// Copyright (c) the JPEG XL Project Authors. All rights reserved.
//
// Use of this source code is governed by a BSD-style
// license that can be found in the LICENSE file.

#include "lib/jxl/dec_frame.h"

#include <stddef.h>
#include <stdint.h>

#include <algorithm>
#include <atomic>
#include <hwy/aligned_allocator.h>
#include <numeric>
#include <utility>
#include <vector>

#include "jxl/types.h"
#include "lib/jxl/ac_context.h"
#include "lib/jxl/ac_strategy.h"
#include "lib/jxl/ans_params.h"
#include "lib/jxl/base/bits.h"
#include "lib/jxl/base/compiler_specific.h"
#include "lib/jxl/base/data_parallel.h"
#include "lib/jxl/base/printf_macros.h"
#include "lib/jxl/base/profiler.h"
#include "lib/jxl/base/status.h"
#include "lib/jxl/chroma_from_luma.h"
#include "lib/jxl/coeff_order.h"
#include "lib/jxl/coeff_order_fwd.h"
#include "lib/jxl/color_management.h"
#include "lib/jxl/common.h"
#include "lib/jxl/compressed_dc.h"
#include "lib/jxl/dec_ans.h"
#include "lib/jxl/dec_bit_reader.h"
#include "lib/jxl/dec_cache.h"
#include "lib/jxl/dec_group.h"
#include "lib/jxl/dec_modular.h"
#include "lib/jxl/dec_params.h"
#include "lib/jxl/dec_patch_dictionary.h"
#include "lib/jxl/dec_xyb.h"
#include "lib/jxl/epf.h"
#include "lib/jxl/fields.h"
#include "lib/jxl/frame_header.h"
#include "lib/jxl/image.h"
#include "lib/jxl/image_bundle.h"
#include "lib/jxl/image_ops.h"
#include "lib/jxl/jpeg/jpeg_data.h"
#include "lib/jxl/loop_filter.h"
#include "lib/jxl/luminance.h"
#include "lib/jxl/passes_state.h"
#include "lib/jxl/quant_weights.h"
#include "lib/jxl/quantizer.h"
#include "lib/jxl/sanitizers.h"
#include "lib/jxl/splines.h"
#include "lib/jxl/toc.h"

namespace jxl {

namespace {
Status DecodeGlobalDCInfo(BitReader* reader, bool is_jpeg,
                          PassesDecoderState* state, ThreadPool* pool) {
  PROFILER_FUNC;
  JXL_RETURN_IF_ERROR(state->shared_storage.quantizer.Decode(reader));

  JXL_RETURN_IF_ERROR(
      DecodeBlockCtxMap(reader, &state->shared_storage.block_ctx_map));

  JXL_RETURN_IF_ERROR(state->shared_storage.cmap.DecodeDC(reader));

  // Pre-compute info for decoding a group.
  if (is_jpeg) {
    state->shared_storage.quantizer.ClearDCMul();  // Don't dequant DC
  }

  state->shared_storage.ac_strategy.FillInvalid();
  return true;
}
}  // namespace

Status DecodeFrameHeader(BitReader* JXL_RESTRICT reader,
                         FrameHeader* JXL_RESTRICT frame_header) {
  JXL_ASSERT(frame_header->nonserialized_metadata != nullptr);
  JXL_RETURN_IF_ERROR(ReadFrameHeader(reader, frame_header));
  return true;
}

static BitReader* GetReaderForSection(
    size_t num_groups, size_t num_passes, size_t group_codes_begin,
    const std::vector<uint64_t>& group_offsets,
    const std::vector<uint32_t>& group_sizes, BitReader* JXL_RESTRICT reader,
    BitReader* JXL_RESTRICT store, size_t index) {
  if (num_groups == 1 && num_passes == 1) return reader;
  const size_t group_offset = group_codes_begin + group_offsets[index];
  const size_t next_group_offset =
      group_codes_begin + group_offsets[index] + group_sizes[index];
  // The order of these variables must be:
  // group_codes_begin <= group_offset <= next_group_offset <= file.size()
  JXL_DASSERT(group_codes_begin <= group_offset);
  JXL_DASSERT(group_offset <= next_group_offset);
  JXL_DASSERT(next_group_offset <= reader->TotalBytes());
  const size_t group_size = next_group_offset - group_offset;
  const size_t remaining_size = reader->TotalBytes() - group_offset;
  const size_t size = std::min(group_size + 8, remaining_size);
  *store =
      BitReader(Span<const uint8_t>(reader->FirstByte() + group_offset, size));
  return store;
}

Status DecodeFrame(const DecompressParams& dparams,
                   PassesDecoderState* dec_state, ThreadPool* JXL_RESTRICT pool,
                   BitReader* JXL_RESTRICT reader, ImageBundle* decoded,
                   const CodecMetadata& metadata,
                   const SizeConstraints* constraints, bool is_preview) {
  PROFILER_ZONE("DecodeFrame uninstrumented");

  FrameDecoder frame_decoder(dec_state, metadata, pool,
                             dparams.use_slow_render_pipeline);

  frame_decoder.SetFrameSizeLimits(constraints);

  JXL_RETURN_IF_ERROR(frame_decoder.InitFrame(
      reader, decoded, is_preview, dparams.allow_partial_files,
      dparams.allow_partial_files && dparams.allow_more_progressive_steps,
      true));

  // Handling of progressive decoding.
  const FrameHeader& frame_header = frame_decoder.GetFrameHeader();
  {
    size_t max_passes = dparams.max_passes;
    size_t max_downsampling = std::max(
        dparams.max_downsampling >> (frame_header.dc_level * 3), size_t(1));
    // TODO(veluca): deal with downsamplings >= 8.
    if (max_downsampling >= 8) {
      max_passes = 0;
    } else {
      for (uint32_t i = 0; i < frame_header.passes.num_downsample; ++i) {
        if (max_downsampling >= frame_header.passes.downsample[i] &&
            max_passes > frame_header.passes.last_pass[i]) {
          max_passes = frame_header.passes.last_pass[i] + 1;
        }
      }
    }
    // Do not use downsampling for kReferenceOnly frames.
    if (frame_header.frame_type == FrameType::kReferenceOnly) {
      max_passes = frame_header.passes.num_passes;
    }
    max_passes = std::min<size_t>(max_passes, frame_header.passes.num_passes);
    frame_decoder.SetMaxPasses(max_passes);
  }
  frame_decoder.SetRenderSpotcolors(dparams.render_spotcolors);
  frame_decoder.SetCoalescing(dparams.coalescing);

  size_t processed_bytes = reader->TotalBitsConsumed() / kBitsPerByte;

  Status close_ok = true;
  std::vector<std::unique_ptr<BitReader>> section_readers;
  {
    std::vector<std::unique_ptr<BitReaderScopedCloser>> section_closers;
    std::vector<FrameDecoder::SectionInfo> section_info;
    std::vector<FrameDecoder::SectionStatus> section_status;
    size_t bytes_to_skip = 0;
    for (size_t i = 0; i < frame_decoder.NumSections(); i++) {
      size_t b = frame_decoder.SectionOffsets()[i];
      size_t e = b + frame_decoder.SectionSizes()[i];
      bytes_to_skip += e - b;
      size_t pos = reader->TotalBitsConsumed() / kBitsPerByte;
      if (pos + (dparams.allow_more_progressive_steps &&
                         (i == 0 ||
                          frame_header.encoding == FrameEncoding::kModular)
                     ? b
                     : e) <=
              reader->TotalBytes() ||
          (i == 0 && dparams.allow_more_progressive_steps)) {
        auto br = make_unique<BitReader>(Span<const uint8_t>(
            reader->FirstByte() + b + pos,
            (pos + b > reader->TotalBytes()
                 ? 0
                 : std::min(reader->TotalBytes() - pos - b, e - b))));
        section_info.emplace_back(FrameDecoder::SectionInfo{br.get(), i});
        section_closers.emplace_back(
            make_unique<BitReaderScopedCloser>(br.get(), &close_ok));
        section_readers.emplace_back(std::move(br));
      } else if (!dparams.allow_partial_files) {
        return JXL_FAILURE("Premature end of stream.");
      }
    }
    // Skip over the to-be-decoded sections.
    reader->SkipBits(kBitsPerByte * bytes_to_skip);
    section_status.resize(section_info.size());

    JXL_RETURN_IF_ERROR(frame_decoder.ProcessSections(
        section_info.data(), section_info.size(), section_status.data()));

    for (size_t i = 0; i < section_status.size(); i++) {
      auto s = section_status[i];
      if (s == FrameDecoder::kDone) {
        processed_bytes += frame_decoder.SectionSizes()[i];
        continue;
      }
      if (dparams.allow_more_progressive_steps && s == FrameDecoder::kPartial) {
        continue;
      }
      if (dparams.max_downsampling > 1 && s == FrameDecoder::kSkipped) {
        continue;
      }
      return JXL_FAILURE("Invalid section %" PRIuS " status: %d",
                         section_info[i].id, s);
    }
  }

  JXL_RETURN_IF_ERROR(close_ok);

  JXL_RETURN_IF_ERROR(frame_decoder.FinalizeFrame());
  decoded->SetDecodedBytes(processed_bytes);
  return true;
}

Status FrameDecoder::InitFrame(BitReader* JXL_RESTRICT br, ImageBundle* decoded,
                               bool is_preview, bool allow_partial_frames,
                               bool allow_partial_dc_global,
                               bool output_needed) {
  PROFILER_FUNC;
  decoded_ = decoded;
  JXL_ASSERT(is_finalized_);

  allow_partial_frames_ = allow_partial_frames;
  allow_partial_dc_global_ = allow_partial_dc_global;

  // Reset the dequantization matrices to their default values.
  dec_state_->shared_storage.matrices = DequantMatrices();

  frame_header_.nonserialized_is_preview = is_preview;
  size_t pos = br->TotalBitsConsumed() / kBitsPerByte;
  Status have_frameheader =
      br->TotalBytes() > pos && DecodeFrameHeader(br, &frame_header_);
  JXL_RETURN_IF_ERROR(have_frameheader || allow_partial_frames);
  if (!have_frameheader) {
    if (dec_state_->shared_storage.dc_frames[0].xsize() > 0) {
      // If we have a (partial) DC frame available, but we don't have the next
      // frame header (so allow_partial_frames is true), then we'll assume the
      // next frame uses that DC frame (which may not be true, e.g. there might
      // first be a ReferenceOnly patch frame, but it's reasonable to assume
      // that the DC frame is a good progressive preview)
      frame_header_.flags |= FrameHeader::kUseDcFrame;
      frame_header_.encoding = FrameEncoding::kVarDCT;
      frame_header_.dc_level = 0;
    } else
      return JXL_FAILURE("Couldn't read frame header");
  }
  frame_dim_ = frame_header_.ToFrameDimensions();

  const size_t num_passes = frame_header_.passes.num_passes;
  const size_t xsize = frame_dim_.xsize;
  const size_t ysize = frame_dim_.ysize;
  const size_t num_groups = frame_dim_.num_groups;

  // Check validity of frame dimensions.
  JXL_RETURN_IF_ERROR(VerifyDimensions(constraints_, xsize, ysize));

  // If the previous frame was not a kRegularFrame, `decoded` may have different
  // dimensions; must reset to avoid errors.
  decoded->RemoveColor();
  decoded->ClearExtraChannels();

  decoded->duration = frame_header_.animation_frame.duration;

  if (!frame_header_.nonserialized_is_preview &&
      (frame_header_.is_last || frame_header_.animation_frame.duration > 0) &&
      (frame_header_.frame_type == kRegularFrame ||
       frame_header_.frame_type == kSkipProgressive)) {
    ++dec_state_->visible_frame_index;
    dec_state_->nonvisible_frame_index = 0;
  } else {
    ++dec_state_->nonvisible_frame_index;
  }

  // Read TOC.
  uint64_t groups_total_size;
  const bool has_ac_global = true;
  const size_t toc_entries = NumTocEntries(num_groups, frame_dim_.num_dc_groups,
                                           num_passes, has_ac_global);
  JXL_RETURN_IF_ERROR(ReadGroupOffsets(toc_entries, br, &section_offsets_,
                                       &section_sizes_, &groups_total_size) ||
                      allow_partial_frames);

  JXL_DASSERT((br->TotalBitsConsumed() % kBitsPerByte) == 0);
  const size_t group_codes_begin = br->TotalBitsConsumed() / kBitsPerByte;
  JXL_DASSERT(!section_offsets_.empty());

  // Overflow check.
  if (group_codes_begin + groups_total_size < group_codes_begin) {
    return JXL_FAILURE("Invalid group codes");
  }

  if (!frame_header_.chroma_subsampling.Is444() &&
      !(frame_header_.flags & FrameHeader::kSkipAdaptiveDCSmoothing) &&
      frame_header_.encoding == FrameEncoding::kVarDCT) {
    return JXL_FAILURE(
        "Non-444 chroma subsampling is not allowed when adaptive DC "
        "smoothing is enabled");
  }

  if (!output_needed) return true;
  JXL_RETURN_IF_ERROR(
      InitializePassesSharedState(frame_header_, &dec_state_->shared_storage));
  JXL_RETURN_IF_ERROR(dec_state_->Init());
  modular_frame_decoder_.Init(frame_dim_);

  if (decoded->IsJPEG()) {
    if (frame_header_.encoding == FrameEncoding::kModular) {
      return JXL_FAILURE("Cannot output JPEG from Modular");
    }
    jpeg::JPEGData* jpeg_data = decoded->jpeg_data.get();
    size_t num_components = jpeg_data->components.size();
    if (num_components != 1 && num_components != 3) {
      return JXL_FAILURE("Invalid number of components");
    }
    if (frame_header_.nonserialized_metadata->m.xyb_encoded) {
      return JXL_FAILURE("Cannot decode to JPEG an XYB image");
    }
    auto jpeg_c_map = JpegOrder(ColorTransform::kYCbCr, num_components == 1);
    decoded->jpeg_data->width = frame_dim_.xsize;
    decoded->jpeg_data->height = frame_dim_.ysize;
    for (size_t c = 0; c < num_components; c++) {
      auto& component = jpeg_data->components[jpeg_c_map[c]];
      component.width_in_blocks =
          frame_dim_.xsize_blocks >> frame_header_.chroma_subsampling.HShift(c);
      component.height_in_blocks =
          frame_dim_.ysize_blocks >> frame_header_.chroma_subsampling.VShift(c);
      component.h_samp_factor =
          1 << frame_header_.chroma_subsampling.RawHShift(c);
      component.v_samp_factor =
          1 << frame_header_.chroma_subsampling.RawVShift(c);
      component.coeffs.resize(component.width_in_blocks *
                              component.height_in_blocks * jxl::kDCTBlockSize);
    }
  }

  // Clear the state.
  decoded_dc_global_ = false;
  decoded_ac_global_ = false;
  is_finalized_ = false;
  finalized_dc_ = false;
  num_sections_done_ = 0;
  decoded_dc_groups_.clear();
  decoded_dc_groups_.resize(frame_dim_.num_dc_groups);
  decoded_passes_per_ac_group_.clear();
  decoded_passes_per_ac_group_.resize(frame_dim_.num_groups, 0);
  processed_section_.clear();
  processed_section_.resize(section_offsets_.size());
  max_passes_ = frame_header_.passes.num_passes;
  num_renders_ = 0;
  allocated_ = false;
  return true;
}

Status FrameDecoder::ProcessDCGlobal(BitReader* br) {
  PROFILER_FUNC;
  PassesSharedState& shared = dec_state_->shared_storage;
  if (shared.frame_header.flags & FrameHeader::kPatches) {
    bool uses_extra_channels = false;
    JXL_RETURN_IF_ERROR(shared.image_features.patches.Decode(
        br, frame_dim_.xsize_padded, frame_dim_.ysize_padded,
        &uses_extra_channels));
    if (uses_extra_channels && frame_header_.upsampling != 1) {
      for (size_t ecups : frame_header_.extra_channel_upsampling) {
        if (ecups != frame_header_.upsampling) {
          return JXL_FAILURE(
              "Cannot use extra channels in patches if color channels are "
              "subsampled differently from extra channels");
        }
      }
    }
  } else {
    shared.image_features.patches.Clear();
  }
  shared.image_features.splines.Clear();
  if (shared.frame_header.flags & FrameHeader::kSplines) {
    JXL_RETURN_IF_ERROR(shared.image_features.splines.Decode(
        br, frame_dim_.xsize * frame_dim_.ysize));
  }
  if (shared.frame_header.flags & FrameHeader::kNoise) {
    JXL_RETURN_IF_ERROR(DecodeNoise(br, &shared.image_features.noise_params));
  }
  if (!allow_partial_dc_global_ ||
      br->TotalBitsConsumed() < br->TotalBytes() * kBitsPerByte) {
    JXL_RETURN_IF_ERROR(dec_state_->shared_storage.matrices.DecodeDC(br));

    if (frame_header_.encoding == FrameEncoding::kVarDCT) {
      JXL_RETURN_IF_ERROR(
          jxl::DecodeGlobalDCInfo(br, decoded_->IsJPEG(), dec_state_, pool_));
    }
  }
  // Splines' draw cache uses the color correlation map.
  if (shared.frame_header.flags & FrameHeader::kSplines) {
    JXL_RETURN_IF_ERROR(shared.image_features.splines.InitializeDrawCache(
        frame_dim_.xsize_upsampled, frame_dim_.ysize_upsampled,
        dec_state_->shared->cmap));
  }
  Status dec_status = modular_frame_decoder_.DecodeGlobalInfo(
      br, frame_header_, allow_partial_dc_global_);
  if (dec_status.IsFatalError()) return dec_status;
  if (dec_status) {
    decoded_dc_global_ = true;
  }
  return dec_status;
}

Status FrameDecoder::ProcessDCGroup(size_t dc_group_id, BitReader* br) {
  PROFILER_FUNC;
  const size_t gx = dc_group_id % frame_dim_.xsize_dc_groups;
  const size_t gy = dc_group_id / frame_dim_.xsize_dc_groups;
  const LoopFilter& lf = dec_state_->shared->frame_header.loop_filter;
  if (frame_header_.encoding == FrameEncoding::kVarDCT &&
      !(frame_header_.flags & FrameHeader::kUseDcFrame)) {
    JXL_RETURN_IF_ERROR(
        modular_frame_decoder_.DecodeVarDCTDC(dc_group_id, br, dec_state_));
  }
  const Rect mrect(gx * frame_dim_.dc_group_dim, gy * frame_dim_.dc_group_dim,
                   frame_dim_.dc_group_dim, frame_dim_.dc_group_dim);
  JXL_RETURN_IF_ERROR(modular_frame_decoder_.DecodeGroup(
      mrect, br, 3, 1000, ModularStreamId::ModularDC(dc_group_id),
      /*zerofill=*/false, nullptr, nullptr, nullptr, allow_partial_frames_));
  if (frame_header_.encoding == FrameEncoding::kVarDCT) {
    JXL_RETURN_IF_ERROR(
        modular_frame_decoder_.DecodeAcMetadata(dc_group_id, br, dec_state_));
  } else if (lf.epf_iters > 0) {
    FillImage(kInvSigmaNum / lf.epf_sigma_for_modular, &dec_state_->sigma);
  }
  decoded_dc_groups_[dc_group_id] = uint8_t{true};
  return true;
}

void FrameDecoder::FinalizeDC() {
  // Do Adaptive DC smoothing if enabled. This *must* happen between all the
  // ProcessDCGroup and ProcessACGroup.
  if (frame_header_.encoding == FrameEncoding::kVarDCT &&
      !(frame_header_.flags & FrameHeader::kSkipAdaptiveDCSmoothing) &&
      !(frame_header_.flags & FrameHeader::kUseDcFrame)) {
    AdaptiveDCSmoothing(dec_state_->shared->quantizer.MulDC(),
                        &dec_state_->shared_storage.dc_storage, pool_);
  }

  finalized_dc_ = true;
}

Status FrameDecoder::AllocateOutput() {
  if (allocated_) return true;
  modular_frame_decoder_.MaybeDropFullImage();
  decoded_->origin = dec_state_->shared->frame_header.frame_origin;
  JXL_RETURN_IF_ERROR(dec_state_->InitForAC(nullptr));
  allocated_ = true;
  return true;
}

Status FrameDecoder::ProcessACGlobal(BitReader* br) {
  JXL_CHECK(finalized_dc_);

  // Decode AC group.
  if (frame_header_.encoding == FrameEncoding::kVarDCT) {
    JXL_RETURN_IF_ERROR(dec_state_->shared_storage.matrices.Decode(
        br, &modular_frame_decoder_));
    JXL_RETURN_IF_ERROR(dec_state_->shared_storage.matrices.EnsureComputed(
        dec_state_->used_acs));

    size_t num_histo_bits =
        CeilLog2Nonzero(dec_state_->shared->frame_dim.num_groups);
    dec_state_->shared_storage.num_histograms =
        1 + br->ReadBits(num_histo_bits);

    dec_state_->code.resize(kMaxNumPasses);
    dec_state_->context_map.resize(kMaxNumPasses);
    // Read coefficient orders and histograms.
    size_t max_num_bits_ac = 0;
    for (size_t i = 0;
         i < dec_state_->shared_storage.frame_header.passes.num_passes; i++) {
      uint16_t used_orders = U32Coder::Read(kOrderEnc, br);
      JXL_RETURN_IF_ERROR(DecodeCoeffOrders(
          used_orders, dec_state_->used_acs,
          &dec_state_->shared_storage
               .coeff_orders[i * dec_state_->shared_storage.coeff_order_size],
          br));
      size_t num_contexts =
          dec_state_->shared->num_histograms *
          dec_state_->shared_storage.block_ctx_map.NumACContexts();
      JXL_RETURN_IF_ERROR(DecodeHistograms(
          br, num_contexts, &dec_state_->code[i], &dec_state_->context_map[i]));
      // Add extra values to enable the cheat in hot loop of DecodeACVarBlock.
      dec_state_->context_map[i].resize(
          num_contexts + kZeroDensityContextLimit - kZeroDensityContextCount);
      max_num_bits_ac =
          std::max(max_num_bits_ac, dec_state_->code[i].max_num_bits);
    }
    max_num_bits_ac += CeilLog2Nonzero(
        dec_state_->shared_storage.frame_header.passes.num_passes);
    // 16-bit buffer for decoding to JPEG are not implemented.
    // TODO(veluca): figure out the exact limit - 16 should still work with
    // 16-bit buffers, but we are excluding it for safety.
    bool use_16_bit = max_num_bits_ac < 16 && !decoded_->IsJPEG();
    bool store = frame_header_.passes.num_passes > 1;
    size_t xs = store ? kGroupDim * kGroupDim : 0;
    size_t ys = store ? frame_dim_.num_groups : 0;
    if (use_16_bit) {
      dec_state_->coefficients = make_unique<ACImageT<int16_t>>(xs, ys);
    } else {
      dec_state_->coefficients = make_unique<ACImageT<int32_t>>(xs, ys);
    }
    if (store) {
      dec_state_->coefficients->ZeroFill();
    }
  }

  // Set JPEG decoding data.
  if (decoded_->IsJPEG()) {
    decoded_->color_transform = frame_header_.color_transform;
    decoded_->chroma_subsampling = frame_header_.chroma_subsampling;
    const std::vector<QuantEncoding>& qe =
        dec_state_->shared_storage.matrices.encodings();
    if (qe.empty() || qe[0].mode != QuantEncoding::Mode::kQuantModeRAW ||
        std::abs(qe[0].qraw.qtable_den - 1.f / (8 * 255)) > 1e-8f) {
      return JXL_FAILURE(
          "Quantization table is not a JPEG quantization table.");
    }
    jpeg::JPEGData* jpeg_data = decoded_->jpeg_data.get();
    size_t num_components = jpeg_data->components.size();
    bool is_gray = (num_components == 1);
    auto jpeg_c_map = JpegOrder(frame_header_.color_transform, is_gray);
    size_t qt_set = 0;
    for (size_t c = 0; c < num_components; c++) {
      // TODO(eustas): why 1-st quant table for gray?
      size_t quant_c = is_gray ? 1 : c;
      size_t qpos = jpeg_data->components[jpeg_c_map[c]].quant_idx;
      JXL_CHECK(qpos != jpeg_data->quant.size());
      qt_set |= 1 << qpos;
      for (size_t x = 0; x < 8; x++) {
        for (size_t y = 0; y < 8; y++) {
          jpeg_data->quant[qpos].values[x * 8 + y] =
              (*qe[0].qraw.qtable)[quant_c * 64 + y * 8 + x];
        }
      }
    }
    for (size_t i = 0; i < jpeg_data->quant.size(); i++) {
      if (qt_set & (1 << i)) continue;
      if (i == 0) return JXL_FAILURE("First quant table unused.");
      // Unused quant table is set to copy of previous quant table
      for (size_t j = 0; j < 64; j++) {
        jpeg_data->quant[i].values[j] = jpeg_data->quant[i - 1].values[j];
      }
    }
  }
  decoded_ac_global_ = true;
  return true;
}

Status FrameDecoder::ProcessACGroup(size_t ac_group_id,
                                    BitReader* JXL_RESTRICT* br,
                                    size_t num_passes, size_t thread,
                                    bool force_draw, bool dc_only) {
  PROFILER_ZONE("process_group");
  size_t group_dim = frame_dim_.group_dim;
  const size_t gx = ac_group_id % frame_dim_.xsize_groups;
  const size_t gy = ac_group_id / frame_dim_.xsize_groups;
  const size_t x = gx * group_dim;
  const size_t y = gy * group_dim;

  RenderPipelineInput render_pipeline_input =
      dec_state_->render_pipeline->GetInputBuffers(ac_group_id, thread);

  bool should_run_pipeline = true;

  if (frame_header_.encoding == FrameEncoding::kVarDCT) {
    group_dec_caches_[thread].InitOnce(frame_header_.passes.num_passes,
                                       dec_state_->used_acs);
    JXL_RETURN_IF_ERROR(DecodeGroup(br, num_passes, ac_group_id, dec_state_,
                                    &group_dec_caches_[thread], thread,
                                    render_pipeline_input, decoded_,
                                    decoded_passes_per_ac_group_[ac_group_id],
                                    force_draw, dc_only, &should_run_pipeline));
  }

  // don't limit to image dimensions here (is done in DecodeGroup)
  const Rect mrect(x, y, group_dim, group_dim);
  for (size_t i = 0; i < frame_header_.passes.num_passes; i++) {
    int minShift, maxShift;
    frame_header_.passes.GetDownsamplingBracket(i, minShift, maxShift);
    if (i >= decoded_passes_per_ac_group_[ac_group_id] &&
        i < decoded_passes_per_ac_group_[ac_group_id] + num_passes) {
      JXL_RETURN_IF_ERROR(modular_frame_decoder_.DecodeGroup(
          mrect, br[i - decoded_passes_per_ac_group_[ac_group_id]], minShift,
          maxShift, ModularStreamId::ModularAC(ac_group_id, i),
          /*zerofill=*/false, dec_state_, &render_pipeline_input, decoded_,
          allow_partial_frames_));
    } else if (i >= decoded_passes_per_ac_group_[ac_group_id] + num_passes &&
               force_draw) {
      JXL_RETURN_IF_ERROR(modular_frame_decoder_.DecodeGroup(
          mrect, nullptr, minShift, maxShift,
          ModularStreamId::ModularAC(ac_group_id, i), /*zerofill=*/true,
          dec_state_, &render_pipeline_input, decoded_, allow_partial_frames_));
    }
  }
  decoded_passes_per_ac_group_[ac_group_id] += num_passes;

  if ((frame_header_.flags & FrameHeader::kNoise) != 0) {
    PROFILER_ZONE("GenerateNoise");
    size_t noise_c_start =
        3 + frame_header_.nonserialized_metadata->m.num_extra_channels;
    // When the color channels are downsampled, we need to generate more noise
    // input for the current group than just the group dimensions.
    std::pair<ImageF*, Rect> rects[3];
    for (size_t iy = 0; iy < frame_header_.upsampling; iy++) {
      for (size_t ix = 0; ix < frame_header_.upsampling; ix++) {
        for (size_t c = 0; c < 3; c++) {
          auto r = render_pipeline_input.GetBuffer(noise_c_start + c);
          rects[c].first = r.first;
          size_t x1 = r.second.x0() + r.second.xsize();
          size_t y1 = r.second.y0() + r.second.ysize();
          rects[c].second = Rect(r.second.x0() + ix * group_dim,
                                 r.second.y0() + iy * group_dim, group_dim,
                                 group_dim, x1, y1);
        }
        Random3Planes(dec_state_->visible_frame_index,
                      dec_state_->nonvisible_frame_index,
                      (gx * frame_header_.upsampling + ix) * group_dim,
                      (gy * frame_header_.upsampling + iy) * group_dim,
                      rects[0], rects[1], rects[2]);
      }
    }
  }

  if (!modular_frame_decoder_.UsesFullImage() && !decoded_->IsJPEG() &&
      should_run_pipeline) {
    render_pipeline_input.Done();
  }
  return true;
}

void FrameDecoder::MarkSections(const SectionInfo* sections, size_t num,
                                SectionStatus* section_status) {
  num_sections_done_ = num;
  for (size_t i = 0; i < num; i++) {
    if (section_status[i] == SectionStatus::kSkipped ||
        section_status[i] == SectionStatus::kPartial) {
      processed_section_[sections[i].id] = false;
      num_sections_done_--;
    }
  }
}

Status FrameDecoder::ProcessSections(const SectionInfo* sections, size_t num,
                                     SectionStatus* section_status) {
  if (num == 0) return true;  // Nothing to process
  std::fill(section_status, section_status + num, SectionStatus::kSkipped);
  size_t dc_global_sec = num;
  size_t ac_global_sec = num;
  std::vector<size_t> dc_group_sec(frame_dim_.num_dc_groups, num);
  std::vector<std::vector<size_t>> ac_group_sec(
      frame_dim_.num_groups,
      std::vector<size_t>(frame_header_.passes.num_passes, num));
  // This keeps track of the number of ac passes we want to process during this
  // call of ProcessSections.
  std::vector<size_t> desired_num_ac_passes(frame_dim_.num_groups);
  bool single_section =
      frame_dim_.num_groups == 1 && frame_header_.passes.num_passes == 1;
  if (single_section) {
    JXL_ASSERT(num == 1);
    JXL_ASSERT(sections[0].id == 0);
    if (processed_section_[0] == false) {
      processed_section_[0] = true;
      ac_group_sec[0].resize(1);
      dc_global_sec = ac_global_sec = dc_group_sec[0] = ac_group_sec[0][0] = 0;
      desired_num_ac_passes[0] = 1;
    } else {
      section_status[0] = SectionStatus::kDuplicate;
    }
  } else {
    size_t ac_global_index = frame_dim_.num_dc_groups + 1;
    for (size_t i = 0; i < num; i++) {
      JXL_ASSERT(sections[i].id < processed_section_.size());
      if (processed_section_[sections[i].id]) {
        section_status[i] = SectionStatus::kDuplicate;
        continue;
      }
      if (sections[i].id == 0) {
        dc_global_sec = i;
      } else if (sections[i].id < ac_global_index) {
        dc_group_sec[sections[i].id - 1] = i;
      } else if (sections[i].id == ac_global_index) {
        ac_global_sec = i;
      } else {
        size_t ac_idx = sections[i].id - ac_global_index - 1;
        size_t acg = ac_idx % frame_dim_.num_groups;
        size_t acp = ac_idx / frame_dim_.num_groups;
        if (acp >= frame_header_.passes.num_passes) {
          return JXL_FAILURE("Invalid section ID");
        }
        if (acp >= max_passes_) {
          continue;
        }
        ac_group_sec[acg][acp] = i;
      }
      processed_section_[sections[i].id] = true;
    }
    // Count number of new passes per group.
    for (size_t g = 0; g < ac_group_sec.size(); g++) {
      size_t j = 0;
      for (; j + decoded_passes_per_ac_group_[g] < max_passes_; j++) {
        if (ac_group_sec[g][j + decoded_passes_per_ac_group_[g]] == num) {
          break;
        }
      }
      desired_num_ac_passes[g] = j;
    }
  }
  if (dc_global_sec != num) {
    Status dc_global_status = ProcessDCGlobal(sections[dc_global_sec].br);
    if (dc_global_status.IsFatalError()) return dc_global_status;
    if (dc_global_status) {
      section_status[dc_global_sec] = SectionStatus::kDone;
    } else {
      section_status[dc_global_sec] = SectionStatus::kPartial;
    }
  }

  std::atomic<bool> has_error{false};
  if (decoded_dc_global_) {
    JXL_RETURN_IF_ERROR(RunOnPool(
        pool_, 0, dc_group_sec.size(), ThreadPool::NoInit,
        [this, &dc_group_sec, &num, &sections, &section_status, &has_error](
            size_t i, size_t thread) {
          if (dc_group_sec[i] != num) {
            if (!ProcessDCGroup(i, sections[dc_group_sec[i]].br)) {
              has_error = true;
            } else {
              section_status[dc_group_sec[i]] = SectionStatus::kDone;
            }
          }
        },
        "DecodeDCGroup"));
  }
  if (has_error) return JXL_FAILURE("Error in DC group");

  bool do_progressive = false;
  if (pause_at_progressive_ && (frame_header_.frame_type != kSkipProgressive)) {
    do_progressive = true;
    if (single_section) {
      // If there's only one group and one pass, there is no separate section
      // for DC and the entire full resolution image is available at once.
      do_progressive = false;
    }
    if (!decoded_->metadata()->extra_channel_info.empty()) {
      // If extra channels are encoded with modular without squeeze, they
      // don't support DC. If the are encoded with squeeze, DC works in theory
      // but the implementation may not yet correctly support this for Flush.
      // Therefore, can't correctly pause for a progressive step if there is
      // an extra channel (including alpha channel)
      // TOOD(firsching): Check if this is still the case.
      do_progressive = false;
    }
    if (frame_header_.encoding != FrameEncoding::kVarDCT) {
      // DC is not guaranteed to be available in modular mode and may be a
      // black image. If squeeze is used, it may be available depending on the
      // current implementation.
      // TODO(lode): do return DC if it's known that flushing at this point will
      // produce a valid 1/8th downscaled image with modular encoding.
      do_progressive = false;
    }
  }
  if (*std::min_element(decoded_dc_groups_.begin(), decoded_dc_groups_.end()) &&
      !finalized_dc_) {
    PassesDecoderState::PipelineOptions pipeline_options;
    pipeline_options.use_slow_render_pipeline = use_slow_rendering_pipeline_;
    pipeline_options.coalescing = coalescing_;
    pipeline_options.render_spotcolors = render_spotcolors_;
    JXL_RETURN_IF_ERROR(
        dec_state_->PreparePipeline(decoded_, pipeline_options));
    FinalizeDC();
    JXL_RETURN_IF_ERROR(AllocateOutput());
    if (do_progressive && progressive_detail_ >= JxlProgressiveDetail::kDC) {
      MarkSections(sections, num, section_status);
      return true;
    }
  }

  if (finalized_dc_ && ac_global_sec != num && !decoded_ac_global_) {
    JXL_RETURN_IF_ERROR(ProcessACGlobal(sections[ac_global_sec].br));
    section_status[ac_global_sec] = SectionStatus::kDone;
  }

  if (do_progressive && progressive_detail_ >= JxlProgressiveDetail::kPasses) {
    // Mark that we only want the next pass.
    size_t num_complete_passes = NumCompletePasses();
    for (size_t i = 0; i < ac_group_sec.size(); i++) {
      desired_num_ac_passes[i] =
          std::min(desired_num_ac_passes[i],
                   1 + num_complete_passes - decoded_passes_per_ac_group_[i]);
    }
  }

  if (decoded_ac_global_) {
    // Mark all the AC groups that we received as not complete yet.
    for (size_t i = 0; i < ac_group_sec.size(); i++) {
      if (desired_num_ac_passes[i] == 0 &&
          !modular_frame_decoder_.UsesFullImage()) {
        continue;
      }
      dec_state_->render_pipeline->ClearDone(i);
    }

    JXL_RETURN_IF_ERROR(RunOnPool(
        pool_, 0, ac_group_sec.size(),
        [this](size_t num_threads) {
          return PrepareStorage(num_threads,
                                decoded_passes_per_ac_group_.size());
        },
        [this, &ac_group_sec, &desired_num_ac_passes, &num, &sections,
         &section_status, &has_error](size_t g, size_t thread) {
          if (desired_num_ac_passes[g] == 0) {
            // no new AC pass, nothing to do
            return;
          }
          (void)num;
          size_t first_pass = decoded_passes_per_ac_group_[g];
          BitReader* JXL_RESTRICT readers[kMaxNumPasses];
          for (size_t i = 0; i < desired_num_ac_passes[g]; i++) {
            JXL_ASSERT(ac_group_sec[g][first_pass + i] != num);
            readers[i] = sections[ac_group_sec[g][first_pass + i]].br;
          }
          if (!ProcessACGroup(g, readers, desired_num_ac_passes[g],
                              GetStorageLocation(thread, g),
                              /*force_draw=*/false, /*dc_only=*/false)) {
            has_error = true;
          } else {
            for (size_t i = 0; i < desired_num_ac_passes[g]; i++) {
              section_status[ac_group_sec[g][first_pass + i]] =
                  SectionStatus::kDone;
            }
          }
        },
        "DecodeGroup"));
  }
  if (has_error) return JXL_FAILURE("Error in AC group");

  MarkSections(sections, num, section_status);
  return true;
}

Status FrameDecoder::Flush() {
  bool has_blending = frame_header_.blending_info.mode != BlendMode::kReplace ||
                      frame_header_.custom_size_or_origin;
  for (const auto& blending_info_ec :
       frame_header_.extra_channel_blending_info) {
    if (blending_info_ec.mode != BlendMode::kReplace) has_blending = true;
  }
  // No early Flush() if blending is enabled.
  if (has_blending && !is_finalized_) {
    return false;
  }
  // No early Flush() - nothing to do - if the frame is a kSkipProgressive
  // frame.
  if (frame_header_.frame_type == FrameType::kSkipProgressive &&
      !is_finalized_) {
    return true;
  }
  if (decoded_->IsJPEG()) {
    // Nothing to do.
    return true;
  }
  JXL_RETURN_IF_ERROR(AllocateOutput());

  uint32_t completely_decoded_ac_pass = *std::min_element(
      decoded_passes_per_ac_group_.begin(), decoded_passes_per_ac_group_.end());
  if (completely_decoded_ac_pass < frame_header_.passes.num_passes) {
    // We don't have all AC yet: force a draw of all the missing areas.
    // Mark all sections as not complete.
    for (size_t i = 0; i < decoded_passes_per_ac_group_.size(); i++) {
      if (decoded_passes_per_ac_group_[i] == frame_header_.passes.num_passes)
        continue;
      dec_state_->render_pipeline->ClearDone(i);
    }
    std::atomic<bool> has_error{false};
    JXL_RETURN_IF_ERROR(RunOnPool(
        pool_, 0, decoded_passes_per_ac_group_.size(),
        [this](const size_t num_threads) {
          return PrepareStorage(num_threads,
                                decoded_passes_per_ac_group_.size());
        },
        [this, &has_error](const uint32_t g, size_t thread) {
          if (decoded_passes_per_ac_group_[g] ==
              frame_header_.passes.num_passes) {
            // This group was drawn already, nothing to do.
            return;
          }
          BitReader* JXL_RESTRICT readers[kMaxNumPasses] = {};
          bool ok = ProcessACGroup(
              g, readers, /*num_passes=*/0, GetStorageLocation(thread, g),
              /*force_draw=*/true, /*dc_only=*/!decoded_ac_global_);
          if (!ok) has_error = true;
        },
        "ForceDrawGroup"));
    if (has_error) {
      return JXL_FAILURE("Drawing groups failed");
    }
  }

  // undo global modular transforms and copy int pixel buffers to float ones
  JXL_RETURN_IF_ERROR(modular_frame_decoder_.FinalizeDecoding(
      dec_state_, pool_, decoded_, is_finalized_));

  num_renders_++;
  return true;
}

int FrameDecoder::SavedAs(const FrameHeader& header) {
  if (header.frame_type == FrameType::kDCFrame) {
    // bits 16, 32, 64, 128 for DC level
    return 16 << (header.dc_level - 1);
  } else if (header.CanBeReferenced()) {
    // bits 1, 2, 4 and 8 for the references
    return 1 << header.save_as_reference;
  }

  return 0;
}

bool FrameDecoder::HasEverything() const {
  if (!decoded_dc_global_) return false;
  if (!decoded_ac_global_) return false;
  for (auto& have_dc_group : decoded_dc_groups_) {
    if (!have_dc_group) return false;
  }
  for (auto& nb_passes : decoded_passes_per_ac_group_) {
    if (nb_passes < max_passes_) return false;
  }
  return true;
}

int FrameDecoder::References() const {
  if (is_finalized_) {
    return 0;
  }
  if (!HasEverything()) return 0;

  int result = 0;

  // Blending
  if (frame_header_.frame_type == FrameType::kRegularFrame ||
      frame_header_.frame_type == FrameType::kSkipProgressive) {
    bool cropped = frame_header_.custom_size_or_origin;
    if (cropped || frame_header_.blending_info.mode != BlendMode::kReplace) {
      result |= (1 << frame_header_.blending_info.source);
    }
    const auto& extra = frame_header_.extra_channel_blending_info;
    for (size_t i = 0; i < extra.size(); ++i) {
      if (cropped || extra[i].mode != BlendMode::kReplace) {
        result |= (1 << extra[i].source);
      }
    }
  }

  // Patches
  if (frame_header_.flags & FrameHeader::kPatches) {
    result |= dec_state_->shared->image_features.patches.GetReferences();
  }

  // DC Level
  if (frame_header_.flags & FrameHeader::kUseDcFrame) {
    // Reads from the next dc level
    int dc_level = frame_header_.dc_level + 1;
    // bits 16, 32, 64, 128 for DC level
    result |= (16 << (dc_level - 1));
  }

  return result;
}

Status FrameDecoder::FinalizeFrame() {
  if (is_finalized_) {
    return JXL_FAILURE("FinalizeFrame called multiple times");
  }
  is_finalized_ = true;
  if (decoded_->IsJPEG()) {
    // Nothing to do.
    return true;
  }
  if (!finalized_dc_) {
    // We don't have all of DC, and render pipeline is not created yet, so we
    // can not call Flush() yet.
    return JXL_FAILURE("FinalizeFrame called before DC was fully decoded");
  }

  JXL_RETURN_IF_ERROR(Flush());

  if (frame_header_.CanBeReferenced()) {
    auto& info = dec_state_->shared_storage
                     .reference_frames[frame_header_.save_as_reference];
    info.storage = std::move(dec_state_->frame_storage_for_referencing);
    info.ib_is_in_xyb = frame_header_.save_before_color_transform;
    info.frame = &info.storage;
  }
  return true;
}

}  // namespace jxl