/*

 * Copyright (c) 2017 Fastly, 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"

#include "brotli/encode.h"

struct st_brotli_context_t {

    h2o_compress_context_t super;

    BrotliEncoderState *state;

    H2O_VECTOR(h2o_sendvec_t) bufs;

    size_t buf_capacity;

};

static void expand_buf(struct st_brotli_context_t *self)

{

    h2o_vector_reserve(NULL, &self->bufs, self->bufs.size + 1);

    h2o_sendvec_init_raw(self->bufs.entries + self->bufs.size++, h2o_mem_alloc(self->buf_capacity), 0);

}

static void shrink_buf(struct st_brotli_context_t *self, size_t new_size)

{

    while (new_size < self->bufs.size)

        free(self->bufs.entries[--self->bufs.size].raw);

}

static void compress_core(struct st_brotli_context_t *self, BrotliEncoderOperation op, const uint8_t **src, size_t *srclen)

{

    size_t bufindex = self->bufs.size - 1;

    if (self->bufs.entries[bufindex].len == self->buf_capacity) {

        expand_buf(self);

        ++bufindex;

    }

    uint8_t *dst = (uint8_t *)self->bufs.entries[bufindex].raw + self->bufs.entries[bufindex].len;

    size_t dstlen = self->buf_capacity - self->bufs.entries[bufindex].len;

    if (!BrotliEncoderCompressStream(self->state, op, srclen, src, &dstlen, &dst, NULL))

        h2o_fatal("BrotliEncoderCompressStream");

    self->bufs.entries[bufindex].len = self->buf_capacity - dstlen;

}

static h2o_send_state_t compress_(h2o_compress_context_t *_self, h2o_sendvec_t *inbufs, size_t inbufcnt, h2o_send_state_t state,

                                  h2o_sendvec_t **outbufs, size_t *outbufcnt)

{

    struct st_brotli_context_t *self = (void *)_self;

    BrotliEncoderOperation final_op = h2o_send_state_is_in_progress(state) ? BROTLI_OPERATION_FLUSH : BROTLI_OPERATION_FINISH;

    const uint8_t *src;

    size_t i, srclen;

    shrink_buf(self, 1);

    self->bufs.entries[0].len = 0;

    /* encode chunks and flush */

    if (inbufcnt != 0) {

        for (i = 0; i < inbufcnt; ++i) {

            assert(inbufs[i].callbacks->read_ == h2o_sendvec_read_raw);

            src = (void *)inbufs[i].raw;

            srclen = inbufs[i].len;

            BrotliEncoderOperation op = i + 1 == inbufcnt ? final_op : BROTLI_OPERATION_PROCESS;

            while (srclen != 0)

                compress_core(self, op, &src, &srclen);

        }

    } else {

        src = NULL;

        srclen = 0;

        compress_core(self, final_op, &src, &srclen);

    }

    /* emit pending output, if any */

    while (BrotliEncoderHasMoreOutput(self->state)) {

        src = NULL;

        srclen = 0;

        compress_core(self, final_op, &src, &srclen);

    }

    *outbufs = self->bufs.entries;

    *outbufcnt = self->bufs.size - (self->bufs.entries[self->bufs.size - 1].len == 0);

    return state;

}

static void on_dispose(void *_self)

{

    struct st_brotli_context_t *self = _self;

    BrotliEncoderDestroyInstance(self->state);

    shrink_buf(self, 0);

    free(self->bufs.entries);

    free(self->super.push_buf);

}

h2o_compress_context_t *h2o_compress_brotli_open(h2o_mem_pool_t *pool, int quality, size_t estimated_content_length,

                                                 size_t preferred_chunk_size)

{

    struct st_brotli_context_t *self = h2o_mem_alloc_shared(pool, sizeof(struct st_brotli_context_t), on_dispose);

    self->super.name = h2o_iovec_init(H2O_STRLIT("br"));

    self->super.do_transform = compress_;

    self->super.push_buf = NULL;

    self->state = BrotliEncoderCreateInstance(NULL, NULL, NULL);

    memset(&self->bufs, 0, sizeof(self->bufs));

    self->buf_capacity = preferred_chunk_size;

    if (self->buf_capacity > estimated_content_length)

        self->buf_capacity = estimated_content_length;

    if (self->buf_capacity > 65536)

        self->buf_capacity = 65536;

    if (self->buf_capacity < 1024)

        self->buf_capacity = 1024;

    expand_buf(self);

    BrotliEncoderSetParameter(self->state, BROTLI_PARAM_QUALITY, quality);

    if (estimated_content_length < (1 << BROTLI_DEFAULT_WINDOW) / 2) {

        unsigned bits =

            estimated_content_length > 1 ? sizeof(unsigned long long) * 8 - __builtin_clzll(estimated_content_length - 1) : 1;

        if (bits < 5) {

            bits = 5;

        }

        BrotliEncoderSetParameter(self->state, BROTLI_PARAM_LGWIN, bits);

    }

    return &self->super;

}