// This file is part of OpenCV project.
// It is subject to the license terms in the LICENSE file found in the top-level
// directory of this distribution and at http://opencv.org/license.html.
//
// Copyright (C) 2018-2019 Intel Corporation

#include <opencv2/gapi.hpp>
#include <opencv2/gapi/core.hpp>
#include <opencv2/gapi/imgproc.hpp>
#include <opencv2/gapi/fluid/core.hpp>
#include <opencv2/gapi/infer.hpp>
#include <opencv2/gapi/infer/ie.hpp>
#include <opencv2/gapi/cpu/gcpukernel.hpp>
#include "opencv2/gapi/streaming/cap.hpp"

#include <opencv2/videoio.hpp>
#include <opencv2/highgui.hpp>
#include <iomanip>

namespace config
{
constexpr char       kWinFaceBeautification[] = "FaceBeautificator";
constexpr char       kWinInput[]              = "Input";
const     cv::Scalar kClrWhite (255, 255, 255);
const     cv::Scalar kClrGreen (  0, 255,   0);
const     cv::Scalar kClrYellow(  0, 255, 255);

constexpr float      kConfThresh   = 0.7f;

const     cv::Size   kGKernelSize(5, 5);
constexpr double     kGSigma       = 0.0;
constexpr int        kBSize        = 9;
constexpr double     kBSigmaCol    = 30.0;
constexpr double     kBSigmaSp     = 30.0;
constexpr int        kUnshSigma    = 3;
constexpr float      kUnshStrength = 0.7f;
constexpr int        kAngDelta     = 1;
constexpr bool       kClosedLine   = true;

const size_t kNumPointsInHalfEllipse = 180 / config::kAngDelta + 1;
} // namespace config

namespace
{
using VectorROI = std::vector<cv::Rect>;
using GArrayROI = cv::GArray<cv::Rect>;
using Contour   = std::vector<cv::Point>;
using Landmarks = std::vector<cv::Point>;


// Wrapper function
template<typename Tp> inline int toIntRounded(const Tp x)
{
    return static_cast<int>(std::lround(x));
}

template<typename Tp> inline double toDouble(const Tp x)
{
    return static_cast<double>(x);
}

std::string getWeightsPath(const std::string &mdlXMLPath) // mdlXMLPath =
                                                          // "The/Full/Path.xml"
{
    size_t size = mdlXMLPath.size();
    CV_Assert(mdlXMLPath.substr(size - 4, size)           // The last 4 symbols
                  == ".xml");                             // must be ".xml"
    std::string mdlBinPath(mdlXMLPath);
    return mdlBinPath.replace(size - 3, 3, "bin");        // return
                                                          // "The/Full/Path.bin"
}
} // anonymous namespace



namespace custom
{
using TplPtsFaceElements_Jaw = std::tuple<cv::GArray<Landmarks>,
                                          cv::GArray<Contour>>;
using TplFaces_FaceElements  = std::tuple<cv::GArray<Contour>,
                                          cv::GArray<Contour>>;

// Wrapper-functions
inline int getLineInclinationAngleDegrees(const cv::Point &ptLeft,
                                          const cv::Point &ptRight);
inline Contour getForeheadEllipse(const cv::Point &ptJawLeft,
                                  const cv::Point &ptJawRight,
                                  const cv::Point &ptJawMiddle,
                                  const size_t     capacity);
inline Contour getEyeEllipse(const cv::Point &ptLeft,
                             const cv::Point &ptRight,
                             const size_t     capacity);
inline Contour getPatchedEllipse(const cv::Point &ptLeft,
                                 const cv::Point &ptRight,
                                 const cv::Point &ptUp,
                                 const cv::Point &ptDown);

// Networks
G_API_NET(FaceDetector,  <cv::GMat(cv::GMat)>, "face_detector");
G_API_NET(LandmDetector, <cv::GMat(cv::GMat)>, "landm_detector");

// Function kernels
G_TYPED_KERNEL(GBilatFilter,
               <cv::GMat(cv::GMat,int,double,double)>,
               "custom.faceb12n.bilateralFilter")
{
    static cv::GMatDesc outMeta(cv::GMatDesc in, int,double,double)
    {
        return in;
    }
};

G_TYPED_KERNEL(GLaplacian,
               <cv::GMat(cv::GMat,int)>,
               "custom.faceb12n.Laplacian")
{
    static cv::GMatDesc outMeta(cv::GMatDesc in, int)
    {
        return in;
    }
};

G_TYPED_KERNEL(GFillPolyGContours,
               <cv::GMat(cv::GMat,cv::GArray<Contour>)>,
               "custom.faceb12n.fillPolyGContours")
{
    static cv::GMatDesc outMeta(cv::GMatDesc in, cv::GArrayDesc)
    {
        return in.withType(CV_8U, 1);
    }
};

G_TYPED_KERNEL(GPolyLines,
               <cv::GMat(cv::GMat,cv::GArray<Contour>,bool,cv::Scalar)>,
               "custom.faceb12n.polyLines")
{
    static cv::GMatDesc outMeta(cv::GMatDesc in, cv::GArrayDesc,bool,cv::Scalar)
    {
        return in;
    }
};

G_TYPED_KERNEL(GRectangle,
               <cv::GMat(cv::GMat,GArrayROI,cv::Scalar)>,
               "custom.faceb12n.rectangle")
{
    static cv::GMatDesc outMeta(cv::GMatDesc in, cv::GArrayDesc,cv::Scalar)
    {
        return in;
    }
};

G_TYPED_KERNEL(GFacePostProc,
               <GArrayROI(cv::GMat,cv::GMat,float)>,
               "custom.faceb12n.faceDetectPostProc")
{
    static cv::GArrayDesc outMeta(const cv::GMatDesc&,const cv::GMatDesc&,float)
    {
        return cv::empty_array_desc();
    }
};

G_TYPED_KERNEL_M(GLandmPostProc,
                 <TplPtsFaceElements_Jaw(cv::GArray<cv::GMat>,GArrayROI)>,
                 "custom.faceb12n.landmDetectPostProc")
{
    static std::tuple<cv::GArrayDesc,cv::GArrayDesc> outMeta(
                const cv::GArrayDesc&,const cv::GArrayDesc&)
    {
        return std::make_tuple(cv::empty_array_desc(), cv::empty_array_desc());
    }
};

G_TYPED_KERNEL_M(GGetContours,
                 <TplFaces_FaceElements(cv::GArray<Landmarks>,
                                        cv::GArray<Contour>)>,
                 "custom.faceb12n.getContours")
{
    static std::tuple<cv::GArrayDesc,cv::GArrayDesc> outMeta(
                const cv::GArrayDesc&,const cv::GArrayDesc&)
    {
        return std::make_tuple(cv::empty_array_desc(), cv::empty_array_desc());
    }
};


// OCV_Kernels
// This kernel applies Bilateral filter to an input src with default
//  "cv::bilateralFilter" border argument
GAPI_OCV_KERNEL(GCPUBilateralFilter, custom::GBilatFilter)
{
    static void run(const cv::Mat &src,
                    const int      diameter,
                    const double   sigmaColor,
                    const double   sigmaSpace,
                          cv::Mat &out)
    {
        cv::bilateralFilter(src, out, diameter, sigmaColor, sigmaSpace);
    }
};

// This kernel applies Laplace operator to an input src with default
//  "cv::Laplacian" arguments
GAPI_OCV_KERNEL(GCPULaplacian, custom::GLaplacian)
{
    static void run(const cv::Mat &src,
                    const int      ddepth,
                          cv::Mat &out)
    {
        cv::Laplacian(src, out, ddepth);
    }
};

// This kernel draws given white filled contours "cnts" on a clear Mat "out"
//  (defined by a Scalar(0)) with standard "cv::fillPoly" arguments.
//  It should be used to create a mask.
// The input Mat seems unused inside the function "run", but it is used deeper
//  in the kernel to define an output size.
GAPI_OCV_KERNEL(GCPUFillPolyGContours, custom::GFillPolyGContours)
{
    static void run(const cv::Mat              &,
                    const std::vector<Contour> &cnts,
                          cv::Mat              &out)
    {
        out = cv::Scalar(0);
        cv::fillPoly(out, cnts, config::kClrWhite);
    }
};

// This kernel draws given contours on an input src with default "cv::polylines"
//  arguments
GAPI_OCV_KERNEL(GCPUPolyLines, custom::GPolyLines)
{
    static void run(const cv::Mat              &src,
                    const std::vector<Contour> &cnts,
                    const bool                  isClosed,
                    const cv::Scalar           &color,
                          cv::Mat              &out)
    {
        src.copyTo(out);
        cv::polylines(out, cnts, isClosed, color);
    }
};

// This kernel draws given rectangles on an input src with default
//  "cv::rectangle" arguments
GAPI_OCV_KERNEL(GCPURectangle, custom::GRectangle)
{
    static void run(const cv::Mat    &src,
                    const VectorROI  &vctFaceBoxes,
                    const cv::Scalar &color,
                          cv::Mat    &out)
    {
        src.copyTo(out);
        for (const cv::Rect &box : vctFaceBoxes)
        {
            cv::rectangle(out, box, color);
        }
    }
};

// A face detector outputs a blob with the shape: [1, 1, N, 7], where N is
//  the number of detected bounding boxes. Structure of an output for every
//  detected face is the following:
//  [image_id, label, conf, x_min, y_min, x_max, y_max]; all the seven elements
//  are floating point. For more details please visit:
//  https://github.com/opencv/open_model_zoo/blob/master/intel_models/face-detection-adas-0001
// This kernel is the face detection output blob parsing that returns a vector
//  of detected faces' rects:
GAPI_OCV_KERNEL(GCPUFacePostProc, GFacePostProc)
{
    static void run(const cv::Mat   &inDetectResult,
                    const cv::Mat   &inFrame,
                    const float      faceConfThreshold,
                          VectorROI &outFaces)
    {
        const int kObjectSize  = 7;
        const int imgCols = inFrame.size().width;
        const int imgRows = inFrame.size().height;
        const cv::Rect borders({0, 0}, inFrame.size());
        outFaces.clear();
        const int    numOfDetections = inDetectResult.size[2];
        const float *data            = inDetectResult.ptr<float>();
        for (int i = 0; i < numOfDetections; i++)
        {
            const float faceId         = data[i * kObjectSize + 0];
            if (faceId < 0.f)  // indicates the end of detections
            {
                break;
            }
            const float faceConfidence = data[i * kObjectSize + 2];
            if (faceConfidence > faceConfThreshold)
            {
                const float left   = data[i * kObjectSize + 3];
                const float top    = data[i * kObjectSize + 4];
                const float right  = data[i * kObjectSize + 5];
                const float bottom = data[i * kObjectSize + 6];
                cv::Point tl(toIntRounded(left   * imgCols),
                             toIntRounded(top    * imgRows));
                cv::Point br(toIntRounded(right  * imgCols),
                             toIntRounded(bottom * imgRows));
                outFaces.push_back(cv::Rect(tl, br) & borders);
            }
        }
    }
};

// This kernel is the facial landmarks detection output Mat parsing for every
//  detected face; returns a tuple containing a vector of vectors of
//  face elements' Points and a vector of vectors of jaw's Points:
GAPI_OCV_KERNEL(GCPULandmPostProc, GLandmPostProc)
{
    static void run(const std::vector<cv::Mat>   &vctDetectResults,
                    const VectorROI              &vctRects,
                          std::vector<Landmarks> &vctPtsFaceElems,
                          std::vector<Contour>   &vctCntJaw)
    {
        // There are 35 landmarks given by the default detector for each face
        //  in a frame; the first 18 of them are face elements (eyes, eyebrows,
        //  a nose, a mouth) and the last 17 - a jaw contour. The detector gives
        //  floating point values for landmarks' normed coordinates relatively
        //  to an input ROI (not the original frame).
        //  For more details please visit:
        //  https://github.com/opencv/open_model_zoo/blob/master/intel_models/facial-landmarks-35-adas-0002
        static constexpr int kNumFaceElems = 18;
        static constexpr int kNumTotal     = 35;
        const size_t numFaces = vctRects.size();
        CV_Assert(vctPtsFaceElems.size() == 0ul);
        CV_Assert(vctCntJaw.size()       == 0ul);
        vctPtsFaceElems.reserve(numFaces);
        vctCntJaw.reserve(numFaces);

        Landmarks ptsFaceElems;
        Contour   cntJaw;
        ptsFaceElems.reserve(kNumFaceElems);
        cntJaw.reserve(kNumTotal - kNumFaceElems);

        for (size_t i = 0; i < numFaces; i++)
        {
            const float *data = vctDetectResults[i].ptr<float>();
            // The face elements points:
            ptsFaceElems.clear();
            for (int j = 0; j < kNumFaceElems * 2; j += 2)
            {
                cv::Point pt =
                        cv::Point(toIntRounded(data[j]   * vctRects[i].width),
                                  toIntRounded(data[j+1] * vctRects[i].height))
                        + vctRects[i].tl();
                ptsFaceElems.push_back(pt);
            }
            vctPtsFaceElems.push_back(ptsFaceElems);

            // The jaw contour points:
            cntJaw.clear();
            for(int j = kNumFaceElems * 2; j < kNumTotal * 2; j += 2)
            {
                cv::Point pt =
                        cv::Point(toIntRounded(data[j]   * vctRects[i].width),
                                  toIntRounded(data[j+1] * vctRects[i].height))
                        + vctRects[i].tl();
                cntJaw.push_back(pt);
            }
            vctCntJaw.push_back(cntJaw);
        }
    }
};

// This kernel is the facial landmarks detection post-processing for every face
//  detected before; output is a tuple of vectors of detected face contours and
//  facial elements contours:
GAPI_OCV_KERNEL(GCPUGetContours, GGetContours)
{
    static void run(const std::vector<Landmarks> &vctPtsFaceElems,
                    const std::vector<Contour>   &vctCntJaw,
                          std::vector<Contour>   &vctElemsContours,
                          std::vector<Contour>   &vctFaceContours)
    {
        size_t numFaces = vctCntJaw.size();
        CV_Assert(numFaces == vctPtsFaceElems.size());
        CV_Assert(vctElemsContours.size() == 0ul);
        CV_Assert(vctFaceContours.size()  == 0ul);
        // vctFaceElemsContours will store all the face elements' contours found
        //  on an input image, namely 4 elements (two eyes, nose, mouth)
        //  for every detected face
        vctElemsContours.reserve(numFaces * 4);
        // vctFaceElemsContours will store all the faces' contours found on
        //  an input image
        vctFaceContours.reserve(numFaces);

        Contour cntFace, cntLeftEye, cntRightEye, cntNose, cntMouth;
        cntNose.reserve(4);

        for (size_t i = 0ul; i < numFaces; i++)
        {
            // The face elements contours
            // A left eye:
            // Approximating the lower eye contour by half-ellipse
            //  (using eye points) and storing in cntLeftEye:
            cntLeftEye = getEyeEllipse(vctPtsFaceElems[i][1],
                                       vctPtsFaceElems[i][0],
                                       config::kNumPointsInHalfEllipse + 3);
            // Pushing the left eyebrow clock-wise:
            cntLeftEye.insert(cntLeftEye.cend(), {vctPtsFaceElems[i][12],
                                                  vctPtsFaceElems[i][13],
                                                  vctPtsFaceElems[i][14]});
            // A right eye:
            // Approximating the lower eye contour by half-ellipse
            //  (using eye points) and storing in vctRightEye:
            cntRightEye = getEyeEllipse(vctPtsFaceElems[i][2],
                                        vctPtsFaceElems[i][3],
                                        config::kNumPointsInHalfEllipse + 3);
            // Pushing the right eyebrow clock-wise:
            cntRightEye.insert(cntRightEye.cend(), {vctPtsFaceElems[i][15],
                                                    vctPtsFaceElems[i][16],
                                                    vctPtsFaceElems[i][17]});
            // A nose:
            // Storing the nose points clock-wise
            cntNose.clear();
            cntNose.insert(cntNose.cend(), {vctPtsFaceElems[i][4],
                                            vctPtsFaceElems[i][7],
                                            vctPtsFaceElems[i][5],
                                            vctPtsFaceElems[i][6]});
            // A mouth:
            // Approximating the mouth contour by two half-ellipses
            //  (using mouth points) and storing in vctMouth:
            cntMouth = getPatchedEllipse(vctPtsFaceElems[i][8],
                                         vctPtsFaceElems[i][9],
                                         vctPtsFaceElems[i][10],
                                         vctPtsFaceElems[i][11]);
            // Storing all the elements in a vector:
            vctElemsContours.insert(vctElemsContours.cend(), {cntLeftEye,
                                                              cntRightEye,
                                                              cntNose,
                                                              cntMouth});

            // The face contour:
            // Approximating the forehead contour by half-ellipse
            //  (using jaw points) and storing in vctFace:
            cntFace = getForeheadEllipse(vctCntJaw[i][0], vctCntJaw[i][16],
                                         vctCntJaw[i][8],
                                         config::kNumPointsInHalfEllipse +
                                            vctCntJaw[i].size());
            // The ellipse is drawn clock-wise, but jaw contour points goes
            //  vice versa, so it's necessary to push cntJaw from the end
            //  to the begin using a reverse iterator:
            std::copy(vctCntJaw[i].crbegin(), vctCntJaw[i].crend(),
                      std::back_inserter(cntFace));
            // Storing the face contour in another vector:
            vctFaceContours.push_back(cntFace);
        }
    }
};

// GAPI subgraph functions
inline cv::GMat unsharpMask(const cv::GMat &src,
                            const int       sigma,
                            const float     strength);
inline cv::GMat mask3C(const cv::GMat &src,
                       const cv::GMat &mask);
} // namespace custom


// Functions implementation:
// Returns an angle (in degrees) between a line given by two Points and
//  the horison. Note that the result depends on the arguments order:
inline int custom::getLineInclinationAngleDegrees(const cv::Point &ptLeft,
                                                  const cv::Point &ptRight)
{
    const cv::Point residual = ptRight - ptLeft;
    if (residual.y == 0 && residual.x == 0)
        return 0;
    else
        return toIntRounded(atan2(toDouble(residual.y), toDouble(residual.x))
                                * 180.0 / M_PI);
}

// Approximates a forehead by half-ellipse using jaw points and some geometry
//  and then returns points of the contour; "capacity" is used to reserve enough
//  memory as there will be other points inserted.
inline Contour custom::getForeheadEllipse(const cv::Point &ptJawLeft,
                                          const cv::Point &ptJawRight,
                                          const cv::Point &ptJawLower,
                                          const size_t     capacity = 0)
{
    Contour cntForehead;
    cntForehead.reserve(std::max(capacity, config::kNumPointsInHalfEllipse));
    // The point amid the top two points of a jaw:
    const cv::Point ptFaceCenter((ptJawLeft + ptJawRight) / 2);
    // This will be the center of the ellipse.

    // The angle between the jaw and the vertical:
    const int angFace = getLineInclinationAngleDegrees(ptJawLeft, ptJawRight);
    // This will be the inclination of the ellipse

    // Counting the half-axis of the ellipse:
    const double jawWidth  = cv::norm(ptJawLeft - ptJawRight);
    // A forehead width equals the jaw width, and we need a half-axis:
    const int axisX        = toIntRounded(jawWidth / 2.0);

    const double jawHeight = cv::norm(ptFaceCenter - ptJawLower);
    // According to research, in average a forehead is approximately 2/3 of
    //  a jaw:
    const int axisY        = toIntRounded(jawHeight * 2 / 3.0);

    // We need the upper part of an ellipse:
    static constexpr int kAngForeheadStart = 180;
    static constexpr int kAngForeheadEnd   = 360;
    cv::ellipse2Poly(ptFaceCenter, cv::Size(axisX, axisY), angFace,
                     kAngForeheadStart, kAngForeheadEnd, config::kAngDelta,
                     cntForehead);
    return cntForehead;
}

// Approximates the lower eye contour by half-ellipse using eye points and some
//  geometry and then returns points of the contour; "capacity" is used
//  to reserve enough memory as there will be other points inserted.
inline Contour custom::getEyeEllipse(const cv::Point &ptLeft,
                                     const cv::Point &ptRight,
                                     const size_t     capacity = 0)
{
    Contour cntEyeBottom;
    cntEyeBottom.reserve(std::max(capacity, config::kNumPointsInHalfEllipse));
    const cv::Point ptEyeCenter((ptRight + ptLeft) / 2);
    const int angle = getLineInclinationAngleDegrees(ptLeft, ptRight);
    const int axisX = toIntRounded(cv::norm(ptRight - ptLeft) / 2.0);
    // According to research, in average a Y axis of an eye is approximately
    //  1/3 of an X one.
    const int axisY = axisX / 3;
    // We need the lower part of an ellipse:
    static constexpr int kAngEyeStart = 0;
    static constexpr int kAngEyeEnd   = 180;
    cv::ellipse2Poly(ptEyeCenter, cv::Size(axisX, axisY), angle, kAngEyeStart,
                     kAngEyeEnd, config::kAngDelta, cntEyeBottom);
    return cntEyeBottom;
}

//This function approximates an object (a mouth) by two half-ellipses using
//  4 points of the axes' ends and then returns points of the contour:
inline Contour custom::getPatchedEllipse(const cv::Point &ptLeft,
                                         const cv::Point &ptRight,
                                         const cv::Point &ptUp,
                                         const cv::Point &ptDown)
{
    // Shared characteristics for both half-ellipses:
    const cv::Point ptMouthCenter((ptLeft + ptRight) / 2);
    const int angMouth = getLineInclinationAngleDegrees(ptLeft, ptRight);
    const int axisX    = toIntRounded(cv::norm(ptRight - ptLeft) / 2.0);

    // The top half-ellipse:
    Contour cntMouthTop;
    const int axisYTop = toIntRounded(cv::norm(ptMouthCenter - ptUp));
    // We need the upper part of an ellipse:
    static constexpr int angTopStart = 180;
    static constexpr int angTopEnd   = 360;
    cv::ellipse2Poly(ptMouthCenter, cv::Size(axisX, axisYTop), angMouth,
                     angTopStart, angTopEnd, config::kAngDelta, cntMouthTop);

    // The bottom half-ellipse:
    Contour cntMouth;
    const int axisYBot = toIntRounded(cv::norm(ptMouthCenter - ptDown));
    // We need the lower part of an ellipse:
    static constexpr int angBotStart = 0;
    static constexpr int angBotEnd   = 180;
    cv::ellipse2Poly(ptMouthCenter, cv::Size(axisX, axisYBot), angMouth,
                     angBotStart, angBotEnd, config::kAngDelta, cntMouth);

    // Pushing the upper part to vctOut
    cntMouth.reserve(cntMouth.size() + cntMouthTop.size());
    std::copy(cntMouthTop.cbegin(), cntMouthTop.cend(),
              std::back_inserter(cntMouth));
    return cntMouth;
}

inline cv::GMat custom::unsharpMask(const cv::GMat &src,
                                    const int       sigma,
                                    const float     strength)
{
    cv::GMat blurred   = cv::gapi::medianBlur(src, sigma);
    cv::GMat laplacian = custom::GLaplacian::on(blurred, CV_8U);
    return (src - (laplacian * strength));
}

inline cv::GMat custom::mask3C(const cv::GMat &src,
                               const cv::GMat &mask)
{
    std::tuple<cv::GMat,cv::GMat,cv::GMat> tplIn = cv::gapi::split3(src);
    cv::GMat masked0 = cv::gapi::mask(std::get<0>(tplIn), mask);
    cv::GMat masked1 = cv::gapi::mask(std::get<1>(tplIn), mask);
    cv::GMat masked2 = cv::gapi::mask(std::get<2>(tplIn), mask);
    return cv::gapi::merge3(masked0, masked1, masked2);
}


int main(int argc, char** argv)
{
    cv::CommandLineParser parser(argc, argv,
"{ help         h ||      print the help message. }"

"{ facepath     f ||      a path to a Face detection model file (.xml).}"
"{ facedevice     |GPU|   the face detection computation device.}"

"{ landmpath    l ||      a path to a Landmarks detection model file (.xml).}"
"{ landmdevice    |CPU|   the landmarks detection computation device.}"

"{ input        i ||      a path to an input. Skip to capture from a camera.}"
"{ boxes        b |false| set true to draw face Boxes in the \"Input\" window.}"
"{ landmarks    m |false| set true to draw landMarks in the \"Input\" window.}"
    );
    parser.about("Use this script to run the face beautification"
                 " algorithm on G-API.");
    if (argc == 1 || parser.has("help"))
    {
        parser.printMessage();
        return 0;
    }

    cv::namedWindow(config::kWinFaceBeautification, cv::WINDOW_NORMAL);
    cv::namedWindow(config::kWinInput,              cv::WINDOW_NORMAL);

    // Parsing input arguments
    const std::string faceXmlPath = parser.get<std::string>("facepath");
    const std::string faceBinPath = getWeightsPath(faceXmlPath);
    const std::string faceDevice  = parser.get<std::string>("facedevice");

    const std::string landmXmlPath = parser.get<std::string>("landmpath");
    const std::string landmBinPath = getWeightsPath(landmXmlPath);
    const std::string landmDevice  = parser.get<std::string>("landmdevice");

    // The flags for drawing/not drawing face boxes or/and landmarks in the
    //  \"Input\" window:
    const bool flgBoxes     = parser.get<bool>("boxes");
    const bool flgLandmarks = parser.get<bool>("landmarks");
    // To provide this opportunity, it is necessary to check the flags when
    //  compiling a graph

    // Declaring a graph
    // Streaming-API version of a pipeline expression with a lambda-based
    //  constructor is used to keep all temporary objects in a dedicated scope.
    cv::GComputation pipeline([=]()
    {
        cv::GMat  gimgIn;
        // Infering
        cv::GMat  faceOut  = cv::gapi::infer<custom::FaceDetector>(gimgIn);
        GArrayROI garRects = custom::GFacePostProc::on(faceOut, gimgIn,
                                                       config::kConfThresh);
        cv::GArray<Landmarks> garElems;
        cv::GArray<Contour>   garJaws;
        cv::GArray<cv::GMat> landmOut  = cv::gapi::infer<custom::LandmDetector>(
                                                         garRects, gimgIn);
        std::tie(garElems, garJaws)    = custom::GLandmPostProc::on(landmOut,
                                                                 garRects);
        cv::GArray<Contour> garElsConts;
        cv::GArray<Contour> garFaceConts;
        std::tie(garElsConts, garFaceConts) = custom::GGetContours::on(garElems,
                                                                       garJaws);
        // Masks drawing
        // All masks are created as CV_8UC1
        cv::GMat mskSharp        = custom::GFillPolyGContours::on(gimgIn,
                                                                  garElsConts);
        cv::GMat mskSharpG       = cv::gapi::gaussianBlur(mskSharp,
                                                          config::kGKernelSize,
                                                          config::kGSigma);
        cv::GMat mskBlur         = custom::GFillPolyGContours::on(gimgIn,
                                                                  garFaceConts);
        cv::GMat mskBlurG        = cv::gapi::gaussianBlur(mskBlur,
                                                          config::kGKernelSize,
                                                          config::kGSigma);
        // The first argument in mask() is Blur as we want to subtract from
        // BlurG the next step:
        cv::GMat mskBlurFinal    = mskBlurG - cv::gapi::mask(mskBlurG,
                                                             mskSharpG);
        cv::GMat mskFacesGaussed = mskBlurFinal + mskSharpG;
        cv::GMat mskFacesWhite   = cv::gapi::threshold(mskFacesGaussed, 0, 255,
                                                       cv::THRESH_BINARY);
        cv::GMat mskNoFaces      = cv::gapi::bitwise_not(mskFacesWhite);
        cv::GMat gimgBilat       = custom::GBilatFilter::on(gimgIn,
                                                            config::kBSize,
                                                            config::kBSigmaCol,
                                                            config::kBSigmaSp);
        cv::GMat gimgSharp       = custom::unsharpMask(gimgIn,
                                                       config::kUnshSigma,
                                                       config::kUnshStrength);
        // Applying the masks
        // Custom function mask3C() should be used instead of just gapi::mask()
        //  as mask() provides CV_8UC1 source only (and we have CV_8U3C)
        cv::GMat gimgBilatMasked = custom::mask3C(gimgBilat, mskBlurFinal);
        cv::GMat gimgSharpMasked = custom::mask3C(gimgSharp, mskSharpG);
        cv::GMat gimgInMasked    = custom::mask3C(gimgIn,    mskNoFaces);
        cv::GMat gimgBeautif     = gimgBilatMasked + gimgSharpMasked +
                                   gimgInMasked;
        // Drawing face boxes and landmarks if necessary:
        cv::GMat gimgTemp;
        if (flgLandmarks == true)
        {
            cv::GMat gimgTemp2 = custom::GPolyLines::on(gimgIn, garFaceConts,
                                                        config::kClosedLine,
                                                        config::kClrYellow);
                     gimgTemp  = custom::GPolyLines::on(gimgTemp2, garElsConts,
                                                        config::kClosedLine,
                                                        config::kClrYellow);
        }
        else
        {
            gimgTemp = gimgIn;
        }
        cv::GMat gimgShow;
        if (flgBoxes == true)
        {
            gimgShow = custom::GRectangle::on(gimgTemp, garRects,
                                              config::kClrGreen);
        }
        else
        {
        // This action is necessary because an output node must be a result of
        //  some operations applied to an input node, so it handles the case
        //  when it should be nothing to draw
            gimgShow = cv::gapi::copy(gimgTemp);
        }
        return cv::GComputation(cv::GIn(gimgIn),
                                cv::GOut(gimgBeautif, gimgShow));
    });
    // Declaring IE params for networks
    auto faceParams  = cv::gapi::ie::Params<custom::FaceDetector>
    {
        faceXmlPath,
        faceBinPath,
        faceDevice
    };
    auto landmParams = cv::gapi::ie::Params<custom::LandmDetector>
    {
        landmXmlPath,
        landmBinPath,
        landmDevice
    };
    auto networks      = cv::gapi::networks(faceParams, landmParams);
    // Declaring custom and fluid kernels have been used:
    auto customKernels = cv::gapi::kernels<custom::GCPUBilateralFilter,
                                           custom::GCPULaplacian,
                                           custom::GCPUFillPolyGContours,
                                           custom::GCPUPolyLines,
                                           custom::GCPURectangle,
                                           custom::GCPUFacePostProc,
                                           custom::GCPULandmPostProc,
                                           custom::GCPUGetContours>();
    auto kernels       = cv::gapi::combine(cv::gapi::core::fluid::kernels(),
                                           customKernels);
    // Now we are ready to compile the pipeline to a stream with specified
    //  kernels, networks and image format expected to process
    auto stream = pipeline.compileStreaming(cv::GMatDesc{CV_8U,3,
                                                         cv::Size(1280,720)},
                                            cv::compile_args(kernels,
                                                             networks));
    // Setting the source for the stream:
    if (parser.has("input"))
    {
        stream.setSource(cv::gapi::wip::make_src<cv::gapi::wip::GCaptureSource>
                         (parser.get<cv::String>("input")));
    }
    else
    {
        stream.setSource(cv::gapi::wip::make_src<cv::gapi::wip::GCaptureSource>
                         (0));
    }
    // Declaring output variables
    cv::Mat imgShow;
    cv::Mat imgBeautif;
    // Streaming:
    stream.start();
    while (stream.running())
    {
        auto out_vector = cv::gout(imgBeautif, imgShow);
        if (!stream.try_pull(std::move(out_vector)))
        {
            // Use a try_pull() to obtain data.
            // If there's no data, let UI refresh (and handle keypress)
            if (cv::waitKey(1) >= 0) break;
            else continue;
        }
        cv::imshow(config::kWinInput,              imgShow);
        cv::imshow(config::kWinFaceBeautification, imgBeautif);
    }
    return 0;
}