"""
CLI Meter
====================================================================
Takes a reading of the light using the meter attached via to the
intended Raspberry PI. The reading is the sent to a server where the
reading is stored. The intended use for this script is to be run via
the command-line without the need for a G.U.I. This should be the
version used when the "Return to Ritherdon" project is live.
"""

import json
import RPi.GPIO as GPIO
import time, math
import requests
from datetime import datetime
# import pdb

# 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.

api_url = "http://3.9.19.84/api/readings/add/1"

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 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)
    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)
    push_reading(light)

def main():
    try:
        while True:
            #pdb.set_trace()
            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__":
    main()