from machine import Pin, SoftI2C, ADC
from math import log
import time
import ssd1306



class LDR:
    """This class read a value from a light dependent resistor (LDR)"""

    def __init__(self, pin, min_value=0, max_value=100):
        """
        Initializes a new instance.
        :parameter pin A pin that's connected to an LDR.
        :parameter min_value A min value that can be returned by value() method.
        :parameter max_value A max value that can be returned by value() method.
        """
        if min_value >= max_value:
            raise Exception('Min value is greater or equal to max value')

        # initialize ADC (analog to digital conversion)
        # create an object ADC
        self.adc = ADC(Pin(pin))
        self.min_value = min_value
        self.max_value = max_value

    def read(self):
        """
        Read a raw value from the LDR.
        :return a value from 0 to 4095.
        """
        return self.adc.read()

    def value(self):
        """
        Read a value from the LDR in the specified range.
        :return A value from the specified [min, max] range.
        """
        return (self.max_value - self.min_value) * self.read() / 4095


# initialize an LDR
ldr = LDR(34)
led = Pin(23, Pin.OUT)
# ESP32 Pin assignment 
i2c = SoftI2C(sda=Pin(21), scl=Pin(22))

oled_width = 128
oled_height = 64
oled = ssd1306.SSD1306_I2C(oled_width, oled_height, i2c)


def show_value(raw): 
    oled.text("Value:", 30, 20)
    oled.text(str(raw), 30, 30)     
    oled.show()

def clear():
    oled.fill(0)
    oled.show()

prev_value = ldr.value()
show_value(prev_value)

while True:
    c_value = ldr.value()
    if c_value != prev_value:
        clear()
        show_value(c_value)
        prev_value = c_value
    if c_value < 20:
        led.on()
    else:
        led.off()
    time.sleep(3)