// Copyright 2013 The Chromium Authors
// Use of this source code is governed by a BSD-style license that can be
// found in the LICENSE file.

#include "components/autofill/core/common/autofill_regexes.h"

#include <tuple>

#include "base/check.h"
#include "base/containers/to_vector.h"
#include "base/debug/crash_logging.h"
#include "base/i18n/unicodestring.h"
#include "base/memory/ptr_util.h"
#include "base/not_fatal_until.h"
#include "base/notreached.h"
#include "base/strings/utf_string_conversions.h"

namespace {

// Maximum length of the string to match to avoid causing an icu::RegexMatcher
// stack overflow. (crbug.com/1198219)
constexpr int kMaxStringLength = 5000;

}  // namespace

namespace autofill {

std::unique_ptr<const icu::RegexPattern> CompileRegex(std::u16string_view regex,
                                                      uint32_t flags) {
  const icu::UnicodeString icu_regex(false, regex.data(), regex.length());
  UErrorCode status = U_ZERO_ERROR;
  std::unique_ptr<icu::RegexPattern> regex_pattern =
      base::WrapUnique(icu::RegexPattern::compile(icu_regex, flags, status));

  // TODO(crbug.com/468309430): The following is temporary instrumentation to
  // investigate regex compilation failures. Once fixed, replace this with
  // `CHECK(U_SUCCESS(status));`
  if (U_FAILURE(status)) {
    SCOPED_CRASH_KEY_STRING32("autofill", "bad-regex",
                              base::UTF16ToUTF8(regex));
    DUMP_WILL_BE_NOTREACHED();
    return nullptr;
  }
  return regex_pattern;
}

bool MatchesRegex(std::u16string_view input,
                  const icu::RegexPattern* regex_pattern,
                  std::vector<std::u16string>* groups) {
  // TODO(crbug.com/468309430): Make this a `CHECK` once issue is fixed.
  if (!regex_pattern) {
    return false;
  }

  if (input.size() > kMaxStringLength)
    return false;

  UErrorCode status = U_ZERO_ERROR;
  // `icu_input` must outlive `regex_matcher` because it holds a reference to
  // it.
  icu::UnicodeString icu_input(false, input.data(), input.length());
  std::unique_ptr<icu::RegexMatcher> regex_matcher =
      base::WrapUnique(regex_pattern->matcher(icu_input, status));
  UBool matched = regex_matcher->find(0, status);
  DCHECK(U_SUCCESS(status));

  if (matched && groups) {
    int32_t matched_groups = regex_matcher->groupCount();
    groups->resize(matched_groups + 1);
    for (int32_t i = 0; i < matched_groups + 1; ++i) {
      icu::UnicodeString match_unicode = regex_matcher->group(i, status);
      DCHECK(U_SUCCESS(status));
      (*groups)[i] = base::i18n::UnicodeStringToString16(match_unicode);
    }
  }
  return matched;
}

std::u16string MatchAndReplace(std::u16string_view input,
                               const icu::RegexPattern& pattern,
                               std::string_view replacement) {
  icu::UnicodeString icu_input(input);
  UErrorCode status = U_ZERO_ERROR;
  std::unique_ptr<icu::RegexMatcher> matcher =
      base::WrapUnique(pattern.matcher(icu_input, status));
  DCHECK(U_SUCCESS(status));
  icu_input =
      matcher->replaceAll(icu::UnicodeString::fromUTF8(replacement), status);
  return base::i18n::UnicodeStringToString16(icu_input);
}

std::optional<std::vector<std::u16string>> SplitByRegex(
    std::u16string_view input,
    const icu::RegexPattern& regex_pattern,
    size_t max_groups) {
  UErrorCode status = U_ZERO_ERROR;
  icu::UnicodeString icu_input(false, input.data(), input.length());
  std::vector<icu::UnicodeString> parts(max_groups);
  int32_t part_count =
      regex_pattern.split(icu_input, parts.data(), parts.size(), status);
  if (U_FAILURE(status) || part_count <= 0) {
    return std::nullopt;
  }
  parts.resize(part_count);
  return base::ToVector(parts, &base::i18n::UnicodeStringToString16);
}

AutofillRegexCache::AutofillRegexCache(ThreadSafe thread_safe)
    : thread_safe_(thread_safe) {
  if (!thread_safe_)
    DCHECK_CALLED_ON_VALID_SEQUENCE(sequence_checker_);
}

AutofillRegexCache::~AutofillRegexCache() {
  if (!thread_safe_)
    DCHECK_CALLED_ON_VALID_SEQUENCE(sequence_checker_);
}

const icu::RegexPattern* AutofillRegexCache::GetRegexPattern(
    std::u16string_view regex) {
  auto GetOrCreate = [&] {
    auto it = cache_.find(regex);
    if (it == cache_.end()) {
      bool success;
      std::tie(it, success) =
          cache_.emplace(std::u16string(regex), CompileRegex(regex));
      DCHECK(success);
    }
    CHECK(it != cache_.end());
    DCHECK(it->second.get());
    return it->second.get();
  };
  if (!thread_safe_) {
    DCHECK_CALLED_ON_VALID_SEQUENCE(sequence_checker_);
    return GetOrCreate();
  }
  base::AutoLock lock(lock_);
  return GetOrCreate();
}

}  // namespace autofill