#!/usr/bin/env python3

import RPi.GPIO as GPIO
from xmlrpc.server import SimpleXMLRPCServer, SimpleXMLRPCRequestHandler
import time
import signal
import sys
from lib import send_mail

###############
# Global Vars #
###############

XMLRPC_IP = "0.0.0.0"
XMLRPC_PORT = 9000

RELAY_PIN = 37
RESET_BTN = 35

# Keeps track of the last time a button was pressed
last_reset_button_press_at = 0.0

# Keeps track of the last time the relay was flipped
last_relay_flip_at = 0.0

last_alert = ''
last_alert_at = 0.0

##############
# Setup Pins #
##############

GPIO.setmode(GPIO.BOARD)

GPIO.setup(RELAY_PIN, GPIO.OUT)
GPIO.setup(RESET_BTN, GPIO.IN, pull_up_down=GPIO.PUD_UP)

#######################
# Kill Signal Handler #
#######################

def signal_handler(*_):
    GPIO.cleanup()
    print("\nExiting...")
    sys.exit()

signal.signal(signal.SIGINT, signal_handler)
signal.signal(signal.SIGTERM, signal_handler)

#########################
# Set to Low as Default #
#########################

GPIO.output(RELAY_PIN, GPIO.LOW)

#############
# Functions #
#############

# Makes sure the button is being released - not pressed
# Due to a bug in the GPIO library, a GPIO.FALLING appears the same as
# GPIO.BOTH. This means the callback will be called when the button is
# being released (as it should), and sometimes when the button is being
# pressed. This results in 2 calls per button press. This decorator
# waits 5ms and checks the input's state, to see if it's currently pressed
# or released. This eliminates false positives
def ensure_press(func):
    def wrapper(*args, **kwargs):
        global last_reset_button_press_at

        channel = args[0]

        # Wait before checking state of pin
        time.sleep(0.005)

        if GPIO.input(channel):
            return

        if (time.time() - last_reset_button_press_at) > 1.0:
            last_reset_button_press_at = time.time()

            return func(*args, **kwargs)

    return wrapper

def water_detected(location):
    global last_alert
    global last_alert_at
    global last_relay_flip_at

    # If the reset button was recently pressed, ignore alerts
    # There's some sort of bug where sensors trigger when reset button is pressed
    if (time.time() - last_reset_button_press_at) < 2.0:
        return True

    # If the relay was recently flipped, ignore alerts
    # There's some sort of bug where sensors trigger when relay is flipped
    if (time.time() - last_relay_flip_at) < 2.0:
        return True


    # If the alert we are seeing is the same as the last one we got, and
    # it's been less than 5 minutes since the last alert, ignore it
    # Makes sure it doesn't send us dozens of alerts per minute for the
    # same incident
    if last_alert == location and time.time() - last_alert_at < 300:
        return True

    print("Water detected at %s" % location)

    GPIO.output(RELAY_PIN, GPIO.HIGH)
    last_relay_flip_at = time.time()

    last_alert = location
    last_alert_at = time.time()

    # Send email
    recipients = 'my@email.com, some_other@email.com'
    subject = 'Water Leak Detected'
    body = 'Water detected at %s' % location
    credentials = {"gmail_username": "some_account@gmail.com",
                   "gmail_password": ""}

    send_mail(recipients=recipients,
              subject=subject,
              body=body,
              credentials=credentials)


    return True

@ensure_press
def reset_btn_pressed(channel):
    global last_alert
    global last_alert_at

    print("Reset button pressed - resetting relay to allow water flow")

    GPIO.output(RELAY_PIN, GPIO.LOW)

    last_alert = ''
    last_alert_at = 0.0

########
# Main #
########

# XMLRPC Server
print("Running XMLRPC server on %s:%s..." % (XMLRPC_IP, XMLRPC_PORT))

# Restrict to a particular path
class RequestHandler(SimpleXMLRPCRequestHandler):
    rpc_paths = ('/RPC2',)

# Create server
server = SimpleXMLRPCServer((XMLRPC_IP, XMLRPC_PORT),
                            requestHandler=RequestHandler)

# Register my functions
server.register_function(water_detected)

# Setup reset button handler
GPIO.add_event_detect(RESET_BTN, GPIO.FALLING, callback=reset_btn_pressed, bouncetime=300)

# Run the server
server.serve_forever()