import RPi.GPIO as GPIO
import config

class Changer(object):

    def __init__(self, local_state, remote_state):
        self.local_state = local_state
        self.remote_state = remote_state
        GPIO.setmode(GPIO.BCM) # Broadcom pin-numbering scheme
        GPIO.setup(config.GPIO_PIN_VALVE, GPIO.OUT)

        self.states = {
          'opening': self.open_valve,
          'closing': self.close_valve,
          'open': self.open_valve,
          'closed': self.close_valve

        }

    def process_change(self):
        self.validate_states()
        change = self.states.get(self.remote_state['out_valve'], None )
        if change is not None:
            change()
        return self.local_state

    def open_valve(self):
        GPIO.output(config.GPIO_PIN_VALVE, GPIO.HIGH)
        self.local_state['out_valve'] = 'open'

    def close_valve(self):
        GPIO.output(config.GPIO_PIN_VALVE, GPIO.LOW)
        self.local_state['out_valve'] = 'closed'

    def validate_states(self):
        if self.local_state is None or self.remote_state is None:
            raise ClassNotReadyException("Both local and remote states must be present!")
        # TODO: add detailed validation