#include <Wire.h>
#include <RTClib.h>

RTC_DS3231 rtc;
const int pwmPin = 9; // PWM output pin
const int switchPin = 8; // External switch connected to digital pin 8

// Time constants for Mode 1
const int morningHour1 = 16;
const int morningMinute1 = 38;
const int eveningHour1 = 16;
const int eveningMinute1 = 39;

// Time constants for Mode 0
const int morningHour2 = 16; // Different start times for Mode 2
const int morningMinute2 = 41;
const int eveningHour2 = 16;
const int eveningMinute2 = 42;

const long duration = 0.5L * 60L; // 15 minutes in seconds, as long

void setup() {
  Serial.begin(9600);
  if (!rtc.begin()) {
    Serial.println("Couldn't find RTC");
    while (1);
  }

  pinMode(pwmPin, OUTPUT);
  pinMode(switchPin, INPUT_PULLUP); // Assuming a pull-up resistor is used
}

void loop() {
  DateTime now = rtc.now();
  static int lastPWMValue = 255; // Stores the last PWM value
  bool mode = digitalRead(switchPin); // Read switch state

  // Select mode based on switch state
  int morningHour = mode ? morningHour1 : morningHour2;
  int morningMinute = mode ? morningMinute1 : morningMinute2;
  int eveningHour = mode ? eveningHour1 : eveningHour2;
  int eveningMinute = mode ? eveningMinute1 : eveningMinute2;

  if (isTransitionPeriod(now, morningHour, morningMinute)) {
    lastPWMValue = interpolatePWM(now, morningHour, morningMinute, 255, 0);
  } else if (isTransitionPeriod(now, eveningHour, eveningMinute)) {
    lastPWMValue = interpolatePWM(now, eveningHour, eveningMinute, 0, 255);
  }
  Serial.print(mode, DEC);
  Serial.print('/');
  Serial.print(lastPWMValue, DEC);
  Serial.print('/');
  Serial.print(now.hour(), DEC);
  Serial.print('/');
  Serial.print(now.minute(), DEC);
  Serial.println();
  analogWrite(pwmPin, lastPWMValue);
  delay(1000);
}

bool isTransitionPeriod(DateTime now, int hour, int minute) {
  long nowSeconds = (long)now.hour() * 3600L + (long)now.minute() * 60L + now.second();
  long startSeconds = (long)hour * 3600L + (long)minute * 60L;
  return nowSeconds >= startSeconds && nowSeconds <= startSeconds + duration;
}

int interpolatePWM(DateTime now, int hour, int minute, int startPWM, int endPWM) {
  long nowSeconds = (long)now.hour() * 3600L + (long)now.minute() * 60L + now.second();
  long startSeconds = (long)hour * 3600L + (long)minute * 60L;
  return map(nowSeconds, startSeconds, startSeconds + duration, startPWM, endPWM);
}