/*

 * Copyright (c) Meta Platforms, Inc. and affiliates.

 *

 * This source code is licensed under the MIT license found in the

 * LICENSE file in the root directory of this source tree.

 */

#include "event.h"

#include <atomic>

#include <memory>

namespace facebook::yoga {

const char* LayoutPassReasonToString(const LayoutPassReason value) {

  switch (value) {

    case LayoutPassReason::kInitial:

      return "initial";

    case LayoutPassReason::kAbsLayout:

      return "abs_layout";

    case LayoutPassReason::kStretch:

      return "stretch";

    case LayoutPassReason::kMultilineStretch:

      return "multiline_stretch";

    case LayoutPassReason::kFlexLayout:

      return "flex_layout";

    case LayoutPassReason::kMeasureChild:

      return "measure";

    case LayoutPassReason::kAbsMeasureChild:

      return "abs_measure";

    case LayoutPassReason::kFlexMeasure:

      return "flex_measure";

    case LayoutPassReason::kGridLayout:

      return "grid_layout";

    default:

      return "unknown";

  }

}

namespace {

struct Node {

  std::function<Event::Subscriber> subscriber = nullptr;

  Node* next = nullptr;

  explicit Node(std::function<Event::Subscriber>&& subscriber)

      : subscriber{std::move(subscriber)} {}

};

std::atomic<Node*> subscribers{nullptr};

Node* push(Node* newHead) {

  Node* oldHead = nullptr;

  do {

    oldHead = subscribers.load(std::memory_order_relaxed);

    if (newHead != nullptr) {

      newHead->next = oldHead;

    }

  } while (!subscribers.compare_exchange_weak(

      oldHead, newHead, std::memory_order_release, std::memory_order_relaxed));

  return oldHead;

}

} // namespace

void Event::reset() {

  auto head = push(nullptr);

  while (head != nullptr) {

    auto current = head;

    head = head->next;

    delete current;

  }

}

void Event::subscribe(std::function<Subscriber>&& subscriber) {

  push(new Node{std::move(subscriber)});

}

void Event::publish(

    YGNodeConstRef node,

    Type eventType,

    const Data& eventData) {

  for (auto subscriber = subscribers.load(std::memory_order_relaxed);

       subscriber != nullptr;

       subscriber = subscriber->next) {

    subscriber->subscriber(node, eventType, eventData);

  }

}

} // namespace facebook::yoga