#!/usr/bin/env python
# -*- coding: utf-8 -*-
#
#  Copyright 2017 Dr. M. Luetzelberger <webmaster@raspberryblog.de>
#
#  This program is free software; you can redistribute it and/or modify
#  it under the terms of the GNU General Public License as published by
#  the Free Software Foundation; either version 2 of the License, or
#  (at your option) any later version.
#
#  This program is distributed in the hope that it will be useful,
#  but WITHOUT ANY WARRANTY; without even the implied warranty of
#  MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
#  GNU General Public License for more details.
#
#  You should have received a copy of the GNU General Public License
#  along with this program; if not, write to the Free Software
#  Foundation, Inc., 51 Franklin Street, Fifth Floor, Boston,
#  MA 02110-1301, USA.
#
#

from __future__ import print_function
import serial, struct, time
import psycopg2
import signal
from datetime import datetime, tzinfo

ser = serial.Serial()
ser.port = "COM21"
ser.baudrate = 9600
ser.open()
ser.flushInput()

#Using vrstats because lol
conn_string = "host='localhost' dbname='vrstats' user='kevin' port=5432 password='postgrespassword'"
conn = psycopg2.connect(conn_string)
cursor = conn.cursor()
insert_stmt = """INSERT INTO aqi (pm25, pm10, ts) VALUES (%s, %s, %s);"""

def exit_handler(signum, frame):
    import sys
    cursor.close()
    conn.close()
    sys.exit(0)
signal.signal(signal.SIGINT, exit_handler)
signal.signal(signal.SIGILL, exit_handler)
signal.signal(signal.SIGABRT, exit_handler)
signal.signal(signal.SIGBREAK, exit_handler)
signal.signal(signal.SIGTERM, exit_handler)

def insert(pm25, pm10, ts):
    statement = cursor.mogrify(insert_stmt, (pm25, pm10, ts))
    cursor.execute(statement)
    conn.commit()

def process_frame(d):
    r = struct.unpack('<HHxxBBB', d[2:])
    pm25 = r[0]/10.0
    pm10 = r[1]/10.0
    checksum = sum(ord(v) for v in d[2:8])%256
    valid = (checksum==r[2] and r[3]==0xab)
    if (valid):
        insert(pm25, pm10, datetime.utcnow())
    print("PM 2.5: {} ug/m^3  PM 10: {} ug/m^3 CRC={}".format(pm25, pm10, "OK" if valid else "NOK"))

def sensor_read():
    byte = 0
    while byte != "\xaa":
        byte = ser.read(size=1)
    d = ser.read(size=10)
    if d[0] == "\xc0":
        process_frame(byte + d)

# 0xAA, 0xB4, 0x06, 0x01, 0x01, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0xFF, 0xFF, 0x06, 0xAB
def sensor_wake():
	bytes = ['\xaa', #head
			'\xb4', #command 1
			'\x06', #data byte 1
			'\x01', #data byte 2 (set mode)
			'\x01', #data byte 3 (sleep)
			'\x00', #data byte 4
			'\x00', #data byte 5
			'\x00', #data byte 6
			'\x00', #data byte 7
			'\x00', #data byte 8
			'\x00', #data byte 9
			'\x00', #data byte 10
			'\x00', #data byte 11
			'\x00', #data byte 12
			'\x00', #data byte 13
			'\xff', #data byte 14 (device id byte 1)
			'\xff', #data byte 15 (device id byte 2)
			'\x05', #checksum
			'\xab'] #tail

	for b in bytes:
		ser.write(b)

# xAA, 0xB4, 0x06, 0x01, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0xFF, 0xFF, 0x05, 0xAB
def sensor_sleep():
	bytes = ['\xaa', #head
			'\xb4', #command 1
			'\x06', #data byte 1
			'\x01', #data byte 2 (set mode)
			'\x00', #data byte 3 (sleep)
			'\x00', #data byte 4
			'\x00', #data byte 5
			'\x00', #data byte 6
			'\x00', #data byte 7
			'\x00', #data byte 8
			'\x00', #data byte 9
			'\x00', #data byte 10
			'\x00', #data byte 11
			'\x00', #data byte 12
			'\x00', #data byte 13
			'\xff', #data byte 14 (device id byte 1)
			'\xff', #data byte 15 (device id byte 2)
			'\x05', #checksum
			'\xab'] #tail

	for b in bytes:
		ser.write(b)

def main():
    while (True):
        print("Sensor waking.")
        sensor_wake()
        time.sleep(15)
        ser.flushInput()
        print("Reading data from sensor.")
        sensor_read()
        time.sleep(5)
        print("Entering sleep mode.")
        sensor_sleep()
        time.sleep(10)

if __name__ == '__main__':
    main()