#include <XCEngine/Audio/Reverbation.h>
#include <algorithm>
#include <cstring>

namespace XCEngine {
namespace Audio {

static const uint32 CombTuning[] = { 1116, 1188, 1277, 1356, 1422, 1491, 1557, 1617 };
static const uint32 AllPassTuning[] = { 556, 441, 341, 225 };

Reverbation::Reverbation()
    : m_sampleRate(48000)
{
    for (uint32 i = 0; i < CombCount; ++i) {
        m_combFilters[i].bufferSize = CombTuning[i];
        m_combFilters[i].buffer.resize(m_combFilters[i].bufferSize, 0.0f);
        m_combFilters[i].writeIndex = 0;
        m_combFilters[i].feedback = 0.0f;
        m_combFilters[i].damp1 = 0.0f;
        m_combFilters[i].damp2 = 0.0f;
        m_combFilters[i].filterStore = 0.0f;
    }

    for (uint32 i = 0; i < AllPassCount; ++i) {
        m_allPassFilters[i].bufferSize = AllPassTuning[i];
        m_allPassFilters[i].buffer.resize(m_allPassFilters[i].bufferSize, 0.0f);
        m_allPassFilters[i].writeIndex = 0;
        m_allPassFilters[i].feedback = 0.5f;
    }

    SetRoomSize(0.5f);
    SetDamping(0.5f);
}

Reverbation::~Reverbation() {
}

void Reverbation::ProcessAudio(float* buffer, uint32 sampleCount, uint32 channels) {
    if (!m_enabled || buffer == nullptr || sampleCount == 0) {
        return;
    }

    if (channels == 0) {
        return;
    }

    for (uint32 i = 0; i < sampleCount; ++i) {
        float input = buffer[i * channels];

        float wet = 0.0f;

        for (uint32 c = 0; c < CombCount; ++c) {
            float output = m_combFilters[c].buffer[m_combFilters[c].writeIndex];

            m_combFilters[c].filterStore = output * m_combFilters[c].damp2 + m_combFilters[c].filterStore * m_combFilters[c].damp1;

            m_combFilters[c].buffer[m_combFilters[c].writeIndex] = input + m_combFilters[c].filterStore * m_combFilters[c].feedback;

            m_combFilters[c].writeIndex++;
            if (m_combFilters[c].writeIndex >= m_combFilters[c].bufferSize) {
                m_combFilters[c].writeIndex = 0;
            }

            wet += output;
        }

        for (uint32 a = 0; a < AllPassCount; ++a) {
            float output = m_allPassFilters[a].buffer[m_allPassFilters[a].writeIndex];
            float temp = output;

            m_allPassFilters[a].buffer[m_allPassFilters[a].writeIndex] = wet + output * m_allPassFilters[a].feedback;

            wet = -wet + output;
            wet += temp;

            m_allPassFilters[a].writeIndex++;
            if (m_allPassFilters[a].writeIndex >= m_allPassFilters[a].bufferSize) {
                m_allPassFilters[a].writeIndex = 0;
            }
        }

        float outSample = input * m_dryMix + wet * m_wetMix;

        for (uint32 ch = 0; ch < channels; ++ch) {
            buffer[i * channels + ch] = outSample;
        }
    }
}

void Reverbation::SetRoomSize(float size) {
    m_roomSize = std::max(0.0f, std::min(1.0f, size));
    float roomScale = 0.28f + 0.7f * m_roomSize;
    for (uint32 i = 0; i < CombCount; ++i) {
        m_combFilters[i].feedback = roomScale;
    }
}

void Reverbation::SetDamping(float damping) {
    m_damping = std::max(0.0f, std::min(1.0f, damping));
    for (uint32 i = 0; i < CombCount; ++i) {
        m_combFilters[i].damp1 = m_damping * 0.4f;
        m_combFilters[i].damp2 = 1.0f - m_damping * 0.4f;
    }
}

void Reverbation::SetWetMix(float wetMix) {
    m_wetMix = std::max(0.0f, std::min(1.0f, wetMix));
}

void Reverbation::SetDryMix(float dryMix) {
    m_dryMix = std::max(0.0f, std::min(1.0f, dryMix));
}

void Reverbation::SetWidth(float width) {
    m_width = std::max(0.0f, std::min(1.0f, width));
}

void Reverbation::SetFreeze(bool freeze) {
    m_freeze = freeze;
}

} // namespace Audio
} // namespace XCEngine