/*
 * NANO DRUM ENGINE v6.1 - REVISED FINAL PATCH
 * Revisions based on suggestions:
 * - Added playback protection with !audio.isPlaying()
 * - Improved energy calculation using squared deviation from noise floor
 * - Increased retrigger lock to 80ms for better debounce
 * - Added simple multiple sample layering based on velocity (soft/medium/hard)
 * - Added logarithmic velocity curve for more natural feel
 * - Implemented basic LED fade-out effect
 * - Added hysteresis to threshold (temp increase after hit)
 * - Fixed 'kick.txt' to 'kick.wav' in setup
 * - Minor tweaks for stability
 *
 * Assumptions: You have "kick_soft.wav", "kick_medium.wav", "kick_hard.wav" on SD card.
 * If not, adjust playback logic accordingly.
 */

#include <SPI.h>
#include <SD.h>
#include <TMRpcm.h>

// --- DEBUG & LOGGING MACROS ---
#define DEBUG 1
#if DEBUG
  #define LOG_INIT() Serial.begin(115200)
  #define LOG_THROTTLE(msg, val, interval) { \
    static unsigned long lastLog = 0; \
    if (millis() - lastLog > interval) { \
      Serial.print(F(msg)); Serial.println(val); \
      lastLog = millis(); \
    } \
  }
  #define LOG_HIT(vel, energy) { \
    Serial.print(F(">>> HIT! Velocity: ")); Serial.print(vel); \
    Serial.print(F("% | Energy: ")); Serial.println(energy); \
  }
#else
  #define LOG_INIT()
  #define LOG_THROTTLE(msg, val, interval)
  #define LOG_HIT(vel, energy)
#endif

// --- PIN CONFIGURATION ---
#define PIEZO_PIN      A0
#define POT_PIN        A1
#define SD_CS_PIN      10
#define AUDIO_OUT_PIN  9 

// Pins for 74HC595 Shift Register
#define SR_DATA_PIN    4  // DS (Pin 14 on 74HC595)
#define SR_LATCH_PIN   3  // STCP (Pin 12 on 74HC595)
#define SR_CLOCK_PIN   2  // SHCP (Pin 11 on 74HC595)

TMRpcm audio;

// --- GLOBAL VARIABLES ---
int baseThreshold     = 30;         
int threshold         = 30;  // Dynamic with hysteresis
int lastRaw           = 0;
int envelope          = 0;
int lastPeakEnvelope  = 0;
long noiseFloor       = 0;
bool armed            = true;
unsigned long lastHitTime = 0;
#define RETRIGGER_LOCK_MS 80  // Increased for better debounce

// --- FUNCTIONS ---

// Update 10-segment Bar Graph via Shift Register
void displayGraph(uint16_t mask) {
    digitalWrite(SR_LATCH_PIN, LOW);
    // Send 16-bit data (for 2 daisy-chained 74HC595, but only using 10 bits)
    shiftOut(SR_DATA_PIN, SR_CLOCK_PIN, MSBFIRST, (mask >> 8) & 0xFF); // Chip 2 (LED 9-10)
    shiftOut(SR_DATA_PIN, SR_CLOCK_PIN, MSBFIRST, mask & 0xFF);        // Chip 1 (LED 1-8)
    digitalWrite(SR_LATCH_PIN, HIGH);
}

void setup() {
    LOG_INIT();

    // 1. FAST ADC (Set prescaler to 16 for ~77kHz sampling)
    ADCSRA |= (1 << ADPS2); ADCSRA &= ~(1 << ADPS1); ADCSRA &= ~(1 << ADPS0);

    // 2. PIN MODES
    pinMode(SR_DATA_PIN, OUTPUT);
    pinMode(SR_LATCH_PIN, OUTPUT);
    pinMode(SR_CLOCK_PIN, OUTPUT);
    pinMode(LED_BUILTIN, OUTPUT);

    // 3. SD CARD INIT
    if (!SD.begin(SD_CS_PIN)) {
        LOG_THROTTLE("SD Card Error!", 0, 0);
        displayGraph(0b1111111111); // All LEDs on for error
        while(1); 
    }
    
    // 4. AUDIO WARMUP
    audio.speakerPin = AUDIO_OUT_PIN;
    audio.setVolume(0);
    audio.play("kick_soft.wav");  // Fixed typo, using soft for warmup
    delay(100);
    audio.stopPlayback();

    // 5. CALIBRATE NOISE FLOOR
    long sum = 0;
    for(int i=0; i<100; i++) { sum += analogRead(PIEZO_PIN); delay(2); }
    noiseFloor = sum / 100;

    LOG_THROTTLE("System Ready. Noise Floor: ", noiseFloor, 0);
}

void loop() {
    int rawValue = analogRead(PIEZO_PIN);
    unsigned long now = millis();

    // --- STEP 1: ENVELOPE TRACKING ---
    int signal = abs(rawValue - (int)noiseFloor);
    if (signal > envelope) {
        envelope = signal; // Fast attack
    } else {
        envelope -= envelope >> 4; // Slow decay (bitshift 1/16)
    }

    // --- STEP 2: SLOPE CALCULATION ---
    int slope = rawValue - lastRaw;
    lastRaw = rawValue;

    // --- STEP 3: NON-BLOCKING LOGGING ---
    LOG_THROTTLE("Live Envelope: ", envelope, 1000); // Peek envelope every 1s

    // --- STEP 4: TRIGGER LOGIC ---
    if (armed && slope > 15 && envelope > threshold) {
        if (now - lastHitTime > RETRIGGER_LOCK_MS) { // Increased lock time
            
            // Peak Scan Window (1.2ms)
            int peak = 0;
            long energy = 0;
            int scanLast = rawValue;
            unsigned long startScan = micros();
            while (micros() - startScan < 1200) {
                int r = analogRead(PIEZO_PIN);
                if (r > peak) peak = r;
                int deviation = r - (int)noiseFloor;
                energy += (long)deviation * deviation;  // Squared for true energy
                scanLast = r;
            }

            // Energy Gate Validation (adjusted for squared energy)
            if (energy > 2500) {  // Tune this based on testing
                // Velocity Calculation with Log Curve
                float vel_float = (peak - (noiseFloor + threshold)) / (float)(1023 - noiseFloor - threshold + 1);
                vel_float = pow(vel_float, 1.6f);  // Compression for natural feel
                int velocity = constrain((int)(vel_float * 100), 0, 100);

                // Playback with Layering and Protection
                if (!audio.isPlaying()) {
                    if (velocity < 40) {
                        audio.play("kick_soft.wav");
                    } else if (velocity < 80) {
                        audio.play("kick_medium.wav");
                    } else {
                        audio.play("kick_hard.wav");
                    }
                }

                // LED Graph Visual (Mapping 100 velocity to 10 LEDs)
                int ledsToLight = map(velocity, 0, 100, 1, 10);
                uint16_t mask = (1 << ledsToLight) - 1;
                displayGraph(mask);

                LOG_HIT(velocity, energy);
                
                lastHitTime = now;
                lastPeakEnvelope = envelope;
                armed = false; 
                threshold = baseThreshold * 2;  // Hysteresis: Temp increase threshold
            }
        }
    }

    // --- STEP 5: ADAPTIVE RE-ARMING ---
    if (!armed && envelope < (lastPeakEnvelope >> 2)) {
        armed = true;
        threshold = baseThreshold;  // Reset threshold after re-arm
    }

    // --- STEP 6: UI & CLEANUP ---
    // LED Fade-Out Effect
    if (now - lastHitTime > 60) {
        if (now - lastHitTime < 400) {
            // Simple linear fade: Reduce LEDs over time
            int fadeTime = now - lastHitTime - 60;
            int maxLeds = map(100, 0, 100, 1, 10);  // Assume max for simplicity
            int ledsToLight = map(fadeTime, 0, 340, maxLeds, 0);
            uint16_t mask = (1 << ledsToLight) - 1;
            displayGraph(mask);
        } else {
            displayGraph(0);
        }
    }

    // Monitor Potentiometer for Base Threshold
    static unsigned long lastPotRead = 0;
    if (now - lastPotRead > 200) {
        baseThreshold = map(analogRead(POT_PIN), 0, 1023, 10, 400);
        if (armed) threshold = baseThreshold;  // Update only if armed
        lastPotRead = now;
    }
}