#define LDR_PIN           A0
#define RED_PIN            9
#define GREEN_PIN         10
#define BLUE_PIN          11
#define BUZZER_PIN         4
#define DARK_THRESHOLD    700
#define DARK_DELAY       5000
#define BUZZER_DURATION   200
#define COLOR_STEP         5
#define COLOR_INTERVAL    30

unsigned long darkStart       = 0;
bool        nightLightOn      = false;
unsigned long buzzerStart     = 0;
bool        buzzerOn          = false;
unsigned long prevMillisColor = 0;
int         phase            = 0;
int         rVal = 255, gVal = 0, bVal = 0;

void setup() {
  pinMode(RED_PIN, OUTPUT);
  pinMode(GREEN_PIN, OUTPUT);
  pinMode(BLUE_PIN, OUTPUT);
  pinMode(BUZZER_PIN, OUTPUT);
  Serial.begin(9600);
}

void loop() {
  unsigned long now = millis();
  int luxVal = analogRead(LDR_PIN);

  if (luxVal > DARK_THRESHOLD) {
    if (darkStart == 0) darkStart = now;
  } else {
    darkStart = 0;
    nightLightOn = false;
  }
  if (!nightLightOn && darkStart && now - darkStart >= DARK_DELAY) {
    nightLightOn = true;
    Serial.println("Night‑light ON");
  }

  if (luxVal > DARK_THRESHOLD && !buzzerOn) {
    buzzerOn = true;
    buzzerStart = now;
    tone(BUZZER_PIN, 1000);
  }
  if (buzzerOn && now - buzzerStart >= BUZZER_DURATION) {
    buzzerOn = false;
    noTone(BUZZER_PIN);
  }

  if (!nightLightOn) {
    analogWrite(RED_PIN, 0);
    analogWrite(GREEN_PIN, 0);
    analogWrite(BLUE_PIN, 0);
    delay(10);
    return;
  }

  if (now - prevMillisColor >= COLOR_INTERVAL) {
    prevMillisColor = now;
    switch (phase) {
      case 0: gVal += COLOR_STEP; if (gVal >= 255) { gVal = 255; phase = 1; } break;
      case 1: rVal -= COLOR_STEP; if (rVal <= 0)   { rVal = 0;   phase = 2; } break;
      case 2: bVal += COLOR_STEP; if (bVal >= 255) { bVal = 255; phase = 3; } break;
      case 3: gVal -= COLOR_STEP; if (gVal <= 0)   { gVal = 0;   phase = 4; } break;
      case 4: rVal += COLOR_STEP; if (rVal >= 255) { rVal = 255; phase = 5; } break;
      case 5: bVal -= COLOR_STEP; if (bVal <= 0)   { bVal = 0;   phase = 0; } break;
    }
  }

  analogWrite(RED_PIN, rVal);
  analogWrite(GREEN_PIN, gVal);
  analogWrite(BLUE_PIN, bVal);

  Serial.print("LDR: "); Serial.print(luxVal);
  Serial.print("  |  R="); Serial.print(rVal * 100L / 255); Serial.print("%");
  Serial.print("  G="); Serial.print(gVal * 100L / 255); Serial.print("%");
  Serial.print("  B="); Serial.print(bVal * 100L / 255); Serial.println("%");

  delay(10);
}