// SPDX-License-Identifier: GPL-3.0-only
#include "audio.h"

#include <ESP_I2S.h>  // bundled with Arduino-ESP32 3.x

#include "audio_config.h"
#include "pins.h"

namespace {
I2SClass i2s;
}

namespace audio {

bool begin() {
#if defined(OPENSCRIBE_BOARD_XIAO)
  // XIAO ESP32-S3 Sense onboard PDM microphone.
  i2s.setPinsPdmRx(PIN_PDM_CLK, PIN_PDM_DIN);
  return i2s.begin(I2S_MODE_PDM_RX, OSC_SAMPLE_RATE,
                   I2S_DATA_BIT_WIDTH_16BIT, I2S_SLOT_MODE_MONO);
#else
  // I2S standard mode from an external MEMS mic (INMP441 / ICS-43434).
  // Args: bclk, ws, dout(unused for RX = -1), din, mclk(unused = -1).
  i2s.setPins(PIN_I2S_BCLK, PIN_I2S_WS, -1, PIN_I2S_DIN, -1);
  return i2s.begin(I2S_MODE_STD, OSC_SAMPLE_RATE,
                   I2S_DATA_BIT_WIDTH_16BIT, I2S_SLOT_MODE_MONO);
#endif
}

size_t audio::read(uint8_t *dst, size_t maxBytes) {
  // I2SClass::readBytes blocks until data is available or the DMA times out.
  int n = i2s.readBytes(reinterpret_cast<char *>(dst), maxBytes);
  return n < 0 ? 0 : static_cast<size_t>(n);
}

void end() { i2s.end(); }

}  // namespace audio

// NOTE (calibration, revisit with hardware): INMP441 emits 24-bit samples in a 32-bit
// slot. Reading in 16-bit mode captures the top bits and is usable for speech but may be
// quiet. If levels are low on the dev build, switch to 32-bit capture and right-shift into
// int16 here. Tracked in state/TODO.md.