// native_bridge/juce_fx/JuceFxEngine.cpp
// Implementation: AudioProcessorGraph với input/output node — chain rỗng G1.
#include "JuceFxEngine.h"

#include <juce_audio_processors/juce_audio_processors.h>

#include <algorithm>
#include <array>
#include <vector>

struct JuceFxEngine::Impl {
    juce::AudioProcessorGraph graph;
    juce::AudioBuffer<float> buf;
    uint32_t sampleRate = 0;
    uint32_t blockSize = 0;
    bool prepared = false;
};

JuceFxEngine::JuceFxEngine() : impl_(std::make_unique<Impl>()) {}

JuceFxEngine::~JuceFxEngine() { shutdown(); }

void JuceFxEngine::shutdown() {
    if (impl_->prepared) {
        impl_->graph.releaseResources();
        impl_->graph.clear();
        impl_->prepared = false;
        impl_->sampleRate = 0;
        impl_->blockSize = 0;
    }
}

void JuceFxEngine::prepare(uint32_t sampleRate, uint32_t blockSize) {
    if (impl_->prepared && impl_->sampleRate == sampleRate &&
        impl_->blockSize == blockSize)
        return;  // không đổi — giữ graph
    shutdown();

    impl_->sampleRate = sampleRate;
    impl_->blockSize = blockSize;
    impl_->graph.setPlayConfigDetails(2, 2, (double)sampleRate, (int)blockSize);

    // Chain rỗng G1: audio input -> audio output (passthrough). G2: chèn
    // plugin node giữa hai node này theo fx_chain.
    auto& g = impl_->graph;
    const auto inNode = g.addNode(std::make_unique<
        juce::AudioProcessorGraph::AudioGraphIOProcessor>(
        juce::AudioProcessorGraph::AudioGraphIOProcessor::audioInputNode));
    const auto outNode = g.addNode(std::make_unique<
        juce::AudioProcessorGraph::AudioGraphIOProcessor>(
        juce::AudioProcessorGraph::AudioGraphIOProcessor::audioOutputNode));
    using NCh = juce::AudioProcessorGraph::NodeAndChannel;
    using Conn = juce::AudioProcessorGraph::Connection;
    for (int ch = 0; ch < 2; ++ch) {
        NCh src; src.nodeID = inNode->nodeID; src.channelIndex = ch;
        NCh dst; dst.nodeID = outNode->nodeID; dst.channelIndex = ch;
        g.addConnection(Conn(src, dst));
    }

    g.prepareToPlay((double)sampleRate, (int)(blockSize * 4));  // batch tối đa 4 block
    impl_->buf.setSize(2, (int)(blockSize * 4), false, false, true);
    impl_->prepared = true;
}

void JuceFxEngine::process(float* inL, float* inR, uint32_t n) {
    if (!impl_->prepared || n == 0) return;
    auto& b = impl_->buf;
    b.setSize(2, (int)n, false, false, true);
    b.copyFrom(0, 0, inL, (int)n);
    b.copyFrom(1, 0, inR, (int)n);
    juce::MidiBuffer midi;
    impl_->graph.processBlock(b, midi);
    // G1 passthrough: copy kết quả về buffer đầu vào (in-place như contract).
    const auto* outL = b.getReadPointer(0);
    const auto* outR = b.getReadPointer(1);
    std::copy(outL, outL + n, inL);
    std::copy(outR, outR + n, inR);
}

uint32_t JuceFxEngine::latencySamples() const {
    return impl_->prepared ? (uint32_t)impl_->graph.getLatencySamples() : 0u;
}