// Copyright 2015 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.

#ifndef THIRD_PARTY_BLINK_RENDERER_MODULES_WEBAUDIO_AUDIO_CONTEXT_H_
#define THIRD_PARTY_BLINK_RENDERER_MODULES_WEBAUDIO_AUDIO_CONTEXT_H_

#include "third_party/blink/public/mojom/webaudio/audio_context_manager.mojom-blink.h"
#include "third_party/blink/renderer/bindings/core/v8/script_promise.h"
#include "third_party/blink/renderer/bindings/core/v8/script_promise_resolver.h"
#include "third_party/blink/renderer/bindings/modules/v8/v8_audio_context_options.h"
#include "third_party/blink/renderer/core/html/media/autoplay_policy.h"
#include "third_party/blink/renderer/modules/webaudio/base_audio_context.h"
#include "third_party/blink/renderer/platform/heap/handle.h"
#include "third_party/blink/renderer/platform/heap/self_keep_alive.h"
#include "third_party/blink/renderer/platform/mojo/heap_mojo_remote.h"
#include "third_party/blink/renderer/platform/mojo/heap_mojo_wrapper_mode.h"

namespace blink {

class AudioContextOptions;
class AudioTimestamp;
class Document;
class ExceptionState;
class HTMLMediaElement;
class MediaElementAudioSourceNode;
class MediaStream;
class MediaStreamAudioDestinationNode;
class MediaStreamAudioSourceNode;
class ScriptState;
class WebAudioLatencyHint;

// This is an BaseAudioContext which actually plays sound, unlike an
// OfflineAudioContext which renders sound into a buffer.
class MODULES_EXPORT AudioContext : public BaseAudioContext {
  DEFINE_WRAPPERTYPEINFO();

 public:
  static AudioContext* Create(Document&,
                              const AudioContextOptions*,
                              ExceptionState&);

  AudioContext(Document&,
               const WebAudioLatencyHint&,
               base::Optional<float> sample_rate);
  ~AudioContext() override;
  void Trace(Visitor*) const override;

  // For ContextLifeCycleObserver
  void ContextDestroyed() final;
  bool HasPendingActivity() const override;

  ScriptPromise closeContext(ScriptState*, ExceptionState&);
  bool IsContextClosed() const final;

  ScriptPromise suspendContext(ScriptState*);
  ScriptPromise resumeContext(ScriptState*, ExceptionState&);

  bool HasRealtimeConstraint() final { return true; }

  bool IsPullingAudioGraph() const final;

  AudioTimestamp* getOutputTimestamp(ScriptState*) const;
  double baseLatency() const;

  MediaElementAudioSourceNode* createMediaElementSource(HTMLMediaElement*,
                                                        ExceptionState&);
  MediaStreamAudioSourceNode* createMediaStreamSource(MediaStream*,
                                                      ExceptionState&);
  MediaStreamAudioDestinationNode* createMediaStreamDestination(
      ExceptionState&);

  // Called by handlers of AudioScheduledSourceNode and AudioBufferSourceNode to
  // notify their associated AudioContext when start() is called. It may resume
  // the AudioContext if it is now allowed to start.
  void NotifySourceNodeStart() final;

  void set_was_audible_for_testing(bool value) { was_audible_ = value; }

  bool HandlePreRenderTasks(const AudioIOPosition* output_position,
                            const AudioCallbackMetric* metric) final;

  // Called at the end of each render quantum.
  void HandlePostRenderTasks() final;

  void HandleAudibility(AudioBus* destination_bus);

  AudioCallbackMetric GetCallbackMetric() const;

 protected:
  void Uninitialize() final;

 private:
  friend class AudioContextAutoplayTest;
  friend class AudioContextTest;

  // These values are persisted to logs. Entries should not be renumbered and
  // numeric values should never be reused.
  enum class AutoplayStatus {
    // The AudioContext failed to activate because of user gesture requirements.
    kFailed = 0,
    // Same as AutoplayStatusFailed but start() on a node was called with a user
    // gesture.
    // This value is no longer used but the enum entry should not be re-used
    // because it is used for metrics.
    // kAutoplayStatusFailedWithStart = 1,
    // The AudioContext had user gesture requirements and was able to activate
    // with a user gesture.
    kSucceeded = 2,

    kMaxValue = kSucceeded,
  };

  // Returns the AutoplayPolicy currently applying to this instance.
  AutoplayPolicy::Type GetAutoplayPolicy() const;

  // Returns whether the autoplay requirements are fulfilled.
  bool AreAutoplayRequirementsFulfilled() const;

  // Do not change the order of this enum, it is used for metrics.
  enum class AutoplayUnlockType {
    kContextConstructor = 0,
    kContextResume = 1,
    kSourceNodeStart = 2,
    kMaxValue = kSourceNodeStart,
  };

  // If possible, allows autoplay for the AudioContext and marke it as allowed
  // by the given type.
  void MaybeAllowAutoplayWithUnlockType(AutoplayUnlockType);

  // Returns whether the AudioContext is allowed to start rendering.
  bool IsAllowedToStart() const;

  // Record the current autoplay metrics.
  void RecordAutoplayMetrics();

  // Starts rendering via AudioDestinationNode. This sets the self-referencing
  // pointer to this object.
  void StartRendering() override;

  // Called when the context is being closed to stop rendering audio and clean
  // up handlers. This clears the self-referencing pointer, making this object
  // available for the potential GC.
  void StopRendering();

  // Called when suspending the context to stop reundering audio, but don't
  // clean up handlers because we expect to be resuming where we left off.
  void SuspendRendering();

  void DidClose();

  // Called by the audio thread to handle Promises for resume() and suspend(),
  // posting a main thread task to perform the actual resolving, if needed.
  void ResolvePromisesForUnpause();

  AudioIOPosition OutputPosition() const;

  // Send notification to browser that an AudioContext has started or stopped
  // playing audible audio.
  void NotifyAudibleAudioStarted();
  void NotifyAudibleAudioStopped();

  void EnsureAudioContextManagerService();
  void OnAudioContextManagerServiceConnectionError();

  unsigned context_id_;
  Member<ScriptPromiseResolver> close_resolver_;

  AudioIOPosition output_position_;
  AudioCallbackMetric callback_metric_;

  // Whether a user gesture is required to start this AudioContext.
  bool user_gesture_required_ = false;

  // Autoplay status associated with this AudioContext, if any.
  // Will only be set if there is an autoplay policy in place.
  // Will never be set for OfflineAudioContext.
  base::Optional<AutoplayStatus> autoplay_status_;

  // Autoplay unlock type for this AudioContext.
  // Will only be set if there is an autoplay policy in place.
  // Will never be set for OfflineAudioContext.
  base::Optional<AutoplayUnlockType> autoplay_unlock_type_;

  // Records if start() was ever called for any source node in this context.
  bool source_node_started_ = false;

  // Represents whether a context is suspended by explicit |context.suspend()|.
  bool suspended_by_user_ = false;

  // baseLatency for this context
  double base_latency_ = 0;

  // AudioContextManager for reporting audibility.
  HeapMojoRemote<mojom::blink::AudioContextManager,
                 HeapMojoWrapperMode::kWithoutContextObserver>
      audio_context_manager_;

  // Keeps track if the output of this destination was audible, before the
  // current rendering quantum.  Used for recording "playback" time.
  bool was_audible_ = false;

  // Counts the number of render quanta where audible sound was played.  We
  // determine audibility on render quantum boundaries, so counting quanta is
  // all that's needed.
  size_t total_audible_renders_ = 0;

  SelfKeepAlive<AudioContext> keep_alive_;
};

}  // namespace blink

#endif  // THIRD_PARTY_BLINK_RENDERER_MODULES_WEBAUDIO_AUDIO_CONTEXT_H_