#include <LiquidCrystal.h>

LiquidCrystal lcd(12, 11, 5, 4, 3, 2);

const int potPin = A2;
const int buttonPin = 10;

int buttonState = 0;
int mode = 0;
int lastMode = -1;

const unsigned long timeinsecond = 6000; // ✅ 5 วินาที = 5000 มิลลิวินาที
unsigned long startTime = 0;

bool blinkState = false;
unsigned long lastBlinkTime = 0;

void setup() {
  lcd.begin(16, 2);
  pinMode(buttonPin, INPUT_PULLUP);
  lcd.clear();
  lcd.setCursor(3, 0);
  lcd.print("Volt measure");
}

void loop() {
  buttonState = digitalRead(buttonPin);

  static bool lastButton = HIGH;
  if (lastButton == HIGH && buttonState == LOW) {
    mode++;
    if (mode > 2) mode = 0;
    delay(200);
  }
  lastButton = buttonState;

  // ตรวจจับการเปลี่ยนโหมด
  if (mode != lastMode) {
    lcd.clear();

    if (mode == 0) {
      lcd.setCursor(3, 0);
      lcd.print("Volt measure");
    }
    else if (mode == 1) {
      startTime = millis(); // ✅ เริ่มจับเวลาตอนเข้าโหมด 1
      lcd.setCursor(0, 0);
      lcd.print("time in second");
    }
    else if (mode == 2) {
      lcd.setCursor(0, 0);
      lcd.print("Press Button");
    }

    lastMode = mode;
  }

  // โหมด 0: วัดแรงดัน
  if (mode == 0) {
    int sensorValue = analogRead(potPin);
    float voltage = sensorValue * (5.0 / 1023.0);
    lcd.setCursor(0, 1);
    lcd.print("Volt: ");
    lcd.print(voltage, 2);
    lcd.print(" V   ");
  }

  // โหมด 1: ✅ นับถอยหลัง
  else if (mode == 1) {
    unsigned long currentTime = millis();
    long timeLeft = timeinsecond - (currentTime - startTime); // เหลือเวลาเท่าไหร่

    lcd.setCursor(0, 1);

    if (timeLeft > 0) {
      lcd.print("Time: ");
      lcd.print(timeLeft / 1000); // แสดงเป็นวินาที
      lcd.print(" s   ");
    } else {
      lcd.print("Time's up!  ");
    }
  }

  // โหมด 2: blink
  else if (mode == 2) {
    unsigned long currentMillis = millis();
    if (currentMillis - lastBlinkTime >= 500) {
      lastBlinkTime = currentMillis;
      blinkState = !blinkState;
      lcd.setCursor(0, 1);
      lcd.setCursor(0, 0);
    lcd.print("  Press Button");

    for (int i = 0; i < 16; i++) {
      lcd.setCursor(i, 1);
      lcd.print(">>blink<<");
      delay(100);
      lcd.setCursor(i, 1);
      lcd.print(" blink ");
    }
      }
    }
  }