chrome/browser/on_device_translation/translation_manager_util.h

// Copyright 2025 The Chromium Authors
// Use of this source code is governed by a BSD-style license that can be
// found in the LICENSE file.

#ifndef CHROME_BROWSER_ON_DEVICE_TRANSLATION_TRANSLATION_MANAGER_UTIL_H_
#define CHROME_BROWSER_ON_DEVICE_TRANSLATION_TRANSLATION_MANAGER_UTIL_H_

#include <optional>
#include <string_view>
#include <vector>

#include "chrome/browser/on_device_translation/language_pack_util.h"
#include "components/prefs/pref_service.h"
#include "content/public/browser/browser_context.h"

namespace on_device_translation {

// Returns the Accept Languages for a given Profile.
const std::vector<std::string_view> GetAcceptLanguages(
    content::BrowserContext* browser_context);

// Determines if a given language is in the Accept languages.
bool IsInAcceptLanguage(const std::vector<std::string_view>& accept_languages,
                        const std::string_view lang);

// Determines if the Translator API is enabled.
bool IsTranslatorAllowed(content::BrowserContext* browser_context);

// Implementation of LookupMatchingLocaleByBestFit
// (https://tc39.es/ecma402/#sec-lookupmatchinglocalebybestfit) as
// LookupMatchingLocaleByPrefix
// (https://tc39.es/ecma402/#sec-lookupmatchinglocalebyprefix) assuming
// `available_languages` contains no extension.
template <typename SetType>
std::optional<std::string> LookupMatchingLocaleByBestFit(
    const SetType& available_languages,
    std::string requested_language) {
  std::string prefix = std::move(requested_language);
  while (prefix != "") {
    if (available_languages.contains(prefix)) {
      return prefix;
    }
    int pos = prefix.rfind('-');
    if (pos == -1) {
      break;
    }
    prefix.resize(pos);
  }
  return std::nullopt;
}

}  // namespace on_device_translation

#endif  // CHROME_BROWSER_ON_DEVICE_TRANSLATION_TRANSLATION_MANAGER_UTIL_H_