/*
Wokwi | questions
help me with this homework.
thái - Monday, February 2, 2026 10:47 AM

Perform the steps to program the system using a state-based approach, 
and meet the following requirements:

Control an LED to blink in 5 different states:
OFF: LED is turned off.
SLOW_BLINK: LED blinks slowly (1 second per toggle).
MEDIUM_BLINK: LED blinks at medium speed (0.5 seconds per toggle).
FAST_BLINK: LED blinks fast (0.25 seconds per toggle).
VERYFAST_BLINK: LED blinks very fast (0.1 seconds per toggle).
The state changes once for each button press.
UP button: increases the state (from 1 → 5 and then loops back).
DOWN button: decreases the state (from 5 → 1 and then loops back).
*/

const int NUM_BTNS = 2;
const int BTN_PINS[] = {12, 11};
const int LED_PIN = 10;

bool ledState = false;
int btnState[NUM_BTNS];
int oldBtnState[NUM_BTNS];
int mode = 0;
unsigned long prevTime = 0;

void blinkLed(int mode) {
  unsigned long interval = 0;

  switch (mode) {
    case 1:
      interval = 1000;
      break;
    case 2:
      interval = 500;
      break;
    case 3:
      interval = 250;
      break;
    case 4:
      interval = 125;
      break;
    default:
      Serial.println("WTF");
  }
  if (millis() - prevTime >= interval)  {
    prevTime = millis();
    ledState = !ledState;
  }
  digitalWrite(LED_PIN, ledState);
}

int checkButtons()  {
  int btnPressed = 0;

  for (int i = 0; i < NUM_BTNS; i++) {
    btnState[i] = digitalRead(BTN_PINS[i]); // check each button
    if (btnState[i] != oldBtnState[i])  {   // if it changed
      oldBtnState[i] = btnState[i];         // remember state for next time
      if (btnState[i] == 0)  {              // was just pressed
        btnPressed = i + 1;
        if (btnPressed == 1)  {
          Serial.println("UP");
        }
        if (btnPressed == 2)  {
          Serial.println("DOWN");
        }
      }
      delay(20);  // debounce
    }
  }
  return btnPressed;
}

void setup() {
  Serial.begin(115200);
  pinMode(BTN_PINS[0], INPUT_PULLUP);
  pinMode(BTN_PINS[1], INPUT_PULLUP);
  pinMode(LED_PIN, OUTPUT);
  Serial.println("Mode: 0");
}

void loop() {
  int btnNumber = checkButtons();
  if (btnNumber != 0) {
    if (btnNumber == 1) {
      mode++;
      if (mode > 4) mode = 0;
    } else  {
      mode--;
      if (mode < 0) mode = 4;
    }
    Serial.print("Mode: ");
    Serial.println(mode);
  }
  if (mode != 0)  {
    blinkLed(mode);
  } else {
    digitalWrite(LED_PIN, LOW);
  }
}