import socket
import sys
import math
import collections
import numpy as np
import pyqtgraph as pg
from pyqtgraph.Qt import QtGui, QtCore

# HOST = edison ip address, PORT = port on which edison is serving
HOST, PORT = "192.168.1.108", 5000

def get_accl_data():
    # Create a socket (SOCK_STREAM means a TCP socket)
    sock = socket.socket(socket.AF_INET, socket.SOCK_STREAM)
    data = "Ready"
    try:
        # Connect to server and send data
        sock.connect((HOST, PORT))
        sock.sendall(data + "\n")

        # Receive data from the server and shut down
        received = sock.recv(1024)
    finally:
        sock.close()
    return received

app = QtGui.QApplication([])
win = pg.GraphicsWindow(title="Basic plotting examples")
win.resize(1000,600)
win.setWindowTitle('pyqtgraph example: Plotting')

# Enable antialiasing for prettier plots
pg.setConfigOptions(antialias=True)
p6 = win.addPlot(title="accelerometer yaw")
p6.setLabel('left', 'rotation in degrees')
curve = p6.plot(pen='y')
# collections is a module which provides high performance container datatypes.
# deque object can be used as a queue with fast appends and pops to either end of the queue
data = collections.deque(100*[1250], 100)
ptr = 0
def update():
    """ This is the function which updates the plot live.
	It is called periodically depending on timer setting.
	This in turn calls get_accl_data() function which fetches one data point from edison server.  
    """
    try:
        global curve, data, ptr, p6
	# get data from edison server. Here, 3-axis accelerometer reading is being received. However, in general, it can be any data read from a sensor connected to edison.
	# note: the setup is such that edison sends the three axis readings as space seperated values ex: "1300 1500 1350"
	(az, ay, ax) = get_accl_data().split() 
	# subtract the x-axis and y-axis  offsets calculated using calibration program.
        Az = int(az) - 1974
	Ax = int(ax) - 1958
	# convert accelerometer readings to angle in radians and then convert radians to degrees 
        angle = math.atan2(Ax, -1*Az) * (180 / math.pi)
	# append the angle data point to queue
        data.appendleft(angle)
	# convert the queue into an array
        plot_data = np.array(data)
	# modify the curve with the modified array with the new angle reading
        curve.setData(plot_data)
    finally:
	    # initialize timer
	    timer = QtCore.QTimer()
	    # recursively call the update() function every 50 milli-seconds
	    # this causes a new angle reading to be added to the graph periodically
	    timer.singleShot(50, update)
update()

## Start Qt event loop unless running in interactive mode or using pyside.
if __name__ == '__main__':
    import sys
    if (sys.flags.interactive != 1) or not hasattr(QtCore, 'PYQT_VERSION'):
        QtGui.QApplication.instance().exec_()