#include "ros/ros.h"
#include <image_transport/image_transport.h>
#include <cv_bridge/cv_bridge.h>
#include <sensor_msgs/image_encodings.h>
#include <geometry_msgs/Twist.h>
#include <typeinfo>

#include <opencv/cv.h>

#include <sstream>

using namespace cv;
using namespace std;

class Traite_image {
	public:
		const static int THRESHOLD_DETECT_SENSITIVITY = 10;
		const static int BLUR_SIZE = 5;
		const static int THRESHOLD_MOV = 5;
		constexpr static float MOVEMENT_THRES = 0.05;

		constexpr static float FLOW_MIN_QUAL = 0.01;
		const static int FLOW_MIN_DIST = 20;


		Mat prev;

		// Stabilisation transformation matrices
		Mat T, last_T;

		bool first = true;

		// Features vectors
		vector <Point2f> prev_ftr, cur_ftr;

		// Downsize factor
		int resize_f = 1;

		int theObject[2] = {0,0};
		Rect objectBoundingRectangle = Rect(0,0,0,0);

		ros::NodeHandle n;

		image_transport::ImageTransport it;
		image_transport::Publisher      pub_img;
        ros::Publisher                pub_cmd;
		image_transport::Subscriber     sub;


		Traite_image() : n("~"),it(n) {
			pub_img = it.advertise("/image_out", 1);
			pub_cmd = n.advertise<geometry_msgs::Twist>("/vrep/drone/cmd_vel", 1);
			sub = it.subscribe("/usb_cam/image_raw", 1, [this](const sensor_msgs::ImageConstPtr& img) -> void { this->on_image(img);},ros::VoidPtr(),image_transport::TransportHints("compressed"));
		}


		// This processes an image and publishes the result.
		void on_image(const sensor_msgs::ImageConstPtr& msg) {

			cv_bridge::CvImageConstPtr bridge_input;
			try {
				bridge_input = cv_bridge::toCvShare(msg,sensor_msgs::image_encodings::RGB8);
			}
			catch (Exception& e) {
				std::ostringstream errstr;
				errstr << "cv_bridge exception caught: " << e.what();
				return;
			}

			//Mat& input  = const_cast<Mat&>(bridge_input->image);
			const Mat& input = bridge_input->image;
			Mat next;
			resize(input, next, Size(input.size().width/resize_f, input.size().height/resize_f));
			Mat output;// = input.clone(); //   (input.rows, input.cols, CV_32FC2);
			//ROS_INFO("got input");
			if (first) {
				prev = next.clone();
				first = false;
				ROS_INFO("first done");
			}

			Mat next_stab;
			trackFeatures(prev, next);
			stabiliseImg(next, next_stab);
			trackingOptFlow(prev, next_stab, next_stab);
			Mat next_stab2;
			trackFeatures(prev, next);
			stabiliseImg(next, next_stab2);
			trackingOptFlow(prev, next_stab2, output);
			//searchForMovementOptFlow(prev_cropped, next_stab_cropped, output);


			pub_img.publish(cv_bridge::CvImage(msg->header, "rgb8", output).toImageMsg());
			// bridge_input is handled by a smart-pointer. No explicit delete needed.

            droneTracking(Rect(Point(0,0), output.size()));

			//ROS_INFO("pub");

			prev = next.clone();
		}


		void trackFeatures(Mat prev, Mat cur) {
			Mat cur_grey, prev_grey;
			cvtColor(cur, cur_grey, COLOR_BGR2GRAY);
			cvtColor(prev, prev_grey, COLOR_BGR2GRAY);

			// vector from prev to cur
			vector <Point2f> prev_corner, cur_corner;
			vector <uchar> status;
			vector <float> err;

			goodFeaturesToTrack(prev_grey, prev_corner, 200, FLOW_MIN_QUAL, FLOW_MIN_DIST);
			calcOpticalFlowPyrLK(prev_grey, cur_grey, prev_corner, cur_corner, status, err);

			// weed out bad matches
			prev_ftr.resize(0);
			cur_ftr.resize(0);
			for(size_t i=0; i < status.size(); i++) {
				if(status[i]) {
					prev_ftr.push_back(prev_corner[i]);
					cur_ftr.push_back(cur_corner[i]);
				}
			}
		}


		void stabiliseImg(Mat cur, Mat &output){
			T = estimateRigidTransform(prev_ftr, cur_ftr, true); // false = rigid transform, no scaling/shearing

			if(T.data == NULL)
				last_T.copyTo(T);
			else
				T.copyTo(last_T);

			Mat cur2;

			warpAffine(cur, cur2, T, cur.size(),INTER_NEAREST|WARP_INVERSE_MAP);

			cur2.copyTo(output);
		}


		void warpPoints(vector<Point2f> p, vector<Point2f> &p_warp, Mat T, bool invert=false) {
			Mat H;
			if(invert)
				invertAffineTransform(T, H);

			p_warp.clear();
			for(size_t i=0; i < p.size(); ++i) {
				Mat src(3/*rows*/,1 /* cols */,CV_64F);

				src.at<double>(0,0)=p[i].x;
				src.at<double>(1,0)=p[i].y;
				src.at<double>(2,0)=1.0;

				Mat dst = H*src; //USE MATRIX ALGEBRA
				p_warp.push_back(Point2f(dst.at<double>(0,0),dst.at<double>(1,0)));
			}
		}


		void trackingOptFlow(Mat prev, Mat cur, Mat &output) {
			cur.copyTo(output);
			vector <Point2f> cur_ftr_stab;

			//T = estimateRigidTransform(prev_ftr, cur_ftr, true); // false = rigid transform, no scaling/shearing
			//if(T.data == NULL)
			//	last_T.copyTo(T);
			//else
			//	T.copyTo(last_T);

			warpPoints(cur_ftr, cur_ftr_stab, T, true);

			vector <Point2f> objects;
			vector <float> flow_norm;
			for(size_t i=0; i < prev_ftr.size(); ++i) {
				flow_norm.push_back(norm(prev_ftr[i] - cur_ftr_stab[i]) / prev.size().height);
				line(output, prev_ftr[i], cur_ftr[i], Scalar(200,0,0),1);
				line(output, prev_ftr[i], cur_ftr_stab[i], Scalar(0,200,0),1);
			}

			for(size_t i=0; i < flow_norm.size(); ++i) {
				if(flow_norm[i] > MOVEMENT_THRES) {
					objects.push_back(cur_ftr_stab[i]);
					prev_ftr.erase(prev_ftr.begin() + i);
					cur_ftr.erase(cur_ftr.begin() + i);
				}
			}

			for(size_t i=0; i < objects.size(); ++i) {
				circle(output, objects[i], 5, Scalar(0, 200, 0), 1);
			}
		}


		inline bool isFlowCorrect(Point2f u)
		{
			return !cvIsNaN(u.x) && !cvIsNaN(u.y) && fabs(u.x) < 1e9 && fabs(u.y) < 1e9;
		}


        void droneTracking(Rect img_size)
        {
            Point2f centre_image = Point2f(img_size.width/2, img_size.height/2);
            Point2f centre_rect = Point2f(objectBoundingRectangle.x + objectBoundingRectangle.width/2, objectBoundingRectangle.y + objectBoundingRectangle.height/2);

            geometry_msgs::Twist twist = geometry_msgs::Twist();

            if(centre_rect.x < centre_image.x-THRESHOLD_MOV)
            {
                twist.angular.z = 0.2;
            }
            else if(centre_rect.x > centre_image.x+THRESHOLD_MOV)
            {
                twist.angular.z = -0.2;
            }

            pub_cmd.publish(twist);
        }


		//int to string helper function
		string intToString(int number){

			//this function has a number input and string output
			std::stringstream ss;
			ss << number;
			return ss.str();
		}
};


int main(int argc, char **argv)
{
	ros::init(argc, argv, "test_opencv");
	Traite_image dataset=Traite_image();
	ros::spin();

	return 0;
}