// Copyright 2019 the V8 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 <fstream>
#include <iomanip>
#include <iostream>
#include <sstream>

#include "src/base/logging.h"
#include "unicode/uchar.h"
#include "unicode/uniset.h"

namespace v8 {
namespace internal {

// The following code generates BuildSpecialAddSet() and BuildIgnoreSet()
// functions into "src/regexp/special-case.cc".
// See more details in http://shorturl.at/adfO5
void PrintSet(std::ofstream& out, const char* func_name,
              const icu::UnicodeSet& set) {
  out << "icu::UnicodeSet " << func_name << "() {\n"
      << "  icu::UnicodeSet set;\n";
  for (int32_t i = 0; i < set.getRangeCount(); i++) {
    if (set.getRangeStart(i) == set.getRangeEnd(i)) {
      out << "  set.add(0x" << set.getRangeStart(i) << ");\n";
    } else {
      out << "  set.add(0x" << set.getRangeStart(i) << ", 0x"
          << set.getRangeEnd(i) << ");\n";
    }
  }
  out << "  set.freeze();\n"
      << "  return set;\n"
      << "}\n";
}

void PrintSpecial(std::ofstream& out) {
  icu::UnicodeSet current;
  icu::UnicodeSet processed(0xd800, 0xdbff);  // Ignore surrogate range.
  icu::UnicodeSet special_add;
  icu::UnicodeSet ignore;
  UErrorCode status = U_ZERO_ERROR;
  icu::UnicodeSet upper("[\\p{Lu}]", status);
  CHECK(U_SUCCESS(status));
  // Iterate through all chars in BMP except ASCII and Surrogate.
  for (UChar32 i = 0x80; i < 0x010000; i++) {
    // Ignore those characters which is already processed.
    if (!processed.contains(i)) {
      current.set(i, i);
      current.closeOver(USET_CASE_INSENSITIVE);

      // Remember we already processed current.
      processed.addAll(current);

      // All uppercase characters in current.
      icu::UnicodeSet keep_upper(current);
      keep_upper.retainAll(upper);

      // Check if we have more than one uppercase character in current.
      // If there are more than one uppercase character, then it is a special
      // set which need to be added into either "Special Add" set or "Ignore"
      // set.
      int32_t number_of_upper = 0;
      for (int32_t i = 0; i < keep_upper.getRangeCount() && i <= 1; i++) {
        number_of_upper +=
            keep_upper.getRangeEnd(i) - keep_upper.getRangeStart(i) + 1;
      }
      if (number_of_upper > 1) {
        // Add all non uppercase characters (could be Ll or Mn) to special add
        // set.
        current.removeAll(upper);
        special_add.addAll(current);

        // Add the uppercase characters of non uppercase character to
        // special add set.
        CHECK_GT(current.getRangeCount(), 0);
        UChar32 main_upper = u_toupper(current.getRangeStart(0));
        special_add.add(main_upper);

        // Add all uppercase except the main upper to ignore set.
        keep_upper.remove(main_upper);
        ignore.addAll(keep_upper);
      }
    }
  }

  // Remove any ASCII
  special_add.remove(0x0000, 0x007f);
  PrintSet(out, "BuildIgnoreSet", ignore);
  PrintSet(out, "BuildSpecialAddSet", special_add);
}

void WriteHeader(const char* header_filename) {
  std::ofstream out(header_filename);
  out << std::hex << std::setfill('0') << std::setw(4);

  out << "// Automatically generated by regexp/gen-regexp-special-case.cc\n"
      << "// The following functions are used to build icu::UnicodeSet\n"
      << "// for specical cases different between Unicode and ECMA262.\n"
      << "#ifdef V8_INTL_SUPPORT\n"
      << "#include \"src/regexp/special-case.h\"\n\n"
      << "#include \"unicode/uniset.h\"\n"
      << "namespace v8 {\n"
      << "namespace internal {\n\n";

  PrintSpecial(out);

  out << "\n"
      << "}  // namespace internal\n"
      << "}  // namespace v8\n"
      << "#endif  // V8_INTL_SUPPORT\n";
}

}  // namespace internal
}  // namespace v8

int main(int argc, const char** argv) {
  if (argc != 2) {
    std::cerr << "Usage: " << argv[0] << " <output filename>\n";
    std::exit(1);
  }
  v8::internal::WriteHeader(argv[1]);

  return 0;
}