//promt Gemini
// arduino nano, rtc ds1307, ssd1306 oled display, a push button with bounce to switch display pages, ntc temperature sensor.
//Create a code that integrates all the components. eliminate bounce for the buttob. the oled shall display the time from the rtc as the first screen.
//After the button is pushed the temperature screen shall be shown. After the next push the time shall be seen 

#include <Wire.h>
#include <Adafruit_GFX.h>
#include <Adafruit_SSD1306.h>
#include <Adafruit_BMP085.h>
#include "RTClib.h"

// OLED Display Configuration
#define SCREEN_WIDTH 128
#define SCREEN_HEIGHT 64
#define OLED_RESET    -1  // Share Nano reset pin
Adafruit_SSD1306 display(SCREEN_WIDTH, SCREEN_HEIGHT, &Wire, OLED_RESET);

// Sensor & RTC Objects
RTC_DS1307 rtc;
Adafruit_BMP085 bmp;

// Button Pin Configuration
const int BUTTON_PIN = 2;

// Display Page State Tracking
int currentPage = 0;
const int TOTAL_PAGES = 3; // Page 0: Time, Page 1: Temperature, Page 2: Pressure

// Debounce Variables
int buttonState = HIGH;             // Current reading from input pin
int lastButtonState = HIGH;         // Previous reading from input pin
unsigned long lastDebounceTime = 0; // Last time the output pin was toggled
const unsigned long debounceDelay = 50; // Debounce time in milliseconds

void setup() {
  Serial.begin(9600);

  // Initialize Push Button with Internal Pull-up Resistor
  pinMode(BUTTON_PIN, INPUT_PULLUP);

  // Initialize OLED Display (Default I2C address is 0x3C)
  if (!display.begin(SSD1306_SWITCHCAPVCC, 0x3C)) {
    Serial.println(F("SSD1306 allocation failed"));
    for (;;);
  }
  display.clearDisplay();
  display.setTextColor(SSD1306_WHITE);

  // Initialize RTC DS1307
  if (!rtc.begin()) {
    Serial.println(F("Couldn't find RTC"));
    for (;;);
  }
  if (!rtc.isrunning()) {
    // Automatically sets RTC to the date & time this sketch was compiled
    rtc.adjust(DateTime(F(__DATE__), F(__TIME__)));
  }

  // Initialize BMP180 Sensor
  if (!bmp.begin()) {
    Serial.println(F("Could not find a valid BMP180 sensor!"));
    for (;;);
  }
}

void loop() {
  handleButtonDebounce();
  updateDisplay();
  delay(100); // Gentle refresh rate loop
}

// Function to handle software debouncing and page cycling
void handleButtonDebounce() {
  int reading = digitalRead(BUTTON_PIN);

  // Check if button state changed due to noise or pressing
  if (reading != lastButtonState) {
    lastDebounceTime = millis();
  }

  if ((millis() - lastDebounceTime) > debounceDelay) {
    // If state reading has stayed for longer than debounce delay, take it as real
    if (reading != buttonState) {
      buttonState = reading;

      // Only trigger page change on button press down (LOW because of INPUT_PULLUP)
      if (buttonState == LOW) {
        currentPage = (currentPage + 1) % TOTAL_PAGES; // Cycle through 0 -> 1 -> 2 -> 0
      }
    }
  }

  lastButtonState = reading;
}

// Function to render content based on the active page state
void updateDisplay() {
  display.clearDisplay();

  switch (currentPage) {
    case 0:
      showTimeScreen();
      break;
    case 1:
      showTemperatureScreen();
      break;
    case 2:
      showPressureScreen();
      break;
  }

  display.display();
}

// Page 0: RTC Time Display
void showTimeScreen() {
  DateTime now = rtc.now();

  display.setTextSize(1);
  display.setCursor(0, 0);
  //display.print(F("--- REAL TIME ---"));

  // Format Date (YYYY/MM/DD)
/*   display.setCursor(10, 20);
  display.setTextSize(1);
  if (now.year() < 10) display.print('0');
  display.print(now.year(), DEC);
  display.print('/');
  if (now.month() < 10) display.print('0');
  display.print(now.month(), DEC);
  display.print('/');
  if (now.day() < 10) display.print('0');
  display.print(now.day(), DEC); */

  // Format Time (HH:MM:SS)
  display.setCursor(10, 40);
  display.setTextSize(2);
  if (now.hour() < 10) display.print('0');
  display.print(now.hour(), DEC);
  display.print(':');
  if (now.minute() < 10) display.print('0');
  display.print(now.minute(), DEC);
  display.print(':');
  if (now.second() < 10) display.print('0');
  display.print(now.second(), DEC);
}

// Page 1: BMP180 Temperature Display
void showTemperatureScreen() {
  float temp = bmp.readTemperature();

  display.setTextSize(1);
  display.setCursor(0, 0);
  display.print(F("Oeltemperatur"));

  display.setCursor(15, 30);
  display.setTextSize(2);
  display.print(temp, 1);
  display.setTextSize(1);
  display.print(F(" "));
  display.setTextSize(2);
  display.print((char)247); // Degree symbol
  display.print(F("C"));
}

// Page 2: BMP180 Pressure Display
void showPressureScreen() {
  float pressurePa = bmp.readPressure();
  float pressureHpa = pressurePa / 100.0; // Convert Pa to hPa

  display.setTextSize(1);
  display.setCursor(0, 0);
  display.print(F("Oeldruck"));

  display.setCursor(10, 30);
  display.setTextSize(2);
  display.print(pressureHpa, 1);
  display.setTextSize(1);
  display.print(F(" hPa"));
}