/*
  AZ Mandible – Prototype Firmware v1.0
  -------------------------------------
  Hardware:
  - Piezo (27mm) → 1M bias → Op-amp → A0
  - Bone conduction transducer (TT25-8) via PAM8403 → D9 (PWM)
  - Arduino Nano

  Function:
  - Detects intentional jaw movement peaks
  - Simple classification:
      1 clear peak     → YES
      2 quick peaks    → NO
  - Private bone-conduction feedback
*/

const int PIEZO_PIN = A0;
const int FEEDBACK_PIN = 9;          // PWM to PAM8403 / transducer

// ===== TUNABLE VALUES =====
int threshold = 80;                  // Start here, adjust with Serial Plotter
const int DEBOUNCE_MS = 80;
const int WINDOW_MS = 600;           // Time window to count peaks
const int MIN_PEAK_GAP = 120;        // Minimum time between peaks

// ===== STATE =====
int peakCount = 0;
unsigned long lastPeakTime = 0;
unsigned long windowStart = 0;
bool inWindow = false;

void setup() {
  Serial.begin(115200);
  pinMode(FEEDBACK_PIN, OUTPUT);
  analogWrite(FEEDBACK_PIN, 0);

  Serial.println("AZ Mandible v1.0 ready");
  Serial.println("1 peak = YES | 2 peaks = NO");
  Serial.println("Open Serial Plotter to tune threshold");
}

void loop() {
  int value = analogRead(PIEZO_PIN);
  
  // Debug output for Serial Plotter
  Serial.println(value);

  unsigned long now = millis();

  // Peak detection
  if (value > threshold) {
    if (now - lastPeakTime > MIN_PEAK_GAP) {
      // Valid new peak
      if (!inWindow) {
        inWindow = true;
        windowStart = now;
        peakCount = 1;
      } else {
        peakCount++;
      }
      lastPeakTime = now;
    }
  }

  // Window timeout → classify
  if (inWindow && (now - windowStart > WINDOW_MS)) {
    classify(peakCount);
    peakCount = 0;
    inWindow = false;
  }

  delay(5);   // small loop delay
}

void classify(int peaks) {
  if (peaks == 1) {
    Serial.println("→ YES");
    playFeedback(1);          // single tone
  } 
  else if (peaks >= 2) {
    Serial.println("→ NO");
    playFeedback(2);          // double tone
  }
}

void playFeedback(int type) {
  if (type == 1) {
    // YES – single medium beep
    tone(FEEDBACK_PIN, 600, 120);
    delay(140);
  } 
  else if (type == 2) {
    // NO – two short beeps
    tone(FEEDBACK_PIN, 400, 80);
    delay(120);
    tone(FEEDBACK_PIN, 400, 80);
    delay(100);
  }
  analogWrite(FEEDBACK_PIN, 0);
}