// Copyright 2016 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 "components/ntp_snippets/remote/json_request.h"

#include <algorithm>
#include <utility>
#include <vector>

#include "base/bind.h"
#include "base/command_line.h"
#include "base/feature_list.h"
#include "base/json/json_writer.h"
#include "base/metrics/histogram_functions.h"
#include "base/metrics/histogram_macros.h"
#include "base/strings/stringprintf.h"
#include "base/time/clock.h"
#include "base/values.h"
#include "components/ntp_snippets/category_info.h"
#include "components/ntp_snippets/features.h"
#include "components/ntp_snippets/remote/request_params.h"
#include "components/ntp_snippets/user_classifier.h"
#include "components/strings/grit/components_strings.h"
#include "components/variations/net/variations_http_headers.h"
#include "components/variations/variations_associated_data.h"
#include "net/base/load_flags.h"
#include "net/http/http_response_headers.h"
#include "net/http/http_status_code.h"
#include "net/traffic_annotation/network_traffic_annotation.h"
#include "services/network/public/cpp/resource_request.h"
#include "services/network/public/cpp/shared_url_loader_factory.h"
#include "services/network/public/cpp/simple_url_loader.h"
#include "services/network/public/mojom/url_response_head.mojom.h"
#include "third_party/icu/source/common/unicode/uloc.h"
#include "third_party/icu/source/common/unicode/utypes.h"
#include "ui/base/l10n/l10n_util.h"

using language::UrlLanguageHistogram;

namespace ntp_snippets {

namespace internal {

namespace {

// Variation parameter for disabling the retry.
const char kBackground5xxRetriesName[] = "background_5xx_retries_count";

// Variation parameter for sending UrlLanguageHistogram info to the server.
const char kSendTopLanguagesName[] = "send_top_languages";

// Variation parameter for sending UserClassifier info to the server.
const char kSendUserClassName[] = "send_user_class";

bool IsSendingTopLanguagesEnabled() {
  return variations::GetVariationParamByFeatureAsBool(
      ntp_snippets::kArticleSuggestionsFeature, kSendTopLanguagesName,
      /*default_value=*/true);
}

bool IsSendingUserClassEnabled() {
  return variations::GetVariationParamByFeatureAsBool(
      ntp_snippets::kArticleSuggestionsFeature, kSendUserClassName,
      /*default_value=*/true);
}

bool IsSendingOptionalImagesCapabilityEnabled() {
  return base::FeatureList::IsEnabled(
      ntp_snippets::kOptionalImagesEnabledFeature);
}

// Translate the BCP 47 |language_code| into a posix locale string.
std::string PosixLocaleFromBCP47Language(const std::string& language_code) {
  char locale[ULOC_FULLNAME_CAPACITY];
  UErrorCode error = U_ZERO_ERROR;
  // Translate the input to a posix locale.
  uloc_forLanguageTag(language_code.c_str(), locale, ULOC_FULLNAME_CAPACITY,
                      nullptr, &error);
  if (error != U_ZERO_ERROR) {
    DLOG(WARNING) << "Error in translating language code to a locale string: "
                  << error;
    return std::string();
  }
  return locale;
}

std::string ISO639FromPosixLocale(const std::string& locale) {
  char language[ULOC_LANG_CAPACITY];
  UErrorCode error = U_ZERO_ERROR;
  uloc_getLanguage(locale.c_str(), language, ULOC_LANG_CAPACITY, &error);
  if (error != U_ZERO_ERROR) {
    DLOG(WARNING)
        << "Error in translating locale string to a ISO639 language code: "
        << error;
    return std::string();
  }
  return language;
}

void AppendLanguageInfoToList(base::Value::List* list,
                              const UrlLanguageHistogram::LanguageInfo& info) {
  base::Value::Dict lang;
  lang.Set("language", info.language_code);
  lang.Set("frequency", info.frequency);
  list->Append(std::move(lang));
}

std::string GetUserClassString(UserClassifier::UserClass user_class) {
  switch (user_class) {
    case UserClassifier::UserClass::RARE_NTP_USER:
      return "RARE_NTP_USER";
    case UserClassifier::UserClass::ACTIVE_NTP_USER:
      return "ACTIVE_NTP_USER";
    case UserClassifier::UserClass::ACTIVE_SUGGESTIONS_CONSUMER:
      return "ACTIVE_SUGGESTIONS_CONSUMER";
  }
  NOTREACHED();
  return std::string();
}

}  // namespace

JsonRequest::JsonRequest(
    absl::optional<Category> exclusive_category,
    const base::Clock* clock,  // Needed until destruction of the request.
    const ParseJSONCallback& callback)
    : exclusive_category_(exclusive_category),
      clock_(clock),
      parse_json_callback_(callback) {
  creation_time_ = clock_->Now();
}

JsonRequest::~JsonRequest() {
  LOG_IF(DFATAL, !request_completed_callback_.is_null())
      << "The CompletionCallback was never called!";
}

void JsonRequest::Start(CompletedCallback callback) {
  DCHECK(simple_url_loader_);
  DCHECK(url_loader_factory_);
  request_completed_callback_ = std::move(callback);
  last_response_string_.clear();
  simple_url_loader_->SetAllowHttpErrorResults(true);
  simple_url_loader_->DownloadToStringOfUnboundedSizeUntilCrashAndDie(
      url_loader_factory_.get(),
      base::BindOnce(&JsonRequest::OnSimpleLoaderComplete,
                     base::Unretained(this)));
}

// static
int JsonRequest::Get5xxRetryCount(bool interactive_request) {
  if (interactive_request) {
    return 2;
  }
  return std::max(0, variations::GetVariationParamByFeatureAsInt(
                         ntp_snippets::kArticleSuggestionsFeature,
                         kBackground5xxRetriesName, 0));
}

base::TimeDelta JsonRequest::GetFetchDuration() const {
  return clock_->Now() - creation_time_;
}

std::string JsonRequest::GetResponseString() const {
  return last_response_string_;
}

void JsonRequest::OnSimpleLoaderComplete(
    std::unique_ptr<std::string> response_body) {
  int net_error = simple_url_loader_->NetError();
  int response_code = -1;
  if (simple_url_loader_->ResponseInfo() &&
      simple_url_loader_->ResponseInfo()->headers) {
    response_code =
        simple_url_loader_->ResponseInfo()->headers->response_code();
  }
  simple_url_loader_.reset();
  base::UmaHistogramSparse("NewTabPage.Snippets.FetchHttpResponseOrErrorCode",
                           net_error == net::OK ? response_code : net_error);
  if (net_error != net::OK) {
    std::move(request_completed_callback_)
        .Run(/*result=*/base::Value(), FetchResult::URL_REQUEST_STATUS_ERROR,
             /*error_details=*/base::StringPrintf(" %d", net_error));
  } else if (response_code / 100 != 2) {
    FetchResult result = response_code == net::HTTP_UNAUTHORIZED
                             ? FetchResult::HTTP_ERROR_UNAUTHORIZED
                             : FetchResult::HTTP_ERROR;
    std::move(request_completed_callback_)
        .Run(/*result=*/base::Value(), result,
             /*error_details=*/base::StringPrintf(" %d", response_code));
  } else {
    last_response_string_ = std::move(*response_body);
    parse_json_callback_.Run(last_response_string_,
                             base::BindOnce(&JsonRequest::OnJsonParsed,
                                            weak_ptr_factory_.GetWeakPtr()),
                             base::BindOnce(&JsonRequest::OnJsonError,
                                            weak_ptr_factory_.GetWeakPtr()));
  }
}

void JsonRequest::OnJsonParsed(base::Value result) {
  std::move(request_completed_callback_)
      .Run(std::move(result), FetchResult::SUCCESS,
           /*error_details=*/std::string());
}

void JsonRequest::OnJsonError(const std::string& error) {
  LOG(WARNING) << "Received invalid JSON (" << error
               << "): " << last_response_string_;
  std::move(request_completed_callback_)
      .Run(/*result=*/base::Value(), FetchResult::JSON_PARSE_ERROR,
           /*error_details=*/base::StringPrintf(" (error %s)", error.c_str()));
}

JsonRequest::Builder::Builder() : language_histogram_(nullptr) {}
JsonRequest::Builder::Builder(JsonRequest::Builder&&) = default;
JsonRequest::Builder::~Builder() = default;

std::unique_ptr<JsonRequest> JsonRequest::Builder::Build() const {
  DCHECK(!url_.is_empty());
  DCHECK(url_loader_factory_);
  DCHECK(clock_);
  auto request = std::make_unique<JsonRequest>(params_.exclusive_category,
                                               clock_, parse_json_callback_);
  std::string body = BuildBody();
  request->simple_url_loader_ = BuildURLLoader(body);
  request->url_loader_factory_ = std::move(url_loader_factory_);

  return request;
}

JsonRequest::Builder& JsonRequest::Builder::SetAuthentication(
    const std::string& auth_header) {
  auth_header_ = auth_header;
  return *this;
}

JsonRequest::Builder& JsonRequest::Builder::SetLanguageHistogram(
    const language::UrlLanguageHistogram* language_histogram) {
  language_histogram_ = language_histogram;
  return *this;
}

JsonRequest::Builder& JsonRequest::Builder::SetParams(
    const RequestParams& params) {
  params_ = params;
  return *this;
}

JsonRequest::Builder& JsonRequest::Builder::SetParseJsonCallback(
    ParseJSONCallback callback) {
  parse_json_callback_ = callback;
  return *this;
}

JsonRequest::Builder& JsonRequest::Builder::SetClock(const base::Clock* clock) {
  clock_ = clock;
  return *this;
}

JsonRequest::Builder& JsonRequest::Builder::SetUrl(const GURL& url) {
  url_ = url;
  return *this;
}

JsonRequest::Builder& JsonRequest::Builder::SetUrlLoaderFactory(
    scoped_refptr<network::SharedURLLoaderFactory> url_loader_factory) {
  url_loader_factory_ = std::move(url_loader_factory);
  return *this;
}

JsonRequest::Builder& JsonRequest::Builder::SetUserClassifier(
    const UserClassifier& user_classifier) {
  if (IsSendingUserClassEnabled()) {
    user_class_ = GetUserClassString(user_classifier.GetUserClass());
  }
  return *this;
}

JsonRequest::Builder& JsonRequest::Builder::SetOptionalImagesCapability(
    bool supports_optional_images) {
  if (supports_optional_images && IsSendingOptionalImagesCapabilityEnabled()) {
    display_capability_ = "CAPABILITY_OPTIONAL_IMAGES";
  }
  return *this;
}

std::unique_ptr<network::ResourceRequest>
JsonRequest::Builder::BuildResourceRequest() const {
  auto resource_request = std::make_unique<network::ResourceRequest>();
  resource_request->url = url_;
  resource_request->credentials_mode = network::mojom::CredentialsMode::kOmit;
  resource_request->method = "POST";
  resource_request->headers.SetHeader("Content-Type",
                                      "application/json; charset=UTF-8");
  if (!auth_header_.empty()) {
    resource_request->headers.SetHeader("Authorization", auth_header_);
  }
  // Add X-Client-Data header with experiment IDs from field trials.
  // TODO: We should call AppendVariationHeaders with explicit
  // variations::SignedIn::kNo If the auth_header_ is empty
  variations::AppendVariationsHeaderUnknownSignedIn(
      url_, variations::InIncognito::kNo, resource_request.get());
  return resource_request;
}

std::string JsonRequest::Builder::BuildBody() const {
  base::Value::Dict request;
  std::string user_locale = PosixLocaleFromBCP47Language(params_.language_code);
  if (!user_locale.empty()) {
    request.Set("uiLanguage", user_locale);
  }

  request.Set("priority", params_.interactive_request ? "USER_ACTION"
                                                      : "BACKGROUND_PREFETCH");

  base::Value::List excluded;
  for (const auto& id : params_.excluded_ids) {
    excluded.Append(id);
  }
  request.Set("excludedSuggestionIds", std::move(excluded));

  if (!user_class_.empty()) {
    request.Set("userActivenessClass", user_class_);
  }

  if (!display_capability_.empty()) {
    request.Set("displayCapability", display_capability_);
  }

  language::UrlLanguageHistogram::LanguageInfo ui_language;
  language::UrlLanguageHistogram::LanguageInfo other_top_language;
  PrepareLanguages(&ui_language, &other_top_language);
  if (ui_language.frequency != 0 || other_top_language.frequency != 0) {
    base::Value::List language_list;
    if (ui_language.frequency > 0) {
      AppendLanguageInfoToList(&language_list, ui_language);
    }
    if (other_top_language.frequency > 0) {
      AppendLanguageInfoToList(&language_list, other_top_language);
    }
    request.Set("topLanguages", std::move(language_list));
  }

  // TODO(vitaliii): Support count_to_fetch without requiring
  // |exclusive_category|.
  if (params_.exclusive_category.has_value()) {
    base::Value::Dict exclusive_category_parameters;
    exclusive_category_parameters.Set("id",
                                      params_.exclusive_category->remote_id());
    exclusive_category_parameters.Set("numSuggestions", params_.count_to_fetch);
    base::Value::List category_parameters;
    category_parameters.Append(std::move(exclusive_category_parameters));
    request.Set("categoryParameters", std::move(category_parameters));
  }

  std::string request_json;
  bool success = base::JSONWriter::WriteWithOptions(
      request, base::JSONWriter::OPTIONS_PRETTY_PRINT, &request_json);
  DCHECK(success);
  return request_json;
}

std::unique_ptr<network::SimpleURLLoader> JsonRequest::Builder::BuildURLLoader(
    const std::string& body) const {
  net::NetworkTrafficAnnotationTag traffic_annotation =
      net::DefineNetworkTrafficAnnotation("ntp_snippets_fetch", R"(
        semantics {
          sender: "New Tab Page Content Suggestions Fetch"
          description:
            "Chromium can show content suggestions (e.g. news articles) on the "
            "New Tab page. For signed-in users, these may be personalized "
            "based on the user's synced browsing history."
          trigger:
            "Triggered periodically in the background, or upon explicit user "
            "request."
          data:
            "The Chromium UI language, as well as a second language the user "
            "understands, based on language::UrlLanguageHistogram. For "
            "signed-in users, the requests is authenticated."
          destination: GOOGLE_OWNED_SERVICE
        }
        policy {
          cookies_allowed: NO
          setting:
            "This feature cannot be disabled by settings now (but is requested "
            "to be implemented in crbug.com/695129)."
          chrome_policy {
            NTPContentSuggestionsEnabled {
              policy_options {mode: MANDATORY}
              NTPContentSuggestionsEnabled: false
            }
          }
        })");
  auto resource_request = BuildResourceRequest();

  // Log the request for debugging network issues.
  VLOG(1) << "Sending a NTP snippets request to " << url_ << ":\n"
          << resource_request->headers.ToString() << "\n"
          << body;

  auto loader = network::SimpleURLLoader::Create(std::move(resource_request),
                                                 traffic_annotation);
  loader->AttachStringForUpload(body, "application/json");
  int max_retries = JsonRequest::Get5xxRetryCount(params_.interactive_request);
  if (max_retries > 0) {
    loader->SetRetryOptions(
        max_retries, network::SimpleURLLoader::RETRY_ON_5XX |
                         network::SimpleURLLoader::RETRY_ON_NETWORK_CHANGE);
  }
  return loader;
}

void JsonRequest::Builder::PrepareLanguages(
    language::UrlLanguageHistogram::LanguageInfo* ui_language,
    language::UrlLanguageHistogram::LanguageInfo* other_top_language) const {
  // TODO(jkrcal): Add language model factory for iOS and add fakes to tests so
  // that |language_histogram| is never nullptr. Remove this check and add a
  // DCHECK into the constructor.
  if (!language_histogram_ || !IsSendingTopLanguagesEnabled()) {
    return;
  }

  // TODO(jkrcal): Is this back-and-forth converting necessary?
  ui_language->language_code = ISO639FromPosixLocale(
      PosixLocaleFromBCP47Language(params_.language_code));
  ui_language->frequency =
      language_histogram_->GetLanguageFrequency(ui_language->language_code);

  std::vector<UrlLanguageHistogram::LanguageInfo> top_languages =
      language_histogram_->GetTopLanguages();
  for (const UrlLanguageHistogram::LanguageInfo& info : top_languages) {
    if (info.language_code != ui_language->language_code) {
      *other_top_language = info;

      // Report to UMA how important the UI language is.
      DCHECK_GT(other_top_language->frequency, 0)
          << "GetTopLanguages() should not return languages with 0 frequency";
      float ratio_ui_in_both_languages =
          ui_language->frequency /
          (ui_language->frequency + other_top_language->frequency);
      UMA_HISTOGRAM_PERCENTAGE(
          "NewTabPage.Languages.UILanguageRatioInTwoTopLanguages",
          ratio_ui_in_both_languages * 100);
      break;
    }
  }
}

}  // namespace internal

}  // namespace ntp_snippets