// Copyright 2017 The Chromium 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 "components/zucchini/patch_writer.h"

#include <algorithm>
#include <iterator>

#include "base/numerics/checked_math.h"
#include "base/numerics/safe_conversions.h"
#include "components/zucchini/crc32.h"

namespace zucchini {

namespace patch {

bool SerializeElementMatch(const ElementMatch& element_match,
                           BufferSink* sink) {
  if (!element_match.IsValid())
    return false;

  PatchElementHeader element_header;
  element_header.old_offset =
      base::checked_cast<uint32_t>(element_match.old_element.offset);
  element_header.old_length =
      base::checked_cast<uint32_t>(element_match.old_element.size);
  element_header.new_offset =
      base::checked_cast<uint32_t>(element_match.new_element.offset);
  element_header.new_length =
      base::checked_cast<uint32_t>(element_match.new_element.size);
  element_header.exe_type = element_match.exe_type();

  return sink->PutValue<PatchElementHeader>(element_header);
}

size_t SerializedElementMatchSize(const ElementMatch& element_match) {
  return sizeof(PatchElementHeader);
}

bool SerializeBuffer(const std::vector<uint8_t>& buffer, BufferSink* sink) {
  // buffer.size() is not encoded as varint to simplify SerializedBufferSize().
  base::CheckedNumeric<uint32_t> size = buffer.size();
  if (!size.IsValid())
    return false;
  return sink->PutValue<uint32_t>(size.ValueOrDie()) &&
         sink->PutRange(buffer.begin(), buffer.end());
}

size_t SerializedBufferSize(const std::vector<uint8_t>& buffer) {
  return sizeof(uint32_t) + buffer.size();
}

}  // namespace patch

/******** EquivalenceSink ********/

EquivalenceSink::EquivalenceSink() = default;
EquivalenceSink::EquivalenceSink(const std::vector<uint8_t>& src_skip,
                                 const std::vector<uint8_t>& dst_skip,
                                 const std::vector<uint8_t>& copy_count)
    : src_skip_(src_skip), dst_skip_(dst_skip), copy_count_(copy_count) {}

EquivalenceSink::EquivalenceSink(EquivalenceSink&&) = default;
EquivalenceSink::~EquivalenceSink() = default;

void EquivalenceSink::PutNext(const Equivalence& equivalence) {
  // Equivalences are expected to be given ordered by |dst_offset|.
  DCHECK_GE(equivalence.dst_offset, dst_offset_);
  // Unsigned values are ensured by above check.

  // Result of substracting 2 unsigned integers is unsigned. Overflow is allowed
  // for negative values, as long as uint32_t can hold the result.
  uint32_t src_offset_diff =
      base::strict_cast<uint32_t>(equivalence.src_offset - src_offset_);
  EncodeVarInt<int32_t>(static_cast<int32_t>(src_offset_diff),
                        std::back_inserter(src_skip_));

  EncodeVarUInt<uint32_t>(
      base::strict_cast<uint32_t>(equivalence.dst_offset - dst_offset_),
      std::back_inserter(dst_skip_));

  EncodeVarUInt<uint32_t>(base::strict_cast<uint32_t>(equivalence.length),
                          std::back_inserter(copy_count_));

  src_offset_ = equivalence.src_offset + equivalence.length;
  dst_offset_ = equivalence.dst_offset + equivalence.length;
}

size_t EquivalenceSink::SerializedSize() const {
  return patch::SerializedBufferSize(src_skip_) +
         patch::SerializedBufferSize(dst_skip_) +
         patch::SerializedBufferSize(copy_count_);
}

bool EquivalenceSink::SerializeInto(BufferSink* sink) const {
  return patch::SerializeBuffer(src_skip_, sink) &&
         patch::SerializeBuffer(dst_skip_, sink) &&
         patch::SerializeBuffer(copy_count_, sink);
}

/******** ExtraDataSink ********/

ExtraDataSink::ExtraDataSink() = default;
ExtraDataSink::ExtraDataSink(const std::vector<uint8_t>& extra_data)
    : extra_data_(extra_data) {}

ExtraDataSink::ExtraDataSink(ExtraDataSink&&) = default;
ExtraDataSink::~ExtraDataSink() = default;

void ExtraDataSink::PutNext(ConstBufferView region) {
  extra_data_.insert(extra_data_.end(), region.begin(), region.end());
}

size_t ExtraDataSink::SerializedSize() const {
  return patch::SerializedBufferSize(extra_data_);
}

bool ExtraDataSink::SerializeInto(BufferSink* sink) const {
  return patch::SerializeBuffer(extra_data_, sink);
}

/******** RawDeltaSink ********/

RawDeltaSink::RawDeltaSink() = default;
RawDeltaSink::RawDeltaSink(const std::vector<uint8_t>& raw_delta_skip,
                           const std::vector<uint8_t>& raw_delta_diff)
    : raw_delta_skip_(raw_delta_skip), raw_delta_diff_(raw_delta_diff) {}

RawDeltaSink::RawDeltaSink(RawDeltaSink&&) = default;
RawDeltaSink::~RawDeltaSink() = default;

void RawDeltaSink::PutNext(const RawDeltaUnit& delta) {
  DCHECK_GE(delta.copy_offset, copy_offset_compensation_);
  EncodeVarUInt<uint32_t>(base::strict_cast<uint32_t>(
                              delta.copy_offset - copy_offset_compensation_),
                          std::back_inserter(raw_delta_skip_));

  copy_offset_compensation_ = delta.copy_offset + 1;

  raw_delta_diff_.push_back(delta.diff);
}

size_t RawDeltaSink::SerializedSize() const {
  return patch::SerializedBufferSize(raw_delta_skip_) +
         patch::SerializedBufferSize(raw_delta_diff_);
}

bool RawDeltaSink::SerializeInto(BufferSink* sink) const {
  return patch::SerializeBuffer(raw_delta_skip_, sink) &&
         patch::SerializeBuffer(raw_delta_diff_, sink);
}

/******** ReferenceDeltaSink ********/

ReferenceDeltaSink::ReferenceDeltaSink() = default;
ReferenceDeltaSink::ReferenceDeltaSink(
    const std::vector<uint8_t>& reference_delta)
    : reference_delta_(reference_delta) {}

ReferenceDeltaSink::ReferenceDeltaSink(ReferenceDeltaSink&&) = default;
ReferenceDeltaSink::~ReferenceDeltaSink() = default;

void ReferenceDeltaSink::PutNext(int32_t diff) {
  EncodeVarInt<int32_t>(diff, std::back_inserter(reference_delta_));
}

size_t ReferenceDeltaSink::SerializedSize() const {
  return patch::SerializedBufferSize(reference_delta_);
}

bool ReferenceDeltaSink::SerializeInto(BufferSink* sink) const {
  return patch::SerializeBuffer(reference_delta_, sink);
}

/******** TargetSink ********/

TargetSink::TargetSink() = default;
TargetSink::TargetSink(const std::vector<uint8_t>& extra_targets)
    : extra_targets_(extra_targets) {}

TargetSink::TargetSink(TargetSink&&) = default;
TargetSink::~TargetSink() = default;

void TargetSink::PutNext(uint32_t target) {
  DCHECK_GE(target, target_compensation_);

  EncodeVarUInt<uint32_t>(
      base::strict_cast<uint32_t>(target - target_compensation_),
      std::back_inserter(extra_targets_));

  target_compensation_ = target + 1;
}

size_t TargetSink::SerializedSize() const {
  return patch::SerializedBufferSize(extra_targets_);
}

bool TargetSink::SerializeInto(BufferSink* sink) const {
  return patch::SerializeBuffer(extra_targets_, sink);
}

/******** PatchElementWriter ********/

PatchElementWriter::PatchElementWriter() = default;
PatchElementWriter::PatchElementWriter(ElementMatch element_match)
    : element_match_(element_match) {}

PatchElementWriter::PatchElementWriter(PatchElementWriter&&) = default;
PatchElementWriter::~PatchElementWriter() = default;

size_t PatchElementWriter::SerializedSize() const {
  size_t serialized_size =
      patch::SerializedElementMatchSize(element_match_) +
      equivalences_->SerializedSize() + extra_data_->SerializedSize() +
      raw_delta_->SerializedSize() + reference_delta_->SerializedSize();

  serialized_size += sizeof(uint32_t);
  for (const auto& extra_symbols : extra_targets_)
    serialized_size += extra_symbols.second.SerializedSize() + 1;
  return serialized_size;
}

bool PatchElementWriter::SerializeInto(BufferSink* sink) const {
  bool ok =
      patch::SerializeElementMatch(element_match_, sink) &&
      equivalences_->SerializeInto(sink) && extra_data_->SerializeInto(sink) &&
      raw_delta_->SerializeInto(sink) && reference_delta_->SerializeInto(sink);
  if (!ok)
    return false;

  if (!sink->PutValue<uint32_t>(
          base::checked_cast<uint32_t>(extra_targets_.size())))
    return false;
  for (const auto& extra_target_sink : extra_targets_) {
    if (!sink->PutValue<uint8_t>(extra_target_sink.first.value()))
      return false;
    if (!extra_target_sink.second.SerializeInto(sink))
      return false;
  }
  return true;
}

/******** EnsemblePatchWriter ********/

EnsemblePatchWriter::~EnsemblePatchWriter() = default;

EnsemblePatchWriter::EnsemblePatchWriter(const PatchHeader& header)
    : header_(header) {
  DCHECK_EQ(header_.magic, PatchHeader::kMagic);
}

EnsemblePatchWriter::EnsemblePatchWriter(ConstBufferView old_image,
                                         ConstBufferView new_image) {
  header_.magic = PatchHeader::kMagic;
  header_.old_size = base::checked_cast<uint32_t>(old_image.size());
  header_.old_crc = CalculateCrc32(old_image.begin(), old_image.end());
  header_.new_size = base::checked_cast<uint32_t>(new_image.size());
  header_.new_crc = CalculateCrc32(new_image.begin(), new_image.end());
}

void EnsemblePatchWriter::AddElement(PatchElementWriter&& patch_element) {
  DCHECK(patch_element.new_element().offset == current_dst_offset_);
  current_dst_offset_ = patch_element.new_element().EndOffset();
  elements_.push_back(std::move(patch_element));
}

size_t EnsemblePatchWriter::SerializedSize() const {
  size_t serialized_size = sizeof(PatchHeader) + sizeof(uint32_t);
  for (const auto& patch_element : elements_) {
    serialized_size += patch_element.SerializedSize();
  }
  return serialized_size;
}

bool EnsemblePatchWriter::SerializeInto(BufferSink* sink) const {
  DCHECK_EQ(current_dst_offset_, header_.new_size);
  bool ok =
      sink->PutValue<PatchHeader>(header_) &&
      sink->PutValue<uint32_t>(base::checked_cast<uint32_t>(elements_.size()));
  if (!ok)
    return false;

  for (const auto& element : elements_) {
    if (!element.SerializeInto(sink))
      return false;
  }
  return true;
}

}  // namespace zucchini