// Copyright 2013 The Flutter Authors. All rights reserved.
// Use of this source code is governed by a BSD-style license that can be
// found in the LICENSE file.

#define FML_USED_ON_EMBEDDER

#include "flutter/fml/task_source.h"

namespace fml {

TaskSource::TaskSource(TaskQueueId task_queue_id)
 : task_queue_id_(task_queue_id) {}

TaskSource::~TaskSource() {
 ShutDown();
}

void TaskSource::ShutDown() {
 primary_task_queue_ = {};
 secondary_task_queue_ = {};
}

void TaskSource::RegisterTask(const DelayedTask& task) {
 switch (task.GetTaskSourceGrade()) {
 case TaskSourceGrade::kUserInteraction:
 primary_task_queue_.push(task);
 break;
 case TaskSourceGrade::kUnspecified:
 primary_task_queue_.push(task);
 break;
 case TaskSourceGrade::kDartEventLoop:
 secondary_task_queue_.push(task);
 break;
 }
}

void TaskSource::PopTask(TaskSourceGrade grade) {
 switch (grade) {
 case TaskSourceGrade::kUserInteraction:
 primary_task_queue_.pop();
 break;
 case TaskSourceGrade::kUnspecified:
 primary_task_queue_.pop();
 break;
 case TaskSourceGrade::kDartEventLoop:
 secondary_task_queue_.pop();
 break;
 }
}

size_t TaskSource::GetNumPendingTasks() const {
 size_t size = primary_task_queue_.size();
 if (secondary_pause_requests_ == 0) {
 size += secondary_task_queue_.size();
 }
 return size;
}

bool TaskSource::IsEmpty() const {
 return GetNumPendingTasks() == 0;
}

TaskSource::TopTask TaskSource::Top() const {
 FML_CHECK(!IsEmpty());
 if (secondary_pause_requests_ > 0 || secondary_task_queue_.empty()) {
 const auto& primary_top = primary_task_queue_.top();
 return {
 .task_queue_id = task_queue_id_,
 .task = primary_top,
 };
 } else if (primary_task_queue_.empty()) {
 const auto& secondary_top = secondary_task_queue_.top();
 return {
 .task_queue_id = task_queue_id_,
 .task = secondary_top,
 };
 } else {
 const auto& primary_top = primary_task_queue_.top();
 const auto& secondary_top = secondary_task_queue_.top();
 if (primary_top > secondary_top) {
 return {
 .task_queue_id = task_queue_id_,
 .task = secondary_top,
 };
 } else {
 return {
 .task_queue_id = task_queue_id_,
 .task = primary_top,
 };
 }
 }
}

void TaskSource::PauseSecondary() {
 secondary_pause_requests_++;
}

void TaskSource::ResumeSecondary() {
 secondary_pause_requests_--;
 FML_DCHECK(secondary_pause_requests_ >= 0);
}

} // namespace fml