#!/usr/bin/python3

"""
C.L.I. Meter
======================================================================
I wrote this script with the intention of using it as one part within
a single cron-job. The cron-job begins with "startup.sh" and that,
in-turn, will call this script when it is ready to do so.

This scrip takes a reading of the current light-level in the room,
using the Raspberry Pi (and the attached light-meter attached) it is
running on. From there, it sends a J.S.O.N. object to the server
(specified at "api_url"). The process is then repeated until it is
killed manually or via "shutdown.sh" (as a cron-job most likely).

You can use this script on Raspberry Pis without a G.U.I. because it
is all C.L.I. based. If you prefer something more graphical, you can
use "light_meter.py" -- which is part of this repository at time of
writing.

To end this script manually, use the usual "Ctrl-c" keyboard
interrupt -- or something like Htop... doesn't matter.
"""

import json
import RPi.GPIO as GPIO
import time
import math
import requests
from datetime import datetime
import platform
# import pdb # For testing.

# Using BCM (Broadcom) names when referencing the GPIO pins.
GPIO.setmode(GPIO.BCM)
GPIO.setwarnings(True)

a_pin = 18  # Charges the capacitor.
b_pin = 23  # Discharges the capacitor.

device_id = platform.node()  # For servers logs.


def get_api_url():
    # Yes, I know I could do this better. Stop moaning.
    if (device_id == "factory1"):
        return "http://ritherdon.abbether.net/api/readings/add/1"
    elif (device_id == "factory2"):
        return "http://ritherdon.abbether.net/api/readings/add/2"


# Make sure this is valid.
# api_url = "http://ritherdon.abbether.net/api/readings/add/1"
api_url = get_api_url()


def discharge():
    GPIO.setup(a_pin, GPIO.IN)
    GPIO.setup(b_pin, GPIO.OUT)
    GPIO.output(b_pin, False)
    time.sleep(0.01)  # 0.01 -- initial/default value.


def charge_time():
    GPIO.setup(b_pin, GPIO.IN)
    GPIO.setup(a_pin, GPIO.OUT)
    GPIO.output(a_pin, True)
    t1 = time.time()
    while not GPIO.input(b_pin):
        pass
    t2 = time.time()
    return (t2 - t1) * 1000000


def analog_read():
    discharge()
    return charge_time()


def read_resistance():
    n = 20
    total = 0
    for i in range(1, n):
        total = total + analog_read()
    reading = total / float(n)
    resistance = reading * 6.05 - 939
    return resistance


def light_from_r(R):
    return math.log(1000000.0/R) * 10.0


def get_timestamp():
    return datetime.now().strftime(("%Y-%m-%d %H:%M:%S"))


def push_reading(lvalue):
    time = get_timestamp()
    headers = {"content-type": "application/json"}
    payload = {"reading": int(lvalue), "time": time,
               "token": "QWERTYuiopasdfghjklzxcvbnm_1234567890"}
    # print(payload) # For testing.
    res = requests.post(api_url, data=json.dumps(payload), headers=headers)


def update_reading():
    light = light_from_r(read_resistance())
    reading_str = "{:.0f}".format(light)
    # print(reading_str) # For testing.
    push_reading(light)


def main():
    try:
        while True:
            # pdb.set_trace() # For testing.
            update_reading()
    except KeyboardInterrupt:
        print("Keyboard Interrupt: quitting program.")
    except:
        print("Error updating light reading...")
    finally:
        print("Cleaning up GPIO before closing...")
        GPIO.cleanup()


if __name__ == "__main__":
    # time.sleep(60) # For testing/debugging.
    main()