#define LDR_PIN   A0
#define SL1       3
#define SL2       4
#define SL3       5
#define SL4       6
#define SL5       7
#define IND_DAY   9
#define IND_NIGHT 10

// Threshold: below = DARK = lights ON
#define DARK_THRESHOLD  400
// Hysteresis to avoid flickering
#define LIGHT_THRESHOLD 500

const int streetLights[] = {SL1, SL2, SL3, SL4, SL5};
const int NUM_LIGHTS = 5;

bool isNight = false;
bool lastNight = false;
unsigned long lastPrint = 0;

void setStreetLights(bool on) {
  for (int i = 0; i < NUM_LIGHTS; i++) {
    // Cascade ON with small delay for nice effect
    if (on) {
      digitalWrite(streetLights[i], HIGH);
      delay(100);
    } else {
      digitalWrite(streetLights[i], LOW);
      delay(100);
    }
  }
  digitalWrite(IND_NIGHT, on ? HIGH : LOW);
  digitalWrite(IND_DAY,   on ? LOW  : HIGH);
}

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

  for (int i = 0; i < NUM_LIGHTS; i++) {
    pinMode(streetLights[i], OUTPUT);
    digitalWrite(streetLights[i], LOW);
  }
  pinMode(IND_DAY,   OUTPUT);
  pinMode(IND_NIGHT, OUTPUT);
  digitalWrite(IND_DAY, HIGH); // starts as day

  Serial.println("=================================");
  Serial.println("   Smart Street Light System");
  Serial.println("   LDR Auto-Control | Arduino");
  Serial.println("=================================");
  Serial.println("LDR Threshold (Dark) : < 400");
  Serial.println("LDR Threshold (Light): > 500");
  Serial.println("Slide LDR slider in Wokwi to simulate day/night\n");
}

void loop() {
  int ldrValue = analogRead(LDR_PIN);

  // Hysteresis logic
  if (!isNight && ldrValue < DARK_THRESHOLD) {
    isNight = true;
  } else if (isNight && ldrValue > LIGHT_THRESHOLD) {
    isNight = false;
  }

  // Only act on change
  if (isNight != lastNight) {
    lastNight = isNight;
    setStreetLights(isNight);
    Serial.print("[CHANGE] It's now ");
    Serial.println(isNight ? "NIGHT 🌙 — Street lights ON" : "DAY ☀️  — Street lights OFF");
  }

  // Print status every 2 seconds
  if (millis() - lastPrint >= 2000) {
    lastPrint = millis();
    Serial.print("[LDR] Value: ");
    Serial.print(ldrValue);
    Serial.print(" | Mode: ");
    Serial.print(isNight ? "NIGHT" : "DAY");
    Serial.print(" | Lights: ");
    Serial.println(isNight ? "ON" : "OFF");
  }

  delay(200);
}