from time import perf_counter
from datetime import datetime, timedelta
from collections import deque
import re
from os.path import exists

# TODO client: add a way to disable live plotting? server: stop
# sending data periodically to everybody!

from random import random
from time import sleep

class Sensor():
    def __init__(self, autocorr=0.7):
        self.prevval = random() * 100
        self.auto = autocorr
        self.measure = None

    def read(self):
        sleep(0.5)
        return (perf_counter(),
                int((random() * (1-self.auto) + self.prevval * self.auto) * 100) / 100)

class Temperature1W(Sensor):
    def __init__(self, address):
        self.measure = 'Temperature'
        self.address = address

    def path(self):
        return f'/sys/bus/w1/devices/{self.address}/w1_slave'

    def read(self):
        path = self.path()
        if not exists(path):
            # WIP
            return (perf_counter(), 0.0)
        with open(path, "r") as f:
            content = f.readlines()
            time = perf_counter()
        if len(content) < 2:
            return None
        if content[0].strip()[-3:] != "YES":
            print("INVALID CHECKSUM")
            return None
        return (time, int(re.search("t=([0-9]+)", content[1]).group(1)) / 1000.0)

class Sensors():
    def __init__(self, history=2621440):
        self.starttime = (datetime.now(), perf_counter())
        self.scan()
        self.values = {}
        self.history = deque([], maxlen=history)

    def perf_datetime(self, offset):
        time = offset - self.starttime[1]
        return self.starttime[0] + timedelta(seconds=time)

    "Scan for new sensors"
    def scan(self):
        # FIXME: should scan, apply stored data and return this
        self.available_sensors = {
            'T_ext': Temperature1W('28-06214252b671'),
            'T_food': Temperature1W('28-062142531e5a'),
        }

    def list(self):
        return {
            k: self.available_sensors[k].measure
            for k in self.available_sensors.keys()
        }

    def value_tuple(self):
        return tuple((k, *self.values[k]) for k in self.values.keys())

    def read(self):
        for sensor in self.available_sensors.keys():
            time, value = self.available_sensors[sensor].read()
            self.values[sensor] = (str(self.perf_datetime(time)), value)
        self.history.append(self.value_tuple())

    def get_sensor_value(self, sensor_name):
        return self.values.get(sensor_name, None)

    def get(self):
        return self.value_tuple()

    def get_history(self):
        return tuple(self.history)

sensors = Sensors()

def get_sensor_value(sensor_name):
    return sensors.get_sensor_value(sensor_name)[1]