/*
 * Copyright (C) 2010, Google Inc. All rights reserved.
 *
 * Redistribution and use in source and binary forms, with or without
 * modification, are permitted provided that the following conditions
 * are met:
 * 1.  Redistributions of source code must retain the above copyright
 *    notice, this list of conditions and the following disclaimer.
 * 2.  Redistributions in binary form must reproduce the above copyright
 *    notice, this list of conditions and the following disclaimer in the
 *    documentation and/or other materials provided with the distribution.
 *
 * THIS SOFTWARE IS PROVIDED BY APPLE INC. AND ITS CONTRIBUTORS ``AS IS'' AND ANY
 * EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE IMPLIED
 * WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE ARE
 * DISCLAIMED. IN NO EVENT SHALL APPLE INC. OR ITS CONTRIBUTORS BE LIABLE FOR ANY
 * DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES
 * (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES;
 * LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND ON
 * ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT
 * (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE OF THIS
 * SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.
 */

#include "modules/webaudio/AbstractAudioContext.h"
#include "bindings/core/v8/Dictionary.h"
#include "bindings/core/v8/ExceptionMessages.h"
#include "bindings/core/v8/ExceptionState.h"
#include "bindings/core/v8/ScriptPromiseResolver.h"
#include "bindings/core/v8/ScriptState.h"
#include "core/dom/DOMException.h"
#include "core/dom/Document.h"
#include "core/dom/ExceptionCode.h"
#include "core/dom/ExecutionContextTask.h"
#include "core/html/HTMLMediaElement.h"
#include "modules/mediastream/MediaStream.h"
#include "modules/webaudio/AnalyserNode.h"
#include "modules/webaudio/AudioBuffer.h"
#include "modules/webaudio/AudioBufferCallback.h"
#include "modules/webaudio/AudioBufferSourceNode.h"
#include "modules/webaudio/AudioContext.h"
#include "modules/webaudio/AudioListener.h"
#include "modules/webaudio/AudioNodeInput.h"
#include "modules/webaudio/AudioNodeOutput.h"
#include "modules/webaudio/BiquadFilterNode.h"
#include "modules/webaudio/ChannelMergerNode.h"
#include "modules/webaudio/ChannelSplitterNode.h"
#include "modules/webaudio/ConvolverNode.h"
#include "modules/webaudio/DefaultAudioDestinationNode.h"
#include "modules/webaudio/DelayNode.h"
#include "modules/webaudio/DynamicsCompressorNode.h"
#include "modules/webaudio/GainNode.h"
#include "modules/webaudio/IIRFilterNode.h"
#include "modules/webaudio/MediaElementAudioSourceNode.h"
#include "modules/webaudio/MediaStreamAudioDestinationNode.h"
#include "modules/webaudio/MediaStreamAudioSourceNode.h"
#include "modules/webaudio/OfflineAudioCompletionEvent.h"
#include "modules/webaudio/OfflineAudioContext.h"
#include "modules/webaudio/OfflineAudioDestinationNode.h"
#include "modules/webaudio/OscillatorNode.h"
#include "modules/webaudio/PannerNode.h"
#include "modules/webaudio/PeriodicWave.h"
#include "modules/webaudio/ScriptProcessorNode.h"
#include "modules/webaudio/StereoPannerNode.h"
#include "modules/webaudio/WaveShaperNode.h"
#include "platform/ThreadSafeFunctional.h"
#include "platform/audio/IIRFilter.h"
#include "public/platform/Platform.h"
#include "wtf/text/WTFString.h"

namespace blink {

AbstractAudioContext* AbstractAudioContext::create(Document& document, ExceptionState& exceptionState)
{
    return AudioContext::create(document, exceptionState);
}

// FIXME(dominicc): Devolve these constructors to AudioContext
// and OfflineAudioContext respectively.

// Constructor for rendering to the audio hardware.
AbstractAudioContext::AbstractAudioContext(Document* document)
    : ActiveDOMObject(document)
    , m_destinationNode(nullptr)
    , m_isCleared(false)
    , m_isResolvingResumePromises(false)
    , m_connectionCount(0)
    , m_didInitializeContextGraphMutex(false)
    , m_deferredTaskHandler(DeferredTaskHandler::create())
    , m_contextState(Suspended)
    , m_closedContextSampleRate(-1)
    , m_periodicWaveSine(nullptr)
    , m_periodicWaveSquare(nullptr)
    , m_periodicWaveSawtooth(nullptr)
    , m_periodicWaveTriangle(nullptr)
{
    m_didInitializeContextGraphMutex = true;
    m_destinationNode = DefaultAudioDestinationNode::create(this);

    initialize();
}

// Constructor for offline (non-realtime) rendering.
AbstractAudioContext::AbstractAudioContext(Document* document, unsigned numberOfChannels, size_t numberOfFrames, float sampleRate)
    : ActiveDOMObject(document)
    , m_destinationNode(nullptr)
    , m_isCleared(false)
    , m_isResolvingResumePromises(false)
    , m_connectionCount(0)
    , m_didInitializeContextGraphMutex(false)
    , m_deferredTaskHandler(DeferredTaskHandler::create())
    , m_contextState(Suspended)
    , m_closedContextSampleRate(-1)
    , m_periodicWaveSine(nullptr)
    , m_periodicWaveSquare(nullptr)
    , m_periodicWaveSawtooth(nullptr)
    , m_periodicWaveTriangle(nullptr)
{
    m_didInitializeContextGraphMutex = true;
}

AbstractAudioContext::~AbstractAudioContext()
{
    deferredTaskHandler().contextWillBeDestroyed();
    // AudioNodes keep a reference to their context, so there should be no way to be in the destructor if there are still AudioNodes around.
    ASSERT(!isDestinationInitialized());
    ASSERT(!m_activeSourceNodes.size());
    ASSERT(!m_finishedSourceHandlers.size());
    ASSERT(!m_isResolvingResumePromises);
    ASSERT(!m_resumeResolvers.size());
}

void AbstractAudioContext::initialize()
{
    if (isDestinationInitialized())
        return;

    FFTFrame::initialize();
    m_listener = AudioListener::create();

    if (m_destinationNode.get()) {
        m_destinationNode->handler().initialize();
    }
}

void AbstractAudioContext::clear()
{
    m_destinationNode.clear();
    // The audio rendering thread is dead.  Nobody will schedule AudioHandler
    // deletion.  Let's do it ourselves.
    deferredTaskHandler().clearHandlersToBeDeleted();
    m_isCleared = true;
}

void AbstractAudioContext::uninitialize()
{
    ASSERT(isMainThread());

    if (!isDestinationInitialized())
        return;

    // This stops the audio thread and all audio rendering.
    if (m_destinationNode)
        m_destinationNode->handler().uninitialize();

    // Get rid of the sources which may still be playing.
    releaseActiveSourceNodes();

    // Reject any pending resolvers before we go away.
    rejectPendingResolvers();
    didClose();

    ASSERT(m_listener);
    m_listener->waitForHRTFDatabaseLoaderThreadCompletion();

    clear();
}

void AbstractAudioContext::stop()
{
    uninitialize();
}

bool AbstractAudioContext::hasPendingActivity() const
{
    // There's no pending activity if the audio context has been cleared.
    return !m_isCleared;
}

void AbstractAudioContext::throwExceptionForClosedState(ExceptionState& exceptionState)
{
    exceptionState.throwDOMException(InvalidStateError, "AudioContext has been closed.");
}

AudioBuffer* AbstractAudioContext::createBuffer(unsigned numberOfChannels, size_t numberOfFrames, float sampleRate, ExceptionState& exceptionState)
{
    // It's ok to call createBuffer, even if the context is closed because the AudioBuffer doesn't
    // really "belong" to any particular context.

    return AudioBuffer::create(numberOfChannels, numberOfFrames, sampleRate, exceptionState);
}

ScriptPromise AbstractAudioContext::decodeAudioData(ScriptState* scriptState, DOMArrayBuffer* audioData, AudioBufferCallback* successCallback, AudioBufferCallback* errorCallback, ExceptionState& exceptionState)
{
    ASSERT(isMainThread());
    ASSERT(audioData);

    ScriptPromiseResolver* resolver = ScriptPromiseResolver::create(scriptState);
    ScriptPromise promise = resolver->promise();

    float rate = isContextClosed() ? closedContextSampleRate() : sampleRate();

    ASSERT(rate > 0);

    m_decodeAudioResolvers.add(resolver);
    m_audioDecoder.decodeAsync(audioData, rate, successCallback, errorCallback, resolver, this);

    return promise;
}

void AbstractAudioContext::handleDecodeAudioData(AudioBuffer* audioBuffer, ScriptPromiseResolver* resolver, AudioBufferCallback* successCallback, AudioBufferCallback* errorCallback)
{
    ASSERT(isMainThread());

    if (audioBuffer) {
        // Resolve promise successfully and run the success callback
        resolver->resolve(audioBuffer);
        if (successCallback)
            successCallback->handleEvent(audioBuffer);
    } else {
        // Reject the promise and run the error callback
        DOMException* error = DOMException::create(EncodingError, "Unable to decode audio data");
        resolver->reject(error);
        if (errorCallback)
            errorCallback->handleEvent(error);
    }

    // We've resolved the promise.  Remove it now.
    ASSERT(m_decodeAudioResolvers.contains(resolver));
    m_decodeAudioResolvers.remove(resolver);
}

AudioBufferSourceNode* AbstractAudioContext::createBufferSource(ExceptionState& exceptionState)
{
    ASSERT(isMainThread());

    if (isContextClosed()) {
        throwExceptionForClosedState(exceptionState);
        return nullptr;
    }

    AudioBufferSourceNode* node = AudioBufferSourceNode::create(*this, sampleRate());

    // Do not add a reference to this source node now. The reference will be added when start() is
    // called.

    return node;
}

MediaElementAudioSourceNode* AbstractAudioContext::createMediaElementSource(HTMLMediaElement* mediaElement, ExceptionState& exceptionState)
{
    ASSERT(isMainThread());

    if (isContextClosed()) {
        throwExceptionForClosedState(exceptionState);
        return nullptr;
    }

    // First check if this media element already has a source node.
    if (mediaElement->audioSourceNode()) {
        exceptionState.throwDOMException(
            InvalidStateError,
            "HTMLMediaElement already connected previously to a different MediaElementSourceNode.");
        return nullptr;
    }

    MediaElementAudioSourceNode* node = MediaElementAudioSourceNode::create(*this, *mediaElement);

    mediaElement->setAudioSourceNode(node);

    notifySourceNodeStartedProcessing(node); // context keeps reference until node is disconnected
    return node;
}

MediaStreamAudioSourceNode* AbstractAudioContext::createMediaStreamSource(MediaStream* mediaStream, ExceptionState& exceptionState)
{
    ASSERT(isMainThread());

    if (isContextClosed()) {
        throwExceptionForClosedState(exceptionState);
        return nullptr;
    }

    MediaStreamTrackVector audioTracks = mediaStream->getAudioTracks();
    if (audioTracks.isEmpty()) {
        exceptionState.throwDOMException(
            InvalidStateError,
            "MediaStream has no audio track");
        return nullptr;
    }

    // Use the first audio track in the media stream.
    MediaStreamTrack* audioTrack = audioTracks[0];
    OwnPtr<AudioSourceProvider> provider = audioTrack->createWebAudioSource();
    MediaStreamAudioSourceNode* node = MediaStreamAudioSourceNode::create(*this, *mediaStream, audioTrack, provider.release());

    // FIXME: Only stereo streams are supported right now. We should be able to accept multi-channel streams.
    node->setFormat(2, sampleRate());

    notifySourceNodeStartedProcessing(node); // context keeps reference until node is disconnected
    return node;
}

MediaStreamAudioDestinationNode* AbstractAudioContext::createMediaStreamDestination(ExceptionState& exceptionState)
{
    if (isContextClosed()) {
        throwExceptionForClosedState(exceptionState);
        return nullptr;
    }

    // Set number of output channels to stereo by default.
    return MediaStreamAudioDestinationNode::create(*this, 2);
}

ScriptProcessorNode* AbstractAudioContext::createScriptProcessor(ExceptionState& exceptionState)
{
    // Set number of input/output channels to stereo by default.
    return createScriptProcessor(0, 2, 2, exceptionState);
}

ScriptProcessorNode* AbstractAudioContext::createScriptProcessor(size_t bufferSize, ExceptionState& exceptionState)
{
    // Set number of input/output channels to stereo by default.
    return createScriptProcessor(bufferSize, 2, 2, exceptionState);
}

ScriptProcessorNode* AbstractAudioContext::createScriptProcessor(size_t bufferSize, size_t numberOfInputChannels, ExceptionState& exceptionState)
{
    // Set number of output channels to stereo by default.
    return createScriptProcessor(bufferSize, numberOfInputChannels, 2, exceptionState);
}

ScriptProcessorNode* AbstractAudioContext::createScriptProcessor(size_t bufferSize, size_t numberOfInputChannels, size_t numberOfOutputChannels, ExceptionState& exceptionState)
{
    ASSERT(isMainThread());

    if (isContextClosed()) {
        throwExceptionForClosedState(exceptionState);
        return nullptr;
    }

    ScriptProcessorNode* node = ScriptProcessorNode::create(*this, sampleRate(), bufferSize, numberOfInputChannels, numberOfOutputChannels);

    if (!node) {
        if (!numberOfInputChannels && !numberOfOutputChannels) {
            exceptionState.throwDOMException(
                IndexSizeError,
                "number of input channels and output channels cannot both be zero.");
        } else if (numberOfInputChannels > AbstractAudioContext::maxNumberOfChannels()) {
            exceptionState.throwDOMException(
                IndexSizeError,
                "number of input channels (" + String::number(numberOfInputChannels)
                + ") exceeds maximum ("
                + String::number(AbstractAudioContext::maxNumberOfChannels()) + ").");
        } else if (numberOfOutputChannels > AbstractAudioContext::maxNumberOfChannels()) {
            exceptionState.throwDOMException(
                IndexSizeError,
                "number of output channels (" + String::number(numberOfInputChannels)
                + ") exceeds maximum ("
                + String::number(AbstractAudioContext::maxNumberOfChannels()) + ").");
        } else {
            exceptionState.throwDOMException(
                IndexSizeError,
                "buffer size (" + String::number(bufferSize)
                + ") must be a power of two between 256 and 16384.");
        }
        return nullptr;
    }

    notifySourceNodeStartedProcessing(node); // context keeps reference until we stop making javascript rendering callbacks
    return node;
}

StereoPannerNode* AbstractAudioContext::createStereoPanner(ExceptionState& exceptionState)
{
    ASSERT(isMainThread());
    if (isContextClosed()) {
        throwExceptionForClosedState(exceptionState);
        return nullptr;
    }

    return StereoPannerNode::create(*this, sampleRate());
}

BiquadFilterNode* AbstractAudioContext::createBiquadFilter(ExceptionState& exceptionState)
{
    ASSERT(isMainThread());
    if (isContextClosed()) {
        throwExceptionForClosedState(exceptionState);
        return nullptr;
    }

    return BiquadFilterNode::create(*this, sampleRate());
}

WaveShaperNode* AbstractAudioContext::createWaveShaper(ExceptionState& exceptionState)
{
    ASSERT(isMainThread());
    if (isContextClosed()) {
        throwExceptionForClosedState(exceptionState);
        return nullptr;
    }

    return WaveShaperNode::create(*this);
}

PannerNode* AbstractAudioContext::createPanner(ExceptionState& exceptionState)
{
    ASSERT(isMainThread());
    if (isContextClosed()) {
        throwExceptionForClosedState(exceptionState);
        return nullptr;
    }

    return PannerNode::create(*this, sampleRate());
}

ConvolverNode* AbstractAudioContext::createConvolver(ExceptionState& exceptionState)
{
    ASSERT(isMainThread());
    if (isContextClosed()) {
        throwExceptionForClosedState(exceptionState);
        return nullptr;
    }

    return ConvolverNode::create(*this, sampleRate());
}

DynamicsCompressorNode* AbstractAudioContext::createDynamicsCompressor(ExceptionState& exceptionState)
{
    ASSERT(isMainThread());
    if (isContextClosed()) {
        throwExceptionForClosedState(exceptionState);
        return nullptr;
    }

    return DynamicsCompressorNode::create(*this, sampleRate());
}

AnalyserNode* AbstractAudioContext::createAnalyser(ExceptionState& exceptionState)
{
    ASSERT(isMainThread());
    if (isContextClosed()) {
        throwExceptionForClosedState(exceptionState);
        return nullptr;
    }

    return AnalyserNode::create(*this, sampleRate());
}

GainNode* AbstractAudioContext::createGain(ExceptionState& exceptionState)
{
    ASSERT(isMainThread());
    if (isContextClosed()) {
        throwExceptionForClosedState(exceptionState);
        return nullptr;
    }

    return GainNode::create(*this, sampleRate());
}

DelayNode* AbstractAudioContext::createDelay(ExceptionState& exceptionState)
{
    const double defaultMaxDelayTime = 1;
    return createDelay(defaultMaxDelayTime, exceptionState);
}

DelayNode* AbstractAudioContext::createDelay(double maxDelayTime, ExceptionState& exceptionState)
{
    ASSERT(isMainThread());
    if (isContextClosed()) {
        throwExceptionForClosedState(exceptionState);
        return nullptr;
    }

    return DelayNode::create(*this, sampleRate(), maxDelayTime, exceptionState);
}

ChannelSplitterNode* AbstractAudioContext::createChannelSplitter(ExceptionState& exceptionState)
{
    const unsigned ChannelSplitterDefaultNumberOfOutputs = 6;
    return createChannelSplitter(ChannelSplitterDefaultNumberOfOutputs, exceptionState);
}

ChannelSplitterNode* AbstractAudioContext::createChannelSplitter(size_t numberOfOutputs, ExceptionState& exceptionState)
{
    ASSERT(isMainThread());

    if (isContextClosed()) {
        throwExceptionForClosedState(exceptionState);
        return nullptr;
    }

    ChannelSplitterNode* node = ChannelSplitterNode::create(*this, sampleRate(), numberOfOutputs);

    if (!node) {
        exceptionState.throwDOMException(
            IndexSizeError,
            "number of outputs (" + String::number(numberOfOutputs)
            + ") must be between 1 and "
            + String::number(AbstractAudioContext::maxNumberOfChannels()) + ".");
        return nullptr;
    }

    return node;
}

ChannelMergerNode* AbstractAudioContext::createChannelMerger(ExceptionState& exceptionState)
{
    const unsigned ChannelMergerDefaultNumberOfInputs = 6;
    return createChannelMerger(ChannelMergerDefaultNumberOfInputs, exceptionState);
}

ChannelMergerNode* AbstractAudioContext::createChannelMerger(size_t numberOfInputs, ExceptionState& exceptionState)
{
    ASSERT(isMainThread());
    if (isContextClosed()) {
        throwExceptionForClosedState(exceptionState);
        return nullptr;
    }

    ChannelMergerNode* node = ChannelMergerNode::create(*this, sampleRate(), numberOfInputs);

    if (!node) {
        exceptionState.throwDOMException(
            IndexSizeError,
            ExceptionMessages::indexOutsideRange<size_t>(
                "number of inputs",
                numberOfInputs,
                1,
                ExceptionMessages::InclusiveBound,
                AbstractAudioContext::maxNumberOfChannels(),
                ExceptionMessages::InclusiveBound));
        return nullptr;
    }

    return node;
}

OscillatorNode* AbstractAudioContext::createOscillator(ExceptionState& exceptionState)
{
    ASSERT(isMainThread());
    if (isContextClosed()) {
        throwExceptionForClosedState(exceptionState);
        return nullptr;
    }

    OscillatorNode* node = OscillatorNode::create(*this, sampleRate());

    // Do not add a reference to this source node now. The reference will be added when start() is
    // called.

    return node;
}

PeriodicWave* AbstractAudioContext::createPeriodicWave(DOMFloat32Array* real, DOMFloat32Array* imag, ExceptionState& exceptionState)
{
    return PeriodicWave::create(sampleRate(), real, imag, false);
}

PeriodicWave* AbstractAudioContext::createPeriodicWave(DOMFloat32Array* real, DOMFloat32Array* imag, const Dictionary& options, ExceptionState& exceptionState)
{
    ASSERT(isMainThread());

    if (isContextClosed()) {
        throwExceptionForClosedState(exceptionState);
        return nullptr;
    }

    if (real->length() != imag->length()) {
        exceptionState.throwDOMException(
            IndexSizeError,
            "length of real array (" + String::number(real->length())
            + ") and length of imaginary array (" +  String::number(imag->length())
            + ") must match.");
        return nullptr;
    }

    bool isNormalizationDisabled = false;
    DictionaryHelper::getWithUndefinedOrNullCheck(options, "disableNormalization", isNormalizationDisabled);

    return PeriodicWave::create(sampleRate(), real, imag, isNormalizationDisabled);
}

IIRFilterNode* AbstractAudioContext::createIIRFilter(Vector<double> feedforwardCoef, Vector<double> feedbackCoef,  ExceptionState& exceptionState)
{
    ASSERT(isMainThread());

    if (isContextClosed()) {
        throwExceptionForClosedState(exceptionState);
        return nullptr;
    }

    if (feedbackCoef.size() == 0 || (feedbackCoef.size() > IIRFilter::kMaxOrder + 1)) {
        exceptionState.throwDOMException(
            NotSupportedError,
            ExceptionMessages::indexOutsideRange<size_t>(
                "number of feedback coefficients",
                feedbackCoef.size(),
                1,
                ExceptionMessages::InclusiveBound,
                IIRFilter::kMaxOrder + 1,
                ExceptionMessages::InclusiveBound));
        return nullptr;
    }

    if (feedforwardCoef.size() == 0 || (feedforwardCoef.size() > IIRFilter::kMaxOrder + 1)) {
        exceptionState.throwDOMException(
            NotSupportedError,
            ExceptionMessages::indexOutsideRange<size_t>(
                "number of feedforward coefficients",
                feedforwardCoef.size(),
                1,
                ExceptionMessages::InclusiveBound,
                IIRFilter::kMaxOrder + 1,
                ExceptionMessages::InclusiveBound));
        return nullptr;
    }

    if (feedbackCoef[0] == 0) {
        exceptionState.throwDOMException(
            InvalidStateError,
            "First feedback coefficient cannot be zero.");
        return nullptr;
    }

    bool hasNonZeroCoef = false;

    for (size_t k = 0; k < feedforwardCoef.size(); ++k) {
        if (feedforwardCoef[k] != 0) {
            hasNonZeroCoef = true;
            break;
        }
    }

    if (!hasNonZeroCoef) {
        exceptionState.throwDOMException(
            InvalidStateError,
            "At least one feedforward coefficient must be non-zero.");
        return nullptr;
    }

    // Make sure all coefficents are finite.
    for (size_t k = 0; k < feedforwardCoef.size(); ++k) {
        double c = feedforwardCoef[k];
        if (!std::isfinite(c)) {
            String name = "feedforward coefficient " + String::number(k);
            exceptionState.throwDOMException(
                InvalidStateError,
                ExceptionMessages::notAFiniteNumber(c, name.ascii().data()));
            return nullptr;
        }
    }

    for (size_t k = 0; k < feedbackCoef.size(); ++k) {
        double c = feedbackCoef[k];
        if (!std::isfinite(c)) {
            String name = "feedback coefficient " + String::number(k);
            exceptionState.throwDOMException(
                InvalidStateError,
                ExceptionMessages::notAFiniteNumber(c, name.ascii().data()));
            return nullptr;
        }
    }

    return IIRFilterNode::create(*this, sampleRate(), feedforwardCoef, feedbackCoef);
}

PeriodicWave* AbstractAudioContext::periodicWave(int type)
{
    switch (type) {
    case OscillatorHandler::SINE:
        // Initialize the table if necessary
        if (!m_periodicWaveSine)
            m_periodicWaveSine = PeriodicWave::createSine(sampleRate());
        return m_periodicWaveSine;
    case OscillatorHandler::SQUARE:
        // Initialize the table if necessary
        if (!m_periodicWaveSquare)
            m_periodicWaveSquare = PeriodicWave::createSquare(sampleRate());
        return m_periodicWaveSquare;
    case OscillatorHandler::SAWTOOTH:
        // Initialize the table if necessary
        if (!m_periodicWaveSawtooth)
            m_periodicWaveSawtooth = PeriodicWave::createSawtooth(sampleRate());
        return m_periodicWaveSawtooth;
    case OscillatorHandler::TRIANGLE:
        // Initialize the table if necessary
        if (!m_periodicWaveTriangle)
            m_periodicWaveTriangle = PeriodicWave::createTriangle(sampleRate());
        return m_periodicWaveTriangle;
    default:
        ASSERT_NOT_REACHED();
        return nullptr;
    }
}

String AbstractAudioContext::state() const
{
    // These strings had better match the strings for AudioContextState in AudioContext.idl.
    switch (m_contextState) {
    case Suspended:
        return "suspended";
    case Running:
        return "running";
    case Closed:
        return "closed";
    }
    ASSERT_NOT_REACHED();
    return "";
}

void AbstractAudioContext::setContextState(AudioContextState newState)
{
    ASSERT(isMainThread());

    // Validate the transitions.  The valid transitions are Suspended->Running, Running->Suspended,
    // and anything->Closed.
    switch (newState) {
    case Suspended:
        ASSERT(m_contextState == Running);
        break;
    case Running:
        ASSERT(m_contextState == Suspended);
        break;
    case Closed:
        ASSERT(m_contextState != Closed);
        break;
    }

    if (newState == m_contextState) {
        // ASSERTs above failed; just return.
        return;
    }

    m_contextState = newState;

    // Notify context that state changed
    if (executionContext())
        executionContext()->postTask(BLINK_FROM_HERE, createSameThreadTask(&AbstractAudioContext::notifyStateChange, this));
}

void AbstractAudioContext::notifyStateChange()
{
    dispatchEvent(Event::create(EventTypeNames::statechange));
}

void AbstractAudioContext::notifySourceNodeFinishedProcessing(AudioHandler* handler)
{
    ASSERT(isAudioThread());
    m_finishedSourceHandlers.append(handler);
}

void AbstractAudioContext::releaseFinishedSourceNodes()
{
    ASSERT(isGraphOwner());
    ASSERT(isAudioThread());
    for (AudioHandler* handler : m_finishedSourceHandlers) {
        for (unsigned i = 0; i < m_activeSourceNodes.size(); ++i) {
            if (handler == &m_activeSourceNodes[i]->handler()) {
                handler->breakConnection();
                m_activeSourceNodes.remove(i);
                break;
            }
        }
    }

    m_finishedSourceHandlers.clear();
}

void AbstractAudioContext::notifySourceNodeStartedProcessing(AudioNode* node)
{
    ASSERT(isMainThread());
    AutoLocker locker(this);

    m_activeSourceNodes.append(node);
    node->handler().makeConnection();
}

void AbstractAudioContext::releaseActiveSourceNodes()
{
    ASSERT(isMainThread());
    for (auto& sourceNode : m_activeSourceNodes)
        sourceNode->handler().breakConnection();

    m_activeSourceNodes.clear();
}

void AbstractAudioContext::handleStoppableSourceNodes()
{
    ASSERT(isGraphOwner());

    // Find AudioBufferSourceNodes to see if we can stop playing them.
    for (AudioNode* node : m_activeSourceNodes) {
        if (node->handler().getNodeType() == AudioHandler::NodeTypeAudioBufferSource) {
            AudioBufferSourceNode* sourceNode = static_cast<AudioBufferSourceNode*>(node);
            sourceNode->audioBufferSourceHandler().handleStoppableSourceNode();
        }
    }
}

void AbstractAudioContext::handlePreRenderTasks()
{
    ASSERT(isAudioThread());

    // At the beginning of every render quantum, try to update the internal rendering graph state (from main thread changes).
    // It's OK if the tryLock() fails, we'll just take slightly longer to pick up the changes.
    if (tryLock()) {
        deferredTaskHandler().handleDeferredTasks();

        resolvePromisesForResume();

        // Check to see if source nodes can be stopped because the end time has passed.
        handleStoppableSourceNodes();

        unlock();
    }
}

void AbstractAudioContext::handlePostRenderTasks()
{
    ASSERT(isAudioThread());

    // Must use a tryLock() here too.  Don't worry, the lock will very rarely be contended and this method is called frequently.
    // The worst that can happen is that there will be some nodes which will take slightly longer than usual to be deleted or removed
    // from the render graph (in which case they'll render silence).
    if (tryLock()) {
        // Take care of AudioNode tasks where the tryLock() failed previously.
        deferredTaskHandler().breakConnections();

        // Dynamically clean up nodes which are no longer needed.
        releaseFinishedSourceNodes();

        deferredTaskHandler().handleDeferredTasks();
        deferredTaskHandler().requestToDeleteHandlersOnMainThread();

        unlock();
    }
}

void AbstractAudioContext::resolvePromisesForResumeOnMainThread()
{
    ASSERT(isMainThread());
    AutoLocker locker(this);

    for (auto& resolver : m_resumeResolvers) {
        if (m_contextState == Closed) {
            resolver->reject(
                DOMException::create(InvalidStateError, "Cannot resume a context that has been closed"));
        } else {
            resolver->resolve();
        }
    }

    m_resumeResolvers.clear();
    m_isResolvingResumePromises = false;
}

void AbstractAudioContext::resolvePromisesForResume()
{
    // This runs inside the AbstractAudioContext's lock when handling pre-render tasks.
    ASSERT(isAudioThread());
    ASSERT(isGraphOwner());

    // Resolve any pending promises created by resume(). Only do this if we haven't already started
    // resolving these promises. This gets called very often and it takes some time to resolve the
    // promises in the main thread.
    if (!m_isResolvingResumePromises && m_resumeResolvers.size() > 0) {
        m_isResolvingResumePromises = true;
        Platform::current()->mainThread()->taskRunner()->postTask(BLINK_FROM_HERE, threadSafeBind(&AbstractAudioContext::resolvePromisesForResumeOnMainThread, this));
    }
}

void AbstractAudioContext::rejectPendingResolvers()
{
    ASSERT(isMainThread());

    // Audio context is closing down so reject any resume promises that are still pending.

    for (auto& resolver : m_resumeResolvers) {
        resolver->reject(DOMException::create(InvalidStateError, "Audio context is going away"));
    }
    m_resumeResolvers.clear();
    m_isResolvingResumePromises = false;

    // Now reject any pending decodeAudioData resolvers
    for (auto& resolver : m_decodeAudioResolvers)
        resolver->reject(DOMException::create(InvalidStateError, "Audio context is going away"));
    m_decodeAudioResolvers.clear();
}

const AtomicString& AbstractAudioContext::interfaceName() const
{
    return EventTargetNames::AudioContext;
}

ExecutionContext* AbstractAudioContext::executionContext() const
{
    return ActiveDOMObject::executionContext();
}

void AbstractAudioContext::startRendering()
{
    // This is called for both online and offline contexts.
    ASSERT(isMainThread());
    ASSERT(m_destinationNode);

    if (m_contextState == Suspended) {
        destination()->audioDestinationHandler().startRendering();
        setContextState(Running);
    }
}

DEFINE_TRACE(AbstractAudioContext)
{
    visitor->trace(m_destinationNode);
    visitor->trace(m_listener);
    // trace() can be called in AbstractAudioContext constructor, and
    // m_contextGraphMutex might be unavailable.
    if (m_didInitializeContextGraphMutex) {
        AutoLocker lock(this);
        visitor->trace(m_activeSourceNodes);
    } else {
        visitor->trace(m_activeSourceNodes);
    }
    visitor->trace(m_resumeResolvers);
    visitor->trace(m_decodeAudioResolvers);

    visitor->trace(m_periodicWaveSine);
    visitor->trace(m_periodicWaveSquare);
    visitor->trace(m_periodicWaveSawtooth);
    visitor->trace(m_periodicWaveTriangle);
    RefCountedGarbageCollectedEventTargetWithInlineData<AbstractAudioContext>::trace(visitor);
    ActiveDOMObject::trace(visitor);
}

SecurityOrigin* AbstractAudioContext::securityOrigin() const
{
    if (executionContext())
        return executionContext()->securityOrigin();

    return nullptr;
}

} // namespace blink