#include <Wire.h>
#include <Adafruit_GFX.h>
#include <Adafruit_SSD1306.h>
#include <TimerOne.h>

#define BUTTON_PIN 2

Adafruit_SSD1306 display(128, 64, &Wire, -1);

volatile bool displayAnalog = false;
volatile unsigned long lastDebounceTime = 0;
const unsigned long debounceDelay = 50;

byte seconds = 0;
byte minutes = 0;
byte hours = 0;

void setup() {
  pinMode(BUTTON_PIN, INPUT_PULLUP);
  attachInterrupt(digitalPinToInterrupt(BUTTON_PIN), buttonPressed, FALLING);

  display.begin(SSD1306_SWITCHCAPVCC, 0x3C);
  display.clearDisplay();
  display.setTextColor(WHITE);

  Timer1.initialize(1000000);
  Timer1.attachInterrupt(updateTime);
}

void loop() {
  if (displayAnalog) {
    drawAnalogClock();
  } else {
    drawDigitalClock();
  }
}

void updateTime() {
  static unsigned long prevMillis = 0;
  unsigned long currentMillis = millis();

  if (currentMillis - prevMillis >= 1000) {
    prevMillis = currentMillis;
    seconds++;

    if (seconds >= 60) {
      seconds = 0;
      minutes++;

      if (minutes >= 60) {
        minutes = 0;
        hours++;

        if (hours >= 24) {
          hours = 0;
        }
      }
    }
  }
}

void buttonPressed() {
  if ((millis() - lastDebounceTime) > debounceDelay) {
    displayAnalog = !displayAnalog;
    display.clearDisplay();
  }
  lastDebounceTime = millis();
}

void drawDigitalClock() {
  display.clearDisplay();
  display.setTextSize(2);
  display.setCursor(0, 0);
  display.print(hours / 10);
  display.print(hours % 10);
  display.print(':');
  display.print(minutes / 10);
  display.print(minutes % 10);
  display.print(':');
  display.print(seconds / 10);
  display.print(seconds % 10);
  display.display();
}

void drawAnalogClock() {
  display.clearDisplay();
  byte second_angle = map(seconds, 0, 60, 0, 360);
  byte minute_angle = map(minutes, 0, 60, 0, 360) + map(seconds, 0, 60, 0, 6);
  byte hour_angle = map(hours % 12, 0, 12, 0, 360) + map(minutes, 0, 60, 0, 30);

  display.drawCircle(64, 32, 30, WHITE);
  drawClockHand(64, 32, 20, second_angle, WHITE);
  drawClockHand(64, 32, 16, minute_angle, WHITE);
  drawClockHand(64, 32, 12, hour_angle, WHITE);

  display.display();
}

void drawClockHand(int16_t centerX, int16_t centerY, int16_t length, int16_t angle, uint16_t color) {
  float radians = (angle - 90) * (PI / 180.0);
  int16_t x = centerX + length * cos(radians);
  int16_t y = centerY + length * sin(radians);

  display.drawLine(centerX, centerY, x, y, color);
}