#include <AM2302-Sensor.h>
#include <LiquidCrystal_I2C.h>

LiquidCrystal_I2C lcd(0x27, 16, 2);

constexpr unsigned int SENSOR_PIN {7U};
AM2302::AM2302_Sensor am2302{SENSOR_PIN};

const int potPin = A1;
const int buttonPin = 8;


// ---------------- STATE MACHINE ----------------
enum State {
  SET_MAX_TEMP,
  SET_HUMIDITY,
  CONFIRM,
  VIEW
};

State state = SET_MAX_TEMP;

// ---------------- SENSOR VALUES ----------------
float temperature = NAN;
float humidity = NAN;

// ---------------- SETTINGS ----------------
float maxTemperature = 30.0;
float targetHumidity = 50.0;

// ---------------- CONFIRM ----------------
bool confirmYes = false;

// ---------------- TIMING ----------------
unsigned long lastLcdUpdate = 0;
unsigned long lastSensorRead = 0;

const unsigned long lcdInterval = 500;
const unsigned long sensorInterval = 2000;

// ---------------- BUTTON ----------------
bool lastButtonState = HIGH;

// ---------------- SENSOR ----------------
void readSensor(unsigned long now) {
  if (now - lastSensorRead >= sensorInterval) {
    lastSensorRead = now;

    if (am2302.read() == AM2302::AM2302_READ_OK) {
      humidity = am2302.get_Humidity();
      temperature = am2302.get_Temperature();
    }
  }
}

// ---------------- BUTTON HANDLER ----------------
void handleButton() {
  static bool lastReading = HIGH;
  static unsigned long lastDebounce = 0;
  const unsigned long debounceDelay = 50;

  bool reading = digitalRead(buttonPin);

    if (lastReading == HIGH && reading == LOW) {

      // CONFIRM LOGIC
      if (state == CONFIRM) {

        if (confirmYes) {
          state = VIEW;          // accept settings
        } else {
          state = SET_MAX_TEMP;  // restart setup
        }
      }
      else {
        // NORMAL FLOW
        if (state == SET_MAX_TEMP) {
          state = SET_HUMIDITY;
        }
        else if (state == SET_HUMIDITY) {
          state = CONFIRM;
        }
        else if (state == VIEW) {
          state = SET_MAX_TEMP;
        }
      }
  }

  lastReading = reading;
}

// ---------------- LCD ----------------
void updateLCD(unsigned long now) {
  if (now - lastLcdUpdate < lcdInterval) return;
  lastLcdUpdate = now;

  lcd.clear();

  int potValue = analogRead(potPin);

  // ---------------- SET MAX TEMP ----------------
  if (state == SET_MAX_TEMP) {
    maxTemperature = map(potValue, 0, 1023, 20, 60);

    lcd.setCursor(0, 0);
    lcd.print("Set Max Temp:");

    lcd.setCursor(0, 1);
    lcd.print(maxTemperature);
    lcd.print(" C");

    return;
  }

  // ---------------- SET HUMIDITY ----------------
  if (state == SET_HUMIDITY) {
    targetHumidity = map(potValue, 0, 1023, 0, 80);

    lcd.setCursor(0, 0);
    lcd.print("Set Humidity:");

    lcd.setCursor(0, 1);
    lcd.print(targetHumidity);
    lcd.print("%");

    return;
  }

  // ---------------- CONFIRM ----------------
  if (state == CONFIRM) {

    confirmYes = (potValue < 512);

    lcd.setCursor(0, 0);
    lcd.print("Confirm Settings");

    lcd.setCursor(0, 1);

    if (confirmYes) {
      lcd.print("> YES   NO");
    } else {
      lcd.print("  YES > NO");
    }

    return;
  }

  // ---------------- VIEW MODE ----------------
  lcd.setCursor(0, 0);
  lcd.print("AH:");
  lcd.print(humidity);
  lcd.print("%");

  lcd.setCursor(0, 1);
  lcd.print("AT:");
  lcd.print(temperature);
  lcd.print("C");

  // show target humidity

  // show target
  lcd.setCursor(10, 1);
  lcd.print("TH:");
  lcd.print(targetHumidity);

  // show target
  lcd.setCursor(10, 0);
  lcd.print("TT:");
  lcd.print(maxTemperature);
}

// ---------------- SETUP ----------------
void setup() {
  lcd.init();
  lcd.backlight();

  am2302.begin();

  pinMode(buttonPin, INPUT_PULLUP);

  lcd.setCursor(0, 0);
  lcd.print("System Start");
}

// ---------------- LOOP ----------------
void loop() {
  unsigned long now = millis();

  handleButton();
  readSensor(now);
  updateLCD(now);
}