKEN_ACCEPT_RANGES, NULL, H2O_STRLIT("none"));

    }

    /* setup filter */

    encoder = (void *)h2o_add_ostream(req, H2O_ALIGNOF(*encoder), sizeof(*encoder), slot);

    encoder->super.do_send = do_send;

    slot = &encoder->super.next;

    encoder->compressor = compressor;

    /* adjust preferred chunk size (compress by 8192 bytes) */

    if (req->preferred_chunk_size > BUF_SIZE)

        req->preferred_chunk_size = BUF_SIZE;

Next:

    h2o_setup_next_ostream(req, slot);

}

void h2o_compress_register(h2o_pathconf_t *pathconf, h2o_compress_args_t *args)

{

    struct st_compress_filter_t *self = (void *)h2o_create_filter(pathconf, sizeof(*self));

    self->super.on_setup_ostream = on_setup_ostream;

    self->args = *args;

}

h2o_send_state_t h2o_compress_transform(h2o_compress_context_t *self, h2o_req_t *req, h2o_sendvec_t *inbufs, size_t inbufcnt,

                                        h2o_send_state_t state, h2o_sendvec_t **outbufs, size_t *outbufcnt)

{

    h2o_sendvec_t flattened;

    if (inbufcnt != 0 && inbufs->callbacks->read_ != &h2o_sendvec_read_raw) {

        assert(inbufcnt == 1);

        size_t buflen = inbufs->len;

        assert(buflen <= H2O_PULL_SENDVEC_MAX_SIZE);

        if (self->push_buf == NULL)

            self->push_buf = h2o_mem_alloc(h2o_send_state_is_in_progress(state) ? H2O_PULL_SENDVEC_MAX_SIZE : buflen);

        if (!(*inbufs->callbacks->read_)(inbufs, self->push_buf, buflen)) {

            *outbufs = NULL;

            *outbufcnt = 0;

            return H2O_SEND_STATE_ERROR;

        }

        h2o_sendvec_init_raw(&flattened, self->push_buf, buflen);

        inbufs = &flattened;

    }

    return self->do_transform(self, inbufs, inbufcnt, state, outbufs, outbufcnt);

}