/*
 *  Copyright (C) 2007 OpenedHand
 *  Copyright (C) 2007 Alp Toker <alp@atoker.com>
 *  Copyright (C) 2009, 2010, 2011, 2012, 2015, 2016 Igalia S.L
 *  Copyright (C) 2015, 2016 Metrological Group B.V.
 *
 *  This library is free software; you can redistribute it and/or
 *  modify it under the terms of the GNU Lesser General Public
 *  License as published by the Free Software Foundation; either
 *  version 2 of the License, or (at your option) any later version.
 *
 *  This library is distributed in the hope that it will be useful,
 *  but WITHOUT ANY WARRANTY; without even the implied warranty of
 *  MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the GNU
 *  Lesser General Public License for more details.
 *
 *  You should have received a copy of the GNU Lesser General Public
 *  License along with this library; if not, write to the Free Software
 *  Foundation, Inc., 51 Franklin Street, Fifth Floor, Boston, MA  02110-1301  USA
 */

/*
 *
 * WebKitVideoSink is a GStreamer sink element that triggers
 * repaints in the WebKit GStreamer media player for the
 * current video buffer.
 */

#include "config.h"
#include "VideoSinkGStreamer.h"

#if ENABLE(VIDEO) && USE(GSTREAMER)
#include "GStreamerCommon.h"
#include "IntSize.h"
#include <glib.h>
#include <gst/gst.h>
#include <gst/video/gstvideometa.h>
#include <wtf/Condition.h>
#include <wtf/RunLoop.h>
#include <wtf/glib/WTFGType.h>

using namespace WebCore;

// CAIRO_FORMAT_RGB24 used to render the video buffers is little/big endian dependant.
#if G_BYTE_ORDER == G_LITTLE_ENDIAN
#define GST_CAPS_FORMAT "{ BGRx, BGRA }"
#else
#define GST_CAPS_FORMAT "{ xRGB, ARGB }"
#endif

#define WEBKIT_VIDEO_SINK_PAD_CAPS GST_VIDEO_CAPS_MAKE_WITH_FEATURES(GST_CAPS_FEATURE_META_GST_VIDEO_GL_TEXTURE_UPLOAD_META, GST_CAPS_FORMAT) ";" GST_VIDEO_CAPS_MAKE(GST_CAPS_FORMAT)

static GstStaticPadTemplate s_videoSinkTemplate = GST_STATIC_PAD_TEMPLATE("sink", GST_PAD_SINK, GST_PAD_ALWAYS, GST_STATIC_CAPS(WEBKIT_VIDEO_SINK_PAD_CAPS));


GST_DEBUG_CATEGORY_STATIC(webkitVideoSinkDebug);
#define GST_CAT_DEFAULT webkitVideoSinkDebug

enum {
    REPAINT_REQUESTED,
    REPAINT_CANCELLED,
    LAST_SIGNAL
};

static std::array<unsigned, LAST_SIGNAL> webkitVideoSinkSignals;

static void webkitVideoSinkRepaintRequested(WebKitVideoSink*, GstSample*);
static GRefPtr<GstSample> webkitVideoSinkRequestRender(WebKitVideoSink*, GstBuffer*);

class VideoRenderRequestScheduler {
public:
    void start()
    {
        Locker locker { m_sampleLock };
        m_unlocked = false;
    }

    void stop()
    {
        Locker locker { m_sampleLock };
        m_sample = nullptr;
        m_unlocked = true;
    }

    void drain()
    {
        Locker locker { m_sampleLock };
        m_sample = nullptr;
    }

    bool requestRender(WebKitVideoSink* sink, GstBuffer* buffer)
    {
        GRefPtr<GstSample> sample;
        {
            Locker locker { m_sampleLock };
            if (m_unlocked)
                return true;

            m_sample = webkitVideoSinkRequestRender(sink, buffer);
            if (!m_sample)
                return false;

            sample = std::exchange(m_sample, nullptr);
        }

        if (LIKELY(GST_IS_SAMPLE(sample.get())))
            webkitVideoSinkRepaintRequested(sink, sample.get());

        return true;
    }

private:
    Lock m_sampleLock;
    GRefPtr<GstSample> m_sample WTF_GUARDED_BY_LOCK(m_sampleLock);

    // If this is true all processing should finish ASAP
    // This is necessary because there could be a race between
    // unlock() and render(), where unlock() wins, signals the
    // Condition, then render() tries to render a frame although
    // everything else isn't running anymore. This will lead
    // to deadlocks because render() holds the stream lock.
    //
    // Protected by the sample mutex
    bool m_unlocked { false };
};

struct _WebKitVideoSinkPrivate {
    VideoRenderRequestScheduler scheduler;
    GstVideoInfo info;
    GRefPtr<GstCaps> currentCaps;
};

WEBKIT_DEFINE_TYPE_WITH_CODE(WebKitVideoSink, webkit_video_sink, GST_TYPE_VIDEO_SINK, GST_DEBUG_CATEGORY_INIT(webkitVideoSinkDebug, "webkitvideosink", 0, "webkit video sink"))

static void webkitVideoSinkConstructed(GObject* object)
{
    G_OBJECT_CLASS(webkit_video_sink_parent_class)->constructed(object);
    g_object_set(GST_BASE_SINK(object), "enable-last-sample", FALSE, nullptr);
}

static void webkitVideoSinkRepaintRequested(WebKitVideoSink* sink, GstSample* sample)
{
    g_signal_emit(sink, webkitVideoSinkSignals[REPAINT_REQUESTED], 0, sample);
}

static void webkitVideoSinkRepaintCancelled(WebKitVideoSink* sink)
{
    g_signal_emit(sink, webkitVideoSinkSignals[REPAINT_CANCELLED], 0);
}

static GRefPtr<GstSample> webkitVideoSinkRequestRender(WebKitVideoSink* sink, GstBuffer* buffer)
{
    WebKitVideoSinkPrivate* priv = sink->priv;
    GRefPtr<GstSample> sample = adoptGRef(gst_sample_new(buffer, priv->currentCaps.get(), nullptr, nullptr));

    // The video info structure is valid only if the sink handled an allocation query.
    GstVideoFormat format = GST_VIDEO_INFO_FORMAT(&priv->info);
    if (format == GST_VIDEO_FORMAT_UNKNOWN)
        return nullptr;

    return sample;
}

static GstFlowReturn webkitVideoSinkRender(GstBaseSink* baseSink, GstBuffer* buffer)
{
    WebKitVideoSink* sink = WEBKIT_VIDEO_SINK(baseSink);
    return sink->priv->scheduler.requestRender(sink, buffer) ? GST_FLOW_OK : GST_FLOW_ERROR;
}

static gboolean webkitVideoSinkUnlock(GstBaseSink* baseSink)
{
    WebKitVideoSinkPrivate* priv = WEBKIT_VIDEO_SINK(baseSink)->priv;

    priv->scheduler.stop();
    webkitVideoSinkRepaintCancelled(WEBKIT_VIDEO_SINK(baseSink));

    // basesink doesn't have any default unlock vfunc. So no need to chain to parent class here.
    return TRUE;
}

static gboolean webkitVideoSinkUnlockStop(GstBaseSink* baseSink)
{
    WebKitVideoSinkPrivate* priv = WEBKIT_VIDEO_SINK(baseSink)->priv;

    priv->scheduler.start();

    // basesink doesn't have any default unlock_stop vfunc. So no need to chain to parent class here.
    return TRUE;
}

static gboolean webkitVideoSinkStop(GstBaseSink* baseSink)
{
    WebKitVideoSinkPrivate* priv = WEBKIT_VIDEO_SINK(baseSink)->priv;

    priv->scheduler.stop();
    webkitVideoSinkRepaintCancelled(WEBKIT_VIDEO_SINK(baseSink));
    priv->currentCaps.clear();

    return TRUE;
}

static gboolean webkitVideoSinkStart(GstBaseSink* baseSink)
{
    WebKitVideoSinkPrivate* priv = WEBKIT_VIDEO_SINK(baseSink)->priv;

    priv->scheduler.start();

    return TRUE;
}

static gboolean webkitVideoSinkSetCaps(GstBaseSink* baseSink, GstCaps* caps)
{
    WebKitVideoSink* sink = WEBKIT_VIDEO_SINK(baseSink);
    WebKitVideoSinkPrivate* priv = sink->priv;

    GST_DEBUG_OBJECT(sink, "Current caps %" GST_PTR_FORMAT ", setting caps %" GST_PTR_FORMAT, priv->currentCaps.get(), caps);

    GstVideoInfo videoInfo;
    if (!gst_video_info_from_caps(&videoInfo, caps)) {
        GST_ERROR_OBJECT(sink, "Invalid caps %" GST_PTR_FORMAT, caps);
        return FALSE;
    }

    priv->info = videoInfo;
    priv->currentCaps = caps;
    return GST_BASE_SINK_CLASS(webkit_video_sink_parent_class)->set_caps(baseSink, caps);
}

static gboolean webkitVideoSinkProposeAllocation(GstBaseSink* baseSink, GstQuery* query)
{
    GstCaps* caps;
    gst_query_parse_allocation(query, &caps, nullptr);
    if (!caps)
        return FALSE;

    WebKitVideoSink* sink = WEBKIT_VIDEO_SINK(baseSink);
    if (!gst_video_info_from_caps(&sink->priv->info, caps))
        return FALSE;

    gst_query_add_allocation_meta(query, GST_VIDEO_META_API_TYPE, nullptr);
    gst_query_add_allocation_meta(query, GST_VIDEO_CROP_META_API_TYPE, nullptr);
    gst_query_add_allocation_meta(query, GST_VIDEO_GL_TEXTURE_UPLOAD_META_API_TYPE, nullptr);
    return TRUE;
}

static gboolean webkitVideoSinkEvent(GstBaseSink* baseSink, GstEvent* event)
{
    switch (GST_EVENT_TYPE(event)) {
    case GST_EVENT_FLUSH_START: {
        WebKitVideoSink* sink = WEBKIT_VIDEO_SINK(baseSink);
        sink->priv->scheduler.drain();

        GST_DEBUG_OBJECT(sink, "Flush-start, releasing m_sample");
    }
        FALLTHROUGH;
    default:
        return GST_BASE_SINK_CLASS(webkit_video_sink_parent_class)->event(baseSink, event);
    }
}

static void webkit_video_sink_class_init(WebKitVideoSinkClass* klass)
{
    GObjectClass* gobjectClass = G_OBJECT_CLASS(klass);
    GstBaseSinkClass* baseSinkClass = GST_BASE_SINK_CLASS(klass);
    GstElementClass* elementClass = GST_ELEMENT_CLASS(klass);

    gst_element_class_add_pad_template(elementClass, gst_static_pad_template_get(&s_videoSinkTemplate));
    gst_element_class_set_metadata(elementClass, "WebKit video sink", "Sink/Video", "Sends video data from a GStreamer pipeline to WebKit", "Igalia, Alp Toker <alp@atoker.com>");

    gobjectClass->constructed = webkitVideoSinkConstructed;

    baseSinkClass->unlock = webkitVideoSinkUnlock;
    baseSinkClass->unlock_stop = webkitVideoSinkUnlockStop;
    baseSinkClass->render = webkitVideoSinkRender;
    baseSinkClass->preroll = webkitVideoSinkRender;
    baseSinkClass->stop = webkitVideoSinkStop;
    baseSinkClass->start = webkitVideoSinkStart;
    baseSinkClass->set_caps = webkitVideoSinkSetCaps;
    baseSinkClass->propose_allocation = webkitVideoSinkProposeAllocation;
    baseSinkClass->event = webkitVideoSinkEvent;

    webkitVideoSinkSignals[REPAINT_REQUESTED] = g_signal_new("repaint-requested",
            G_TYPE_FROM_CLASS(klass),
            static_cast<GSignalFlags>(G_SIGNAL_RUN_LAST | G_SIGNAL_ACTION),
            0, // Class offset
            0, // Accumulator
            0, // Accumulator data
            g_cclosure_marshal_generic,
            G_TYPE_NONE, // Return type
            1, // Only one parameter
            GST_TYPE_SAMPLE);
    webkitVideoSinkSignals[REPAINT_CANCELLED] = g_signal_new("repaint-cancelled",
        G_TYPE_FROM_CLASS(klass),
        G_SIGNAL_RUN_LAST,
        0, // Class offset
        nullptr, // Accumulator
        nullptr, // Accumulator data
        g_cclosure_marshal_generic,
        G_TYPE_NONE, // Return type
        0, // No parameters
        G_TYPE_NONE);
}


GstElement* webkitVideoSinkNew()
{
    return GST_ELEMENT(g_object_new(WEBKIT_TYPE_VIDEO_SINK, nullptr));
}

#undef GST_CAT_DEFAULT

#endif // ENABLE(VIDEO) && USE(GSTREAMER)