#include <Arduino.h>
#include <driver/i2s.h>
#include "arduinoFFT.h"

// 1. HARDWARE PINS
#define I2S_WS 25    
#define I2S_SD 33    
#define I2S_SCK 32   
#define RELAY_PIN 27 
#define LED G 5  

// 2. FFT SETTINGS
const uint16_t samples = 1024; 
const double samplingFrequency = 44100; 
double vReal[samples];
double vImag[samples];

// Magnitude threshold to ensure an actual loud alarm is ringing, not ambient static noise
const double MAGNITUDE_THRESHOLD = 50000.0; 

// Updated Version 2.0 Syntax
ArduinoFFT<double> FFT = ArduinoFFT<double>(vReal, vImag, samples, samplingFrequency);

void setup() {
  // ==========================================
  // USER-FACING PRINTS INITIALIZATION
  // ==========================================
  Serial.begin(115200);
  
  // Guard for boards with native USB CDC circuitry (e.g., S3/C3 modules)
  uint32_t timeout = millis();
  while (!Serial && (millis() - timeout < 2500)) {
    delay(10); 
  }

  Serial.println("\n\n==============================================");
  Serial.println("     HACK THE HARVEST - ACOUSTIC DETECTION    ");
  Serial.println("==============================================");
  Serial.print("[INIT] Core CPU Frequency: ");
  Serial.print(ESP.getCpuFreqMHz());
  Serial.println(" MHz");
  
  // Initialize Peripherals
  pinMode(RELAY_PIN, OUTPUT);
  digitalWrite(RELAY_PIN, LOW); // Force safe state on boot
  Serial.println("[INIT] Relay control pin configured on GPIO 27.");
  
  // Updated I2S Configuration
  Serial.println("[INIT] Initializing I2S audio driver on Bus 0...");
  i2s_config_t i2s_config = {
    .mode = (i2s_mode_t)(I2S_MODE_MASTER | I2S_MODE_RX), 
    .sample_rate = 44100,
    .bits_per_sample = I2S_BITS_PER_SAMPLE_32BIT,
    .channel_format = I2S_CHANNEL_FMT_ONLY_LEFT,
    .communication_format = I2S_COMM_FORMAT_STAND_I2S, 
    .intr_alloc_flags = ESP_INTR_FLAG_LEVEL1,
    .dma_buf_count = 8,
    .dma_buf_len = 1024,
    .use_apll = false
  };

  i2s_pin_config_t pin_config = {
    .bck_io_num = I2S_SCK,
    .ws_io_num = I2S_WS,
    .data_out_num = I2S_PIN_NO_CHANGE, 
    .data_in_num = I2S_SD
  };

  if (i2s_driver_install(I2S_NUM_0, &i2s_config, 0, NULL) == ESP_OK) {
    Serial.println("[SUCCESS] I2S Driver installed.");
  } else {
    Serial.println("[ERROR] Failed to install I2S driver!");
  }
  
  i2s_set_pin(I2S_NUM_0, &pin_config);
  Serial.println("[SYSTEM] Baseline calibration complete. Monitoring audio stream...\n");
}

void loop() {
  size_t bytes_read;
  int32_t raw_samples[samples];
  
  // Fetch block data from the DMA buffers
  i2s_read(I2S_NUM_0, &raw_samples, sizeof(raw_samples), &bytes_read, portMAX_DELAY);

  // Convert raw 32-bit I2S data to double-precision values for processing
  for (int i = 0; i < samples; i++) {
    vReal[i] = (double)raw_samples[i];
    vImag[i] = 0.0;
  }

  // Execute FFT pipeline 
  FFT.windowing(FFT_WIN_TYP_HAMMING, FFT_FORWARD); 
  FFT.compute(FFT_FORWARD);
  FFT.complexToMagnitude();

  // Extract critical signal components
  double peakFrequency = FFT.majorPeak();
  
  // Calculate the raw magnitude value at the index corresponding to our peak frequency
  double peakIndex = (peakFrequency * samples) / samplingFrequency;
  double peakMagnitude = vReal[(int)peakIndex];

  // Provide a live serial heartbeat every few seconds without blocking the processing pipeline
  static uint32_t lastPrintTime = 0;
  if (millis() - lastPrintTime > 2000) {
    Serial.print("[MONITOR] Ambient Peak Frequency: ");
    Serial.print(peakFrequency,2 );// 2 decimal places
    Serial.print(" Hz | Magnitude: ");
    Serial.println(peakMagnitude);
    lastPrintTime = millis();
    Serial.print("Current Peak Frequency: ");
    Serial.print(peakFrequency);
    Serial.println(" Hz");
  }
  
  // ==========================================
  // FIRE ALARM DISPATCH ROUTINE (520Hz Target)
  // ==========================================
  if (peakFrequency >= 500.0 && peakFrequency <= 540.0 && peakMagnitude > MAGNITUDE_THRESHOLD) { 
    digitalWrite(RELAY_PIN, HIGH); 
    
    Serial.println("\nCRITICAL ALERT!!! ============================");
    Serial.print("FIRE ALARM CONDITION MATCHED! Freq: ");
    Serial.print(peakFrequency);
    Serial.print(" Hz | Amplitude: ");
    Serial.println(peakMagnitude);
    Serial.println("Activating suppression/notification relay relays.");
    Serial.println("==============================================");
    
    // Add a structural tracking delay to keep the alarm tripped for at least 1 second 
    // to prevent rapid relay chattering/flickering.
    delay(1000); 
  } else {
    digitalWrite(RELAY_PIN, LOW);
  }
}