/*
  Photoresistor (LDR) Analog Demo

  Copyright (C) 2021 Uri Shaked.

  https://wokwi.com/arduino/projects/305193627138654786
*/
int LED1 = 25;
int LED2 = 18;
int LED3 = 19;

#include <LiquidCrystal_I2C.h>

#define LDR_PIN 12

// LDR Characteristics
const float GAMMA = 0.7;
const float RL10 = 50;

LiquidCrystal_I2C lcd(0x27, 20, 4);

void setup() {
  pinMode(LDR_PIN, INPUT);
  pinMode(LED1, OUTPUT);
  pinMode(LED2, OUTPUT);
  pinMode(LED3, OUTPUT);
  lcd.init();
  lcd.backlight();
}

void loop() {
  int analogValue = analogRead(12);
  float voltage = analogValue / 4095. * 5;
  float resistance = 2000 * voltage / (1 - voltage / 5);
  float lux = pow(RL10 * 1e3 * pow(10, GAMMA) / resistance, (1 / GAMMA));
  analogWrite(LED1, lux);
  lcd.setCursor(2, 0);
  lcd.print("Room: ");
  if (lux > 50) {
    digitalWrite(LED3, HIGH);
    digitalWrite(LED2, LOW);
    lcd.print("Light!");
  } else {
    digitalWrite(LED2, HIGH);
    digitalWrite(LED3, LOW);
    lcd.print("Dark  ");
  }

  lcd.setCursor(0, 1);
  lcd.print("Lux: ");
  lcd.print(lux);
  lcd.print("          ");

  delay(100);
}