#include <LiquidCrystal.h>

const int RS_Pin = A4;
const int EN_Pin = A5;
const int D4_Pin = A3;
const int D5_Pin = A2;
const int D6_Pin = A1;
const int D7_Pin = A0;

const int MinutesButtonPin = 13; 
const int SecondsButtonPin = 11;  
const int MilliSecondsButtonPin = 9; 
const int ResetButtonPin = 2;  
const int StartButtonPin = 3; 

const int GreenLEDPin = 10;  
const int RedLEDPin = 8; 

int set_minutes = 0;
int set_seconds = 0;
int set_milliseconds = 0;

int display_minutes = 0;
int display_seconds = 0;
int display_milliseconds = 0;

bool timerStarted = false;
unsigned long startTime = 0;

LiquidCrystal lcd(RS_Pin, EN_Pin, D4_Pin, D5_Pin, D6_Pin, D7_Pin);

void setup() {
    lcd.begin(16, 2);
    
    pinMode(MinutesButtonPin, INPUT_PULLUP);
    pinMode(SecondsButtonPin, INPUT_PULLUP);
    pinMode(MilliSecondsButtonPin, INPUT_PULLUP);
    pinMode(ResetButtonPin, INPUT_PULLUP);
    pinMode(StartButtonPin, INPUT_PULLUP);

    pinMode(GreenLEDPin, OUTPUT);
    pinMode(RedLEDPin, OUTPUT);

    reset();
}

void loop() {
    
    if (digitalRead(StartButtonPin) == LOW && !timerStarted) {
        startTime = millis();
        display_minutes = set_minutes;
        display_seconds = set_seconds;
        display_milliseconds = set_milliseconds;
        timerStarted = true;
    }

    if (digitalRead(ResetButtonPin) == LOW) {
        reset();
    }

    if (digitalRead(MinutesButtonPin) == LOW) {
        set_minutes = (set_minutes + 1) % 60;
        lcd.clear();
        lcd.setCursor(0, 0);
        lcd.print(formatTime());
        delay(200);  
    }

    if (digitalRead(SecondsButtonPin) == LOW) {
        set_seconds = (set_seconds + 1) % 60;
        lcd.clear();
        lcd.setCursor(0, 0);
        lcd.print(formatTime());
        delay(200);  
    }

    if (digitalRead(MilliSecondsButtonPin) == LOW) {
        set_milliseconds = (set_milliseconds + 1) % 100;  
        lcd.clear();
        lcd.setCursor(0, 0);
        lcd.print(formatTime());
        delay(200);
    }

    if (timerStarted) {
        unsigned long elapsed = millis() - startTime;
        int elapsed_seconds = (int)(elapsed / 1000) % 60;
        int elapsed_minutes = (int)(elapsed / (60 * 1000));

        // ТУТ НАЧИНАЕТСЯ ОБРАТНЫЙ ОТСЧЕТ
        int total_elapsed_seconds = (elapsed_minutes * 60 + elapsed_seconds);
        int total_set_seconds = (set_minutes * 60 + set_seconds);

        if (total_set_seconds - total_elapsed_seconds <= 1) {
            timerStarted = false;
            reset();
        } else {
            display_minutes = total_set_seconds - total_elapsed_seconds;
            display_seconds = display_minutes % 60;
            display_minutes = (display_minutes / 60) % 60;
            
            lcd.clear();
            lcd.setCursor(0, 0);
            lcd.print(display_minutes);
            lcd.print(":");
            lcd.print(display_seconds);
            lcd.print(":");
            lcd.print(set_milliseconds);
            
            // Обработка светодиодов
            if (display_seconds % 10 == 0) {
                digitalWrite(GreenLEDPin, HIGH);
            } else {
                digitalWrite(GreenLEDPin, LOW);
            }

            if (display_seconds % 5 == 0) {
                digitalWrite(RedLEDPin, HIGH);
            } else {
                digitalWrite(RedLEDPin, LOW);
            }
        }
    }
}

void reset() {
    timerStarted = false;
    set_minutes = 0;
    set_seconds = 0;
    set_milliseconds = 0;

    lcd.clear();
    lcd.setCursor(0, 0);
    lcd.print("00:00:00");
    digitalWrite(GreenLEDPin, LOW);
    digitalWrite(RedLEDPin, LOW);
}

String formatTime() {
    String formattedTime = "";
    formattedTime += (set_minutes < 10) ? "0" + String(set_minutes) : String(set_minutes);
    formattedTime += ":";
    formattedTime += (set_seconds < 10) ? "0" + String(set_seconds) : String(set_seconds);
    formattedTime += ":";
    formattedTime += (set_milliseconds < 10) ? "0" + String(set_milliseconds) : String(set_milliseconds);
    
    return formattedTime;
}