using System;
using System.Collections.Generic;
using System.Linq;
using System.Text;
using System.Threading.Tasks;
using System.Drawing;

using Emgu.CV;
using Emgu.CV.Structure;

using bbiwarg.Utility;
using bbiwarg.Images;
using bbiwarg.Detectors.Fingers;
using bbiwarg.Graphics;

namespace bbiwarg.Detectors.Palm
{
    class PalmDetector
    {
        private int width, height;
        private DepthImage depthImage;
        private EdgeImage edgeImage;
        private OutputImage outputImage;

        private Image<Gray, Byte> handImage;
        private Image<Gray, Byte> pointingHandMask;

        private List<Finger> fingers;

        private Contour<Point> palmContour;
        private List<MCvConvexityDefect> convexityDefects;

        private static Kalman2DPositionFilter thumbDefactFilter;

        private bool valid = false;
        private Vector2D topLeft;
        private Vector2D topRight;
        private Vector2D bottomLeft;
        private Vector2D bottomRight;

        public Quadrangle PalmQuad;

        public PalmDetector(DepthImage depthImage, EdgeImage edgeImage, List<Finger> detectedFingers, OutputImage outputImage)
        {
            // TODO: determine which fingers are index or thumb-fingers and detect palm in thumb-hand

            width = depthImage.Width;
            height = depthImage.Height;
            this.depthImage = depthImage;
            this.edgeImage = edgeImage;
            this.outputImage = outputImage;

            // dst = (src > (MaxDepth - MinDepth)) ? 0 : 1
            handImage = depthImage.Image.ThresholdBinaryInv(new Gray(depthImage.MaxDepth - depthImage.MinDepth - 1), new Gray(1)).Convert<Gray, Byte>();

            fingers = getFingersWithoutThumb(detectedFingers);
            buildPointingHandMask();
            handImage = handImage.And(pointingHandMask);
            
            findLongestPalmContour();
            if (palmContour != null)
            {
                findConvexityDefactsSortedByDepth();
                removeConvexityDefectsNearFingerTips();

                findHandPoints();

                if (valid)
                {
                    draw();
                }
            }
        }

        public static void resetFilter()
        {
            thumbDefactFilter = null;
        }

        private List<Finger> getFingersWithoutThumb(List<Finger> detectedFingers)
        {
            Finger leftMost = null;
            float minX = float.MaxValue;
            foreach (Finger f in detectedFingers)
            {
                float midX = ((f.Hand + f.Tip) / 2).X;
                if (midX < minX)
                {
                    minX = midX;
                    leftMost = f;
                }
            }

            List<Finger> result = new List<Finger>();
            foreach (Finger f in detectedFingers)
            {
                if (f != leftMost)
                    result.Add(f);
            }
            return result;
        }

        private void fillFingerSlices(Image<Gray, Byte> image, byte val)
        {
            foreach (Finger f in fingers)
            {
                foreach (FingerSlice s in f.SliceTrail.Slices)
                {
                    image.Draw(new LineSegment2DF(s.Start, s.End), new Gray(val), 1);
                }
            }
        }

        private Finger getLongestFinger()
        {
            float maxLength = 0;
            Finger longest = null;
            foreach (Finger f in fingers)
            {

                if (f.LineSegment.Length > maxLength)
                {
                    maxLength = f.LineSegment.Length;
                    longest = f;
                }
            }
            return longest;
        }

        private Point getPointInPointingHand()
        {
            Finger finger = getLongestFinger();
            if (finger == null)
                return new Point(0, 0);
            Vector2D direction = (finger.Hand - finger.Tip).normalize();
            Vector2D pos = finger.Hand + 20 * direction;
            return new Point(HelperFunctions.thresholdRange<int>(0, width - 1, pos.IntX), HelperFunctions.thresholdRange<int>(0, height - 1, pos.IntY));
        }

        private void buildPointingHandMask()
        {
            pointingHandMask = new Image<Gray, byte>(width, height, new Gray(0));

            fillFingerSlices(pointingHandMask, 1);
            pointingHandMask = pointingHandMask.Dilate(1);
            // dst = (src > 0) ? 1 : 0;
            pointingHandMask = pointingHandMask.Or(edgeImage.Image.ThresholdBinary(new Gray(0), new Gray(1)));
            pointingHandMask = pointingHandMask.Dilate(1);
            
            MCvConnectedComp tmp = new MCvConnectedComp();
            // fill with value 2
            CvInvoke.cvFloodFill(pointingHandMask.Ptr, getPointInPointingHand(), new MCvScalar(2), new MCvScalar(0), new MCvScalar(0), out tmp, 0, IntPtr.Zero);

            // dst = (src > 1) ? 0 : 1    (src > 1 <-> src == 2 <-> src filled by flood fill)
            pointingHandMask = pointingHandMask.ThresholdBinaryInv(new Gray(1), new Gray(1));
            pointingHandMask = pointingHandMask.Erode(1);
            fillFingerSlices(pointingHandMask, 0);
            pointingHandMask = pointingHandMask.Erode(2);
        }

        private void findLongestPalmContour()
        {
            Contour<Point> contour = handImage.FindContours(Emgu.CV.CvEnum.CHAIN_APPROX_METHOD.CV_CHAIN_APPROX_SIMPLE, Emgu.CV.CvEnum.RETR_TYPE.CV_RETR_EXTERNAL);

            palmContour = contour;
            double maxPerimeter = 0;
            while (contour != null)
            {
                if (contour.Perimeter > maxPerimeter)
                {
                    maxPerimeter = contour.Perimeter;
                    palmContour = contour;
                }
                contour = contour.HNext;
            }
        }

        private void findConvexityDefactsSortedByDepth()
        {
            convexityDefects = new List<MCvConvexityDefect>(palmContour.GetConvexityDefacts(new MemStorage(), Emgu.CV.CvEnum.ORIENTATION.CV_CLOCKWISE));
            convexityDefects.Sort(delegate(MCvConvexityDefect d1, MCvConvexityDefect d2)
            {
                if (d1.Depth < d2.Depth)
                    return 1;
                else if (d1.Depth > d2.Depth)
                    return -1;
                return 0;
            });
        }

        private void removeConvexityDefectsNearFingerTips()
        {
            List<MCvConvexityDefect> newDefects = new List<MCvConvexityDefect>();
            foreach (MCvConvexityDefect d in convexityDefects)
            {
                float minFingerTipDist = float.MaxValue;
                foreach (Finger f in fingers)
                {
                    float dist = f.Tip.getDistanceTo(new Vector2D(d.DepthPoint));
                    if (dist < minFingerTipDist)
                        minFingerTipDist = dist;
                }
                if (minFingerTipDist > 20)
                    newDefects.Add(d);
            }
            convexityDefects = newDefects;
        }

        private void findHandPoints()
        {
            if (convexityDefects.Count > 0)
            {
                MCvConvexityDefect thumbDefect = convexityDefects[0];

                Vector2D thumb;
                if (thumbDefactFilter == null)
                {
                    thumb = new Vector2D(thumbDefect.DepthPoint);
                    thumbDefactFilter = new Kalman2DPositionFilter(thumb, 1.0e-2f, 1.0e-2f);
                }
                else
                {
                    thumb = thumbDefactFilter.getCorrectedPosition(new Vector2D(thumbDefect.DepthPoint));
                }

                Vector2D thumbDefectStart = new Vector2D(thumbDefect.StartPoint);
                Vector2D thumbDefectEnd = new Vector2D(thumbDefect.EndPoint);

                Vector2D handLength, handWidth;
                if (thumb.getDistanceTo(thumbDefectStart) > thumb.getDistanceTo(thumbDefectEnd))
                {
                    //right hand
                    handLength = thumbDefectStart - thumb;
                    handWidth = 0.8f * new Vector2D(-handLength.Y, handLength.X);
                    topLeft = thumbDefectStart;
                    bottomLeft = thumb - 0.4f * handLength;
                    bottomRight = bottomLeft + handWidth;
                    topRight = bottomRight + 1.2f * handLength - 0.3f * handWidth;
                }
                else
                {
                    //left hand
                    handLength = thumbDefectEnd - thumb;
                    handWidth = 0.8f * new Vector2D(handLength.Y, -handLength.X);
                    topRight = thumbDefectEnd;
                    bottomRight = thumb - 0.4f * handLength;
                    bottomLeft = bottomRight + handWidth;
                    topLeft = bottomLeft + 1.2f * handLength - 0.3f * handWidth;
                }

                PalmQuad = new Quadrangle(bottomLeft, topLeft, topRight, bottomRight);

                valid = true;
            }
            else
            {
                PalmQuad = null;
                valid = false;
            }
        }

        private void draw()
        {
            outputImage.drawContour(palmContour, 255, 0, 0);
            outputImage.drawPoints(palmContour.GetConvexHull(Emgu.CV.CvEnum.ORIENTATION.CV_CLOCKWISE), 0, 255, 0);

            if (PalmQuad != null)
            {
                Vector2D[] vertices = PalmQuad.Vertices;
                for (int i = 0; i < 4; ++i)
                    outputImage.drawLineSegment(new bbiwarg.Utility.LineSegment2D(vertices[i], vertices[(i + 1) % 4]), 0, 0, 255);

                drawGrid(new Vector2D(vertices[0]), new Vector2D(vertices[1]), new Vector2D(vertices[2]), new Vector2D(vertices[3]));
            }
        }

        
        private void drawGrid(Vector2D a, Vector2D b, Vector2D c, Vector2D d)
        {
            int numRows = 4;
            int numColumns = 3;

            Vector2D relAB = (b - a) / numRows;
            Vector2D relDC = (c - d) / numRows;
            Vector2D relBC = (c - b) / numColumns;
            Vector2D relAD = (d - a) / numColumns;

            for (int i = 1; i < numRows; i++)
            {
                outputImage.drawLineSegment(new bbiwarg.Utility.LineSegment2D(a + i * relAB, d + i * relDC), 80, 80, 255);
            }

            for (int i = 1; i < numColumns; i++)
            {
                outputImage.drawLineSegment(new bbiwarg.Utility.LineSegment2D(a + i * relAD, b + i * relBC), 80, 80, 255);
            }
        }
    }
}