// native_bridge/src/SandboxVst3Host.cpp
#include "SandboxVst3Host.h"

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

// F-PROC-1 (audit 5.2): Windows CRT command-line parsing escape for an
// argument inside double quotes. A path containing a double quote would
// otherwise break out of --path "..." and inject arbitrary argv (e.g.
// `" && calc`). Metacharacters (& | > <) are inert here: CreateProcessA
// does not run a shell.
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
}

SandboxVst3Host::SandboxVst3Host() {}

SandboxVst3Host::~SandboxVst3Host() {
    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 SandboxVst3Host::loadPlugin(const std::string& path, double sampleRate, uint32_t channel) {
    path_ = path;
    sampleRate_ = sampleRate;
    channel_ = channel;
    char name[128];
    snprintf(name, sizeof(name), "SonicForge_PluginHost_%lu_%u",
             (unsigned long)GetCurrentProcessId(), channel);
    shmName_ = name;
    if (!spawnChild()) return false;
    watchdog_ = std::thread([this]() { watchdogLoop(); });
    return true;
}

bool SandboxVst3Host::spawnChild() {
    // Mapping created by the bridge (parent); the child opens it with --open.
    if (shm_) {
        shm_close(shm_);
        shm_ = nullptr;
        ipc_ = nullptr;
    }
    shm_ = shm_create(shmName_.c_str(), sizeof(SandboxHostIPC));
    if (!shm_) {
        std::cerr << "[SandboxVst3Host] 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";
    // F-PROC-1: lpApplicationName = hostExe (exe path is never parsed as
    // command line), and the VST path goes through quote_arg so a hostile
    // path cannot inject extra arguments.
    std::string cmd = "--open --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 << "[SandboxVst3Host] 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 << "[SandboxVst3Host] 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 (Nexus load can take 30s+).
    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() < 60) {
        if (!proc_alive(childProc_)) {
            std::cerr << "[SandboxVst3Host] child exited during load ch=" << channel_ << std::endl;
            return false;
        }
        if (ipc_->base.heartbeat != hb) {
            alive_.store(true);
            return true;
        }
        Sleep(200);
    }
    std::cerr << "[SandboxVst3Host] child heartbeat timeout ch=" << channel_ << std::endl;
    return false;
}

void SandboxVst3Host::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 << "[SandboxVst3Host] child died ch=" << channel_ << " rc=" << ec << " — respawning" << std::endl;
        ++fails;
        if (fails >= 3) {
            std::cerr << "[SandboxVst3Host] 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;
            std::cerr << "[SandboxVst3Host] ch=" << channel_ << " respawned" << std::endl;
        }
    }
}

bool SandboxVst3Host::init(double sampleRate, uint32_t maxBlockSize) {
    sampleRate_ = sampleRate;
    block_ = maxBlockSize;
    return true;
}

void SandboxVst3Host::noteOn(uint32_t channel, uint32_t pitch, float velocity, uint32_t sampleOffset) {
    if (!alive_.load() || !ipc_) return;
    shm_write_midi(shm_, 0x9, (uint8_t)channel, (uint8_t)pitch,
                   (uint8_t)(velocity * 127.0f), sampleOffset);
}

void SandboxVst3Host::noteOff(uint32_t channel, uint32_t pitch, uint32_t sampleOffset) {
    if (!alive_.load() || !ipc_) return;
    shm_write_midi(shm_, 0x8, (uint8_t)channel, (uint8_t)pitch, 0, sampleOffset);
}

void SandboxVst3Host::controlChange(uint32_t channel, uint32_t cc, uint32_t value) {
    if (!alive_.load() || !ipc_) return;
    shm_write_midi(shm_, 0xB, (uint8_t)channel, (uint8_t)cc, 0, 0, (uint8_t)value, 0);
}

void SandboxVst3Host::programChange(uint32_t channel, uint32_t program) {
    if (!alive_.load() || !ipc_) return;
    shm_write_midi(shm_, 0xC, (uint8_t)channel, 0, 0, 0, (uint8_t)program, 0);
}

void SandboxVst3Host::pitchBend(uint32_t channel, uint32_t bend14) {
    if (!alive_.load() || !ipc_) return;
    shm_write_midi(shm_, 0xE, (uint8_t)channel, 0, 0, 0,
                   (uint8_t)(bend14 & 0x7F), (uint8_t)((bend14 >> 7) & 0x7F));
}

void SandboxVst3Host::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;
    }
    // G4.3: the child publishes the slot it finished rendering (writeSlot).
    // Copy that block. A stale slot means the child is still working on the
    // other one — we repeat the previous block instead of tearing.
    uint32_t slot = ipc_->writeSlot & 1u;
    for (uint32_t i = 0; i < numSamples; ++i) {
        outputL[i] = ipc_->audioLeft[slot][i];
        outputR[i] = ipc_->audioRight[slot][i];
    }
}