#Importing Packages
import cv2
import numpy as np
from bokeh.plotting import figure
from bokeh.io import output_notebook, show, push_notebook
import time
output_notebook()

"""
Dense Optical Flow using Lucas Kanade Method
https://en.wikipedia.org/wiki/Lucas%E2%80%93Kanade_method
"""

cap = cv2.VideoCapture(0)

#Lucas Kanade Parameters
lk_params = dict(
    winSize=(30, 30),
    maxLevel=4,
    criteria=(cv2.TERM_CRITERIA_EPS | cv2.TERM_CRITERIA_COUNT, 10, 0.03),
)

class LucasKanade:
    @staticmethod
    def execute():

        """
        Detects motion in between frames of a video and draws a line between the two
        coordinate points of different frames.

        frame1 and frame2 are the two images taken at time i=1 and i=2 respectively.
        x and y are the point coordinates of the two frames. It tracks the features
        of the first frame(x) and the second frame(y) and draws a line between them
        for every two consecutive frames.
        """

        # get first frame of video
        ret, frame1 = cap.read()
        if ret:
            # convert frame to grayscale
            frame1_gray = cv2.cvtColor(frame1, cv2.COLOR_BGR2GRAY)
            x = cv2.goodFeaturesToTrack(frame1_gray, 100, 0.05, 10, None, None, 7)
            lin = np.zeros_like(frame1)
            i = 0

            while True:
                i = i + 1
                val, frame2 = cap.read()
                if not val:
                    break
                frame2 = cv2.medianBlur(frame2, 5)
                frame2_gray = cv2.cvtColor(frame2, cv2.COLOR_BGR2GRAY)
                y, st, error = cv2.calcOpticalFlowPyrLK(
                    frame1_gray, frame2_gray, x, None, **lk_params
                )

                for j, (new, old) in enumerate(zip(y, x)):
                    a, b = new.ravel()
                    c, d = old.ravel()
                    frame2 = cv2.circle(frame2, (a, b), 5, (0, 0, 255), -1)
                    frame2 = cv2.circle(frame2, (c, d), 5, (255, 0, 0), -1)
                    lin = cv2.line(lin, (a, b), (c, d), (0, 255, 0), 2)

                if i % 2 == 0:
                    # Draw line for every 2 frames
                    lin = np.zeros_like(frame1)

                img = cv2.add(frame2, lin)
                
                if img is not None:
                    img = cv2.flip(img, -1)
                    img = cv2.cvtColor(img, cv2.COLOR_BGR2RGBA) # because Bokeh expects a RGBA image
                    width = img.shape[1]
                    height = img.shape[0]
                    p = figure(x_range=(0,width), y_range=(0,height), output_backend="webgl", width=width, height=height)
                    myImage = p.image_rgba(image=[img], x=0, y=0, dw=width, dh=height)
                    show(p, notebook_handle=True)
                
                if i == 7:
                    break
                # update the new values
                frame1_gray = np.copy(frame2_gray)
                x = cv2.goodFeaturesToTrack(frame1_gray, 100, 0.05, 10, None, None, 10)

#Define class object
run = LucasKanade()
run.execute()
cap.release()
cv2.destroyAllWindows()