#include <LiquidCrystal_I2C.h>

#define I2C_ADDR    0x27
#define LCD_COLUMNS 16
#define LCD_LINES   2

LiquidCrystal_I2C lcd(I2C_ADDR, LCD_COLUMNS, LCD_LINES);

const float BETA = 3950;

boolean protectionMode = false;
const int maxTemp = 25;
const float minVoltage = 12;

int prevBedTemp = -1;
int prevTargetTemp = -1;

void overheatProtection () {
  protectionMode = true;
  lcd.clear();
  lcd.setCursor(6, 0);
  lcd.print("ERROR");
  lcd.setCursor(2, 1);
  lcd.print("BED OVERHEAT");
  digitalWrite(8, LOW);

}

void setup() {
  Serial.begin(115200);
  pinMode(A0, INPUT);
  pinMode(A1, INPUT);
  pinMode(A2, OUTPUT);
  pinMode(8, OUTPUT);
  digitalWrite(8, HIGH);

  lcd.init();
  lcd.backlight();

  lcd.setCursor(0, 0);
  lcd.print("Bed Temp: ---");
  lcd.setCursor(2, 1);
  lcd.print("Target: ---");

}

void loop() {

  if (!protectionMode) {

    int analogBedTemp = analogRead(A1);
    // Serial.println(analogBedTemp);
    // float celsius = 1 / (log(1 / (1023. / analogBedTemp - 1)) / BETA + 1.0 / 298.15) - 273.15;
    // int bedTemp = round(celsius);
    int bedTemp = analogBedTemp;
    // Serial.println(bedTemp);


    if (bedTemp != prevBedTemp) {
      lcd.setCursor(10, 0);
      lcd.print("        ");
      lcd.setCursor(10, 0);
      lcd.print(bedTemp);
      lcd.print((char)223);
      lcd.print("C");
      prevBedTemp = bedTemp;
    }

    int targetValue = analogRead(A0);
    float targetTemp = (targetValue / 1023.0) * 120.0;
    int roundedTargetTemp = round(targetTemp);


    if (bedTemp < (roundedTargetTemp - 1)) {
      digitalWrite(A2, HIGH);
    } else if (bedTemp > (roundedTargetTemp + 1)) {
      digitalWrite(A2, LOW);
    }

    if (roundedTargetTemp != prevTargetTemp) {
      lcd.setCursor(10, 1);
      lcd.print("        ");
      lcd.setCursor(10, 1);
      lcd.print(roundedTargetTemp);
      lcd.print((char)223);
      lcd.print("C");
      prevTargetTemp = roundedTargetTemp;
    }

    if (bedTemp > maxTemp) {
      overheatProtection();
    };
  }


  delay(1000);
}