/*
 * This file is part of FFmpeg.
 *
 * FFmpeg is free software; you can redistribute it and/or
 * modify it under the terms of the GNU Lesser General Public
 * License as published by the Free Software Foundation; either
 * version 2.1 of the License, or (at your option) any later version.
 *
 * FFmpeg is distributed in the hope that it will be useful,
 * but WITHOUT ANY WARRANTY; without even the implied warranty of
 * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the GNU
 * Lesser General Public License for more details.
 *
 * You should have received a copy of the GNU Lesser General Public
 * License along with FFmpeg; if not, write to the Free Software
 * Foundation, Inc., 51 Franklin Street, Fifth Floor, Boston, MA 02110-1301 USA
 */

static int FUNC(sequence_header)(CodedBitstreamContext *ctx, RWContext *rw,
  MPEG2RawSequenceHeader *current) {
  CodedBitstreamMPEG2Context *mpeg2 = ctx->priv_data;
  int err, i;

  HEADER("Sequence Header");

  ui(8, sequence_header_code);

  uir(12, horizontal_size_value);
  uir(12, vertical_size_value);

  mpeg2->horizontal_size = current->horizontal_size_value;
  mpeg2->vertical_size   = current->vertical_size_value;

  uir(4, aspect_ratio_information);
  uir(4, frame_rate_code);
  ui(18, bit_rate_value);

  marker_bit();

  ui(10, vbv_buffer_size_value);
  ui(1, constrained_parameters_flag);

  ui(1, load_intra_quantiser_matrix);
  if(current->load_intra_quantiser_matrix) {
    for(i = 0; i < 64; i++)
      uirs(8, intra_quantiser_matrix[i], 1, i);
  }

  ui(1, load_non_intra_quantiser_matrix);
  if(current->load_non_intra_quantiser_matrix) {
    for(i = 0; i < 64; i++)
      uirs(8, non_intra_quantiser_matrix[i], 1, i);
  }

  return 0;
}

static int FUNC(user_data)(CodedBitstreamContext *ctx, RWContext *rw,
  MPEG2RawUserData *current) {
  size_t k;
  int err;

  HEADER("User Data");

  ui(8, user_data_start_code);

#ifdef READ
  k = get_bits_left(rw);
  av_assert0(k % 8 == 0);
  current->user_data_length = k /= 8;
  if(k > 0) {
    current->user_data_ref = av_buffer_allocz(k + AV_INPUT_BUFFER_PADDING_SIZE);
    if(!current->user_data_ref)
      return AVERROR(ENOMEM);
    current->user_data = current->user_data_ref->data;
  }
#endif

  for(k = 0; k < current->user_data_length; k++)
    uis(8, user_data[k], 1, k);

  return 0;
}

static int FUNC(sequence_extension)(CodedBitstreamContext *ctx, RWContext *rw,
  MPEG2RawSequenceExtension *current) {
  CodedBitstreamMPEG2Context *mpeg2 = ctx->priv_data;
  int err;

  HEADER("Sequence Extension");

  ui(8, profile_and_level_indication);
  ui(1, progressive_sequence);
  ui(2, chroma_format);
  ui(2, horizontal_size_extension);
  ui(2, vertical_size_extension);

  mpeg2->horizontal_size = (mpeg2->horizontal_size & 0xfff) |
                           current->horizontal_size_extension << 12;
  mpeg2->vertical_size = (mpeg2->vertical_size & 0xfff) |
                         current->vertical_size_extension << 12;
  mpeg2->progressive_sequence = current->progressive_sequence;

  ui(12, bit_rate_extension);
  marker_bit();
  ui(8, vbv_buffer_size_extension);
  ui(1, low_delay);
  ui(2, frame_rate_extension_n);
  ui(5, frame_rate_extension_d);

  return 0;
}

static int FUNC(sequence_display_extension)(CodedBitstreamContext *ctx, RWContext *rw,
  MPEG2RawSequenceDisplayExtension *current) {
  int err;

  HEADER("Sequence Display Extension");

  ui(3, video_format);

  ui(1, colour_description);
  if(current->colour_description) {
#ifdef READ
#define READ_AND_PATCH(name)                                                                     \
  do {                                                                                           \
    ui(8, name);                                                                                 \
    if(current->name == 0) {                                                                     \
      current->name = 2;                                                                         \
      av_log(ctx->log_ctx, AV_LOG_WARNING, "%s in a sequence display "                           \
                                           "extension had the invalid value 0. Setting it to 2 " \
                                           "(meaning unknown) instead.\n",                       \
        #name);                                                                                  \
    }                                                                                            \
  } while(0)
    READ_AND_PATCH(colour_primaries);
    READ_AND_PATCH(transfer_characteristics);
    READ_AND_PATCH(matrix_coefficients);
#undef READ_AND_PATCH
#else
    uir(8, colour_primaries);
    uir(8, transfer_characteristics);
    uir(8, matrix_coefficients);
#endif
  }
  else {
    infer(colour_primaries, 2);
    infer(transfer_characteristics, 2);
    infer(matrix_coefficients, 2);
  }

  ui(14, display_horizontal_size);
  marker_bit();
  ui(14, display_vertical_size);

  return 0;
}

static int FUNC(group_of_pictures_header)(CodedBitstreamContext *ctx, RWContext *rw,
  MPEG2RawGroupOfPicturesHeader *current) {
  int err;

  HEADER("Group of Pictures Header");

  ui(8, group_start_code);

  ui(25, time_code);
  ui(1, closed_gop);
  ui(1, broken_link);

  return 0;
}

static int FUNC(extra_information)(CodedBitstreamContext *ctx, RWContext *rw,
  MPEG2RawExtraInformation *current,
  const char *element_name, const char *marker_name) {
  int err;
  size_t k;
#ifdef READ
  GetBitContext start = *rw;
  uint8_t bit;

  for(k = 0; nextbits(1, 1, bit); k++)
    skip_bits(rw, 1 + 8);
  current->extra_information_length = k;
  if(k > 0) {
    *rw = start;
    current->extra_information_ref =
      av_buffer_allocz(k + AV_INPUT_BUFFER_PADDING_SIZE);
    if(!current->extra_information_ref)
      return AVERROR(ENOMEM);
    current->extra_information = current->extra_information_ref->data;
  }
#endif

  for(k = 0; k < current->extra_information_length; k++) {
    bit(marker_name, 1);
    xuia(8, element_name,
      current->extra_information[k], 0, 255, 1, k);
  }

  bit(marker_name, 0);

  return 0;
}

static int FUNC(picture_header)(CodedBitstreamContext *ctx, RWContext *rw,
  MPEG2RawPictureHeader *current) {
  int err;

  HEADER("Picture Header");

  ui(8, picture_start_code);

  ui(10, temporal_reference);
  uir(3, picture_coding_type);
  ui(16, vbv_delay);

  if(current->picture_coding_type == 2 ||
     current->picture_coding_type == 3) {
    ui(1, full_pel_forward_vector);
    ui(3, forward_f_code);
  }

  if(current->picture_coding_type == 3) {
    ui(1, full_pel_backward_vector);
    ui(3, backward_f_code);
  }

  CHECK(FUNC(extra_information)(ctx, rw, &current->extra_information_picture,
    "extra_information_picture[k]", "extra_bit_picture"));

  return 0;
}

static int FUNC(picture_coding_extension)(CodedBitstreamContext *ctx, RWContext *rw,
  MPEG2RawPictureCodingExtension *current) {
  CodedBitstreamMPEG2Context *mpeg2 = ctx->priv_data;
  int err;

  HEADER("Picture Coding Extension");

  uir(4, f_code[0][0]);
  uir(4, f_code[0][1]);
  uir(4, f_code[1][0]);
  uir(4, f_code[1][1]);

  ui(2, intra_dc_precision);
  ui(2, picture_structure);
  ui(1, top_field_first);
  ui(1, frame_pred_frame_dct);
  ui(1, concealment_motion_vectors);
  ui(1, q_scale_type);
  ui(1, intra_vlc_format);
  ui(1, alternate_scan);
  ui(1, repeat_first_field);
  ui(1, chroma_420_type);
  ui(1, progressive_frame);

  if(mpeg2->progressive_sequence) {
    if(current->repeat_first_field) {
      if(current->top_field_first)
        mpeg2->number_of_frame_centre_offsets = 3;
      else
        mpeg2->number_of_frame_centre_offsets = 2;
    }
    else {
      mpeg2->number_of_frame_centre_offsets = 1;
    }
  }
  else {
    if(current->picture_structure == 1 || // Top field.
       current->picture_structure == 2) { // Bottom field.
      mpeg2->number_of_frame_centre_offsets = 1;
    }
    else {
      if(current->repeat_first_field)
        mpeg2->number_of_frame_centre_offsets = 3;
      else
        mpeg2->number_of_frame_centre_offsets = 2;
    }
  }

  ui(1, composite_display_flag);
  if(current->composite_display_flag) {
    ui(1, v_axis);
    ui(3, field_sequence);
    ui(1, sub_carrier);
    ui(7, burst_amplitude);
    ui(8, sub_carrier_phase);
  }

  return 0;
}

static int FUNC(quant_matrix_extension)(CodedBitstreamContext *ctx, RWContext *rw,
  MPEG2RawQuantMatrixExtension *current) {
  int err, i;

  HEADER("Quant Matrix Extension");

  ui(1, load_intra_quantiser_matrix);
  if(current->load_intra_quantiser_matrix) {
    for(i = 0; i < 64; i++)
      uirs(8, intra_quantiser_matrix[i], 1, i);
  }

  ui(1, load_non_intra_quantiser_matrix);
  if(current->load_non_intra_quantiser_matrix) {
    for(i = 0; i < 64; i++)
      uirs(8, non_intra_quantiser_matrix[i], 1, i);
  }

  ui(1, load_chroma_intra_quantiser_matrix);
  if(current->load_chroma_intra_quantiser_matrix) {
    for(i = 0; i < 64; i++)
      uirs(8, intra_quantiser_matrix[i], 1, i);
  }

  ui(1, load_chroma_non_intra_quantiser_matrix);
  if(current->load_chroma_non_intra_quantiser_matrix) {
    for(i = 0; i < 64; i++)
      uirs(8, chroma_non_intra_quantiser_matrix[i], 1, i);
  }

  return 0;
}

static int FUNC(picture_display_extension)(CodedBitstreamContext *ctx, RWContext *rw,
  MPEG2RawPictureDisplayExtension *current) {
  CodedBitstreamMPEG2Context *mpeg2 = ctx->priv_data;
  int err, i;

  HEADER("Picture Display Extension");

  for(i = 0; i < mpeg2->number_of_frame_centre_offsets; i++) {
    sis(16, frame_centre_horizontal_offset[i], 1, i);
    marker_bit();
    sis(16, frame_centre_vertical_offset[i], 1, i);
    marker_bit();
  }

  return 0;
}

static int FUNC(extension_data)(CodedBitstreamContext *ctx, RWContext *rw,
  MPEG2RawExtensionData *current) {
  int err;

  HEADER("Extension Data");

  ui(8, extension_start_code);
  ui(4, extension_start_code_identifier);

  switch(current->extension_start_code_identifier) {
  case MPEG2_EXTENSION_SEQUENCE:
    return FUNC(sequence_extension)(ctx, rw, &current->data.sequence);
  case MPEG2_EXTENSION_SEQUENCE_DISPLAY:
    return FUNC(sequence_display_extension)(ctx, rw, &current->data.sequence_display);
  case MPEG2_EXTENSION_QUANT_MATRIX:
    return FUNC(quant_matrix_extension)(ctx, rw, &current->data.quant_matrix);
  case MPEG2_EXTENSION_PICTURE_DISPLAY:
    return FUNC(picture_display_extension)(ctx, rw, &current->data.picture_display);
  case MPEG2_EXTENSION_PICTURE_CODING:
    return FUNC(picture_coding_extension)(ctx, rw, &current->data.picture_coding);
  default:
    av_log(ctx->log_ctx, AV_LOG_ERROR, "Extension ID %d not supported.\n",
      current->extension_start_code_identifier);
    return AVERROR_PATCHWELCOME;
  }
}

static int FUNC(slice_header)(CodedBitstreamContext *ctx, RWContext *rw,
  MPEG2RawSliceHeader *current) {
  CodedBitstreamMPEG2Context *mpeg2 = ctx->priv_data;
  int err;

  HEADER("Slice Header");

  ui(8, slice_vertical_position);

  if(mpeg2->vertical_size > 2800)
    ui(3, slice_vertical_position_extension);
  if(mpeg2->scalable) {
    if(mpeg2->scalable_mode == 0)
      ui(7, priority_breakpoint);
  }

  uir(5, quantiser_scale_code);

  if(nextbits(1, 1, current->slice_extension_flag)) {
    ui(1, slice_extension_flag);
    ui(1, intra_slice);
    ui(1, slice_picture_id_enable);
    ui(6, slice_picture_id);
  }

  CHECK(FUNC(extra_information)(ctx, rw, &current->extra_information_slice,
    "extra_information_slice[k]", "extra_bit_slice"));

  return 0;
}

static int FUNC(sequence_end)(CodedBitstreamContext *ctx, RWContext *rw,
  MPEG2RawSequenceEnd *current) {
  int err;

  HEADER("Sequence End");

  ui(8, sequence_end_code);

  return 0;
}