#include <Wire.h>
#include <Adafruit_GFX.h>
#include <Adafruit_SSD1306.h>
// 🚨 NEW: Include the custom font header
#include <Fonts/FreeSansBold24pt7b.h>

// --- Pin Definitions ---
#define SCREEN_WIDTH 128
#define SCREEN_HEIGHT 64
#define OLED_RESET -1
#define BUZZER_PIN 8
#define BUTTON_PIN 2

// Initialize the display object (same as before)
Adafruit_SSD1306 display(SCREEN_WIDTH, SCREEN_HEIGHT, &Wire, OLED_RESET);

// --- Timer and State Variables (Same as before) ---
const unsigned long COUNTDOWN_DURATION = 10000; 
unsigned long startTime = 0;
unsigned long timeRemaining = COUNTDOWN_DURATION;
enum TimerState { WAITING, COUNTING, TIMEOUT };
TimerState currentState = WAITING;
unsigned long lastTickTime = 0;
const int TICK_INTERVAL = 1000; 

// --- Function Declarations (Same as before) ---
void buttonPressISR();
void updateDisplay(long remainingMs);
void playTickSound();
void playTimeoutTone();
void turnBuzzerOff();

// =================================================================
// SETUP (Same as before)
// =================================================================
void setup() {
  if(!display.begin(SSD1306_SWITCHCAPVCC, 0x3C)) { 
    for(;;);
  }
  display.display(); 

  pinMode(BUZZER_PIN, OUTPUT);
  pinMode(BUTTON_PIN, INPUT_PULLUP);
  attachInterrupt(digitalPinToInterrupt(BUTTON_PIN), buttonPressISR, FALLING); 
  
  updateDisplay(COUNTDOWN_DURATION);
}

// =================================================================
// LOOP (Same as before)
// =================================================================
void loop() {
  if (currentState == COUNTING) {
    unsigned long currentTime = millis();
    timeRemaining = COUNTDOWN_DURATION - (currentTime - startTime);

    if (timeRemaining <= 0) {
      currentState = TIMEOUT;
      timeRemaining = 0;
      playTimeoutTone();
      updateDisplay(0);
    } else {
      if (currentTime - lastTickTime >= TICK_INTERVAL) {
        updateDisplay(timeRemaining);
        lastTickTime = currentTime;
        playTickSound();
      }
    }
  } else if (currentState == TIMEOUT) {
    currentState = WAITING;
  }
}


// =================================================================
// FUNCTIONS (Updated updateDisplay function)
// =================================================================

/**
 * Updates the OLED display with the remaining time, using FreeSansBold18pt7b font.
 */
void updateDisplay(long remainingMs) {
  display.clearDisplay();
  display.setTextColor(SSD1306_WHITE);

  if (currentState == WAITING) {
    // Use a smaller font for status text
    display.setFont();
    display.setTextSize(2);
    display.setCursor(10, 5);
    display.print("READY");
    display.setTextSize(1);
    display.setCursor(0, 32);
    display.print("Press button to start 10s");

  } else if (currentState == TIMEOUT) {
    // Use a smaller font for status text
    display.setFont();
    display.setTextSize(2);
    display.setCursor(0, 20);
    display.print("TIME'S UP!");

  } else {
    // --- Use the large custom font for the countdown ---
    display.setFont(&FreeSansBold24pt7b);
    display.setTextSize(1);
    
    int seconds = (remainingMs + 999) / 1000; // Rounds up to ensure 10 is shown clearly
    String timeStr = (seconds < 10 ? "0" : "") + String(seconds);

    // Calculate text bounds to center the number
    int16_t x1, y1;
    uint16_t w, h;
    display.getTextBounds(timeStr, 0, 0, &x1, &y1, &w, &h);

    // Center the text: (Screen Width / 2) - (Text Width / 2)
    display.setCursor((SCREEN_WIDTH - w) / 2, 45); 
    
    display.print(timeStr);
  }

  display.display();
}

// --- ISR, Tick, and Tone Functions (Same as before) ---
void buttonPressISR() {
  static unsigned long lastInterruptTime = 0;
  unsigned long interruptTime = millis();
  
  if (interruptTime - lastInterruptTime > 100) { 
    startTime = millis();
    lastTickTime = startTime; 
    timeRemaining = COUNTDOWN_DURATION;
    currentState = COUNTING;
    turnBuzzerOff();
  }
  lastInterruptTime = interruptTime;
}

void playTickSound() {
  //digitalWrite(BUZZER_PIN, HIGH);
  //delay(50);
  //digitalWrite(BUZZER_PIN, LOW);
  tone(8, 440, 50);
}

void playTimeoutTone() {
  //digitalWrite(BUZZER_PIN, HIGH);
  //delay(500); 
  //digitalWrite(BUZZER_PIN, LOW);
  tone(8, 440, 500);
}

void turnBuzzerOff() {
  digitalWrite(BUZZER_PIN, LOW);
}