// Define the digital pins for the PIR motion sensors
const int topSensorPin = 2;    // PIR sensor at the top of the stairs
const int bottomSensorPin = 3; // PIR sensor at the bottom of the stairs

// Define the digital pins for the six LEDs
const int ledPins[] = {4, 5, 6, 7, 8, 9};
const int numLeds = 6;

// The time in milliseconds the light should stay on after motion is detected
const unsigned long lightOnTime = 5000; // 15 seconds

// The delay between lighting up each LED in milliseconds
const int stepDelay = 200; // Adjust this for a faster or slower sequence

// Variables for timing and state management
unsigned long lastMotionTime = 0;
bool lightsOn = false;
bool animating = false;
int currentStep = -1;
unsigned long lastStepTime = 0;

// New feature: fading variables
const int fadeSteps = 50; // Number of steps for fading
const int fadeDelay = 10; // Delay between each fade step (in milliseconds)

// New feature: detection timeout to avoid re-triggering immediately
const unsigned long detectionTimeout = 1000; // 2 seconds to ignore new motion after triggering

void setup() {
  // Initialize the serial monitor for debugging
  Serial.begin(9600);

  // Set the sensor pins as INPUT
  pinMode(topSensorPin, INPUT);
  pinMode(bottomSensorPin, INPUT);

  // Set the LED pins as OUTPUT and turn them all off initially
  for (int i = 0; i < numLeds; i++) {
    pinMode(ledPins[i], OUTPUT);
    digitalWrite(ledPins[i], LOW);
  }
}

void loop() {
  // Read the state of the motion sensors
  int topSensorState = digitalRead(topSensorPin);
  int bottomSensorState = digitalRead(bottomSensorPin);

  // Check for motion at the bottom AND if the lights are off or finished animating
  // Also check if enough time has passed since the last detection
  if (bottomSensorState == HIGH && !lightsOn && !animating && (millis() - lastMotionTime > detectionTimeout)) {
    Serial.println("Motion detected at bottom. Starting forward animation.");
    animating = true;
    currentStep = 0;
    lastStepTime = millis();
    lastMotionTime = millis(); // Update last motion time
  }

  // Check for motion at the top AND if the lights are off or finished animating
  // Also check if enough time has passed since the last detection
  if (topSensorState == HIGH && !lightsOn && !animating && (millis() - lastMotionTime > detectionTimeout)) {
    Serial.println("Motion detected at top. Starting reverse animation.");
    animating = true;
    currentStep = numLeds - 1;
    lastStepTime = millis();
    lastMotionTime = millis(); // Update last motion time
  }

  // Handle the sequential animation
  if (animating) {
    if (millis() - lastStepTime >= stepDelay) {
      if (bottomSensorState == HIGH) { // Animate forward
        if (currentStep < numLeds) {
          digitalWrite(ledPins[currentStep], HIGH);
          currentStep++;
        } else {
          animating = false;
          lightsOn = true;
          lastMotionTime = millis();
        }
      } else if (topSensorState == HIGH) { // Animate reverse
        if (currentStep >= 0) {
          digitalWrite(ledPins[currentStep], HIGH);
          currentStep--;
        } else {
          animating = false;
          lightsOn = true;
          lastMotionTime = millis();
        }
      }
      lastStepTime = millis();
    }
  }

  // Turn off all LEDs with a fading effect if the lightOnTime has elapsed since the last motion detection
  if (lightsOn && millis() - lastMotionTime >= lightOnTime) {
    Serial.println("Duration expired. Turning off all lights with fade.");
    fadeAllLeds(); // Call the fade function
    lightsOn = false; // Reset the state
  }
}

// Function to fade all LEDs out
void fadeAllLeds() {
  for (int i = 0; i < numLeds; i++) {
    // This is a simple on/off fade, more complex analogWrite would be needed for true fading
    digitalWrite(ledPins[i], LOW);
  }
}