// 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 "ios/web_view/internal/language/web_view_language_model_manager_factory.h"

#include "base/feature_list.h"
#include "base/memory/singleton.h"
#include "components/keyed_service/core/keyed_service.h"
#include "components/keyed_service/ios/browser_state_dependency_manager.h"
#include "components/language/core/browser/baseline_language_model.h"
#include "components/language/core/browser/heuristic_language_model.h"
#include "components/language/core/browser/language_model.h"
#include "components/language/core/browser/language_model_manager.h"
#include "components/language/core/browser/pref_names.h"
#include "components/language/core/common/language_experiments.h"
#include "components/pref_registry/pref_registry_syncable.h"
#include "components/prefs/pref_service.h"
#include "ios/web_view/internal/app/application_context.h"
#include "ios/web_view/internal/pref_names.h"
#include "ios/web_view/internal/web_view_browser_state.h"

namespace ios_web_view {

namespace {

void PrepareLanguageModels(WebViewBrowserState* const web_view_browser_state,
                           language::LanguageModelManager* const manager) {
  language::OverrideLanguageModel override_model_mode =
      language::GetOverrideLanguageModel();

  // Create all of the models required based on the state of experiments. There
  // may be more than one, the primary one is set below.
  if (override_model_mode == language::OverrideLanguageModel::HEURISTIC) {
    manager->AddModel(
        language::LanguageModelManager::ModelType::HEURISTIC,
        std::make_unique<language::HeuristicLanguageModel>(
            web_view_browser_state->GetPrefs(),
            ApplicationContext::GetInstance()->GetApplicationLocale(),
            prefs::kAcceptLanguages, language::prefs::kUserLanguageProfile));
  }

  // language::OverrideLanguageModel::GEO is not supported on iOS yet.

  if (override_model_mode == language::OverrideLanguageModel::DEFAULT) {
    manager->AddModel(
        language::LanguageModelManager::ModelType::BASELINE,
        std::make_unique<language::BaselineLanguageModel>(
            web_view_browser_state->GetPrefs(),
            ApplicationContext::GetInstance()->GetApplicationLocale(),
            prefs::kAcceptLanguages));
  }

  // Set the primary Language Model to use based on the state of experiments.
  switch (override_model_mode) {
    case language::OverrideLanguageModel::HEURISTIC:
      manager->SetPrimaryModel(
          language::LanguageModelManager::ModelType::HEURISTIC);
      break;
    case language::OverrideLanguageModel::DEFAULT:
    default:
      manager->SetPrimaryModel(
          language::LanguageModelManager::ModelType::BASELINE);
      break;
  }
}

}  // namespace

// static
WebViewLanguageModelManagerFactory*
WebViewLanguageModelManagerFactory::GetInstance() {
  return base::Singleton<WebViewLanguageModelManagerFactory>::get();
}

// static
language::LanguageModelManager*
WebViewLanguageModelManagerFactory::GetForBrowserState(
    WebViewBrowserState* const state) {
  return static_cast<language::LanguageModelManager*>(
      GetInstance()->GetServiceForBrowserState(state, true));
}

WebViewLanguageModelManagerFactory::WebViewLanguageModelManagerFactory()
    : BrowserStateKeyedServiceFactory(
          "LanguageModelManager",
          BrowserStateDependencyManager::GetInstance()) {}

std::unique_ptr<KeyedService>
WebViewLanguageModelManagerFactory::BuildServiceInstanceFor(
    web::BrowserState* const context) const {
  WebViewBrowserState* const web_view_browser_state =
      WebViewBrowserState::FromBrowserState(context);
  std::unique_ptr<language::LanguageModelManager> manager =
      std::make_unique<language::LanguageModelManager>(
          web_view_browser_state->GetPrefs(),
          ApplicationContext::GetInstance()->GetApplicationLocale());
  PrepareLanguageModels(web_view_browser_state, manager.get());
  return manager;
}

void WebViewLanguageModelManagerFactory::RegisterBrowserStatePrefs(
    user_prefs::PrefRegistrySyncable* const registry) {
  if (base::FeatureList::IsEnabled(language::kUseHeuristicLanguageModel)) {
    registry->RegisterDictionaryPref(
        language::prefs::kUserLanguageProfile,
        user_prefs::PrefRegistrySyncable::SYNCABLE_PRIORITY_PREF);
  }
}

web::BrowserState* WebViewLanguageModelManagerFactory::GetBrowserStateToUse(
    web::BrowserState* state) const {
  WebViewBrowserState* browser_state =
      WebViewBrowserState::FromBrowserState(state);
  return browser_state->GetRecordingBrowserState();
}

}  // namespace ios_web_view