---

#include <Arduino.h>

// 74HC595
const byte DATA_PIN  = 8;
const byte CLOCK_PIN = 7;
const byte LATCH_PIN = 4;

// Кнопки
const byte BTN_INC   = A1;
const byte BTN_MODE  = A2;
const byte BTN_START = A3;

// АКТИВНЫЙ пьезо!
const byte BUZZER_PIN = 3;

// Сегменты (common anode)
const byte SEG_CA[10] = {
  0xC0,0xF9,0xA4,0xB0,0x99,
  0x92,0x82,0xF8,0x80,0x90
};

const byte DIGIT_SEL[4] = {0x01,0x02,0x04,0x08};

struct Button {
  bool last = HIGH;
  bool state = HIGH;
  unsigned long t = 0;
};

Button b1,b2,b3;

const unsigned long DEB = 40;
const unsigned long TICK = 1000;

uint8_t minutes = 14;
uint8_t seconds = 59;

uint16_t remain = 0;

bool running = false;
bool done = false;
bool editMin = true;

unsigned long lastTick = 0;
unsigned long lastBlink = 0;
bool blink = true;

// --- ПИЩАЛКА (активная) ---
void beepShort() {
  digitalWrite(BUZZER_PIN, HIGH);
  delay(60);
  digitalWrite(BUZZER_PIN, LOW);
}

// --- кнопка ---
bool press(Button &b, byte pin){
  bool r = digitalRead(pin);

  if(r != b.last){
    b.t = millis();
    b.last = r;
  }

  if(millis() - b.t > DEB){
    if(r != b.state){
      b.state = r;
      if(r == LOW) return true;
    }
  }
  return false;
}

// --- 595 ---
void send595(byte a, byte b){
  digitalWrite(LATCH_PIN, LOW);
  shiftOut(DATA_PIN,CLOCK_PIN,MSBFIRST,a);
  shiftOut(DATA_PIN,CLOCK_PIN,MSBFIRST,b);
  digitalWrite(LATCH_PIN, HIGH);
}

// --- отображение ---
void show(uint16_t val, bool blank=false){
  byte d[4];

  if(!blank){
    d[3]=val%10; val/=10;
    d[2]=val%10; val/=10;
    d[1]=val%10; val/=10;
    d[0]=val%10;
  }

  for(int i=0;i<4;i++){
    if(blank){
      send595(0xFF,0x00);
    } else {
      send595(SEG_CA[d[i]], DIGIT_SEL[i]);
    }
    delayMicroseconds(800);
  }
}

uint16_t toSec(){
  return minutes*60 + seconds;
}

// --- setup ---
void setup(){
  pinMode(DATA_PIN,OUTPUT);
  pinMode(CLOCK_PIN,OUTPUT);
  pinMode(LATCH_PIN,OUTPUT);

  pinMode(BTN_INC,INPUT_PULLUP);
  pinMode(BTN_MODE,INPUT_PULLUP);
  pinMode(BTN_START,INPUT_PULLUP);

  pinMode(BUZZER_PIN,OUTPUT);
  digitalWrite(BUZZER_PIN, LOW);
}

// --- loop ---
void loop(){

  // --- КНОПКИ ---
  if(press(b1,BTN_INC) && !running){
    done = false;
    if(editMin){
      minutes = (minutes+1)%100;
    } else {
      seconds = (seconds+1)%60;
    }
  }

  if(press(b2,BTN_MODE) && !running){
    editMin = !editMin;
  }

  if(press(b3,BTN_START) && !running){
    remain = toSec();
    if(remain > 0){
      running = true;
      done = false;
      lastTick = millis();
    }
  }

  // --- ТАЙМЕР ---
  if(running){
    if(millis() - lastTick >= TICK){
      lastTick += TICK;

      // последние 10 секунд
      if(remain <= 10 && remain > 0){
        beepShort();
      }

      if(remain > 0) remain--;

      if(remain == 0){
        running = false;
        done = true;
      }
    }
  }

  // --- КОНЕЦ ---
  if(done){
    if(millis() - lastBlink > 300){
      lastBlink = millis();
      blink = !blink;

      // частое пищание
      beepShort();
    }
    show(0, !blink);
    return;
  }

  // --- ОТОБРАЖЕНИЕ ---
  if(running){
    show(remain);
  } else {
    show(toSec());
  }
}