#include <FastLED.h>  

#define LED_PIN     6  
#define NUM_LEDS    30  // Adjust based on your LED strip length  
#define SYNC_PIN    2   // Communication pin to second Arduino  

// Define the LED strip  
CRGB leds[NUM_LEDS];  

// Timing constants (in milliseconds)  
const unsigned long FADE_TIME = 6000;  // 10 minutes  
const unsigned long HOLD_TIME = 3000;  // 5 minutes  
const unsigned long HOLD_TIME_GREEN = 3000;  // 10 minutes  

// State variables  
unsigned long previousMillis = 0;  
int fadeState = 0;  // 0: green->blue fade, 1: blue hold, 2: blue->green fade, 3: green hold  
float fadeProgress = 0;  

void setup() {  
  FastLED.addLeds<WS2812B, LED_PIN, GRB>(leds, NUM_LEDS);  
  pinMode(SYNC_PIN, OUTPUT);  
  FastLED.setBrightness(255);  
}  

void loop() {  
  unsigned long currentMillis = millis();  
  
  switch(fadeState) {  
    case 0: // Green to Blue fade  
      if (currentMillis - previousMillis >= (FADE_TIME / 100)) {  
        previousMillis = currentMillis;  
        fadeProgress += 1;  
        
        if (fadeProgress <= 100) {  
          // Interpolate between aqua green and deep blue  
          for(int i = 0; i < NUM_LEDS; i++) {  
            leds[i] = CRGB(  
              0,  // Red  
              255 - (fadeProgress * 2.55),  // Green fade out  
              fadeProgress * 2.55  // Blue fade in  
            );  
          }  
          FastLED.show();  
          
          // Signal second Arduino about progress  
          digitalWrite(SYNC_PIN, HIGH);  
          delay(10);  
          digitalWrite(SYNC_PIN, LOW);  
        } else {  
          fadeState = 1;  // Move to hold state  
          fadeProgress = 0;  
          previousMillis = currentMillis;  
        }  
      }  
      break;  
      
    case 1: // Hold blue  
      if (currentMillis - previousMillis >= HOLD_TIME) {  
        fadeState = 2;  
        previousMillis = currentMillis;  
      }  
      break;  
      
    case 2: // Blue to Green fade  
      if (currentMillis - previousMillis >= (FADE_TIME / 100)) {  
        previousMillis = currentMillis;  
        fadeProgress += 1;  
        
        if (fadeProgress <= 100) {  
          // Interpolate between deep blue and aqua green  
          for(int i = 0; i < NUM_LEDS; i++) {  
            leds[i] = CRGB(  
              0,  // Red  
              fadeProgress * 2.55,  // Green fade in  
              255 - (fadeProgress * 2.55)  // Blue fade out  
            );  
          }  
          FastLED.show();  
          
          // Signal second Arduino about progress  
          digitalWrite(SYNC_PIN, HIGH);  
          delay(10);  
          digitalWrite(SYNC_PIN, LOW);  
        } else {  
          fadeState = 3;  // Move to hold state  
          fadeProgress = 0;  
          previousMillis = currentMillis;  
        }  
      }  
      break;  
      
    case 3: // Hold green  
      if (currentMillis - previousMillis >= HOLD_TIME_GREEN) {  
        fadeState = 0;  
        fadeProgress = 0;  
        previousMillis = currentMillis;  
      }  
      break;  
  }  
}