/*
 *
 * Copyright 2015-2016, Google Inc.
 * All rights reserved.
 *
 * Redistribution and use in source and binary forms, with or without
 * modification, are permitted provided that the following conditions are
 * met:
 *
 *     * Redistributions of source code must retain the above copyright
 * notice, this list of conditions and the following disclaimer.
 *     * Redistributions in binary form must reproduce the above
 * copyright notice, this list of conditions and the following disclaimer
 * in the documentation and/or other materials provided with the
 * distribution.
 *     * Neither the name of Google Inc. nor the names of its
 * contributors may be used to endorse or promote products derived from
 * this software without specific prior written permission.
 *
 * THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS
 * "AS IS" AND ANY EXPRESS 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 COPYRIGHT
 * OWNER OR 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.
 *
 */

#include "src/core/lib/transport/chttp2/frame_data.h"

#include <string.h>

#include <grpc/support/alloc.h>
#include <grpc/support/log.h>
#include <grpc/support/useful.h>
#include "src/core/lib/support/string.h"
#include "src/core/lib/transport/chttp2/internal.h"
#include "src/core/lib/transport/transport.h"

grpc_chttp2_parse_error grpc_chttp2_data_parser_init(
    grpc_chttp2_data_parser *parser) {
  parser->state = GRPC_CHTTP2_DATA_FH_0;
  parser->parsing_frame = NULL;
  return GRPC_CHTTP2_PARSE_OK;
}

void grpc_chttp2_data_parser_destroy(grpc_exec_ctx *exec_ctx,
                                     grpc_chttp2_data_parser *parser) {
  grpc_byte_stream *bs;
  if (parser->parsing_frame) {
    grpc_chttp2_incoming_byte_stream_finished(exec_ctx, parser->parsing_frame,
                                              0, 1);
  }
  while (
      (bs = grpc_chttp2_incoming_frame_queue_pop(&parser->incoming_frames))) {
    grpc_byte_stream_destroy(exec_ctx, bs);
  }
}

grpc_chttp2_parse_error grpc_chttp2_data_parser_begin_frame(
    grpc_chttp2_data_parser *parser, uint8_t flags) {
  if (flags & ~GRPC_CHTTP2_DATA_FLAG_END_STREAM) {
    gpr_log(GPR_ERROR, "unsupported data flags: 0x%02x", flags);
    return GRPC_CHTTP2_STREAM_ERROR;
  }

  if (flags & GRPC_CHTTP2_DATA_FLAG_END_STREAM) {
    parser->is_last_frame = 1;
  } else {
    parser->is_last_frame = 0;
  }

  return GRPC_CHTTP2_PARSE_OK;
}

void grpc_chttp2_incoming_frame_queue_merge(
    grpc_chttp2_incoming_frame_queue *head_dst,
    grpc_chttp2_incoming_frame_queue *tail_src) {
  if (tail_src->head == NULL) {
    return;
  }

  if (head_dst->head == NULL) {
    *head_dst = *tail_src;
    memset(tail_src, 0, sizeof(*tail_src));
    return;
  }

  head_dst->tail->next_message = tail_src->head;
  head_dst->tail = tail_src->tail;
  memset(tail_src, 0, sizeof(*tail_src));
}

grpc_byte_stream *grpc_chttp2_incoming_frame_queue_pop(
    grpc_chttp2_incoming_frame_queue *q) {
  grpc_byte_stream *out;
  if (q->head == NULL) {
    return NULL;
  }
  out = &q->head->base;
  if (q->head == q->tail) {
    memset(q, 0, sizeof(*q));
  } else {
    q->head = q->head->next_message;
  }
  return out;
}

void grpc_chttp2_encode_data(uint32_t id, gpr_slice_buffer *inbuf,
                             uint32_t write_bytes, int is_eof,
                             gpr_slice_buffer *outbuf) {
  gpr_slice hdr;
  uint8_t *p;

  hdr = gpr_slice_malloc(9);
  p = GPR_SLICE_START_PTR(hdr);
  GPR_ASSERT(write_bytes < (1 << 24));
  *p++ = (uint8_t)(write_bytes >> 16);
  *p++ = (uint8_t)(write_bytes >> 8);
  *p++ = (uint8_t)(write_bytes);
  *p++ = GRPC_CHTTP2_FRAME_DATA;
  *p++ = is_eof ? GRPC_CHTTP2_DATA_FLAG_END_STREAM : 0;
  *p++ = (uint8_t)(id >> 24);
  *p++ = (uint8_t)(id >> 16);
  *p++ = (uint8_t)(id >> 8);
  *p++ = (uint8_t)(id);
  gpr_slice_buffer_add(outbuf, hdr);

  gpr_slice_buffer_move_first(inbuf, write_bytes, outbuf);
}

grpc_chttp2_parse_error grpc_chttp2_data_parser_parse(
    grpc_exec_ctx *exec_ctx, void *parser,
    grpc_chttp2_transport_parsing *transport_parsing,
    grpc_chttp2_stream_parsing *stream_parsing, gpr_slice slice, int is_last) {
  uint8_t *const beg = GPR_SLICE_START_PTR(slice);
  uint8_t *const end = GPR_SLICE_END_PTR(slice);
  uint8_t *cur = beg;
  grpc_chttp2_data_parser *p = parser;
  uint32_t message_flags;
  grpc_chttp2_incoming_byte_stream *incoming_byte_stream;

  if (is_last && p->is_last_frame) {
    stream_parsing->received_close = 1;
  }

  if (cur == end) {
    return GRPC_CHTTP2_PARSE_OK;
  }

  switch (p->state) {
  fh_0:
    case GRPC_CHTTP2_DATA_FH_0:
      p->frame_type = *cur;
      switch (p->frame_type) {
        case 0:
          p->is_frame_compressed = 0; /* GPR_FALSE */
          break;
        case 1:
          p->is_frame_compressed = 1; /* GPR_TRUE */
          break;
        default:
          gpr_log(GPR_ERROR, "Bad GRPC frame type 0x%02x", p->frame_type);
          return GRPC_CHTTP2_STREAM_ERROR;
      }
      if (++cur == end) {
        p->state = GRPC_CHTTP2_DATA_FH_1;
        return GRPC_CHTTP2_PARSE_OK;
      }
    /* fallthrough */
    case GRPC_CHTTP2_DATA_FH_1:
      p->frame_size = ((uint32_t)*cur) << 24;
      if (++cur == end) {
        p->state = GRPC_CHTTP2_DATA_FH_2;
        return GRPC_CHTTP2_PARSE_OK;
      }
    /* fallthrough */
    case GRPC_CHTTP2_DATA_FH_2:
      p->frame_size |= ((uint32_t)*cur) << 16;
      if (++cur == end) {
        p->state = GRPC_CHTTP2_DATA_FH_3;
        return GRPC_CHTTP2_PARSE_OK;
      }
    /* fallthrough */
    case GRPC_CHTTP2_DATA_FH_3:
      p->frame_size |= ((uint32_t)*cur) << 8;
      if (++cur == end) {
        p->state = GRPC_CHTTP2_DATA_FH_4;
        return GRPC_CHTTP2_PARSE_OK;
      }
    /* fallthrough */
    case GRPC_CHTTP2_DATA_FH_4:
      p->frame_size |= ((uint32_t)*cur);
      p->state = GRPC_CHTTP2_DATA_FRAME;
      ++cur;
      message_flags = 0;
      if (p->is_frame_compressed) {
        message_flags |= GRPC_WRITE_INTERNAL_COMPRESS;
      }
      p->parsing_frame = incoming_byte_stream =
          grpc_chttp2_incoming_byte_stream_create(
              exec_ctx, transport_parsing, stream_parsing, p->frame_size,
              message_flags, &p->incoming_frames);
    /* fallthrough */
    case GRPC_CHTTP2_DATA_FRAME:
      if (cur == end) {
        grpc_chttp2_list_add_parsing_seen_stream(transport_parsing,
                                                 stream_parsing);
        return GRPC_CHTTP2_PARSE_OK;
      }
      grpc_chttp2_list_add_parsing_seen_stream(transport_parsing,
                                               stream_parsing);
      if ((uint32_t)(end - cur) == p->frame_size) {
        grpc_chttp2_incoming_byte_stream_push(
            exec_ctx, p->parsing_frame,
            gpr_slice_sub(slice, (size_t)(cur - beg), (size_t)(end - beg)));
        grpc_chttp2_incoming_byte_stream_finished(exec_ctx, p->parsing_frame, 1,
                                                  1);
        p->parsing_frame = NULL;
        p->state = GRPC_CHTTP2_DATA_FH_0;
        return GRPC_CHTTP2_PARSE_OK;
      } else if ((uint32_t)(end - cur) > p->frame_size) {
        grpc_chttp2_incoming_byte_stream_push(
            exec_ctx, p->parsing_frame,
            gpr_slice_sub(slice, (size_t)(cur - beg),
                          (size_t)(cur + p->frame_size - beg)));
        grpc_chttp2_incoming_byte_stream_finished(exec_ctx, p->parsing_frame, 1,
                                                  1);
        p->parsing_frame = NULL;
        cur += p->frame_size;
        goto fh_0; /* loop */
      } else {
        grpc_chttp2_incoming_byte_stream_push(
            exec_ctx, p->parsing_frame,
            gpr_slice_sub(slice, (size_t)(cur - beg), (size_t)(end - beg)));
        GPR_ASSERT((size_t)(end - cur) <= p->frame_size);
        p->frame_size -= (uint32_t)(end - cur);
        return GRPC_CHTTP2_PARSE_OK;
      }
  }

  GPR_UNREACHABLE_CODE(return GRPC_CHTTP2_CONNECTION_ERROR);
}