#!/usr/bin/env python
# -*- coding: utf-8 -*-
#----------------------------------------------------------------
#	Note:
#		ds18b20's data pin must be connected to pin7.
#		replace the 28-XXXXXXXXX as yours.
#----------------------------------------------------------------
import os
import time
import datetime
import openpyxl
from openpyxl.styles import Font
os.system('modprobe w1-gpio')
os.system('modprobe w1-therm')

def temp_raw():
	temp_sensor = "/sys/bus/w1/devices/28-0316b38974ff/w1_slave"
	f = open(temp_sensor, 'r')
	lines = f.readlines()
	f.close()
	return lines

def read_temp():
	lines = temp_raw()
	while lines[0].strip()[-3:] != 'YES':
		time.sleep(0.1)
		lines = temp_raw()
	temp_output = lines[1].find('t=')
	if temp_output != -1:
	temp_string = lines[1].strip()[temp_output+2:]
	temp_c = float(temp_string) / 1000.0
	return temp_c

def percentage_change(current, previous):
	if (current > previous):
		return float(current - previous) / abs(previous) * 100
	else:
		return float(current - previous) / abs(previous) * 100 * (-1)

def main():
	# Check current working directory.
	currentdirectory = os.getcwd()
	print ("Current working directory %s" % currentdirectory)
	# Change Directory
	if not os.path.exists('/home/pi/Logs/'):
		os.mkdir('/home/pi/Logs')
		print ("Directory not found will create one")
	os.chdir('/home/pi/Logs')
	# confirm current working directory.
	currentdirectory = os.getcwd()
	print ("Directory changed successfully %s" % currentdirectory)

	#Create Excel document
	wb = openpyxl.Workbook()
	sheet = wb.active
	sheet.title = 'TemperatureData'

	#Configure Header
	bold20Font = Font(size=20, bold=True)
	sheet['A1'].font = bold20Font
	sheet.column_dimensions['A'].width = 20
	sheet['A1'] = 'Timestamp:'
	sheet['B1'].font = bold20Font
	sheet.column_dimensions['B'].width = 12
	sheet['B1'] = 'Temp:'
	sheet.freeze_panes = 'A2'

	count = 2
	read_temp()
	while True:
		if (percentage_change(temp c, b) > 2):
			sheet["A"+str(count)] = datetime.datetime.now()
			sheet["B"+str(count)] = ("%0.1f" % read_temp())
			wb.save('TemperatureLog.xlsx')
			count = count + 1
			read_temp() = a
			print ("Temp Logged")
		else:
			print ("Temp not logged")



#Run main Program
while True:
		temp_raw()
		read_temp()
		main()