// Photoresistor Light Sensor
// Turns on LED when light level is below 50%

const int ledPin = 27;        // LED connected to GPIO27
const int ldrPin = 33;        // Photoresistor connected to GPIO34 (ADC)

int ldrValue = 0;             // Raw value from photoresistor
int lightPercent = 0;          // Light intensity percentage
const int threshold = 50;      // 50% threshold

void setup() {
  Serial.begin(9600);
  Serial.println("Light Sensor Started");
  
  pinMode(ledPin, OUTPUT);
  digitalWrite(ledPin, LOW);   // Start with LED off
}

void loop() {
  // Read photoresistor value (0-4095 on ESP32)
  ldrValue = analogRead(ldrPin);
  
  // Convert to percentage (0-100%)
  // Note: More light = lower resistance = higher ADC value
  // So we invert: 0% light = dark, 100% light = bright
  lightPercent = map(ldrValue, 0, 4095, 0, 100);
  
  // Print values for debugging
  Serial.print("LDR Value: ");
  Serial.print(ldrValue);
  Serial.print(" | Light: ");
  Serial.print(lightPercent);
  Serial.println("%");
  
  // Check if light is below 50%
  if(lightPercent < threshold) {
    digitalWrite(ledPin, HIGH);   // Turn LED ON
    Serial.println("LED ON - Light below 50%");
  } else {
    digitalWrite(ledPin, LOW);    // Turn LED OFF
    Serial.println("LED OFF - Light above 50%");
  }
  
  delay(500);  // Wait half a second before next reading
}