// YWROBOT
// Compatible with the Arduino IDE 1.0
// Library version:1.1
#define TRIG_PIN 3
#define ECHO_PIN 2
#define LED_RED 13
#define LED_GREEN 12
#define SWITCH_PIN 8 // Switch pin for turning the device on/off
#define VALVE_PIN 11 // Valve control pin

const int hands_present_threshold = 20; // Threshold distance in cm
const unsigned long DETECTION_TIME = 3000; // 10 seconds in milliseconds

unsigned long detectionStartTime = 0; // Tracks when detection starts
bool isDetecting = false; // Tracks if hands are currently detected

void setup() {
  pinMode(TRIG_PIN, OUTPUT);
  pinMode(ECHO_PIN, INPUT);
  pinMode(LED_GREEN, OUTPUT);
  pinMode(LED_RED, OUTPUT);
  pinMode(SWITCH_PIN, INPUT_PULLUP); // Use internal pull-up resistor for the switch
  pinMode(VALVE_PIN, OUTPUT); // Set valve pin as output

  digitalWrite(LED_RED, LOW);
  digitalWrite(LED_GREEN, LOW);
  digitalWrite(VALVE_PIN, LOW); // Ensure valve is initially off

  Serial.begin(9600);
}

void loop() {
  // Check if the switch is ON
  if (digitalRead(SWITCH_PIN) == LOW) {
    long duration, distance;

    // Trigger the HC-SR04
    digitalWrite(TRIG_PIN, LOW);
    delayMicroseconds(2);
    digitalWrite(TRIG_PIN, HIGH);
    delayMicroseconds(10);
    digitalWrite(TRIG_PIN, LOW);

    // Measure the echo duration
    duration = pulseIn(ECHO_PIN, HIGH);

    // Calculate distance in cm
    distance = duration * 0.034 / 2;

    // Debugging output
    Serial.print("Distance: ");
    Serial.print(distance);
    Serial.println(" cm");

    // Check if hands are within range
    if (distance > 0 && distance <= hands_present_threshold) {
      if (!isDetecting) {
        // Start detection process
        detectionStartTime = millis();
        isDetecting = true;

        // Turn on red LED and open the valve
        digitalWrite(LED_RED, HIGH);
        digitalWrite(VALVE_PIN, HIGH);
      } else if (millis() - detectionStartTime >= DETECTION_TIME) {
        // Hands have been detected for 10 seconds
        isDetecting = false;

        // Turn off red LED, close the valve, and turn on green LED
        digitalWrite(LED_RED, LOW);
        digitalWrite(VALVE_PIN, LOW);
        digitalWrite(LED_GREEN, HIGH);
      }
    } else {
      // If hands are out of range, reset
      isDetecting = false;
      detectionStartTime = 0;

      // Turn off red LED, green LED, and valve
      digitalWrite(LED_RED, LOW);
      digitalWrite(LED_GREEN, LOW);
      digitalWrite(VALVE_PIN, LOW);
    }

    delay(100); // Small delay for stability
  } else {
    // If the switch is OFF, turn everything off
    digitalWrite(LED_RED, LOW);
    digitalWrite(LED_GREEN, LOW);
    digitalWrite(VALVE_PIN, LOW);

    isDetecting = false; // Reset detection
    detectionStartTime = 0; // Reset timer
  }
}