// Copyright 2018 The Chromium Authors
// Use of this source code is governed by a BSD-style license that can be
// found in the LICENSE file.

#include "base/task/sequence_manager/tasks.h"

#include <variant>

#include "base/task/sequence_manager/task_order.h"

namespace base::sequence_manager {

Task::Task(internal::PostedTask posted_task,
           EnqueueOrder sequence_order,
           EnqueueOrder enqueue_order,
           TimeTicks queue_time,
           TimeDelta leeway)
    : PendingTask(
          posted_task.location,
          std::move(posted_task.callback),
          queue_time,
          std::holds_alternative<base::TimeTicks>(
              posted_task.delay_or_delayed_run_time)
              ? std::get<base::TimeTicks>(posted_task.delay_or_delayed_run_time)
              : base::TimeTicks(),
          leeway,
          posted_task.delay_policy),
      nestable(posted_task.nestable),
      task_type(posted_task.task_type),
      task_runner(std::move(posted_task.task_runner)),
      enqueue_order_(enqueue_order),
      delayed_task_handle_delegate_(
          std::move(posted_task.delayed_task_handle_delegate)) {
  DCHECK(!std::holds_alternative<base::TimeDelta>(
             posted_task.delay_or_delayed_run_time) ||
         std::get<base::TimeDelta>(posted_task.delay_or_delayed_run_time)
             .is_zero());
  // We use |sequence_num| when comparing PendingTask for ordering purposes
  // and it may wrap around to a negative number during the static cast, hence,
  // TaskQueueImpl::DelayedIncomingQueue is especially sensitive to a potential
  // change of |PendingTask::sequence_num|'s type.
  static_assert(std::is_same_v<decltype(sequence_num), int>, "");
  sequence_num = static_cast<int>(sequence_order);
}

Task::Task(Task&& move_from) = default;

Task::~Task() = default;

Task& Task::operator=(Task&& other) = default;

TaskOrder Task::task_order() const {
  return TaskOrder(
      enqueue_order(),
      delayed_run_time.is_null() ? TimeTicks() : latest_delayed_run_time(),
      sequence_num);
}

void Task::SetHeapHandle(HeapHandle heap_handle) {
  if (!delayed_task_handle_delegate_) {
    return;
  }

  delayed_task_handle_delegate_->SetHeapHandle(heap_handle);
}

void Task::ClearHeapHandle() {
  if (!delayed_task_handle_delegate_) {
    return;
  }
  delayed_task_handle_delegate_->ClearHeapHandle();
}

HeapHandle Task::GetHeapHandle() const {
  if (!delayed_task_handle_delegate_) {
    return HeapHandle::Invalid();
  }
  return delayed_task_handle_delegate_->GetHeapHandle();
}

bool Task::IsCanceled() const {
  CHECK(task);
  if (task.IsCancelled()) {
    return true;
  }

  return delayed_task_handle_delegate_.WasInvalidated();
}

bool Task::WillRunTask() {
  if (delayed_task_handle_delegate_.WasInvalidated()) {
    return false;
  }
  if (delayed_task_handle_delegate_) {
    delayed_task_handle_delegate_->WillRunTask();
  }
  return true;
}

TimeTicks WakeUp::earliest_time() const {
  if (delay_policy == subtle::DelayPolicy::kFlexiblePreferEarly) {
    return time - leeway;
  }
  return time;
}

TimeTicks WakeUp::latest_time() const {
  if (delay_policy == subtle::DelayPolicy::kFlexibleNoSooner) {
    return time + leeway;
  }
  return time;
}

namespace internal {
PostedTask::PostedTask(
    scoped_refptr<SequencedTaskRunner> task_runner,
    OnceClosure callback,
    Location location,
    TimeDelta delay,
    Nestable nestable,
    TaskType task_type,
    WeakPtr<DelayedTaskHandleDelegate> delayed_task_handle_delegate)
    : callback(std::move(callback)),
      location(location),
      nestable(nestable),
      task_type(task_type),
      delay_or_delayed_run_time(delay),
      task_runner(std::move(task_runner)),
      delayed_task_handle_delegate(std::move(delayed_task_handle_delegate)) {}

PostedTask::PostedTask(
    scoped_refptr<SequencedTaskRunner> task_runner,
    OnceClosure callback,
    Location location,
    TimeTicks delayed_run_time,
    subtle::DelayPolicy delay_policy,
    Nestable nestable,
    TaskType task_type,
    WeakPtr<DelayedTaskHandleDelegate> delayed_task_handle_delegate)
    : callback(std::move(callback)),
      location(location),
      nestable(nestable),
      task_type(task_type),
      delay_or_delayed_run_time(delayed_run_time),
      delay_policy(delay_policy),
      task_runner(std::move(task_runner)),
      delayed_task_handle_delegate(std::move(delayed_task_handle_delegate)) {}

PostedTask::PostedTask(PostedTask&& move_from) noexcept = default;
PostedTask::~PostedTask() = default;

}  // namespace internal
}  // namespace base::sequence_manager