#include <Wire.h>
#include <LiquidCrystal_I2C.h>

#define UP_BUTTON 2
#define DOWN_BUTTON 3
#define ENTER_BUTTON 4
#define BACK_BUTTON 5
#define LED1 6
#define LED2 7
#define LED3 8

LiquidCrystal_I2C lcd(0x27, 16, 2);

int selectedLED = 0;
int timerValues[3] = {1, 1, 1};  // Timer values in minutes
bool ledOn[3] = {false, false, false};
unsigned long ledStartTime[3] = {0, 0, 0};
unsigned long lastUpdateTime = 0;

enum State { INIT_SCREEN, MAIN_MENU, SET_TIMER, CONFIRM, RUNNING };
State currentState = INIT_SCREEN;

void setup() {
    pinMode(UP_BUTTON, INPUT_PULLUP);
    pinMode(DOWN_BUTTON, INPUT_PULLUP);
    pinMode(ENTER_BUTTON, INPUT_PULLUP);
    pinMode(BACK_BUTTON, INPUT_PULLUP);

    pinMode(LED1, OUTPUT);
    pinMode(LED2, OUTPUT);
    pinMode(LED3, OUTPUT);

    lcd.init();
    lcd.backlight();
  
    showInitScreen();
}

void loop() {
    checkLEDTurnOff();

    if (currentState == INIT_SCREEN && buttonPressed(ENTER_BUTTON)) {
        currentState = MAIN_MENU;
        showLEDMenu();
    }

    switch (currentState) {
        case MAIN_MENU:
            if (millis() - lastUpdateTime > 1000) {  // Update every second
                lastUpdateTime = millis();
                showLEDMenu();
            }
            navigateLEDMenu();
            break;
        case SET_TIMER:
            adjustTimer();
            break;
        case CONFIRM:
            startLEDTimer();
            break;
        case RUNNING:
            showLEDRunningScreen();
            break;
    }
}

void showInitScreen() {
    lcd.clear();
    lcd.setCursor(0, 0);
    lcd.print("LED Timer Sw V1");
    lcd.setCursor(2, 1);
    lcd.print("Press ENTER");
}

void navigateLEDMenu() {
    if (buttonPressed(UP_BUTTON)) {
        selectedLED = (selectedLED == 0) ? 2 : selectedLED - 1;  // Cyclic up
        showLEDMenu();
    }
    if (buttonPressed(DOWN_BUTTON)) {
        selectedLED = (selectedLED + 1) % 3;  // Cyclic down
        showLEDMenu();
    }
    if (buttonPressed(ENTER_BUTTON)) {
        currentState = SET_TIMER;
        showTimerScreen();
    }
}

void showLEDMenu() {
    lcd.clear();
    
    for (int i = 0; i < 2; i++) {  
        int displayIndex = (selectedLED + i) % 3;  

        lcd.setCursor(0, i);
        lcd.print((i == 0) ? "> " : "  ");
        lcd.print("LED");
        lcd.print(displayIndex + 1);
        lcd.print(": ");

        if (ledOn[displayIndex]) {
            unsigned long elapsedSeconds = (millis() - ledStartTime[displayIndex]) / 1000;
            int remainingTime = (timerValues[displayIndex] * 60) - elapsedSeconds;
            if (remainingTime > 0) {
                int minutes = remainingTime / 60;
                int seconds = remainingTime % 60;
                lcd.print(minutes);
                lcd.print("m ");
                if (seconds < 10) lcd.print("0");
                lcd.print(seconds);
                lcd.print("s");
            } else {
                lcd.print("OFF");
                ledOn[displayIndex] = false;
            }
        } else {
            lcd.print("OFF");
        }
    }
}

void showTimerScreen() {
    lcd.clear();
    lcd.setCursor(0, 0);
    lcd.print("LED ");
    lcd.print(selectedLED + 1);
    lcd.print(" Timer");

    lcd.setCursor(0, 1);
    lcd.print("Time: ");
    lcd.print(timerValues[selectedLED]);
    lcd.print(" min");
}

void adjustTimer() {
    if (buttonPressed(UP_BUTTON) && timerValues[selectedLED] < 60) {
        timerValues[selectedLED]++;
        showTimerScreen();
    }
    if (buttonPressed(DOWN_BUTTON) && timerValues[selectedLED] > 1) {
        timerValues[selectedLED]--;
        showTimerScreen();
    }
    if (buttonPressed(ENTER_BUTTON)) {
        currentState = CONFIRM;
        showConfirmScreen();
    }
    if (buttonPressed(BACK_BUTTON)) {
        currentState = MAIN_MENU;
        showLEDMenu();
    }
}

void showConfirmScreen() {
    lcd.clear();
    lcd.setCursor(0, 0);
    lcd.print("LED ");
    lcd.print(selectedLED + 1);
    lcd.print(" Selected");

    lcd.setCursor(0, 1);
    lcd.print("Enter to Start");
}

void startLEDTimer() {
    if (!ledOn[selectedLED] && buttonPressed(ENTER_BUTTON)) {
        ledOn[selectedLED] = true;
        ledStartTime[selectedLED] = millis();
        digitalWrite(LED1 + selectedLED, HIGH);
        currentState = MAIN_MENU;
        showLEDMenu();
    }
    if (buttonPressed(BACK_BUTTON)) {
        currentState = SET_TIMER;
        showTimerScreen();
    }
}

void showLEDRunningScreen() {
    lcd.clear();
    lcd.setCursor(0, 0);
    lcd.print("LED ");
    lcd.print(selectedLED + 1);
    lcd.print(" ON");

    lcd.setCursor(0, 1);
    lcd.print("Time Left: ");

    unsigned long elapsedSeconds = (millis() - ledStartTime[selectedLED]) / 1000;
    int remainingTime = (timerValues[selectedLED] * 60) - elapsedSeconds;
    lcd.print(remainingTime / 60);
    lcd.print("m ");
    if (remainingTime % 60 < 10) lcd.print("0");
    lcd.print(remainingTime % 60);
    lcd.print("s");

    if (buttonPressed(BACK_BUTTON)) {
        currentState = MAIN_MENU;
        showLEDMenu();
    }
}

void checkLEDTurnOff() {
    for (int i = 0; i < 3; i++) {
        if (ledOn[i]) {
            unsigned long elapsedSeconds = (millis() - ledStartTime[i]) / 1000;
            if (elapsedSeconds >= (timerValues[i] * 60)) {
                ledOn[i] = false;
                digitalWrite(LED1 + i, LOW);
            }
        }
    }
}

bool buttonPressed(int buttonPin) {
    if (digitalRead(buttonPin) == LOW) {
        delay(200);
        while (digitalRead(buttonPin) == LOW);
        return true;
    }
    return false;
}