// Copyright 2023 The Chromium Authors
// Use of this source code is governed by a BSD-style license that can be
// found in the LICENSE file.

#include "chrome/browser/ui/ash/glanceables/glanceables_classroom_client_impl.h"

#include <algorithm>
#include <functional>
#include <memory>
#include <numeric>
#include <optional>
#include <string>
#include <utility>
#include <vector>

#include "ash/constants/ash_features.h"
#include "ash/constants/ash_pref_names.h"
#include "ash/constants/web_app_id_constants.h"
#include "ash/glanceables/classroom/glanceables_classroom_types.h"
#include "ash/glanceables/glanceables_metrics.h"
#include "base/barrier_closure.h"
#include "base/check.h"
#include "base/containers/contains.h"
#include "base/containers/flat_map.h"
#include "base/functional/bind.h"
#include "base/functional/callback_forward.h"
#include "base/memory/weak_ptr.h"
#include "base/metrics/histogram_functions.h"
#include "base/notreached.h"
#include "base/strings/string_util.h"
#include "base/time/clock.h"
#include "base/time/time.h"
#include "base/types/expected.h"
#include "chrome/browser/apps/app_service/app_service_proxy.h"
#include "chrome/browser/apps/app_service/app_service_proxy_factory.h"
#include "chrome/browser/profiles/profile.h"
#include "chrome/browser/ui/ash/glanceables/glanceables_classroom_course_work_item.h"
#include "components/policy/content/policy_blocklist_service.h"
#include "components/policy/core/browser/url_blocklist_manager.h"
#include "components/prefs/pref_service.h"
#include "components/services/app_service/public/cpp/app_types.h"
#include "google_apis/classroom/classroom_api_course_work_response_types.h"
#include "google_apis/classroom/classroom_api_courses_response_types.h"
#include "google_apis/classroom/classroom_api_list_course_work_request.h"
#include "google_apis/classroom/classroom_api_list_courses_request.h"
#include "google_apis/classroom/classroom_api_list_student_submissions_request.h"
#include "google_apis/classroom/classroom_api_student_submissions_response_types.h"
#include "google_apis/common/api_error_codes.h"
#include "google_apis/common/request_sender.h"
#include "google_apis/gaia/gaia_constants.h"
#include "net/traffic_annotation/network_traffic_annotation.h"

namespace ash {
namespace {

using ::google_apis::ApiErrorCode;
using ::google_apis::RequestSender;
using ::google_apis::classroom::Course;
using ::google_apis::classroom::Courses;
using ::google_apis::classroom::CourseWork;
using ::google_apis::classroom::CourseWorkItem;
using ::google_apis::classroom::ListCoursesRequest;
using ::google_apis::classroom::ListCourseWorkRequest;
using ::google_apis::classroom::ListStudentSubmissionsRequest;
using ::google_apis::classroom::StudentSubmission;
using ::google_apis::classroom::StudentSubmissions;

// Special filter value for `ListCoursesRequest` to request courses with access
// limited to the requesting user.
constexpr char kOwnCoursesFilterValue[] = "me";

// Special parameter value to request student submissions for all course work in
// the specified course.
constexpr char kAllStudentSubmissionsParameterValue[] = "-";

constexpr char kClassroomUrl[] = "https://classroom.google.com/";

constexpr auto kCoursesCacheDuration = base::Hours(4);

constexpr net::NetworkTrafficAnnotationTag kTrafficAnnotationTag =
    net::DefineNetworkTrafficAnnotation("glanceables_classroom_integration", R"(
        semantics {
          sender: "Glanceables keyed service"
          description: "Provide ChromeOS users quick access to their "
                       "classroom items without opening the app or website"
          trigger: "User presses the calendar pill in shelf, which triggers "
                   "opening the calendar, classroom (if available) and tasks "
                   "widgets. This specific client implementation "
                   "is responsible for fetching user's classroom data from "
                   "Google Classroom API."
          internal {
            contacts {
              email: "chromeos-launcher@google.com"
            }
          }
          user_data {
            type: ACCESS_TOKEN
          }
          data: "The request is authenticated with an OAuth2 access token "
                "identifying the Google account"
          destination: GOOGLE_OWNED_SERVICE
          last_reviewed: "2023-08-21"
        }
        policy {
          cookies_allowed: NO
          setting: "This feature cannot be disabled in settings"
          chrome_policy {
            ContextualGoogleIntegrationsEnabled {
              ContextualGoogleIntegrationsEnabled: false
            }
          }
        }
    )");

}  // namespace

GlanceablesClassroomClientImpl::CourseListState::CourseListState(
    base::Clock* clock)
    : clock_(clock) {}

GlanceablesClassroomClientImpl::CourseListState::~CourseListState() = default;

bool GlanceablesClassroomClientImpl::CourseListState::
    RunOrEnqueueCallbackAndUpdateFetchStatus(
        GlanceablesClassroomClientImpl::FetchCoursesCallback callback) {
  if (fetch_status_ == FetchStatus::kFetched &&
      clock_->Now() - last_successful_fetch_time_ < kCoursesCacheDuration) {
    std::move(callback).Run(/*success=*/true, courses_);
    return false;
  }

  callbacks_.push_back(std::move(callback));

  const bool needs_fetch = fetch_status_ != FetchStatus::kFetching;
  fetch_status_ = FetchStatus::kFetching;
  return needs_fetch;
}

void GlanceablesClassroomClientImpl::CourseListState::FinalizeFetch(
    std::unique_ptr<CourseList> fetched_courses) {
  const bool success = fetched_courses.get();

  if (success) {
    switch (fetch_status_) {
      case FetchStatus::kNotFetched:
      case FetchStatus::kFetched:
      case FetchStatus::kFetchingInvalidated:
        NOTREACHED();
      case FetchStatus::kFetching:
        fetch_status_ = FetchStatus::kFetched;
        break;
    }

    courses_.swap(*fetched_courses);
    last_successful_fetch_time_ = clock_->Now();
  } else {
    fetch_status_ = FetchStatus::kNotFetched;
    // NOTE: Keeping existing `courses_` state around, so it can be reused to
    // surface some, potentially unfresh data to the user. Marking the list
    // status as not fetched to force another fetch when courses get requested
    // again.
  }

  RunCallbacks(success);
}

void GlanceablesClassroomClientImpl::CourseListState::RunCallbacks(
    bool success) {
  std::vector<FetchCoursesCallback> callbacks;
  callbacks_.swap(callbacks);

  for (auto& callback : callbacks) {
    std::move(callback).Run(success, courses_);
  }
}

GlanceablesClassroomClientImpl::CourseWorkRequest::CourseWorkRequest(
    base::OnceClosure callback)
    : callback_(std::move(callback)) {
  CHECK(callback_);
}

GlanceablesClassroomClientImpl::CourseWorkRequest::~CourseWorkRequest() =
    default;

void GlanceablesClassroomClientImpl::CourseWorkRequest::
    IncrementPendingPageCount() {
  ++pending_page_requests_;
}

void GlanceablesClassroomClientImpl::CourseWorkRequest::
    DecrementPendingPageCount() {
  CHECK_GT(pending_page_requests_, 0);
  --pending_page_requests_;
}

bool GlanceablesClassroomClientImpl::CourseWorkRequest::RespondIfComplete() {
  CHECK(callback_);

  if (pending_page_requests_ == 0) {
    std::move(callback_).Run();
    return true;
  }
  return false;
}

GlanceablesClassroomClientImpl::GlanceablesClassroomClientImpl(
    Profile* profile,
    base::Clock* clock,
    const GlanceablesClassroomClientImpl::CreateRequestSenderCallback&
        create_request_sender_callback)
    : profile_(profile),
      clock_(clock),
      create_request_sender_callback_(create_request_sender_callback),
      student_courses_(CourseListState(clock_)) {}

GlanceablesClassroomClientImpl::~GlanceablesClassroomClientImpl() = default;

bool GlanceablesClassroomClientImpl::IsDisabledByAdmin() const {
  // 1) Check the pref.
  const auto* const pref_service = profile_->GetPrefs();
  if (!pref_service ||
      !base::Contains(pref_service->GetList(
                          prefs::kContextualGoogleIntegrationsConfiguration),
                      prefs::kGoogleClassroomIntegrationName)) {
    RecordContextualGoogleIntegrationStatus(
        prefs::kGoogleClassroomIntegrationName,
        ContextualGoogleIntegrationStatus::kDisabledByPolicy);
    return true;
  }

  // 2) Check if the Classroom app is disabled by policy.
  if (!apps::AppServiceProxyFactory::IsAppServiceAvailableForProfile(
          profile_)) {
    return true;
  }
  auto classroom_app_readiness = apps::Readiness::kUnknown;
  apps::AppServiceProxyFactory::GetForProfile(profile_)
      ->AppRegistryCache()
      .ForOneApp(ash::kGoogleClassroomAppId,
                 [&classroom_app_readiness](const apps::AppUpdate& update) {
                   classroom_app_readiness = update.Readiness();
                 });
  if (classroom_app_readiness == apps::Readiness::kDisabledByPolicy) {
    RecordContextualGoogleIntegrationStatus(
        prefs::kGoogleClassroomIntegrationName,
        ContextualGoogleIntegrationStatus::kDisabledByAppBlock);
    return true;
  }

  // 3) Check if the Classroom URL is blocked by policy.
  const auto* const policy_blocklist_service =
      PolicyBlocklistFactory::GetForBrowserContext(profile_);
  if (!policy_blocklist_service ||
      policy_blocklist_service->GetURLBlocklistState(GURL(kClassroomUrl)) ==
          policy::URLBlocklist::URLBlocklistState::URL_IN_BLOCKLIST) {
    RecordContextualGoogleIntegrationStatus(
        prefs::kGoogleClassroomIntegrationName,
        ContextualGoogleIntegrationStatus::kDisabledByUrlBlock);
    return true;
  }

  RecordContextualGoogleIntegrationStatus(
      prefs::kGoogleClassroomIntegrationName,
      ContextualGoogleIntegrationStatus::kEnabled);
  return false;
}

void GlanceablesClassroomClientImpl::IsStudentRoleActive(
    IsRoleEnabledCallback callback) {
  CHECK(callback);

  FetchStudentCourses(base::BindOnce(
      [](IsRoleEnabledCallback callback, bool success,
         const CourseList& courses) {
        const bool is_active = !courses.empty();
        base::UmaHistogramBoolean(
            "Ash.Glanceables.Api.Classroom.IsStudentRoleActiveResult",
            is_active);
        std::move(callback).Run(is_active);
      },
      std::move(callback)));
}

void GlanceablesClassroomClientImpl::GetCompletedStudentAssignments(
    GetAssignmentsCallback callback) {
  CHECK(callback);

  auto due_predicate = base::BindRepeating(
      [](const std::optional<base::Time>& due) { return true; });
  auto submission_state_predicate =
      base::BindRepeating([](GlanceablesClassroomStudentSubmissionState state) {
        return state == GlanceablesClassroomStudentSubmissionState::kTurnedIn ||
               state == GlanceablesClassroomStudentSubmissionState::kGraded;
      });
  auto sort_comparator =
      base::BindRepeating([](const GlanceablesClassroomCourseWorkItem* lhs,
                             const GlanceablesClassroomCourseWorkItem* rhs) {
        // Order by the submission's last update time in descending order.
        return lhs->most_recent_submission_update_time() >
               rhs->most_recent_submission_update_time();
      });
  InvokeOnceStudentDataFetched(base::BindOnce(
      &GlanceablesClassroomClientImpl::GetFilteredStudentAssignments,
      base::Unretained(this), std::move(due_predicate),
      std::move(submission_state_predicate), std::move(sort_comparator),
      std::move(callback)));
}

void GlanceablesClassroomClientImpl::
    GetStudentAssignmentsWithApproachingDueDate(
        GetAssignmentsCallback callback) {
  CHECK(callback);

  auto due_predicate = base::BindRepeating(
      [](const base::Time& now, const std::optional<base::Time>& due) {
        return due.has_value() && now < due.value();
      },
      clock_->Now());
  auto submission_state_predicate =
      base::BindRepeating([](GlanceablesClassroomStudentSubmissionState state) {
        return state == GlanceablesClassroomStudentSubmissionState::kAssigned;
      });
  auto sort_comparator =
      base::BindRepeating([](const GlanceablesClassroomCourseWorkItem* lhs,
                             const GlanceablesClassroomCourseWorkItem* rhs) {
        // `due_predicate` should have filtered out items with no due date.
        CHECK(lhs->due());
        CHECK(rhs->due());

        // Order by due date in ascending order.
        return *lhs->due() < *rhs->due();
      });
  InvokeOnceStudentDataFetched(base::BindOnce(
      &GlanceablesClassroomClientImpl::GetFilteredStudentAssignments,
      base::Unretained(this), std::move(due_predicate),
      std::move(submission_state_predicate), std::move(sort_comparator),
      std::move(callback)));
}

void GlanceablesClassroomClientImpl::GetStudentAssignmentsWithMissedDueDate(
    GetAssignmentsCallback callback) {
  CHECK(callback);

  auto due_predicate = base::BindRepeating(
      [](const base::Time& now, const std::optional<base::Time>& due) {
        return due.has_value() && now > due.value();
      },
      clock_->Now());
  auto submission_state_predicate =
      base::BindRepeating([](GlanceablesClassroomStudentSubmissionState state) {
        return state == GlanceablesClassroomStudentSubmissionState::kAssigned;
      });
  auto sort_comparator =
      base::BindRepeating([](const GlanceablesClassroomCourseWorkItem* lhs,
                             const GlanceablesClassroomCourseWorkItem* rhs) {
        // `due_predicate` should have filtered out items with no due date.
        CHECK(lhs->due());
        CHECK(rhs->due());

        // Order by due date in descending order.
        return *lhs->due() > *rhs->due();
      });
  InvokeOnceStudentDataFetched(base::BindOnce(
      &GlanceablesClassroomClientImpl::GetFilteredStudentAssignments,
      base::Unretained(this), std::move(due_predicate),
      std::move(submission_state_predicate), std::move(sort_comparator),
      std::move(callback)));
}

void GlanceablesClassroomClientImpl::GetStudentAssignmentsWithoutDueDate(
    GetAssignmentsCallback callback) {
  CHECK(callback);

  auto due_predicate = base::BindRepeating(
      [](const std::optional<base::Time>& due) { return !due.has_value(); });
  auto submission_state_predicate =
      base::BindRepeating([](GlanceablesClassroomStudentSubmissionState state) {
        return state == GlanceablesClassroomStudentSubmissionState::kAssigned;
      });
  auto sort_comparator =
      base::BindRepeating([](const GlanceablesClassroomCourseWorkItem* lhs,
                             const GlanceablesClassroomCourseWorkItem* rhs) {
        // Order by course work item creation time in descending order.
        return lhs->creation_time() > rhs->creation_time();
      });
  InvokeOnceStudentDataFetched(base::BindOnce(
      &GlanceablesClassroomClientImpl::GetFilteredStudentAssignments,
      base::Unretained(this), std::move(due_predicate),
      std::move(submission_state_predicate), std::move(sort_comparator),
      std::move(callback)));
}

void GlanceablesClassroomClientImpl::OnGlanceablesBubbleClosed() {
  for (FetchStatus* fetch_status :
       {&student_data_fetch_status_, &teacher_data_fetch_status_}) {
    InvalidateFetchStatus(fetch_status);
  }
}

// static
void GlanceablesClassroomClientImpl::InvalidateFetchStatus(
    FetchStatus* fetch_status) {
  switch (*fetch_status) {
    case FetchStatus::kNotFetched:
      break;
    case FetchStatus::kFetched:
      *fetch_status = FetchStatus::kNotFetched;
      break;
    case FetchStatus::kFetching:
      *fetch_status = FetchStatus::kFetchingInvalidated;
      break;
    case FetchStatus::kFetchingInvalidated:
      // Do no restart fetch if it's still in progress, which could happen if
      // the user toggles glanceables bubble in quick succession.
      *fetch_status = FetchStatus::kFetching;
      break;
  }
}

void GlanceablesClassroomClientImpl::FetchStudentCourses(
    FetchCoursesCallback callback) {
  CHECK(callback);

  const bool needs_refetch =
      student_courses_.RunOrEnqueueCallbackAndUpdateFetchStatus(
          std::move(callback));
  if (needs_refetch) {
    auto courses = std::make_unique<CourseList>();
    FetchCoursesPage(/*page_token=*/"", std::move(courses));
  }
}

bool GlanceablesClassroomClientImpl::ShouldFetchSubmissionsPerCourseWork(
    CourseWorkType course_work_type) const {
  return course_work_type == CourseWorkType::kTeacher;
}

GlanceablesClassroomClientImpl::CourseWorkPerCourse&
GlanceablesClassroomClientImpl::GetCourseWork(CourseWorkType type) {
  return type == CourseWorkType::kStudent ? student_course_work_
                                          : teacher_course_work_;
}

void GlanceablesClassroomClientImpl::SetCourseWorkFetchHadFailure(
    CourseWorkType type) {
  switch (type) {
    case CourseWorkType::kStudent:
      student_data_fetch_had_failure_ = true;
      break;
    case CourseWorkType::kTeacher:
      teacher_data_fetch_had_failure_ = true;
      break;
  }
}

void GlanceablesClassroomClientImpl::FetchCourseWork(
    const std::string& course_id,
    CourseWorkType course_work_type,
    base::OnceClosure callback) {
  CHECK(!course_id.empty());
  CHECK(callback);

  const int request_id = next_course_work_request_id_++;
  const auto [request_it, request_inserted] = course_work_requests_.emplace(
      request_id, std::make_unique<CourseWorkRequest>(std::move(callback)));
  CHECK(request_inserted);

  auto& course_work = GetCourseWork(course_work_type);
  for (auto& course_work_info : course_work[course_id]) {
    course_work_info.second.InvalidateCourseWorkItem();
  }

  FetchCourseWorkPage(request_id, course_id, /*page_token=*/"",
                      /*page_number=*/1, course_work_type);
}

void GlanceablesClassroomClientImpl::FetchStudentSubmissions(
    const std::string& course_id,
    const std::string& course_work_id,
    CourseWorkType course_work_type,
    base::OnceClosure callback) {
  CHECK(!course_id.empty());
  CHECK(callback);

  CourseWorkPerCourse& course_work = GetCourseWork(course_work_type);
  // Invalidate any preexisting cached student submissions info for requested
  // course work ID.
  if (course_work_id == kAllStudentSubmissionsParameterValue) {
    for (auto& course_work_info : course_work[course_id]) {
      course_work_info.second.InvalidateStudentSubmissions();
    }
  } else {
    course_work[course_id][course_work_id].InvalidateStudentSubmissions();
  }

  FetchStudentSubmissionsPage(course_id, course_work_id,
                              /*page_token=*/"", /*page_number=*/1,
                              course_work_type, std::move(callback));
}

void GlanceablesClassroomClientImpl::InvokeOnceStudentDataFetched(
    base::OnceClosure callback) {
  CHECK(callback);

  if (student_data_fetch_status_ == FetchStatus::kFetched) {
    std::move(callback).Run();
    return;
  }

  callbacks_waiting_for_student_data_.push_back(std::move(callback));

  const bool needs_fetch =
      student_data_fetch_status_ != FetchStatus::kFetching &&
      student_data_fetch_status_ != FetchStatus::kFetchingInvalidated;
  student_data_fetch_status_ = FetchStatus::kFetching;

  if (needs_fetch) {
    student_data_fetch_had_failure_ = false;
    FetchStudentCourses(base::BindOnce(
        &GlanceablesClassroomClientImpl::OnCoursesFetched,
        weak_factory_.GetWeakPtr(), CourseWorkType::kStudent,
        base::BindOnce(&GlanceablesClassroomClientImpl::OnStudentDataFetched,
                       weak_factory_.GetWeakPtr(), clock_->Now())));
  }
}

void GlanceablesClassroomClientImpl::FetchCoursesPage(
    const std::string& page_token,
    std::unique_ptr<CourseList> fetched_courses) {
  auto* const request_sender = GetRequestSender();
  request_sender->StartRequestWithAuthRetry(
      std::make_unique<ListCoursesRequest>(
          request_sender, /*student_id=*/kOwnCoursesFilterValue,
          /*teacher_id=*/"", page_token,
          base::BindOnce(&GlanceablesClassroomClientImpl::OnCoursesPageFetched,
                         weak_factory_.GetWeakPtr(), std::move(fetched_courses),
                         clock_->Now())));
}

void GlanceablesClassroomClientImpl::OnCoursesPageFetched(
    std::unique_ptr<CourseList> fetched_courses,
    const base::Time& request_start_time,
    base::expected<std::unique_ptr<Courses>, ApiErrorCode> result) {
  base::UmaHistogramTimes("Ash.Glanceables.Api.Classroom.GetCourses.Latency",
                          clock_->Now() - request_start_time);
  base::UmaHistogramSparse("Ash.Glanceables.Api.Classroom.GetCourses.Status",
                           result.error_or(ApiErrorCode::HTTP_SUCCESS));

  if (!result.has_value()) {
    student_courses_.FinalizeFetch(nullptr);
    return;
  }

  for (const auto& item : result.value()->items()) {
    if (item->state() == Course::State::kActive) {
      fetched_courses->push_back(std::make_unique<GlanceablesClassroomCourse>(
          item->id(), item->name()));
    }
  }

  if (result.value()->next_page_token().empty()) {
    base::UmaHistogramCounts100(
        "Ash.Glanceables.Api.Classroom.StudentCoursesCount",
        fetched_courses->size());
    student_courses_.FinalizeFetch(std::move(fetched_courses));
  } else {
    FetchCoursesPage(result.value()->next_page_token(),
                     std::move(fetched_courses));
  }
}

void GlanceablesClassroomClientImpl::OnCoursesFetched(
    CourseWorkType course_work_type,
    base::OnceClosure on_course_work_and_student_submissions_fetched,
    bool success,
    const CourseList& course_list) {
  CHECK(on_course_work_and_student_submissions_fetched);

  if (!success) {
    SetCourseWorkFetchHadFailure(course_work_type);
  }

  const bool fetch_submissions_per_course_work =
      ShouldFetchSubmissionsPerCourseWork(course_work_type);
  // `FetchCourseWork()` + `FetchStudentSubmissions()` per course.
  const auto expected_callback_calls =
      course_list.size() * (fetch_submissions_per_course_work ? 1 : 2);
  const auto barrier_closure = base::BarrierClosure(
      expected_callback_calls,
      std::move(on_course_work_and_student_submissions_fetched));

  for (const auto& course : course_list) {
    FetchCourseWork(course->id, course_work_type, barrier_closure);

    if (!fetch_submissions_per_course_work) {
      FetchStudentSubmissions(course->id, kAllStudentSubmissionsParameterValue,
                              course_work_type, barrier_closure);
    }
  }
}

void GlanceablesClassroomClientImpl::FetchCourseWorkPage(
    int request_id,
    const std::string& course_id,
    const std::string& page_token,
    int page_number,
    CourseWorkType course_work_type) {
  CHECK(!course_id.empty());

  auto request_it = course_work_requests_.find(request_id);
  if (request_it == course_work_requests_.end() || !request_it->second) {
    return;
  }
  request_it->second->IncrementPendingPageCount();

  auto* const request_sender = GetRequestSender();
  request_sender->StartRequestWithAuthRetry(
      std::make_unique<ListCourseWorkRequest>(
          request_sender, course_id, page_token,
          base::BindOnce(
              &GlanceablesClassroomClientImpl::OnCourseWorkPageFetched,
              weak_factory_.GetWeakPtr(), request_id, course_id,
              course_work_type, clock_->Now(), page_number)));
}

void GlanceablesClassroomClientImpl::OnCourseWorkPageFetched(
    int request_id,
    const std::string& course_id,
    CourseWorkType course_work_type,
    const base::Time& request_start_time,
    int page_number,
    base::expected<std::unique_ptr<CourseWork>, ApiErrorCode> result) {
  CHECK(!course_id.empty());

  base::UmaHistogramTimes("Ash.Glanceables.Api.Classroom.GetCourseWork.Latency",
                          clock_->Now() - request_start_time);
  base::UmaHistogramSparse("Ash.Glanceables.Api.Classroom.GetCourseWork.Status",
                           result.error_or(ApiErrorCode::HTTP_SUCCESS));

  auto request_it = course_work_requests_.find(request_id);
  if (request_it == course_work_requests_.end() || !request_it->second) {
    return;
  }

  CourseWorkPerCourse& course_work = GetCourseWork(course_work_type);
  CourseWorkInfo& course_work_for_course = course_work[course_id];

  if (!result.has_value()) {
    SetCourseWorkFetchHadFailure(course_work_type);

    for (auto& course_work_item : course_work_for_course) {
      course_work_item.second.RevalidateCourseWorkItem();
    }

    request_it->second->DecrementPendingPageCount();
    if (request_it->second->RespondIfComplete()) {
      course_work_requests_.erase(request_it);
    }
    return;
  }

  const bool fetch_submissions =
      ShouldFetchSubmissionsPerCourseWork(course_work_type);
  std::set<std::string> submissions_to_fetch;
  for (const auto& item : result.value()->items()) {
    if (item->state() != CourseWorkItem::State::kPublished) {
      course_work_for_course.erase(item->id());
      continue;
    }

    auto& course_work_item = course_work_for_course[item->id()];
    course_work_item.SetCourseWorkItem(item.get());
    if (fetch_submissions) {
      if (course_work_item.StudentSubmissionsNeedRefetch(clock_->Now())) {
        submissions_to_fetch.insert(item->id());
      } else {
        course_work_item.SetHasFreshSubmissionsState(false, clock_->Now());
      }
    }
  }

  if (!result.value()->next_page_token().empty()) {
    FetchCourseWorkPage(request_id, course_id,
                        result.value()->next_page_token(), page_number + 1,
                        course_work_type);
  } else {
    base::UmaHistogramCounts100(
        "Ash.Glanceables.Api.Classroom.GetCourseWork.PagesCount", page_number);
  }

  // NOTE: If `submissions_to_fetch` is empty, `barrier_closure` will run
  // immediately.
  const auto barrier_closure = base::BarrierClosure(
      submissions_to_fetch.size(),
      base::BindOnce(
          &GlanceablesClassroomClientImpl::OnCourseWorkSubmissionsFetched,
          weak_factory_.GetWeakPtr(), request_id, course_id));
  for (const auto& course_work_id : submissions_to_fetch) {
    FetchStudentSubmissions(course_id, course_work_id, course_work_type,
                            barrier_closure);
  }
}

void GlanceablesClassroomClientImpl::OnCourseWorkSubmissionsFetched(
    int request_id,
    const std::string& course_id) {
  auto request_it = course_work_requests_.find(request_id);
  if (request_it == course_work_requests_.end() || !request_it->second) {
    return;
  }

  request_it->second->DecrementPendingPageCount();

  if (request_it->second->RespondIfComplete()) {
    course_work_requests_.erase(request_it);
  }
}

void GlanceablesClassroomClientImpl::FetchStudentSubmissionsPage(
    const std::string& course_id,
    const std::string& course_work_id,
    const std::string& page_token,
    int page_number,
    CourseWorkType course_work_type,
    base::OnceClosure callback) {
  CHECK(!course_id.empty());
  CHECK(callback);

  auto* const request_sender = GetRequestSender();
  request_sender->StartRequestWithAuthRetry(
      std::make_unique<ListStudentSubmissionsRequest>(
          request_sender, course_id, course_work_id, page_token,
          base::BindOnce(
              &GlanceablesClassroomClientImpl::OnStudentSubmissionsPageFetched,
              weak_factory_.GetWeakPtr(), course_id, course_work_id,
              course_work_type, clock_->Now(), page_number,
              std::move(callback))));
}

void GlanceablesClassroomClientImpl::OnStudentSubmissionsPageFetched(
    const std::string& course_id,
    const std::string& course_work_id,
    CourseWorkType course_work_type,
    const base::Time& request_start_time,
    int page_number,
    base::OnceClosure callback,
    base::expected<std::unique_ptr<StudentSubmissions>, ApiErrorCode> result) {
  CHECK(!course_id.empty());
  CHECK(callback);

  base::UmaHistogramTimes(
      "Ash.Glanceables.Api.Classroom.GetStudentSubmissions.Latency",
      clock_->Now() - request_start_time);
  base::UmaHistogramSparse(
      "Ash.Glanceables.Api.Classroom.GetStudentSubmissions.Status",
      result.error_or(ApiErrorCode::HTTP_SUCCESS));

  CourseWorkPerCourse& course_work = GetCourseWork(course_work_type);
  auto& course_work_info_map = course_work[course_id];
  GlanceablesClassroomCourseWorkItem* const shared_course_work_info =
      (course_work_id == kAllStudentSubmissionsParameterValue)
          ? nullptr
          : &course_work_info_map[course_work_id];

  if (!result.has_value()) {
    SetCourseWorkFetchHadFailure(course_work_type);

    // On failure, restore the student submissions state for all course work
    // item that are in scope for the fetch.
    if (course_work_id == kAllStudentSubmissionsParameterValue) {
      for (auto& course_work_info : course_work_info_map) {
        course_work_info.second.RestorePreviousStudentSubmissions();
      }
    } else {
      shared_course_work_info->RestorePreviousStudentSubmissions();
    }

    std::move(callback).Run();
    return;
  }

  for (const auto& item : result.value()->items()) {
    if (shared_course_work_info) {
      CHECK_EQ(course_work_id, item->course_work_id());
    }

    GlanceablesClassroomCourseWorkItem* const submission_course_work_info =
        shared_course_work_info ? shared_course_work_info
                                : &course_work_info_map[item->course_work_id()];
    submission_course_work_info->AddStudentSubmission(item.get());
  }

  if (result.value()->next_page_token().empty()) {
    base::UmaHistogramCounts100(
        "Ash.Glanceables.Api.Classroom.GetStudentSubmissions.PagesCount",
        page_number);
    if (shared_course_work_info) {
      shared_course_work_info->SetHasFreshSubmissionsState(true, clock_->Now());
    }
    std::move(callback).Run();
  } else {
    FetchStudentSubmissionsPage(
        course_id, course_work_id, result.value()->next_page_token(),
        page_number + 1, course_work_type, std::move(callback));
  }
}

void GlanceablesClassroomClientImpl::OnStudentDataFetched(
    const base::Time& sequence_start_time) {
  base::UmaHistogramMediumTimes(
      "Ash.Glanceables.Api.Classroom.StudentDataFetchTime",
      clock_->Now() - sequence_start_time);

  if (student_data_fetch_had_failure_) {
    student_data_fetch_status_ = FetchStatus::kNotFetched;
  } else {
    switch (student_data_fetch_status_) {
      case FetchStatus::kNotFetched:
      case FetchStatus::kFetched:
        NOTREACHED();
      case FetchStatus::kFetching:
        student_data_fetch_status_ = FetchStatus::kFetched;
        break;
      case FetchStatus::kFetchingInvalidated:
        student_data_fetch_status_ = FetchStatus::kNotFetched;
        break;
    }
  }

  PruneInvalidCourseWork(student_courses_.courses(), student_course_work_);

  if (!student_data_fetch_had_failure_) {
    for (const auto& course : student_courses_.courses()) {
      const auto iter = student_course_work_.find(course->id);
      if (iter == student_course_work_.end()) {
        continue;
      }

      base::UmaHistogramCounts1000(
          "Ash.Glanceables.Api.Classroom.CourseWorkItemsPerStudentCourseCount",
          iter->second.size());
      base::UmaHistogramCounts1000(
          "Ash.Glanceables.Api.Classroom."
          "StudentSubmissionsPerStudentCourseCount",
          std::accumulate(iter->second.begin(), iter->second.end(), 0,
                          [](int count, const auto& x) {
                            return count + x.second.total_submissions();
                          }));
    }
  }

  std::list<base::OnceClosure> callbacks;
  callbacks_waiting_for_student_data_.swap(callbacks);

  for (auto& cb : callbacks) {
    std::move(cb).Run();
  }
}

void GlanceablesClassroomClientImpl::GetFilteredStudentAssignments(
    base::RepeatingCallback<bool(const std::optional<base::Time>&)>
        due_predicate,
    base::RepeatingCallback<bool(GlanceablesClassroomStudentSubmissionState)>
        submission_state_predicate,
    SortComparator sort_comparator,
    GetAssignmentsCallback callback) {
  CHECK(due_predicate);
  CHECK(submission_state_predicate);
  CHECK(callback);

  if (callback.IsCancelled()) {
    return;
  }

  using CourseNameAndCourseWork =
      std::pair<std::string, const GlanceablesClassroomCourseWorkItem*>;
  std::vector<CourseNameAndCourseWork> filtered_items;

  for (const auto& course : student_courses_.courses()) {
    const auto course_work_iter = student_course_work_.find(course->id);
    if (course_work_iter == student_course_work_.end()) {
      continue;
    }

    for (const auto& course_work_item : course_work_iter->second) {
      if (!course_work_item.second.SatisfiesPredicates(
              due_predicate, submission_state_predicate)) {
        continue;
      }
      filtered_items.push_back(
          std::make_pair(course->name, &course_work_item.second));
    }
  }

  std::sort(filtered_items.begin(), filtered_items.end(),
            [&sort_comparator](const CourseNameAndCourseWork& lhs,
                               const CourseNameAndCourseWork& rhs) {
              return sort_comparator.Run(lhs.second, rhs.second);
            });

  std::vector<std::unique_ptr<GlanceablesClassroomAssignment>>
      filtered_assignments;
  for (const auto& item : filtered_items) {
    filtered_assignments.push_back(item.second->CreateClassroomAssignment(
        item.first, /*include_aggregated_submissions_state=*/false));
  }
  std::move(callback).Run(!student_data_fetch_had_failure_,
                          std::move(filtered_assignments));
}

void GlanceablesClassroomClientImpl::PruneInvalidCourseWork(
    const CourseList& courses,
    CourseWorkPerCourse& course_work) {
  std::set<std::string> course_ids;
  for (const auto& course : courses) {
    course_ids.insert(course->id);
  }

  base::EraseIf(course_work, [&course_ids](const auto& per_course_info) {
    return !course_ids.contains(per_course_info.first);
  });

  for (const auto& course : courses) {
    const auto course_work_iter = course_work.find(course->id);
    if (course_work_iter != course_work.end()) {
      base::EraseIf(course_work_iter->second, [](const auto& course_work_item) {
        return !course_work_item.second.IsValid();
      });
    }
  }
}

RequestSender* GlanceablesClassroomClientImpl::GetRequestSender() {
  if (!request_sender_) {
    CHECK(create_request_sender_callback_);
    request_sender_ =
        std::move(create_request_sender_callback_)
            .Run(/*scopes=*/
                 {
                     GaiaConstants::kClassroomReadOnlyCoursesOAuth2Scope,
                     GaiaConstants::kClassroomReadOnlyCourseWorkSelfOAuth2Scope,
                     GaiaConstants::
                         kClassroomReadOnlyStudentSubmissionsSelfOAuth2Scope,
                 },
                 kTrafficAnnotationTag);
    CHECK(request_sender_);
  }
  return request_sender_.get();
}

}  // namespace ash