#include <mutex>
#include "AudioThread.h"
#include "SharedState.h"
#include <I2S.h>
#include <math.h>
#include "synth_engine.h"

// I2S Pin definitions
// You may need to change these to match your hardware setup (e.g., for a specific DAC).
const int I2S_BCLK_PIN = 9;  // Bit Clock (GP9)
const int I2S_LRC_PIN  = 10; // Left-Right Clock (GP10)
const int I2S_DOUT_PIN = 11; // Data Out (GP11)

// Audio parameters
const int SAMPLE_RATE = 44100 / 2;
const int16_t AMPLITUDE = 16383 / 2; // Use a lower amplitude to avoid clipping (max is 32767 for 16-bit)

// Create an I2S output object
I2S i2s(OUTPUT);

extern SynthEngine* globalSynth;

// --- Synthesizer State ---
float currentFrequency = 440.0f;
double phase = 0.0;
unsigned long lastNoteChangeTime = 0;
// ---

void setupAudio() {
  // Configure I2S pins
  i2s.setBCLK(I2S_BCLK_PIN);
  i2s.setDATA(I2S_DOUT_PIN);

  // Set the sample rate and start I2S communication
  i2s.setFrequency(SAMPLE_RATE);
  if (!i2s.begin()) {
    Serial.println("Failed to initialize I2S!");
    while (1); // Halt on error
  }

  // Seed the random number generator from an unconnected analog pin
  randomSeed(analogRead(A0));
  
  // Initialize the portable synth engine
  globalSynth = new SynthEngine(SAMPLE_RATE);
  globalSynth->loadPreset(2);
}

void loopAudio() {
  unsigned long now = millis();

  // Every 500ms, pick a new random note to play
  if (now - lastNoteChangeTime > 500) {
    lastNoteChangeTime = now;
    int noteIndex = random(0, SCALES[currentScaleIndex].numNotes + 2);
    
    bool rest = noteIndex >= SCALES[currentScaleIndex].numNotes;
    if (!rest) {
      // Calculate frequency based on key, scale, and octave
      const float baseFrequency = 261.63f; // C4
      float keyFrequency = baseFrequency * pow(2.0f, currentKeyIndex / 12.0f);
      int semitoneOffset = SCALES[currentScaleIndex].semitones[noteIndex];
      currentFrequency = keyFrequency * pow(2.0f, semitoneOffset / 12.0f);
    } else {
      currentFrequency = 0;
    }

    if (globalSynth) {
        globalSynth->setFrequency(currentFrequency > 0 ? currentFrequency : 440.0f);
        globalSynth->setGate(!rest); // Trigger envelope
    }
  }

  const int BATCH_SIZE = 16;

  // Ensure we don't generate samples faster than the I2S can consume them.
  // We write 2 samples (Left + Right) for every 1 synth sample.
  if (i2s.availableForWrite() < BATCH_SIZE * 2) {
      return;
  }

  // Process a small batch of samples
  static int16_t samples[BATCH_SIZE];

  // Generate sound samples
  if (globalSynth) {
    // using synth engine
    globalSynth->process(samples, BATCH_SIZE);
  } else {
    // using fallback sawtooth
    for (int i = 0; i < BATCH_SIZE; ++i) {
        if (currentFrequency > 0) {
            //samples[i] = (int16_t)(sin(phase) * AMPLITUDE);
            phase += 2.0 * M_PI * currentFrequency / SAMPLE_RATE;
            if (phase >= 2.0 * M_PI) phase -= 2.0 * M_PI;
            samples[i] = phase * 0.1f * AMPLITUDE;
        } else {
            samples[i] = 0;
        }
    }
  }

  // write out stereo samples
  for (int i = 0; i < BATCH_SIZE; ++i) {
      i2s.write(samples[i]);
      i2s.write(samples[i]);
  }
}