import tkinter as tk

encoders = []
class SMBus:
    def __init__(self, bus):
        print(f"fake SMBus initialized on bus {bus}")
        self.bus = bus
        

    def read_i2c_block_data(self, addr, cmd, length):
        data = []
        for encoder in encoders:
            pos_as_byte_array = encoder.get_position().to_bytes(2, 'little', signed=True)
            data.append(pos_as_byte_array[0])
            data.append(pos_as_byte_array[1])
            
        #print(f"SMBus data set to: {data}")
        return data

def createTestEncoder():
    encoder = TestEncoder()
    encoders.append(encoder)
    return encoder
          
class TestEncoder:
    """ represent a test encoder controlled by keyboard input """
    def __init__(self):
        self._position = 0
        
    def _rotate_cw(self, event=None):
        self._position += 1

    def _rotate_ccw(self, event=None):
        self._position -= 1

    def get_position(self) -> int:
        return self._position