#include <Wire.h>
#include <RTClib.h>
#include <Adafruit_GFX.h>
#include <Adafruit_SSD1306.h>
String getMoonPhaseName(float age);
#define SCREEN_WIDTH 128 // OLED display width, in pixels
#define SCREEN_HEIGHT 64 // OLED display height, in pixels

RTC_DS3231 rtc;
Adafruit_SSD1306 display(SCREEN_WIDTH, SCREEN_HEIGHT, &Wire, -1);
const int LED_PIN = 9;
const int BUTTON_PIN = 2;

int brightness = 0;
bool simulate = true;
bool preview = false;
bool lastButtonState = HIGH;
unsigned long simStartTime = 0;
unsigned long simTime = 0;
unsigned long simInterval = 5000; // simulate moon phases every 5 seconds

// helper function to return the name of the moon phase based on its age
String getMoonPhaseName(float age) {
  if (age < 1.845) {
    return "New Moon";
  } else if (age < 5.555) {
    return "Waxing Crescent";
  } else if (age < 9.265) {
    return "First Quarter";
  } else if (age < 12.985) {
    return "Waxing Gibbous";
  } else if (age < 16.695) {
    return "Full Moon";
  } else if (age < 20.405) {
    return "Waning Gibbous";
  } else if (age < 24.115) {
    return "Last Quarter";
  } else if (age < 27.825) {
    return "Waning Crescent";
  } else {
    return "New Moon";
  }
}

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

  if (! rtc.begin()) {
    Serial.println("Couldn't find RTC");
    while (1);
  }

  if (rtc.lostPower()) {
    Serial.println("RTC lost power, lets set the time!");
    rtc.adjust(DateTime(F(__DATE__), F(__TIME__)));
  }

  pinMode(LED_PIN, OUTPUT);
  pinMode(BUTTON_PIN, INPUT_PULLUP);

  display.begin(SSD1306_SWITCHCAPVCC, 0x3C);
  display.clearDisplay();
  display.setTextSize(1);
  display.setTextColor(WHITE);
}

void loop() {
  DateTime now = rtc.now();

  // check for button press to toggle preview mode
  int buttonState = digitalRead(BUTTON_PIN);
  if (buttonState != lastButtonState && buttonState == LOW) {
    if (!preview) { // enter preview mode
      simStartTime = millis();
    }
    preview = !preview;
    Serial.print("Preview mode: ");
    Serial.println(preview);
    if (preview) {
      simulate = false;
    } else {
      simulate = true;
    }
  }
  lastButtonState = buttonState;

  if (simulate) {
    // calculate the brightness based on the moon phase
    unsigned long midnight = now.unixtime() - (now.unixtime() % 86400UL); // midnight in seconds
    int seconds = now.unixtime() - midnight;
    int minutes= seconds / 60;
int hours = minutes / 60;
int days = (now.unixtime() / 86400UL) - 1; // days since Jan 1, 1970 (0-indexed)

float moonAge = fmod(days + 0.5, 29.53);
brightness = map(moonAge, 0, 29.53, 255, 0);

// update the LED brightness
analogWrite(LED_PIN, brightness);

// display the time, date, and moon phase on the OLED display
display.clearDisplay();
display.setCursor(0, 0);
display.print("Time: ");
display.print(now.year(), DEC);
display.print('/');
display.print(now.month(), DEC);
display.print('/');
display.print(now.day(), DEC);
display.print(' ');
display.print(hours, DEC);
display.print(':');
if (minutes < 10) {
  display.print('0');
}
display.print(minutes, DEC);
display.setCursor(0, 10);
display.print("Moon Phase: ");
display.print(getMoonPhaseName(moonAge));
display.setCursor(0, 20);
display.print("Brightness: ");
display.print(brightness);
display.display();

// print the time, date, and moon phase to the serial monitor
Serial.print("Time: ");
Serial.print(now.year(), DEC);
Serial.print('/');
Serial.print(now.month(), DEC);
Serial.print('/');
Serial.print(now.day(), DEC);
Serial.print(' ');
Serial.print(hours, DEC);
Serial.print(':');
if (minutes < 10) {
  Serial.print('0');
}
Serial.print(minutes, DEC);
Serial.print(':');
Serial.print(now.second(), DEC);
Serial.print("  Moon phase: ");
Serial.print(moonAge);
Serial.print("  Brightness: ");
Serial.println(brightness);
} else if (preview) {
// calculate the moon phase based on the simulated time
simTime = millis() - simStartTime;
float moonAge = fmod(simTime / (simInterval / 29.53), 29.53);
brightness = map(moonAge, 0, 29.53, 255, 0);
// update the LED brightness
analogWrite(LED_PIN, brightness);

// display the simulated time and moon phase on the OLED display
display.clearDisplay();
display.setCursor(0, 0);
display.print("Preview Mode");
display.setCursor(0, 10);
display.print("Moon Phase: ");
display.print(getMoonPhaseName(moonAge));
display.setCursor(0, 20);
display.print("Sim Time: ");
display.print(simTime);
display.display();

// print the simulated time and moon phase to the serial monitor
Serial.print("Simulation time: ");
Serial.print(simTime);
Serial.print("  Moon phase: ");
Serial.print(moonAge);
Serial.print("  Brightness: ");
Serial.println(brightness);
}

// check for serial input to set the simulation interval
if (Serial.available() > 0) {
String input = Serial.readStringUntil('\n');
if (input.startsWith("setinterval ")) {
simInterval = input.substring(12).toInt();
Serial.print("Simulation interval set to: ");
Serial.println(simInterval);
}
}
}