third_party/blink/renderer/modules/presentation/presentation_availability_state.cc

// Copyright 2017 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 "third_party/blink/renderer/modules/presentation/presentation_availability_state.h"

#include "third_party/blink/public/platform/platform.h"
#include "third_party/blink/renderer/modules/presentation/presentation_availability_observer.h"
#include "third_party/blink/renderer/modules/presentation/presentation_controller.h"
#include "third_party/blink/renderer/platform/scheduler/public/thread.h"
#include "third_party/blink/renderer/platform/wtf/functional.h"

namespace blink {

PresentationAvailabilityState::PresentationAvailabilityState(
    mojom::blink::PresentationService* presentation_service)
    : presentation_service_(presentation_service) {}

PresentationAvailabilityState::~PresentationAvailabilityState() = default;

void PresentationAvailabilityState::RequestAvailability(
    const Vector<KURL>& urls,
    std::unique_ptr<PresentationAvailabilityCallbacks> callback) {
  auto screen_availability = GetScreenAvailability(urls);
  // Reject Promise if screen availability is unsupported for all URLs.
  if (screen_availability == mojom::blink::ScreenAvailability::DISABLED) {
    Platform::Current()->CurrentThread()->GetTaskRunner()->PostTask(
        FROM_HERE,
        WTF::Bind(
            &PresentationAvailabilityCallbacks::RejectAvailabilityNotSupported,
            std::move(callback)));
    // Do not listen to urls if we reject the promise.
    return;
  }

  auto* listener = GetAvailabilityListener(urls);
  if (!listener) {
    listener = new AvailabilityListener(urls);
    availability_listeners_.emplace_back(listener);
  }

  if (screen_availability != mojom::blink::ScreenAvailability::UNKNOWN) {
    Platform::Current()->CurrentThread()->GetTaskRunner()->PostTask(
        FROM_HERE, WTF::Bind(&PresentationAvailabilityCallbacks::Resolve,
                             std::move(callback),
                             screen_availability ==
                                 mojom::blink::ScreenAvailability::AVAILABLE));
  } else {
    listener->availability_callbacks.push_back(std::move(callback));
  }

  for (const auto& availability_url : urls)
    StartListeningToURL(availability_url);
}

void PresentationAvailabilityState::AddObserver(
    PresentationAvailabilityObserver* observer) {
  const auto& urls = observer->Urls();
  auto* listener = GetAvailabilityListener(urls);
  if (!listener) {
    listener = new AvailabilityListener(urls);
    availability_listeners_.emplace_back(listener);
  }

  listener->availability_observers.insert(observer);
  for (const auto& availability_url : urls)
    StartListeningToURL(availability_url);
}

void PresentationAvailabilityState::RemoveObserver(
    PresentationAvailabilityObserver* observer) {
  const auto& urls = observer->Urls();
  auto* listener = GetAvailabilityListener(urls);
  if (!listener) {
    DLOG(WARNING) << "Stop listening for availability for unknown URLs.";
    return;
  }

  listener->availability_observers.erase(observer);
  for (const auto& availability_url : urls)
    MaybeStopListeningToURL(availability_url);

  TryRemoveAvailabilityListener(listener);
}

void PresentationAvailabilityState::UpdateAvailability(
    const KURL& url,
    mojom::blink::ScreenAvailability availability) {
  auto* listening_status = GetListeningStatus(url);
  if (!listening_status)
    return;

  if (listening_status->listening_state == ListeningState::WAITING)
    listening_status->listening_state = ListeningState::ACTIVE;

  if (listening_status->last_known_availability == availability)
    return;

  listening_status->last_known_availability = availability;

  std::vector<AvailabilityListener*> modified_listeners;
  for (auto& listener : availability_listeners_) {
    if (!listener->urls.Contains<KURL>(url))
      continue;

    auto screen_availability = GetScreenAvailability(listener->urls);
    DCHECK(screen_availability != mojom::blink::ScreenAvailability::UNKNOWN);
    for (auto* observer : listener->availability_observers)
      observer->AvailabilityChanged(screen_availability);

    if (screen_availability == mojom::blink::ScreenAvailability::DISABLED) {
      for (auto& callback_ptr : listener->availability_callbacks) {
        callback_ptr->RejectAvailabilityNotSupported();
      }
    } else {
      for (auto& callback_ptr : listener->availability_callbacks) {
        callback_ptr->Resolve(screen_availability ==
                              mojom::blink::ScreenAvailability::AVAILABLE);
      }
    }
    listener->availability_callbacks.clear();

    for (const auto& availability_url : listener->urls)
      MaybeStopListeningToURL(availability_url);

    modified_listeners.push_back(listener.get());
  }

  for (auto* listener : modified_listeners)
    TryRemoveAvailabilityListener(listener);
}

void PresentationAvailabilityState::StartListeningToURL(const KURL& url) {
  auto* listening_status = GetListeningStatus(url);
  if (!listening_status) {
    listening_status = new ListeningStatus(url);
    availability_listening_status_.emplace_back(listening_status);
  }

  // Already listening.
  if (listening_status->listening_state != ListeningState::INACTIVE)
    return;

  listening_status->listening_state = ListeningState::WAITING;
  presentation_service_->ListenForScreenAvailability(url);
}

void PresentationAvailabilityState::MaybeStopListeningToURL(const KURL& url) {
  for (const auto& listener : availability_listeners_) {
    if (!listener->urls.Contains(url))
      continue;

    // URL is still observed by some availability object.
    if (!listener->availability_callbacks.empty() ||
        !listener->availability_observers.empty()) {
      return;
    }
  }

  auto* listening_status = GetListeningStatus(url);
  if (!listening_status) {
    LOG(WARNING) << "Stop listening to unknown url: " << url.GetString();
    return;
  }

  if (listening_status->listening_state == ListeningState::INACTIVE)
    return;

  listening_status->listening_state = ListeningState::INACTIVE;
  presentation_service_->StopListeningForScreenAvailability(url);
}

mojom::blink::ScreenAvailability
PresentationAvailabilityState::GetScreenAvailability(
    const Vector<KURL>& urls) const {
  bool has_disabled = false;
  bool has_source_not_supported = false;
  bool has_unavailable = false;

  for (const auto& url : urls) {
    auto* status = GetListeningStatus(url);
    auto screen_availability = status
                                   ? status->last_known_availability
                                   : mojom::blink::ScreenAvailability::UNKNOWN;
    switch (screen_availability) {
      case mojom::blink::ScreenAvailability::AVAILABLE:
        return mojom::blink::ScreenAvailability::AVAILABLE;
      case mojom::blink::ScreenAvailability::DISABLED:
        has_disabled = true;
        break;
      case mojom::blink::ScreenAvailability::SOURCE_NOT_SUPPORTED:
        has_source_not_supported = true;
        break;
      case mojom::blink::ScreenAvailability::UNAVAILABLE:
        has_unavailable = true;
        break;
      case mojom::blink::ScreenAvailability::UNKNOWN:
        break;
    }
  }

  if (has_disabled)
    return mojom::blink::ScreenAvailability::DISABLED;
  if (has_source_not_supported)
    return mojom::blink::ScreenAvailability::SOURCE_NOT_SUPPORTED;
  if (has_unavailable)
    return mojom::blink::ScreenAvailability::UNAVAILABLE;
  return mojom::blink::ScreenAvailability::UNKNOWN;
}

PresentationAvailabilityState::AvailabilityListener*
PresentationAvailabilityState::GetAvailabilityListener(
    const Vector<KURL>& urls) const {
  auto listener_it = std::find_if(
      availability_listeners_.begin(), availability_listeners_.end(),
      [&urls](const std::unique_ptr<AvailabilityListener>& x) {
        return x->urls == urls;
      });
  return listener_it == availability_listeners_.end() ? nullptr
                                                      : listener_it->get();
}

void PresentationAvailabilityState::TryRemoveAvailabilityListener(
    AvailabilityListener* listener) {
  // URL is still observed by some availability object.
  if (!listener->availability_callbacks.empty() ||
      !listener->availability_observers.empty()) {
    return;
  }

  auto listener_it = availability_listeners_.begin();
  while (listener_it != availability_listeners_.end()) {
    if (listener_it->get() == listener) {
      availability_listeners_.erase(listener_it);
      return;
    }
    ++listener_it;
  }
}

PresentationAvailabilityState::ListeningStatus*
PresentationAvailabilityState::GetListeningStatus(const KURL& url) const {
  auto status_it =
      std::find_if(availability_listening_status_.begin(),
                   availability_listening_status_.end(),
                   [&url](const std::unique_ptr<ListeningStatus>& status) {
                     return status->url == url;
                   });
  return status_it == availability_listening_status_.end() ? nullptr
                                                           : status_it->get();
}

PresentationAvailabilityState::AvailabilityListener::AvailabilityListener(
    const Vector<KURL>& availability_urls)
    : urls(availability_urls) {}

PresentationAvailabilityState::AvailabilityListener::~AvailabilityListener() =
    default;

PresentationAvailabilityState::ListeningStatus::ListeningStatus(
    const KURL& availability_url)
    : url(availability_url),
      last_known_availability(mojom::blink::ScreenAvailability::UNKNOWN),
      listening_state(ListeningState::INACTIVE) {}

PresentationAvailabilityState::ListeningStatus::~ListeningStatus() = default;

}  // namespace blink