// Tests the wav->spec->wav roundtrip SNR.
// Generates a sine wave, runs OLA encode then OLA decode,
// and asserts the reconstruction SNR exceeds the threshold.

#include "audio/ola.h"
#include <assert.h>
#include <cmath>
#include <cstdio>
#include <vector>

static const int SAMPLE_RATE = 32000;
static const float PI = 3.14159265358979323846f;

static float compute_snr_db(const std::vector<float>& ref,
                            const std::vector<float>& out, int skip_samples) {
  const int n = (int)std::min(ref.size(), out.size());
  double sig = 0.0, noise = 0.0;
  for (int i = skip_samples; i < n; ++i) {
    sig += (double)ref[i] * ref[i];
    double e = ref[i] - out[i];
    noise += e * e;
  }
  if (noise < 1e-30)
    return 999.0f;
  return 10.0f * (float)log10(sig / noise);
}

int main() {
  printf("Running WAV roundtrip test...\n");

  // 1-second 440 Hz sine at 32 kHz
  const int n_samples = SAMPLE_RATE;
  std::vector<float> input(n_samples);
  for (int i = 0; i < n_samples; ++i)
    input[i] = 0.5f * sinf(2.0f * PI * 440.0f * i / SAMPLE_RATE);

  // Encode
  const int num_frames = ola_num_frames(n_samples);
  std::vector<float> spec(num_frames * DCT_SIZE);
  ola_encode(input.data(), n_samples, spec.data(), num_frames);

  // Decode
  std::vector<float> output(num_frames * OLA_HOP_SIZE);
  ola_decode(spec.data(), num_frames, output.data());

  // SNR — skip first DCT_SIZE samples (ramp-up transient)
  const float snr = compute_snr_db(input, output, DCT_SIZE);
  printf("Roundtrip SNR: %.1f dB  (frames=%d, out_samples=%zu)\n", snr,
         num_frames, output.size());

  const float MIN_SNR_DB = 30.0f;
  if (snr < MIN_SNR_DB) {
    printf("FAIL: SNR %.1f dB < %.0f dB threshold\n", snr, MIN_SNR_DB);
    return 1;
  }

  printf("PASS\n");
  return 0;
}