import pigpio as GPIO
from time import sleep

class keypad():
    # CONSTANTS
    KEYPAD = [
    [1,2,3],
    [4,5,6],
    [7,8,9],
    [10,0,11]
    ]

    ROW         = [18,23,24,25]
    COLUMN      = [4,17,22]

    def __init__(self, gpio=None):
        self.GPIO = gpio
        if (self.GPIO == None):
            self.GPIO =GPIO.pi()
        # Set all columns as output low
        for j in range(len(self.COLUMN)):
            self.GPIO.set_mode(self.COLUMN[j], GPIO.OUTPUT)
            self.GPIO.write(self.COLUMN[j], 0)

        for i in range(len(self.ROW)):
            self.GPIO.set_mode(self.ROW[i], GPIO.INPUT)
            self.GPIO.set_pull_up_down(self.ROW[i], GPIO.PUD_DOWN)
        print ('Init done')

    def getKey(self):
        colVal = -1
        rowVal = -1
        # Assert each column
        for j in range(len(self.COLUMN)):
            colVal = j
            self.GPIO.write(self.COLUMN[j], 1)
            sleep(0.01)
            rowVal = -1
            for i in range(len(self.ROW)):
        # Scan rows for pushed key/button
        # A valid key press should set "rowVal"  between 0 and 3.
                 tmpRead = self.GPIO.read(self.ROW[i])
                 if tmpRead != 0:
                     if rowVal < 0:
                        rowVal = i
                     else:
                        rowVal = 999
            self.GPIO.write(self.COLUMN[j], 0)
            if rowVal >= 0:
                break
        if rowVal <0 or rowVal >3:
            return

        # Return the value of the key pressed
        return self.KEYPAD[rowVal][colVal]

if __name__ == '__main__':
    # Initialize the keypad class
    kp = keypad()

    # Loop while waiting for a keypress
    digit = None
    while True:
        digit = kp.getKey()
        if digit != None:
            print digit
            sleep(0.25)
        sleep(0.05)