#include <Wire.h>
#include <Adafruit_GFX.h>
#include <Adafruit_SSD1306.h>
#include <RTClib.h> // RTC library

#define OLED_RESET 4 // Reset pin # (or -1 if sharing Arduino reset pin)
Adafruit_SSD1306 display(128, 64, &Wire, OLED_RESET);
RTC_DS1307 rtc; // Create RTC object

#define C_X 63
#define C_Y 31

void setup() {
  // 初始化 OLED
  display.begin(SSD1306_SWITCHCAPVCC, 0x3c); // Address 0x3C for 128x64
  display.display();
  delay(1000);
  display.clearDisplay();
  
  // 初始化 RTC
  if (!rtc.begin()) {
    display.println("Couldn't find RTC");
    display.display();
    while (1);
  }
  
  if (!rtc.isrunning()) {
    display.println("RTC is NOT running!");
    // 設定時間 (只需執行一次後可註解掉)
    rtc.adjust(DateTime(F(__DATE__), F(__TIME__)));
  }
  
  // 畫時鐘刻度
  display.drawCircle(C_X, C_Y, 31, SSD1306_WHITE);
  for (int i = 0; i < 360; i += 30) {
    float t = 90 - i; 
    float theta_r = t * (PI / 180.0);
    float x1 = C_X + 23 * cos(theta_r);
    float y1 = C_Y - 23 * sin(theta_r);
    float x2 = C_X + 27 * cos(theta_r);
    float y2 = C_Y - 27 * sin(theta_r);
    display.drawLine(x1, y1, x2, y2, SSD1306_WHITE);
  }
  display.display();
}

void loop() {
  // 清除顯示畫面
  display.clearDisplay();
  
  // 取得 RTC 當前時間
  DateTime now = rtc.now();
  int h = now.hour();
  int m = now.minute();

  // 畫時鐘框架和刻度
  display.drawCircle(C_X, C_Y, 31, SSD1306_WHITE);
  for (int i = 0; i < 360; i += 30) {
    float t = 90 - i;
    float theta_r = t * (PI / 180.0);
    float x1 = C_X + 23 * cos(theta_r);
    float y1 = C_Y - 23 * sin(theta_r);
    float x2 = C_X + 27 * cos(theta_r);
    float y2 = C_Y - 27 * sin(theta_r);
    display.drawLine(x1, y1, x2, y2, SSD1306_WHITE);
  }

  // 顯示時間文字
  display.setTextSize(1);
  display.setTextColor(SSD1306_WHITE);
  display.setCursor(0, 30);
  display.print(h);
  display.print(":");
  display.print(m);

  // 繪製時針
  float t = 90 - (h % 12) * 30 - m * 0.5; 
  float theta_r = t * (PI / 180.0);
  float x = C_X + 15 * cos(theta_r);
  float y = C_Y - 15 * sin(theta_r);
  display.drawLine(C_X, C_Y, x, y, SSD1306_WHITE);

  // 繪製分針
  t = 90 - m * 6; 
  theta_r = t * (PI / 180.0);
  x = C_X + 25 * cos(theta_r);
  y = C_Y - 25 * sin(theta_r);
  display.drawLine(C_X, C_Y, x, y, SSD1306_WHITE);

  // 顯示畫面
  display.display();
  delay(1000);
}