// Copyright 2010-2014, Google Inc.
// All rights reserved.
//
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// 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
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// contributors may be used to endorse or promote products derived from
// this software without specific prior written permission.
//
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// OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.

#include <algorithm>
#include <string>

#include "base/codegen_bytearray_stream.h"
#include "base/file_stream.h"
#include "base/flags.h"
#include "base/logging.h"
#include "base/util.h"
#include "storage/existence_filter.h"

DEFINE_string(input, "", "per-line suggestion filter list");
DEFINE_string(output, "", "output bloom filter");
DEFINE_bool(header, true,
            "make header file instead of raw bloom filter");
DEFINE_string(name, "SuggestionFilterData",
              "name for variable name in the header file");

namespace {
void ReadWords(const string &name, vector<uint64> *words) {
  string line;
  mozc::InputFileStream input(name.c_str());
  while (getline(input, line)) {
    if (line.empty() || line[0] == '#') {
      continue;
    }
    string lower_value = line;
    mozc::Util::LowerString(&lower_value);
    words->push_back(mozc::Util::Fingerprint(lower_value));
  }
}

const size_t kMinimumFilterBytes = 100 * 1000;
}  // namespace

using mozc::storage::ExistenceFilter;

// read per-line word list and generate
// bloom filter in raw byte array or header file format
int main(int argc, char **argv) {
  InitGoogle(argv[0], &argc, &argv, true);

  if ((FLAGS_input.empty() ||
       FLAGS_output.empty()) && argc > 2) {
    FLAGS_input = argv[1];
    FLAGS_output = argv[2];
  }

  vector<uint64> words;

  ReadWords(FLAGS_input, &words);

  LOG(INFO) << words.size() << " words found";

  static const float kErrorRate = 0.00001;
  const size_t num_bytes = max(
      ExistenceFilter::MinFilterSizeInBytesForErrorRate(
          kErrorRate, words.size()),
      kMinimumFilterBytes);

  LOG(INFO) << "num_bytes: " << num_bytes;

  scoped_ptr<ExistenceFilter> filter(
      ExistenceFilter::CreateOptimal(num_bytes, words.size()));
  for (size_t i = 0; i < words.size(); ++i) {
    filter->Insert(words[i]);
  }

  char *buf = NULL;
  size_t size = 0;

  LOG(INFO) << "writing bloomfilter: " << FLAGS_output;
  filter->Write(&buf, &size);

  if (FLAGS_header) {
    mozc::OutputFileStream ofs(FLAGS_output.c_str());
    mozc::CodeGenByteArrayOutputStream codegen_stream(
        &ofs, mozc::codegenstream::NOT_OWN_STREAM);
    codegen_stream.OpenVarDef(FLAGS_name);
    codegen_stream.write(buf, size);
    codegen_stream.CloseVarDef();
  } else {
    mozc::OutputFileStream ofs(FLAGS_output.c_str(),
                               ios::out | ios::trunc | ios::binary);
    ofs.write(buf, size);
  }

  delete [] buf;

  return 0;
}