#include "VideoBackend.h"

#include "DeckLinkSession.h"
#include "OpenGLVideoIOBridge.h"
#include "HealthTelemetry.h"
#include "RenderEngine.h"

#include <chrono>

VideoBackend::VideoBackend(RenderEngine& renderEngine, HealthTelemetry& healthTelemetry) :
	mHealthTelemetry(healthTelemetry),
	mVideoIODevice(std::make_unique<DeckLinkSession>()),
	mBridge(std::make_unique<OpenGLVideoIOBridge>(renderEngine))
{
}

VideoBackend::~VideoBackend()
{
	ReleaseResources();
}

void VideoBackend::ReleaseResources()
{
	if (mVideoIODevice)
		mVideoIODevice->ReleaseResources();
}

bool VideoBackend::DiscoverDevicesAndModes(const VideoFormatSelection& videoModes, std::string& error)
{
	return mVideoIODevice->DiscoverDevicesAndModes(videoModes, error);
}

bool VideoBackend::SelectPreferredFormats(const VideoFormatSelection& videoModes, bool outputAlphaRequired, std::string& error)
{
	return mVideoIODevice->SelectPreferredFormats(videoModes, outputAlphaRequired, error);
}

bool VideoBackend::ConfigureInput(const VideoFormat& inputVideoMode, std::string& error)
{
	return mVideoIODevice->ConfigureInput(
		[this](const VideoIOFrame& frame) { HandleInputFrame(frame); },
		inputVideoMode,
		error);
}

bool VideoBackend::ConfigureOutput(const VideoFormat& outputVideoMode, bool externalKeyingEnabled, std::string& error)
{
	return mVideoIODevice->ConfigureOutput(
		[this](const VideoIOCompletion& completion) { HandleOutputFrameCompletion(completion); },
		outputVideoMode,
		externalKeyingEnabled,
		error);
}

bool VideoBackend::Start()
{
	return mVideoIODevice->Start();
}

bool VideoBackend::Stop()
{
	return mVideoIODevice->Stop();
}

const VideoIOState& VideoBackend::State() const
{
	return mVideoIODevice->State();
}

VideoIOState& VideoBackend::MutableState()
{
	return mVideoIODevice->MutableState();
}

bool VideoBackend::BeginOutputFrame(VideoIOOutputFrame& frame)
{
	return mVideoIODevice->BeginOutputFrame(frame);
}

void VideoBackend::EndOutputFrame(VideoIOOutputFrame& frame)
{
	mVideoIODevice->EndOutputFrame(frame);
}

bool VideoBackend::ScheduleOutputFrame(const VideoIOOutputFrame& frame)
{
	return mVideoIODevice->ScheduleOutputFrame(frame);
}

void VideoBackend::AccountForCompletionResult(VideoIOCompletionResult result)
{
	mVideoIODevice->AccountForCompletionResult(result);
}

bool VideoBackend::HasInputDevice() const
{
	return mVideoIODevice->HasInputDevice();
}

bool VideoBackend::HasInputSource() const
{
	return mVideoIODevice->HasInputSource();
}

unsigned VideoBackend::InputFrameWidth() const
{
	return mVideoIODevice->InputFrameWidth();
}

unsigned VideoBackend::InputFrameHeight() const
{
	return mVideoIODevice->InputFrameHeight();
}

unsigned VideoBackend::OutputFrameWidth() const
{
	return mVideoIODevice->OutputFrameWidth();
}

unsigned VideoBackend::OutputFrameHeight() const
{
	return mVideoIODevice->OutputFrameHeight();
}

unsigned VideoBackend::CaptureTextureWidth() const
{
	return mVideoIODevice->CaptureTextureWidth();
}

unsigned VideoBackend::OutputPackTextureWidth() const
{
	return mVideoIODevice->OutputPackTextureWidth();
}

VideoIOPixelFormat VideoBackend::InputPixelFormat() const
{
	return mVideoIODevice->InputPixelFormat();
}

const std::string& VideoBackend::InputDisplayModeName() const
{
	return mVideoIODevice->InputDisplayModeName();
}

const std::string& VideoBackend::OutputModelName() const
{
	return mVideoIODevice->OutputModelName();
}

bool VideoBackend::SupportsInternalKeying() const
{
	return mVideoIODevice->SupportsInternalKeying();
}

bool VideoBackend::SupportsExternalKeying() const
{
	return mVideoIODevice->SupportsExternalKeying();
}

bool VideoBackend::KeyerInterfaceAvailable() const
{
	return mVideoIODevice->KeyerInterfaceAvailable();
}

bool VideoBackend::ExternalKeyingActive() const
{
	return mVideoIODevice->ExternalKeyingActive();
}

const std::string& VideoBackend::StatusMessage() const
{
	return mVideoIODevice->StatusMessage();
}

void VideoBackend::SetStatusMessage(const std::string& message)
{
	mVideoIODevice->SetStatusMessage(message);
}

void VideoBackend::PublishStatus(bool externalKeyingConfigured, const std::string& statusMessage)
{
	if (!statusMessage.empty())
		SetStatusMessage(statusMessage);

	mHealthTelemetry.ReportVideoIOStatus(
		"decklink",
		OutputModelName(),
		SupportsInternalKeying(),
		SupportsExternalKeying(),
		KeyerInterfaceAvailable(),
		externalKeyingConfigured,
		ExternalKeyingActive(),
		StatusMessage());
}

void VideoBackend::ReportNoInputDeviceSignalStatus()
{
	mHealthTelemetry.ReportSignalStatus(
		false,
		InputFrameWidth(),
		InputFrameHeight(),
		InputDisplayModeName());
}

void VideoBackend::HandleInputFrame(const VideoIOFrame& frame)
{
	const VideoIOState& state = mVideoIODevice->State();
	mHealthTelemetry.TryReportSignalStatus(!frame.hasNoInputSource, state.inputFrameSize.width, state.inputFrameSize.height, state.inputDisplayModeName);

	if (mBridge)
		mBridge->UploadInputFrame(frame, state);
}

void VideoBackend::HandleOutputFrameCompletion(const VideoIOCompletion& completion)
{
	RecordFramePacing(completion.result);

	VideoIOOutputFrame outputFrame;
	if (!BeginOutputFrame(outputFrame))
		return;

	const VideoIOState& state = mVideoIODevice->State();
	if (mBridge)
		mBridge->RenderScheduledFrame(state, completion, outputFrame);

	EndOutputFrame(outputFrame);
	AccountForCompletionResult(completion.result);

	// Schedule the next frame after render work is complete so device-side
	// bookkeeping stays with the backend seam and the bridge stays render-only.
	ScheduleOutputFrame(outputFrame);
}

void VideoBackend::RecordFramePacing(VideoIOCompletionResult completionResult)
{
	const auto now = std::chrono::steady_clock::now();
	if (mLastPlayoutCompletionTime != std::chrono::steady_clock::time_point())
	{
		mCompletionIntervalMilliseconds = std::chrono::duration_cast<std::chrono::duration<double, std::milli>>(now - mLastPlayoutCompletionTime).count();
		if (mSmoothedCompletionIntervalMilliseconds <= 0.0)
			mSmoothedCompletionIntervalMilliseconds = mCompletionIntervalMilliseconds;
		else
			mSmoothedCompletionIntervalMilliseconds = mSmoothedCompletionIntervalMilliseconds * 0.9 + mCompletionIntervalMilliseconds * 0.1;
		if (mCompletionIntervalMilliseconds > mMaxCompletionIntervalMilliseconds)
			mMaxCompletionIntervalMilliseconds = mCompletionIntervalMilliseconds;
	}
	mLastPlayoutCompletionTime = now;

	if (completionResult == VideoIOCompletionResult::DisplayedLate)
		++mLateFrameCount;
	else if (completionResult == VideoIOCompletionResult::Dropped)
		++mDroppedFrameCount;
	else if (completionResult == VideoIOCompletionResult::Flushed)
		++mFlushedFrameCount;

	mHealthTelemetry.TryRecordFramePacingStats(
		mCompletionIntervalMilliseconds,
		mSmoothedCompletionIntervalMilliseconds,
		mMaxCompletionIntervalMilliseconds,
		mLateFrameCount,
		mDroppedFrameCount,
		mFlushedFrameCount);
}