// native_bridge/src/SandboxVst2Host.cpp
#include "SandboxVst2Host.h"

#include <chrono>
#include <cstdio>
#include <cstring>
#include <iostream>
#include <vector>

// Same escaping as SandboxVst3Host.cpp (F-PROC-1): CreateProcessA does not
// run a shell, but a path containing a double quote must not break out of
// --path "..." and inject arbitrary argv.
static std::string quote_arg(const std::string& s) {
    std::string out = "\"";
    size_t bs = 0;
    for (char c : s) {
        if (c == '\\') { ++bs; continue; }
        if (c == '"') { out.append(bs * 2 + 1, '\\'); out += '"'; bs = 0; }
        else { out.append(bs, '\\'); out += c; bs = 0; }
    }
    out.append(bs * 2, '\\');
    out += '"';
    return out;
}

static bool proc_alive(HANDLE h) {
#ifdef _WIN32
    if (!h) return false;
    DWORD code = 0;
    if (!GetExitCodeProcess(h, &code)) return false;
    return code == STILL_ACTIVE;
#else
    return true;
#endif
}

// Unique SHM name per LOAD, not per channel: a same-channel reload (frontend
// LOAD retry spam) runs while the OLD child + mapping still exist - a name
// keyed only on channel would reopen the old mapping and two children would
// fight over one audio handoff. A per-load counter keeps each child isolated.
static std::atomic<uint32_t> g_seq{0};

SandboxVst2Host::SandboxVst2Host() {}

SandboxVst2Host::~SandboxVst2Host() {
    stop_.store(true);
    if (watchdog_.joinable()) watchdog_.join();
#ifdef _WIN32
    if (childProc_) {
        TerminateProcess(childProc_, 0);
        CloseHandle(childProc_);
        childProc_ = nullptr;
    }
#endif
    if (shm_) {
        shm_close(shm_);
        shm_ = nullptr;
        ipc_ = nullptr;
    }
}

bool SandboxVst2Host::loadPlugin(const std::string& path, double sampleRate, uint32_t channel) {
    path_ = path;
    sampleRate_ = sampleRate;
    channel_ = channel;
    char name[160];
    snprintf(name, sizeof(name), "SonicForge_PluginHost2_%lu_%u_%u",
             (unsigned long)GetCurrentProcessId(), channel, g_seq.fetch_add(1));
    shmName_ = name;
    if (!spawnChild()) return false;
    seedDefaultPreset();
    watchdog_ = std::thread([this]() { watchdogLoop(); });
    return true;
}

bool SandboxVst2Host::spawnChild() {
    if (shm_) {
        shm_close(shm_);
        shm_ = nullptr;
        ipc_ = nullptr;
    }
    shm_ = shm_create(shmName_.c_str(), sizeof(SandboxHostIPC));
    if (!shm_) {
        std::cerr << "[SandboxVst2Host] shm_create failed ch=" << channel_ << std::endl;
        return false;
    }
    ipc_ = shm_sandbox_ptr(shm_);

    // plugin_host.exe sits next to daw_vst_bridge.exe (same dir, install/).
    char exePath[MAX_PATH] = {};
    GetModuleFileNameA(nullptr, exePath, MAX_PATH);
    std::string dir(exePath);
    size_t slash = dir.find_last_of("\\/");
    std::string hostExe = (slash == std::string::npos)
                              ? "plugin_host.exe"
                              : dir.substr(0, slash + 1) + "plugin_host.exe";
    std::string cmd = "--open --vst2 --channel " + std::to_string(channel_) +
                      " --shm " + shmName_ +
                      " --path " + quote_arg(path_) +
                      " --sr " + std::to_string((int)sampleRate_) +
                      " --block " + std::to_string(block_) +
                      " --parent " + std::to_string((unsigned long)GetCurrentProcessId());
    std::cerr << "[SandboxVst2Host] spawn ch=" << channel_ << " " << cmd << std::endl;

    STARTUPINFOA si = {};
    si.cb = sizeof(si);
    PROCESS_INFORMATION pi = {};
    std::vector<char> buf(cmd.begin(), cmd.end());
    buf.push_back('\0');
    if (!CreateProcessA(hostExe.c_str(), buf.data(), nullptr, nullptr, FALSE,
                        CREATE_NO_WINDOW, nullptr, nullptr, &si, &pi)) {
        std::cerr << "[SandboxVst2Host] CreateProcessA failed err=" << (int)GetLastError()
                  << " ch=" << channel_ << std::endl;
        return false;
    }
    CloseHandle(pi.hThread);
#ifdef _WIN32
    if (childProc_) CloseHandle(childProc_);
    childProc_ = pi.hProcess;
#endif

    // Wait for the child heartbeat (Qin load spawns auxhost + engine, can
    // take tens of seconds).
    uint32_t hb = ipc_->base.heartbeat;
    auto t0 = std::chrono::steady_clock::now();
    while (std::chrono::duration_cast<std::chrono::seconds>(
               std::chrono::steady_clock::now() - t0).count() < 90) {
        if (!proc_alive(childProc_)) {
            std::cerr << "[SandboxVst2Host] child exited during load ch=" << channel_ << std::endl;
            return false;
        }
        if (ipc_->base.heartbeat != hb) {
            alive_.store(true);
            return true;
        }
        Sleep(200);
    }
    std::cerr << "[SandboxVst2Host] child heartbeat timeout ch=" << channel_ << std::endl;
    return false;
}

void SandboxVst2Host::watchdogLoop() {
    int fails = 0;
    while (!stop_.load()) {
        Sleep(500);
        if (stop_.load()) break;
        if (!alive_.load()) continue;
        if (proc_alive(childProc_)) {
            fails = 0;
            continue;
        }
        alive_.store(false);
        DWORD ec = 0; GetExitCodeProcess(childProc_, &ec);
        std::cerr << "[SandboxVst2Host] child died ch=" << channel_ << " rc=" << ec << " - respawning" << std::endl;
        ++fails;
        if (fails >= 3) {
            std::cerr << "[SandboxVst2Host] ch=" << channel_
                      << " respawn limit hit - muted until reload" << std::endl;
            continue;  // stays dead; processAudioBlock returns silence
        }
        Sleep(1000);
        if (stop_.load()) break;
        if (spawnChild()) {
            fails = 0;
            // G4.6: respawned child starts from FACTORY state — re-queue the
            // last preset (real patch or seed) so it does not publish/sound
            // silent factory and clobber the state file.
            if (!lastPreset_.empty()) {
                queuePreset(lastPreset_);
                std::cerr << "[SandboxVst2Host] preset re-queued after respawn ch="
                          << channel_ << " (" << lastPreset_.size() << "B)" << std::endl;
            }
            std::cerr << "[SandboxVst2Host] ch=" << channel_ << " respawned" << std::endl;
        }
    }
}

bool SandboxVst2Host::init(double sampleRate, uint32_t maxBlockSize) {
    sampleRate_ = sampleRate;
    block_ = maxBlockSize;
    return true;
}

void SandboxVst2Host::pushControl(uint32_t type, uint32_t arg0, uint32_t arg1) {
    if (!alive_.load() || !ipc_) return;
    if (ipc_->base.controlQueueCount >= 8) return;
    auto& c = ipc_->base.controlQueue[ipc_->base.controlQueueCount];
    c.type = type;
    c.arg0 = arg0;
    c.arg1 = arg1;
    c.channel = channel_;
    std::memset(c.arg2, 0, sizeof(c.arg2));
    ipc_->base.controlQueueCount++;
}

void SandboxVst2Host::noteOn(uint32_t channel, uint32_t pitch, float velocity, uint32_t sampleOffset) {
    if (!alive_.load() || !ipc_) return;
    std::cerr << "[Vst2Sandbox] ON ch=" << channel << " p=" << pitch << " v=" << (int)(velocity * 127.0f) << std::endl;
    (void)channel;  // one instrument per child; Qin listens only on MIDI ch 0
    shm_write_midi(shm_, 0x9, 0, (uint8_t)pitch,
                   (uint8_t)(velocity * 127.0f), sampleOffset);
}

void SandboxVst2Host::noteOff(uint32_t channel, uint32_t pitch, uint32_t sampleOffset) {
    if (!alive_.load() || !ipc_) return;
    std::cerr << "[Vst2Sandbox] OFF ch=" << channel << " p=" << pitch << std::endl;
    (void)channel;  // see noteOn
    shm_write_midi(shm_, 0x8, 0, (uint8_t)pitch, 0, sampleOffset);
}

void SandboxVst2Host::controlChange(uint32_t channel, uint32_t cc, uint32_t value) {
    if (!alive_.load() || !ipc_) return;
    std::cerr << "[Vst2Sandbox] CC ch=" << channel << " cc=" << cc << " v=" << value << std::endl;
    (void)channel;  // see noteOn
    shm_write_midi(shm_, 0xB, 0, (uint8_t)cc, 0, 0, (uint8_t)value, 0);
}

void SandboxVst2Host::programChange(uint32_t channel, uint32_t program) {
    if (!alive_.load() || !ipc_) return;
    (void)channel;  // see noteOn
    shm_write_midi(shm_, 0xC, 0, 0, 0, 0, (uint8_t)program, 0);
}

void SandboxVst2Host::pitchBend(uint32_t channel, uint32_t bend14) {
    if (!alive_.load() || !ipc_) return;
    (void)channel;  // see noteOn
    shm_write_midi(shm_, 0xE, 0, 0, 0, 0,
                   (uint8_t)(bend14 & 0x7F), (uint8_t)((bend14 >> 7) & 0x7F));
}

void SandboxVst2Host::allNotesOff(uint32_t /*channel*/) {
    if (!alive_.load() || !ipc_) return;
    std::cerr << "[Vst2Sandbox] ALL_NOTES_OFF ch=" << channel_ << std::endl;
    pushControl(7);  // plugin_host panics locally - no 64-cap MIDI flood
}

bool SandboxVst2Host::openGUI(void* parentWindowHandle) {
    (void)parentWindowHandle;  // child owns its window
    if (!alive_.load() || !ipc_) return false;
    pushControl(4);
    guiOpen_.store(true);
    return true;
}

bool SandboxVst2Host::attachView(void* parentWindowHandle) {
    return openGUI(parentWindowHandle);
}

void SandboxVst2Host::closeGUI() {
    if (!alive_.load() || !ipc_) return;
    pushControl(5);
    guiOpen_.store(false);
}

void SandboxVst2Host::seedDefaultPreset() {
    // Qin_RV renders SILENT from factory state (no instrument loaded).
    // Seed a known-good captured chunk so preset-less loads still sound;
    // the restore path writes the real saved preset to presetIn AFTER
    // loadPlugin returns, so by ordering the real one wins.
    if (!ipc_) return;
    char buf[MAX_PATH];
    if (!GetEnvironmentVariableA("APPDATA", buf, MAX_PATH)) return;
    std::string file = std::string(buf) + "\\SonicForgeDAW\\qin_default.b64";
    FILE* f = fopen(file.c_str(), "rb");
    if (!f) return;
    fseek(f, 0, SEEK_END);
    long sz = ftell(f);
    fseek(f, 0, SEEK_SET);
    if (sz <= 0 || (size_t)sz >= PRESET_BLOB_SIZE) { fclose(f); return; }
    std::string b64;
    b64.resize((size_t)sz);
    if (fread(&b64[0], 1, (size_t)sz, f) == (size_t)sz && !b64.empty()) {
        lastPreset_ = b64;
        queuePreset(b64);
        std::cerr << "[SandboxVst2Host] default preset seeded ch=" << channel_
                  << " (" << b64.size() << "B)" << std::endl;
    }
    fclose(f);
}

void SandboxVst2Host::queuePreset(const std::string& base64, bool waitApply) {
    if (!ipc_ || base64.empty()) return;
    size_t n = base64.size();
    if (n >= PRESET_BLOB_SIZE) n = PRESET_BLOB_SIZE - 1;
    memcpy((void*)ipc_->presetIn, base64.data(), n);
    ipc_->presetIn[n] = 0;
    ipc_->presetInLen = (uint32_t)n;
    // waitApply: block until the child has APPLIED this preset (presetOut
    // echoes the chunk) before returning. The restore path queues the real
    // saved preset right after spawn; without this wait a saveStateJob can
    // fire while the child is still applying the seed default and persist the
    // seed over the real chunk (restore clobber). Qin round-trips
    // byte-identical; 20s timeout guards a stuck child.
    if (!waitApply) return;
    if (ipc_->presetOutLen == (uint32_t)n &&
        memcmp(ipc_->presetOut, base64.data(), n) == 0) return;
    auto t0 = std::chrono::steady_clock::now();
    while (std::chrono::steady_clock::now() - t0 < std::chrono::seconds(20)) {
        if (ipc_->presetOutLen == (uint32_t)n &&
            memcmp(ipc_->presetOut, base64.data(), n) == 0) break;
        Sleep(50);
    }
    bool confirmed = ipc_->presetOutLen == (uint32_t)n &&
                     memcmp(ipc_->presetOut, base64.data(), n) == 0;
    std::cerr << "[SandboxVst2Host] preset apply waited ch=" << channel_
              << " (" << base64.size() << "B)"
              << (confirmed ? " confirmed" : " TIMEOUT")
              << std::endl;
}

void SandboxVst2Host::loadSerializedState(const std::string& base64) {
    if (base64.empty()) return;
    lastPreset_ = base64;  // keep for watchdog respawn re-queue
    if (!alive_.load() || !ipc_) return;
    // V45.2: non-blocking. The old byte-identical echo wait (memcmp presetOut==input)
    // NEVER matched for Qin — the child republishes its own round-trip chunk (differs
    // at byte 144) so waitApply always burned the full 20s TIMEOUT. VST2 restore runs
    // on the audio thread (runOnMain), so every bridge startup stalled ALL audio 20s —
    // the user's first play pressed in that window = silence. Bridge now holds
    // reloading + defers saves until the child republishes (see main.cpp doRestore).
    queuePreset(base64, false);
    std::cerr << "[SandboxVst2Host] presetIn queued ch=" << channel_
              << " (" << base64.size() << "B)" << std::endl;
}

std::string SandboxVst2Host::serializeState() const {
    if (!ipc_) return std::string();
    uint32_t n = ipc_->presetOutLen;
    if (n == 0 || n >= PRESET_BLOB_SIZE) return std::string();
    return std::string(ipc_->presetOut, n);
}

void SandboxVst2Host::processAudioBlock(float* outputL, float* outputR, uint32_t numSamples) {
    if (!alive_.load() || !ipc_) {
        std::memset(outputL, 0, numSamples * sizeof(float));
        std::memset(outputR, 0, numSamples * sizeof(float));
        return;
    }
    // G4.7: copy the newest child block into a LOCAL buffer once per slot
    // change, then serve every segment of this DAW block from it. The old
    // direct read tore when the unpaced child (~50x real-time) overwrote
    // the slot mid-read, and mixed samples from several child blocks across
    // the segments of one DAW block. With consumer-sync pacing the child
    // publishes exactly one block per DAW block, so the slot only changes
    // at a block boundary. ponytail: a child publish landing between two
    // segments of one DAW block (sub-ms race) would still copy mid-block;
    // impossible in practice - the child is asleep in Sleep(1) when the
    // DAW dispatches segments (<100us). Upgrade path: pass the DAW block
    // index into processAudioBlock and copy once per block.
    uint32_t slot = ipc_->writeSlot & 1u;
    if (slot != lastWriteSlot_) {
        std::memcpy(lastLeft_, ipc_->audioLeft[slot], sizeof(lastLeft_));
        std::memcpy(lastRight_, ipc_->audioRight[slot], sizeof(lastRight_));
        ipc_->bridgeConsumed[slot]++;
        lastWriteSlot_ = slot;
    }
    for (uint32_t i = 0; i < numSamples; ++i) {
        outputL[i] = lastLeft_[i];
        outputR[i] = lastRight_[i];
    }
}