from machine import ADC, Pin
import math,time

led_pins = [13,12,14,27,26,25,33,32,23,22]
leds = [Pin(pin, Pin.OUT) for pin in led_pins]

def clear_leds():
    for led in leds:
        led.value(0)

def light_up_to(n):
    clear_leds()
    for i in range(n):
        leds[i].value(1)

adc = ADC(Pin(2))  
adc.atten(ADC.ATTN_11DB)  

rl10 = 50e3     #LDR resistance at 10lux
gamma = 0.7     #log(Ra/Rb) / log(La/Lb) 

#R2 =  R1 * Vout / (Vin - Vout)
def calculate_resistance():
  value = adc.read()  
  voltage_ratio = value / (4095 - value)
  return 10e3 * voltage_ratio

#R = R_10 * (lux / 10) ^ -γ => R10/​R​=(10/lux​)^−γ => R/R10​​=(10/lux​)^γ => (R10​​/R)^(1/γ​)=10/lux​ => lux=10*(R10/R​​)^(1/γ)​
def calculate_lux(resistance):
  return 10 * math.pow(rl10/resistance, 1/gamma)

points = [
    (0.1, 1.25e6),
    (1, 250e3),
    (10, 50e3),
    (50, 16.2e3),
    (100, 9.98e3),
    (400, 3.78e3),
    (1000, 1.99e3),
    (10000, 397),
    (100000, 79)
]

#y = y1 + ((x - x1) / (x2 - x1)) * (y2 - y1)
def linear_interpolation(resistance):
  if resistance >= 1.25e6:
    light_up_to(1)
    return 0.1
  elif resistance <= 79:
    light_up_to(10)
    return 100000

  for i in range(len(points) - 1):
    if points[i+1][1] <= resistance <= points[i][1]:
      x1, y1 = points[i]
      x2, y2 = points[i + 1]
      light_up_to(i + 2)
      return x1 + ((resistance - y1) / (y2 - y1)) * (x2 - x1)


while 1:
  resistance = calculate_resistance()
  print('Lux:', round(calculate_lux(resistance),1) ,'\tInterpolated Lux:', round(linear_interpolation(resistance),1))
  time.sleep(1)