Source/WebCore/platform/audio/PlatformMediaSession.cpp

/*
 * Copyright (C) 2014-2015 Apple 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 "config.h"
#include "PlatformMediaSession.h"

#if ENABLE(VIDEO) || ENABLE(WEB_AUDIO)
#include "HTMLMediaElement.h"
#include "Logging.h"
#include "MediaPlayer.h"
#include "PlatformMediaSessionManager.h"

namespace WebCore {

static const Seconds clientDataBufferingTimerThrottleDelay { 100_ms };

#if !LOG_DISABLED
static const char* stateName(PlatformMediaSession::State state)
{
#define STATE_CASE(state) case PlatformMediaSession::state: return #state
    switch (state) {
    STATE_CASE(Idle);
    STATE_CASE(Autoplaying);
    STATE_CASE(Playing);
    STATE_CASE(Paused);
    STATE_CASE(Interrupted);
    }

    ASSERT_NOT_REACHED();
    return "";
}

static const char* interruptionName(PlatformMediaSession::InterruptionType type)
{
#define INTERRUPTION_CASE(type) case PlatformMediaSession::type: return #type
    switch (type) {
    INTERRUPTION_CASE(NoInterruption);
    INTERRUPTION_CASE(SystemSleep);
    INTERRUPTION_CASE(EnteringBackground);
    INTERRUPTION_CASE(SystemInterruption);
    INTERRUPTION_CASE(SuspendedUnderLock);
    INTERRUPTION_CASE(InvisibleAutoplay);
    INTERRUPTION_CASE(ProcessInactive);
    }
    
    ASSERT_NOT_REACHED();
    return "";
}
#endif

std::unique_ptr<PlatformMediaSession> PlatformMediaSession::create(PlatformMediaSessionClient& client)
{
    return std::make_unique<PlatformMediaSession>(client);
}

PlatformMediaSession::PlatformMediaSession(PlatformMediaSessionClient& client)
    : m_client(client)
    , m_clientDataBufferingTimer(*this, &PlatformMediaSession::clientDataBufferingTimerFired)
    , m_state(Idle)
    , m_stateToRestore(Idle)
    , m_notifyingClient(false)
{
    ASSERT(m_client.mediaType() >= None && m_client.mediaType() <= MediaStreamCapturingAudio);
    PlatformMediaSessionManager::sharedManager().addSession(*this);
}

PlatformMediaSession::~PlatformMediaSession()
{
    PlatformMediaSessionManager::sharedManager().removeSession(*this);
}

void PlatformMediaSession::setState(State state)
{
    LOG(Media, "PlatformMediaSession::setState(%p) - %s", this, stateName(state));
    m_state = state;
}

void PlatformMediaSession::beginInterruption(InterruptionType type)
{
    LOG(Media, "PlatformMediaSession::beginInterruption(%p), state = %s, interruption type = %s, interruption count = %i", this, stateName(m_state), interruptionName(type), m_interruptionCount);

    // When interruptions are overridden, m_interruptionType doesn't get set.
    // Give nested interruptions a chance when the previous interruptions were overridden.
    if (++m_interruptionCount > 1 && m_interruptionType != NoInterruption)
        return;

    if (client().shouldOverrideBackgroundPlaybackRestriction(type)) {
        LOG(Media, "PlatformMediaSession::beginInterruption(%p), returning early because client says to override interruption", this);
        return;
    }

    m_stateToRestore = state();
    m_notifyingClient = true;
    setState(Interrupted);
    m_interruptionType = type;
    client().suspendPlayback();
    m_notifyingClient = false;
}

void PlatformMediaSession::endInterruption(EndInterruptionFlags flags)
{
    LOG(Media, "PlatformMediaSession::endInterruption(%p) - flags = %i, stateToRestore = %s, interruption count = %i", this, (int)flags, stateName(m_stateToRestore), m_interruptionCount);

    if (!m_interruptionCount) {
        LOG(Media, "PlatformMediaSession::endInterruption(%p) - !! ignoring spurious interruption end !!", this);
        return;
    }

    if (--m_interruptionCount)
        return;

    State stateToRestore = m_stateToRestore;
    m_stateToRestore = Idle;
    m_interruptionType = NoInterruption;
    setState(stateToRestore);

    if (stateToRestore == Autoplaying)
        client().resumeAutoplaying();

    bool shouldResume = flags & MayResumePlaying && stateToRestore == Playing;
    client().mayResumePlayback(shouldResume);
}

void PlatformMediaSession::clientWillBeginAutoplaying()
{
    if (m_notifyingClient)
        return;

    LOG(Media, "PlatformMediaSession::clientWillBeginAutoplaying(%p)- state = %s", this, stateName(m_state));
    if (state() == Interrupted) {
        m_stateToRestore = Autoplaying;
        LOG(Media, "      setting stateToRestore to \"Autoplaying\"");
        return;
    }

    setState(Autoplaying);
    updateClientDataBuffering();
}

bool PlatformMediaSession::clientWillBeginPlayback()
{
    if (m_notifyingClient)
        return true;

    if (!PlatformMediaSessionManager::sharedManager().sessionWillBeginPlayback(*this)) {
        if (state() == Interrupted)
            m_stateToRestore = Playing;
        return false;
    }

    setState(Playing);
    updateClientDataBuffering();
    return true;
}

bool PlatformMediaSession::clientWillPausePlayback()
{
    if (m_notifyingClient)
        return true;

    LOG(Media, "PlatformMediaSession::clientWillPausePlayback(%p)- state = %s", this, stateName(m_state));
    if (state() == Interrupted) {
        m_stateToRestore = Paused;
        LOG(Media, "      setting stateToRestore to \"Paused\"");
        return false;
    }
    
    setState(Paused);
    PlatformMediaSessionManager::sharedManager().sessionWillEndPlayback(*this);
    scheduleClientDataBufferingCheck();
    return true;
}

void PlatformMediaSession::pauseSession()
{
    LOG(Media, "PlatformMediaSession::pauseSession(%p)", this);
    m_client.suspendPlayback();
}

void PlatformMediaSession::stopSession()
{
    LOG(Media, "PlatformMediaSession::stopSession(%p)", this);
    m_client.suspendPlayback();
    PlatformMediaSessionManager::sharedManager().removeSession(*this);
}

PlatformMediaSession::MediaType PlatformMediaSession::mediaType() const
{
    return m_client.mediaType();
}

PlatformMediaSession::MediaType PlatformMediaSession::presentationType() const
{
    return m_client.presentationType();
}

PlatformMediaSession::CharacteristicsFlags PlatformMediaSession::characteristics() const
{
    return m_client.characteristics();
}

#if ENABLE(VIDEO)
String PlatformMediaSession::title() const
{
    return m_client.mediaSessionTitle();
}

double PlatformMediaSession::duration() const
{
    return m_client.mediaSessionDuration();
}

double PlatformMediaSession::currentTime() const
{
    return m_client.mediaSessionCurrentTime();
}
#endif
    
bool PlatformMediaSession::canReceiveRemoteControlCommands() const
{
    return m_client.canReceiveRemoteControlCommands();
}

void PlatformMediaSession::didReceiveRemoteControlCommand(RemoteControlCommandType command, const PlatformMediaSession::RemoteCommandArgument* argument)
{
    m_client.didReceiveRemoteControlCommand(command, argument);
}

bool PlatformMediaSession::supportsSeeking() const
{
    return m_client.supportsSeeking();
}

void PlatformMediaSession::visibilityChanged()
{
    scheduleClientDataBufferingCheck();
}

void PlatformMediaSession::scheduleClientDataBufferingCheck()
{
    if (!m_clientDataBufferingTimer.isActive())
        m_clientDataBufferingTimer.startOneShot(clientDataBufferingTimerThrottleDelay);
}

void PlatformMediaSession::clientDataBufferingTimerFired()
{
    LOG(Media, "PlatformMediaSession::clientDataBufferingTimerFired(%p)- visible = %s", this, m_client.elementIsHidden() ? "false" : "true");

    updateClientDataBuffering();

#if PLATFORM(IOS)
    PlatformMediaSessionManager::sharedManager().configureWireLessTargetMonitoring();
#endif

    if (m_state != Playing || !m_client.elementIsHidden())
        return;

    PlatformMediaSessionManager::SessionRestrictions restrictions = PlatformMediaSessionManager::sharedManager().restrictions(mediaType());
    if ((restrictions & PlatformMediaSessionManager::BackgroundTabPlaybackRestricted) == PlatformMediaSessionManager::BackgroundTabPlaybackRestricted)
        pauseSession();
}

void PlatformMediaSession::updateClientDataBuffering()
{
    if (m_clientDataBufferingTimer.isActive())
        m_clientDataBufferingTimer.stop();

    m_client.setShouldBufferData(PlatformMediaSessionManager::sharedManager().sessionCanLoadMedia(*this));
}

String PlatformMediaSession::sourceApplicationIdentifier() const
{
    return m_client.sourceApplicationIdentifier();
}

bool PlatformMediaSession::isHidden() const
{
    return m_client.elementIsHidden();
}

bool PlatformMediaSession::isSuspended() const
{
    return m_client.isSuspended();
}

bool PlatformMediaSession::shouldOverrideBackgroundLoadingRestriction() const
{
    return m_client.shouldOverrideBackgroundLoadingRestriction();
}

void PlatformMediaSession::isPlayingToWirelessPlaybackTargetChanged(bool isWireless)
{
    if (isWireless == m_isPlayingToWirelessPlaybackTarget)
        return;

    m_isPlayingToWirelessPlaybackTarget = isWireless;

    // Save and restore the interruption count so it doesn't get out of sync if beginInterruption is called because
    // if we in the background.
    int interruptionCount = m_interruptionCount;
    PlatformMediaSessionManager::sharedManager().sessionIsPlayingToWirelessPlaybackTargetChanged(*this);
    m_interruptionCount = interruptionCount;
}

PlatformMediaSession::DisplayType PlatformMediaSession::displayType() const
{
    return m_client.displayType();
}

bool PlatformMediaSession::activeAudioSessionRequired()
{
    if (mediaType() == PlatformMediaSession::None)
        return false;
    if (state() != PlatformMediaSession::State::Playing)
        return false;
    return canProduceAudio();
}

bool PlatformMediaSession::canProduceAudio() const
{
    return m_client.canProduceAudio();
}

void PlatformMediaSession::canProduceAudioChanged()
{
    PlatformMediaSessionManager::sharedManager().sessionCanProduceAudioChanged(*this);
}

#if ENABLE(VIDEO)
String PlatformMediaSessionClient::mediaSessionTitle() const
{
    return String();
}

double PlatformMediaSessionClient::mediaSessionDuration() const
{
    return MediaPlayer::invalidTime();
}

double PlatformMediaSessionClient::mediaSessionCurrentTime() const
{
    return MediaPlayer::invalidTime();
}
#endif

void PlatformMediaSession::clientCharacteristicsChanged()
{
    PlatformMediaSessionManager::sharedManager().clientCharacteristicsChanged(*this);
}

}
#endif