/*
 * Copyright 2006 Milan Digital Audio LLC
 * Copyright 2009-2026 GrandOrgue contributors (see AUTHORS)
 * License GPL-2.0 or later
 * (https://www.gnu.org/licenses/old-licenses/gpl-2.0.html).
 */

#include "GOSoundReverbPartition.h"

#include <algorithm>
#include <assert.h>
#include <string.h>

GOSoundReverbPartition::GOSoundReverbPartition(
  unsigned size, unsigned cnt, unsigned start_pos)
  : m_PartitionSize(size),
    m_PartitionCount(cnt),
    m_fftwTmpReal(0),
    m_fftwTmpComplex(0),
    m_TimeToFreq(0),
    m_FreqToTime(0),
    m_Input(0),
    m_Output(0),
    m_InputPos(start_pos),
    m_InputStartPos(start_pos),
    m_OutputPos(0),
    m_InputHistory(),
    m_IRData(),
    m_InputHistoryPos(0) {
  m_fftwTmpReal = new float[m_PartitionSize * 2];
  m_fftwTmpComplex = new fftwf_complex[m_PartitionSize + 1];

  m_TimeToFreq = fftwf_plan_dft_r2c_1d(
    2 * m_PartitionSize, m_fftwTmpReal, m_fftwTmpComplex, FFTW_ESTIMATE);
  m_FreqToTime = fftwf_plan_dft_c2r_1d(
    2 * m_PartitionSize, m_fftwTmpComplex, m_fftwTmpReal, FFTW_ESTIMATE);
  assert(m_TimeToFreq);
  assert(m_FreqToTime);

  m_Input = new float[m_PartitionSize];
  m_Output = new float[2 * m_PartitionSize];

  for (unsigned i = 0; i < m_PartitionCount; i++)
    m_InputHistory.push_back(new fftwf_complex[m_PartitionSize + 1]);

  for (unsigned i = 0; i < m_PartitionCount; i++)
    m_IRData.push_back(NULL);

  Reset();
}

GOSoundReverbPartition::~GOSoundReverbPartition() {
  if (m_TimeToFreq)
    fftwf_destroy_plan(m_TimeToFreq);
  if (m_FreqToTime)
    fftwf_destroy_plan(m_FreqToTime);
  if (m_fftwTmpReal)
    delete[] m_fftwTmpReal;
  if (m_fftwTmpComplex)
    delete[] m_fftwTmpComplex;
  if (m_Input)
    delete[] m_Input;
  if (m_Output)
    delete[] m_Output;
}

void GOSoundReverbPartition::Reset() {
  std::fill(m_Input, m_Input + m_PartitionSize, 0);
  std::fill(m_Output, m_Output + 2 * m_PartitionSize, 0);
  m_InputPos = m_InputStartPos;
  m_OutputPos = 0;
  m_InputHistoryPos = 0;

  for (unsigned i = 0; i < m_InputHistory.size(); i++)
    ZeroComplex(m_InputHistory[i], m_PartitionSize + 1);
}

void GOSoundReverbPartition::ZeroComplex(fftwf_complex *data, unsigned len) {
  for (unsigned i = 0; i < len; i++) {
    data[i][0] = 0;
    data[i][1] = 0;
  }
}

void GOSoundReverbPartition::Process(
  float *output_buf, const float *input_buf, unsigned len) {
  unsigned in_pos = 0, out_pos = 0;
  while (in_pos < len) {
    while (m_OutputPos < m_PartitionSize && out_pos < len)
      output_buf[out_pos++] += m_Output[m_OutputPos++];

    while (m_InputPos < m_PartitionSize && in_pos < len)
      m_Input[m_InputPos++] = input_buf[in_pos++];

    if (m_InputPos == m_PartitionSize) {
      std::copy(m_Input, m_Input + m_PartitionSize, m_fftwTmpReal);
      std::fill(
        m_fftwTmpReal + m_PartitionSize,
        m_fftwTmpReal + 2 * m_PartitionSize,
        0);
      fftwf_execute(m_TimeToFreq);
      memcpy(
        m_InputHistory[m_InputHistoryPos],
        m_fftwTmpComplex,
        (m_PartitionSize + 1) * sizeof(fftwf_complex));

      ZeroComplex(m_fftwTmpComplex, m_PartitionSize + 1);
      for (unsigned i = 0, j = m_InputHistoryPos; i < m_IRData.size(); i++) {
        if (m_IRData[i]) {
          const fftwf_complex *ir = m_IRData[i];
          const fftwf_complex *in = m_InputHistory[j];

          for (unsigned k = 0; k <= m_PartitionSize; k++) {
            m_fftwTmpComplex[k][0] += in[k][0] * ir[k][0] - in[k][1] * ir[k][1];
            m_fftwTmpComplex[k][1] += in[k][0] * ir[k][1] + in[k][1] * ir[k][0];
          }
        }
        if (j)
          j--;
        else
          j = m_PartitionCount - 1;
      }
      fftwf_execute(m_FreqToTime);

      for (unsigned i = 0; i < m_PartitionSize; i++)
        m_Output[i] = m_Output[i + m_PartitionSize] + m_fftwTmpReal[i];
      std::copy(
        m_fftwTmpReal + m_PartitionSize,
        m_fftwTmpReal + 2 * m_PartitionSize,
        m_Output + m_PartitionSize);

      m_InputHistoryPos = (m_InputHistoryPos + 1) % m_PartitionCount;
      m_OutputPos = 0;
      m_InputPos = 0;
    }
  }
}

unsigned GOSoundReverbPartition::GetLength() {
  return m_PartitionSize * m_PartitionCount;
}

void GOSoundReverbPartition::AddIR(
  const float *data, unsigned pos, unsigned len, unsigned offset) {
  for (unsigned i = 0; i < m_PartitionCount; i++) {
    unsigned minpos = offset + i * m_PartitionSize;
    unsigned maxpos = offset + (i + 1) * m_PartitionSize;
    if (pos + len < minpos || pos >= maxpos)
      continue;
    std::fill(m_fftwTmpReal, m_fftwTmpReal + 2 * m_PartitionSize, 0);
    unsigned startpos = minpos < pos ? pos : minpos;
    unsigned endpos = pos + len > maxpos ? maxpos : pos + len;
    float factor = 0.5 / m_PartitionSize;
    for (unsigned j = startpos; j < endpos; j++)
      m_fftwTmpReal[j - minpos] = factor * data[j - pos];
    fftwf_execute(m_TimeToFreq);
    if (!m_IRData[i]) {
      m_IRData[i] = new fftwf_complex[m_PartitionSize + 1];
      ZeroComplex(m_IRData[i], m_PartitionSize + 1);
    }
    for (unsigned j = 0; j < m_PartitionSize; j++) {
      m_IRData[i][j][0] += m_fftwTmpComplex[j][0];
      m_IRData[i][j][1] += m_fftwTmpComplex[j][1];
    }
  }
}
