#include <LiquidCrystal_I2C.h>
#include <PID_v1.h>

#define I2C_ADDR    0x27
#define LCD_COLUMNS 16
#define LCD_LINES   4

#define tempSensorPin A0
#define relayPin 2

LiquidCrystal_I2C lcd(I2C_ADDR, LCD_COLUMNS, LCD_LINES);


int WindowSize = 5000;
unsigned long windowStartTime;
double setpoint, temperature, output;

//Specify the links and initial tuning parameters
PID pidControl(&temperature, &output, &setpoint, 10, 5, 5, DIRECT);

void setup() {
  // Init
  lcd.init();
  lcd.backlight();

  pinMode(tempSensorPin, INPUT);
  pinMode(relayPin, OUTPUT);

  // Print something
  // lcd.setCursor(3, 0);
  // lcd.print("Hello, world!");
  lcd.setCursor(2, 1);
  lcd.print("Wokwi Online IoT");
  lcd.setCursor(0, 2);
  lcd.print("Current T");

  lcd.setCursor(10, 2);
  lcd.print("Output %");
  // lcd.setCursor(7, 3);
  // lcd.print("Enjoy!");

  windowStartTime = millis();
  
  //initialize the variables we're linked to
  setpoint = 60;

  //tell the PID to range between 0 and the full window size
  pidControl.SetOutputLimits(0, WindowSize);

  //turn the PID on
  pidControl.SetMode(AUTOMATIC);
}

void loop() {
  float value = analogRead(A0);

  float temperature = readTemperature();
  lcd.setCursor(0, 3);
  lcd.print(temperature, 1);

  pidControl.Compute();

  double outputPercent = 100. * output / 5000.;

  lcd.setCursor(10, 3);
  lcd.print(outputPercent, 1);

  lcd.setCursor(0, 0);
  lcd.print(output, 1);

  /************************************************
     turn the output pin on/off based on pid output
   ************************************************/
  unsigned long now = millis();
  if (now - windowStartTime > WindowSize)
  { //time to shift the Relay Window
    windowStartTime += WindowSize;
  }
  if (output > now - windowStartTime) digitalWrite(relayPin, HIGH);
  else digitalWrite(relayPin, LOW);
}

double readTemperature() {
  const float BETA = 3950; // should match the Beta Coefficient of the thermistor
  int analogValue = analogRead(A0);
  double celsius = 1 / (log(1 / (1023. / analogValue - 1)) / BETA + 1.0 / 298.15) - 273.15;
  return celsius;
}