// 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/zucchini_tools.h"

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

#include <algorithm>
#include <memory>
#include <ostream>
#include <utility>

#include "base/bind.h"
#include "base/check_op.h"
#include "base/strings/stringprintf.h"
#include "components/zucchini/disassembler.h"
#include "components/zucchini/element_detection.h"
#include "components/zucchini/ensemble_matcher.h"
#include "components/zucchini/heuristic_ensemble_matcher.h"
#include "components/zucchini/imposed_ensemble_matcher.h"
#include "components/zucchini/io_utils.h"

namespace zucchini {

status::Code ReadReferences(ConstBufferView image,
                            bool do_dump,
                            std::ostream& out) {
  std::unique_ptr<Disassembler> disasm = MakeDisassemblerWithoutFallback(image);
  if (!disasm) {
    out << "Input file not recognized as executable." << std::endl;
    return status::kStatusInvalidOldImage;
  }

  std::vector<offset_t> targets;
  for (const auto& group : disasm->MakeReferenceGroups()) {
    targets.clear();
    auto refs = group.GetReader(disasm.get());
    for (auto ref = refs->GetNext(); ref.has_value(); ref = refs->GetNext())
      targets.push_back(ref->target);

    size_t num_locations = targets.size();
    std::sort(targets.begin(), targets.end());
    targets.erase(std::unique(targets.begin(), targets.end()), targets.end());
    size_t num_targets = targets.size();

    out << "Type " << int(group.type_tag().value())
        << ": Pool=" << static_cast<uint32_t>(group.pool_tag().value())
        << ", width=" << group.width() << ", #locations=" << num_locations
        << ", #targets=" << num_targets;
    if (num_targets > 0) {
      double ratio = static_cast<double>(num_locations) / num_targets;
      out << " (ratio=" << base::StringPrintf("%.4f", ratio) << ")";
    }
    out << std::endl;

    if (do_dump) {
      refs = group.GetReader(disasm.get());

      for (auto ref = refs->GetNext(); ref; ref = refs->GetNext()) {
        out << "  " << AsHex<8>(ref->location) << " " << AsHex<8>(ref->target)
            << std::endl;
      }
    }
  }

  return status::kStatusSuccess;
}

status::Code DetectAll(ConstBufferView image,
                       std::ostream& out,
                       std::vector<ConstBufferView>* sub_image_list) {
  DCHECK_NE(sub_image_list, nullptr);
  sub_image_list->clear();

  const size_t size = image.size();
  size_t last_out_pos = 0;
  size_t total_bytes_found = 0;

  auto print_range = [&out](size_t pos, size_t size, const std::string& msg) {
    out << "-- " << AsHex<8, size_t>(pos) << " +" << AsHex<8, size_t>(size)
        << ": " << msg << std::endl;
  };

  ElementFinder finder(image,
                       base::BindRepeating(DetectElementFromDisassembler));
  for (auto element = finder.GetNext(); element.has_value();
       element = finder.GetNext()) {
    ConstBufferView sub_image = image[element->region()];
    sub_image_list->push_back(sub_image);
    size_t pos = sub_image.begin() - image.begin();
    size_t prog_size = sub_image.size();
    if (last_out_pos < pos)
      print_range(last_out_pos, pos - last_out_pos, "?");
    auto disasm = MakeDisassemblerOfType(sub_image, element->exe_type);
    print_range(pos, prog_size, disasm->GetExeTypeString());
    total_bytes_found += prog_size;
    last_out_pos = pos + prog_size;
  }
  if (last_out_pos < size)
    print_range(last_out_pos, size - last_out_pos, "?");
  out << std::endl;

  // Print summary, using decimal instead of hexadecimal.
  out << "Detected " << total_bytes_found << "/" << size << " bytes => ";
  double percent = total_bytes_found * 100.0 / size;
  out << base::StringPrintf("%.2f", percent) << "%." << std::endl;

  return status::kStatusSuccess;
}

status::Code MatchAll(ConstBufferView old_image,
                      ConstBufferView new_image,
                      std::string imposed_matches,
                      std::ostream& out) {
  std::unique_ptr<EnsembleMatcher> matcher;
  if (imposed_matches.empty()) {
    matcher = std::make_unique<HeuristicEnsembleMatcher>(&out);
  } else {
    matcher =
        std::make_unique<ImposedEnsembleMatcher>(std::move(imposed_matches));
  }
  if (!matcher->RunMatch(old_image, new_image)) {
    out << "RunMatch() failed.";
    return status::kStatusFatal;
  }
  out << "Found " << matcher->matches().size() << " nontrivial matches and "
      << matcher->num_identical() << " identical matches." << std::endl
      << "To impose the same matches by command line, use: " << std::endl
      << "  -impose=";
  PrefixSep sep(",");
  for (const ElementMatch& match : matcher->matches())
    out << sep << match.ToString();
  out << std::endl;

  return status::kStatusSuccess;
}

}  // namespace zucchini