/*
  Photoresistor (LDR) Analog Demo

  Copyright (C) 2021 Uri Shaked.

  https://wokwi.com/arduino/projects/305193627138654786
*/

#include <LiquidCrystal_I2C.h>
#include <Servo.h>

#define LDR_PIN 2

// LDR Characteristics
const float GAMMA = 0.7;
const float RL10 = 50;
Servo servo;  
int servoPosition = 0;
bool isShutterDown = false;
const int relayPin = 13;

LiquidCrystal_I2C lcd(0x27, 16, 2);

void setup() {
  pinMode(LDR_PIN, INPUT);

  lcd.init();
  lcd.backlight();
  servo.attach(0);
  servo.write(0); 
}

float getLux() {
  int analogValue = analogRead(A0);
  float voltage = analogValue / 1024. * 5;
  float resistance = 2000 * voltage / (1 - voltage / 5);
  float lux = pow(RL10 * 1e3 * pow(10, GAMMA) / resistance, (1 / GAMMA));
  return lux;
}

void loop() {
  float lux = getLux();
  lcd.setCursor(0, 0);
  lcd.print("Room: ");
  lcd.setCursor(0, 1);
  lcd.print("Lux: ");
  lcd.print(lux);
  lcd.print("          ");
if (lux > 10000) {
    digitalWrite(relayPin, LOW);
    lcd.print("Shutter down");
    if (!isShutterDown) {
      for (servoPosition = 0; servoPosition <= 180; servoPosition += 1) {
        servo.write(servoPosition);         
        delay(15); 
      }
      isShutterDown = true;
    }
  } else {
    lcd.print("Shutter up");
    if (isShutterDown) {
      for (servoPosition = 180; servoPosition >= 0; servoPosition -= 1) {
        servo.write(servoPosition);         
        delay(15); 
      }
      isShutterDown = false;
    }
    if (lux < 3000) {
      digitalWrite(relayPin, HIGH);
    } else {
      digitalWrite(relayPin, LOW);
    }
  }
  delay(100);
}