#!/usr/bin/python3

import csv
from datetime import datetime, date, timedelta
from matplotlib import pyplot as plt

filename = 'log.csv'
'''
Time,TS,CO2,Temp
21:02:02,0,661,24
21:02:08,5021,657,24

'''

def parsedatetime(timevalue, currentdate):
    dt = datetime.strptime(timevalue, '%H:%M:%S')
    return datetime.combine(currentdate, dt.time())

with open(filename) as f:
    reader = csv.reader(f)
    headers = next(reader)

    time = []
    co2 = []
    temp = []
    startdate = date(2020, 10, 22)
    for row in reader:
        dt = parsedatetime(row[0], startdate)
        if len(time) > 0 and dt - time[-1] < timedelta(hours=-2): # DST switch!
            startdate += timedelta(days=1)
            dt += timedelta(days=1)
        time.append(dt)
        co2.append(int(row[2]))
        temp.append(int(row[3]))

    plt.plot(time, co2, c = 'red')
    plt.title('CO₂')
    plt.xlabel('time')
    plt.ylabel('ppm')
    plt.tick_params(axis = 'both', which = 'major')
    plt.gca().twinx()
    plt.plot(time, temp, c = 'blue')
    plt.show()