// native_bridge/include/NativeInstrumentEngine.h
#ifndef NATIVE_INSTRUMENT_ENGINE_H
#define NATIVE_INSTRUMENT_ENGINE_H

#include "INativeInstrument.h"
#include "StateStore.h"

#include <sfizz.hpp>

#include <map>
#include <mutex>
#include <functional>
#include <memory>
#include <string>
#include <vector>
#include <atomic>

// FluidSynth (.sf2 / .sf3)
class FluidSynthInstrument : public INativeInstrument {
public:
    FluidSynthInstrument();
    ~FluidSynthInstrument() override;

    bool loadSoundFontFile(const std::string& path, double sampleRate);

    bool init(double sampleRate, uint32_t maxBlockSize) override;
    void selectProgram(uint32_t channel, uint32_t bank, uint32_t program) override;
    void noteOn(uint32_t channel, uint32_t pitch, float velocity, uint32_t sampleOffset) override;
    void noteOff(uint32_t channel, uint32_t pitch, uint32_t sampleOffset) override;
    void controlChange(uint32_t channel, uint32_t cc, uint32_t value) override;
    void programChange(uint32_t channel, uint32_t program) override;
    void pitchBend(uint32_t channel, uint32_t bend14) override;
    bool openGUI(void* parentWindowHandle) override;
    void closeGUI() override;
    // G2.1: expose last bank/program for the state snapshot.
    uint32_t bankOf(uint32_t channel) const override;
    uint32_t programOf(uint32_t channel) const override;
    void processAudioBlock(float* outputL, float* outputR, uint32_t numSamples) override;

private:
    void* settings; // fluid_settings_t*
    void* synth;    // fluid_synth_t*
    int sfontId;
    // Per-channel bank select (CC0<<7 | CC32) — programChange phai dung bank
    // that (truoc day hardcode bank 0 -> preset o bank != 0 khong chon duoc).
    uint32_t bank_[16];
    uint32_t program_[16];
};

// sfizz (.sfz)
class SfizzInstrument : public INativeInstrument {
public:
    bool loadSfzFile(const std::string& path, double sampleRate);

    bool init(double sampleRate, uint32_t maxBlockSize) override;
    void selectProgram(uint32_t channel, uint32_t bank, uint32_t program) override;
    void noteOn(uint32_t channel, uint32_t pitch, float velocity, uint32_t sampleOffset) override;
    void noteOff(uint32_t channel, uint32_t pitch, uint32_t sampleOffset) override;
    void controlChange(uint32_t channel, uint32_t cc, uint32_t value) override;
    void programChange(uint32_t channel, uint32_t program) override;
    void pitchBend(uint32_t channel, uint32_t bend14) override;
    bool openGUI(void* parentWindowHandle) override;
    void closeGUI() override;
    void processAudioBlock(float* outputL, float* outputR, uint32_t numSamples) override;

private:
    sfz::Sfizz sfizzSynth;
};

// Multi-instrument host (A10): one engine instance per MIDI channel, so two
// tracks can play two different soundfonts/VSTs simultaneously. All channels
// render into the same output block (mixed), keyed by evt.channel.
class InstrumentEngineManager {
public:
    // Create (or replace) the instrument on `channel` for `path`.
    // Returns false if the type is unsupported or the file fails to load.
    bool assign(uint32_t channel, InstrumentType type, const std::string& path,
                double sampleRate, uint32_t blockSize);

    INativeInstrument* get(uint32_t channel);

    // F-MEM-5 (audit 5.2): get() releases mu_ before the caller derefs, so a
    // worker thread's assign()/unload() can destroy the instance mid-use.
    // has() is a safe existence check; withInstrument() runs code against the
    // instance while mu_ is still held. Use these from non-Ui threads.
    bool has(uint32_t channel);
    template <typename F>
    auto withInstrument(uint32_t channel, F&& fn) -> decltype(fn((INativeInstrument*)nullptr)) {
        std::lock_guard<std::mutex> lock(mu_);
        auto it = channels_.find(channel);
        return fn(it == channels_.end() ? nullptr : it->second.get());
    }

    // Real-time MIDI dispatch (audio loop thread). Each call holds mu_ for the
    // WHOLE call — lookup + reloading check + instrument call under one lock —
    // so a worker thread's assign()/unload() can never swap the map and destroy
    // the old instance while dispatch is inside a method on it (use-after-free
    // when loading a new VSTi while others play). Events for unassigned or
    // reloading channels are dropped (a mid-reload instance must not be touched
    // while its worker rebuilds state_ in place).
    void noteOn(uint32_t channel, uint32_t pitch, float velocity);
    void noteOff(uint32_t channel, uint32_t pitch);
    void controlChange(uint32_t channel, uint32_t cc, uint32_t value);
    void programChange(uint32_t channel, uint32_t program);
    void pitchBend(uint32_t channel, uint32_t bend14);

    // Remove and destroy the instrument on `channel` (its destructor may call
    // VST terminate — MUST run on the channel worker thread, caller's duty).
    // Used by Option B: two live instances of the same plugin DLL (Nexus)
    // hang createView on the second — unload the other channel's copy.
    void unload(uint32_t channel);

    // Path last assigned to a channel (empty if none). Windows paths are
    // case-insensitive — caller must lowercase before comparing.
    std::string pathOf(uint32_t channel);

    // G2.1: copy every assigned channel into a state snapshot (channel,
    // type, path, VST3 preset blob -> base64, SF2/SF3 bank/program).
    // MUST run on the channel worker (captureState enters the plugin);
    // takes mu_ for the whole call so the audio loop cannot be inside
    // process() on the same instance while its state is captured.
    // Channels mid-reload are skipped (their old instance is dying).
    bool snapshot(BridgeStateSnapshot& out);

    // Mark a channel as rebuilding its VST instance (GUI reopen): the
    // real-time loop then skips processAudioBlock for that channel so VST
    // teardown never races the audio thread.
    void setReloading(uint32_t channel, bool on);

    // True while a channel is being rebuilt (instance teardown/reload on its
    // worker thread): real-time code drops MIDI for it. Channel-level flag —
    // survives the instance swap (the per-instance flag dies with the object).
    bool isReloading(uint32_t channel) const;

    // G3.3: mark a channel whose plugin crashed inside processAudioBlock
    // (SEH access violation). The channel is muted (real-time dispatch +
    // renderAll skip it) until the next assign() — the plugin's state is
    // undefined after a fault, so re-processing would fault again.
    void markCrashed(uint32_t channel);
    bool isCrashed(uint32_t channel) const;
    // Editor-open predicate: while any VST editor is attached, channels whose
    // plugin DLL path has an open editor count as quiet (same-plugin channels
    // too -- the worker pumps the editor's window proc inside the DLL while the
    // audio loop process()es other instances of the same DLL).

    // Flush every sounding note on every assigned channel.
    void allNotesOff();

    // Zero L/R then sum each assigned instrument into it.
    void renderAll(float* outputL, float* outputR, uint32_t numSamples);

    size_t count() const { std::lock_guard<std::mutex> lock(mu_); return channels_.size(); }

    void setBypassed(bool on) { isBypassed_.store(on); }
    bool isBypassed() const { return isBypassed_.load(); }

private:
    static std::unique_ptr<INativeInstrument> create_instrument(InstrumentType type);
    // Probe-render 3 notes sau khi load, do peak, tinh makeup de note don ra
    // ~ -6 dBFS (0.5) - can bang am luong moi engine (VST2/VST3/SF2/SFZ).
    static float calibrate(INativeInstrument* inst, double sampleRate, uint32_t blockSize);

    mutable std::mutex mu_;
    std::map<uint32_t, std::unique_ptr<INativeInstrument>> channels_;
    std::map<uint32_t, std::string> paths_;  // last assigned path per channel
    std::map<uint32_t, InstrumentType> types_;  // last assigned type per channel (G2.1)
    std::map<uint32_t, float> makeup_;  // calibrated per-channel output gain (renderAll ap dung)
    // Per-instrument scratch so engines that overwrite (not mix) stay additive.
    std::vector<float> scratchL_, scratchR_;
    // Channel-level reload flag (see isReloading) — indexed by MIDI channel.
    bool reloadingCh_[16] = {};
    // G3.3: channel muted after a plugin fault inside processAudioBlock.
    bool crashedCh_[16] = {};
    float limiterGain_ = 1.0f;  // smoothed mix limiter state (renderAll)
    // True when the channel's plugin DLL has an attached editor (or its reload
    // is in progress): real-time code drops MIDI and skips rendering. Lowercased
    // compare inside -- Windows plugin paths are case-insensitive.
    bool channelQuiet(uint32_t ch) const;
    std::atomic<bool> isBypassed_{false};
};

#endif // NATIVE_INSTRUMENT_ENGINE_H