#include <TM1637Display.h>
#include <Preferences.h>

#define CLK 22
#define DIO 21
#define BTN_START 18
#define BTN_RESET 19

TM1637Display display(CLK, DIO);
Preferences prefs;

bool running = false;
unsigned long lastMillis = 0;
unsigned long lastBlink = 0;
bool colonOn = true;

uint8_t hours = 0;
uint8_t minutes = 0;

void saveTime() {
  prefs.begin("timer", false);
  prefs.putUChar("hours", hours);
  prefs.putUChar("minutes", minutes);
  prefs.end();
}

void loadTime() {
  prefs.begin("timer", true);
  hours = prefs.getUChar("hours", 0);
  minutes = prefs.getUChar("minutes", 0);
  prefs.end();
  if (hours > 99 || minutes > 59) {
    hours = 0;
    minutes = 0;
  }
}

void showTime(bool colon) {
  int displayTime = hours * 100 + minutes; // HHMM
  uint8_t dots = colon ? 0b01000000 : 0;
  display.showNumberDecEx(displayTime, dots, true);
}

void setup() {
  pinMode(BTN_START, INPUT_PULLUP);
  pinMode(BTN_RESET, INPUT_PULLUP);
  display.setBrightness(0x0f);

  loadTime();
  showTime(true);
}

void loop() {
  // --- Start/Stop button ---
  if (digitalRead(BTN_START) == LOW) {
    delay(50);
    if (digitalRead(BTN_START) == LOW) {
      running = !running;
      if (running) {
        lastBlink = millis();  // reset blink timing
        colonOn = true;
      } else {
        saveTime();
        colonOn = true;        // colon steady ON when stopped
      }
      showTime(colonOn);
      while (digitalRead(BTN_START) == LOW);
    }
  }

  // --- Reset button ---
  if (digitalRead(BTN_RESET) == LOW) {
    delay(50);
    if (digitalRead(BTN_RESET) == LOW) {
      hours = 0;
      minutes = 0;
      saveTime();
      colonOn = true;
      showTime(true);
      while (digitalRead(BTN_RESET) == LOW);
    }
  }

  // --- Timer update every 1 min ---
  if (running && millis() - lastMillis >= 60000UL) {
    lastMillis += 60000UL;
    minutes++;
    if (minutes > 59) {
      minutes = 0;
      hours++;
      if (hours > 99) hours = 0;
    }
    showTime(colonOn); // don't force colon, keep blink state
  }

  // --- Colon blink ---
  if (running && millis() - lastBlink >= 500UL) {
    lastBlink += 500UL;
    colonOn = !colonOn;
    showTime(colonOn);
  }
}