#include <Wire.h>
#include <Adafruit_GFX.h>
#include <Adafruit_SSD1306.h>

#define SCREEN_WIDTH 128
#define SCREEN_HEIGHT 64
#define OLED_RESET -1
Adafruit_SSD1306 display(SCREEN_WIDTH, SCREEN_HEIGHT, &Wire, OLED_RESET);

#define SDA_PIN 21 // OLED SDA pin
#define SCL_PIN 22 // OLED SCL pin

#define BUTTON_MENU 25     // Menu button
#define BUTTON_SELECT 26   // Select button
#define BUTTON_EXIT 27     // Exit button

int menuIndex = 0;
String menuItems[] = {"ECG", "Temperature", "Pulse"};
bool menuActive = false;
bool sensorActive = false;

void setup() {
    Serial.begin(115200);
    
    pinMode(BUTTON_MENU, INPUT_PULLUP);
    pinMode(BUTTON_SELECT, INPUT_PULLUP);
    pinMode(BUTTON_EXIT, INPUT_PULLUP);
    
    Wire.begin(SDA_PIN, SCL_PIN); // Initialize I2C with explicit SDA and SCL pins

    if (!display.begin(SSD1306_SWITCHCAPVCC, 0x3C)) {
        Serial.println(F("SSD1306 allocation failed"));
        for (;;);
    }
    displayHomeScreen();
}

void loop() {
    if (digitalRead(BUTTON_MENU) == LOW) {
        if (!menuActive) {
            menuActive = true;
            displayMenu();
        } else {
            menuIndex = (menuIndex + 1) % 3;
            displayMenu();
        }
        delay(300);
    }
    if (digitalRead(BUTTON_SELECT) == LOW && menuActive && !sensorActive) {
        sensorActive = true;
        displaySensorSelected(menuItems[menuIndex]);
        delay(300);
    }
    if (digitalRead(BUTTON_EXIT) == LOW && sensorActive) {
        sensorActive = false;
        displayExitMessage();
        delay(300);
    }
}

void displayHomeScreen() {
    display.clearDisplay();
    display.setTextSize(1);
    display.setTextColor(WHITE);
    display.setCursor(10, 10);
    display.println("IoT Based");
    display.setCursor(10, 20);
    display.println("Health");
    display.setCursor(10, 30);
    display.println("Monitoring");
    display.setCursor(10, 40);
    display.println("System");
    display.display();
}

void displayMenu() {
    display.clearDisplay();
    display.setTextSize(1);
    display.setCursor(10, 10);
    display.println("Select a sensor:");
    display.println();
    for (int i = 0; i < 3; i++) {
        if (i == menuIndex) {
            display.print("> ");
        } else {
            display.print("  ");
        }
        display.println(menuItems[i]);
    }
    display.display();
}

void displaySensorSelected(String sensor) {
    display.clearDisplay();
    display.setCursor(10, 10);
    display.print("Selected: ");
    display.println(sensor);
    display.display();
}

void displayExitMessage() {
    display.clearDisplay();
    display.setCursor(10, 10);
    display.println("Exiting...");
    display.display();
    delay(1000);
    displayHomeScreen();
}