#include "fgc/VimbaCameraSource.h"

// The SDK comes first on purpose. <VmbCPP/VmbCPP.h> pulls in
// VmbCPP/LoggerDefines.h, which on some SDK versions (the 2024-era /opt/VimbaX on
// the LattePanda, though not 2025-3) defines a FUNCTION-like LOG_ERROR(txt,
// errCode). Ours is object-like - `LOG_ERROR << "..."` - so whichever header is
// included last wins the redefinition, and when theirs wins the stream form never
// expands and fails to compile. Take the SDK's macros, drop them, then define
// ours over the top. The #undefs are harmless no-ops on SDKs that lack them.
#include <VmbCPP/VmbCPP.h>
#undef LOG_ERROR
#undef LOG_FREE_TEXT

#include "fgc/Logger.h"

#include <algorithm>
#include <atomic>
#include <chrono>
#include <memory>
#include <mutex>
#include <stdexcept>
#include <string>
#include <thread>

using namespace VmbCPP;

namespace fgc {

namespace {

long long nowMs() {
    return std::chrono::duration_cast<std::chrono::milliseconds>(
               std::chrono::system_clock::now().time_since_epoch())
        .count();
}

// Cumulative per-camera acquisition stats. Lives in Impl (NOT the observer) so it
// survives the restart-on-stall, which recreates the observer each session.
struct CamStats {
    std::atomic<long long> delivered{0};
    std::atomic<long long> dropped{0};
    std::atomic<long long> restarts{0};
    std::atomic<unsigned>  last_w{0};
    std::atomic<unsigned>  last_h{0};
    std::atomic<long long> last_bytes{0};
};

// Frame observer for the free-running stream: keeps the most recent COMPLETE
// frame. trigger() (once per scan waypoint) reads it out; the intermediate frames
// just give the on-camera auto-exposure/gain time to converge to the current
// light.
class FrameObserver : public IFrameObserver {
public:
    FrameObserver(CameraPtr camera, int cam_id, CamStats* stats)
        : IFrameObserver(camera), cam_id_(cam_id), stats_(stats) {}

    // Copy out the latest complete frame; false if none has arrived yet.
    bool takeLatest(Frame& out) {
        std::lock_guard<std::mutex> lock(mutex_);
        if (!has_) return false;
        out = latest_;
        return true;
    }

    // Timestamp of the latest complete frame (0 if none) - lets the source detect a
    // stalled stream (timestamp stops advancing) without copying the whole frame.
    long long latestTimestamp() {
        std::lock_guard<std::mutex> lock(mutex_);
        return has_ ? latest_.timestamp_ms : 0;
    }

    void FrameReceived(const FramePtr pFrame) override {
        VmbFrameStatusType status;
        VmbErrorType       rc = pFrame->GetReceiveStatus(status);
        if (rc == VmbErrorSuccess && status == VmbFrameStatusComplete) {
            VmbUint32_t       w = 0, h = 0, sz = 0;
            const VmbUchar_t* buf = nullptr;
            if (pFrame->GetWidth(w) == VmbErrorSuccess &&
                pFrame->GetHeight(h) == VmbErrorSuccess &&
                pFrame->GetBufferSize(sz) == VmbErrorSuccess &&
                pFrame->GetBuffer(buf) == VmbErrorSuccess && buf && w && h) {
                Frame f;
                f.width        = w;
                f.height       = h;
                f.channels     = static_cast<int>(sz / (static_cast<size_t>(w) * h));
                f.cam_id       = cam_id_;
                f.timestamp_ms = nowMs();
                f.data.assign(buf, buf + sz);
                {
                    std::lock_guard<std::mutex> lock(mutex_);
                    latest_ = std::move(f);
                    has_    = true;
                }
                if (stats_) {
                    stats_->delivered.fetch_add(1);
                    stats_->last_w.store(w);
                    stats_->last_h.store(h);
                    stats_->last_bytes.store(sz);
                }
                LOG_TRACE_CAT(LogCat::Camera)
                    << "RX frame cam" << cam_id_ << ' ' << w << 'x' << h << ' ' << sz << 'B';
            }
        } else {
            // Incomplete/invalid delivery - usually USB bandwidth starvation on large
            // frames. Surface it instead of silently dropping.
            if (stats_) stats_->dropped.fetch_add(1);
            LOG_WARN << "camera cam" << cam_id_ << " dropped frame (status="
                     << (rc == VmbErrorSuccess ? static_cast<int>(status) : -1) << ')';
        }
        m_pCamera->QueueFrame(pFrame);
    }

private:
    int        cam_id_;
    CamStats*  stats_;
    std::mutex mutex_;
    Frame      latest_;
    bool       has_ = false;
};

// Read a float/string feature, returning `fallback`/"" if absent (tolerant, for telemetry).
double getFloat(const CameraPtr& cam, const char* name, double fallback = 0.0) {
    FeaturePtr f;
    double     v = fallback;
    if (SP_ACCESS(cam)->GetFeatureByName(name, f) == VmbErrorSuccess && f->GetValue(v) == VmbErrorSuccess)
        return v;
    return fallback;
}
std::string getString(const CameraPtr& cam, const char* name) {
    FeaturePtr  f;
    std::string v;
    if (SP_ACCESS(cam)->GetFeatureByName(name, f) == VmbErrorSuccess && f->GetValue(v) == VmbErrorSuccess)
        return v;
    return {};
}

// Apply a profile by handing its settings XML to the SDK.
//
// This replaces a hand-rolled feature applier, and the reason is validity rather
// than brevity: GenICam writability is stateful (AcquisitionFrameRate is only
// writable once AcquisitionFrameRateEnable is set, Width's maximum depends on
// binning, and so on), so a text list applied line by line can be individually
// plausible and collectively wrong. The XML comes out of the VimbaX Viewer,
// which greys out invalid combinations as the operator configures, and
// LoadSettings replays exactly that. Nothing else may write settings.
bool applyProfile(const CameraPtr& cam, const CameraProfile& profile) {
    VmbFeaturePersistSettings settings{};
    settings.persistType   = VmbFeaturePersistNoLUT;
    // RemoteDevice only: the transport-layer and stream sections of the export
    // describe the host that produced it, not the sensor.
    settings.modulePersistFlags = VmbModulePersistFlagsRemoteDevice;
    settings.maxIterations = 10;   // features can need several passes to settle
    settings.loggingLevel  = VmbLogLevelWarn;

    const VmbErrorType rc = SP_ACCESS(cam)->LoadSettings(profile.xml_path.c_str(), &settings);
    if (rc != VmbErrorSuccess) {
        LOG_ERROR << "camera: applying profile '" << profile.name << "' from "
                  << profile.xml_path << " failed (error " << rc << ')';
        return false;
    }
    LOG_INFO << "camera profile '" << profile.name << "' applied from " << profile.xml_path
             << " (" << profile.settings.entries.size() << " settings)";
    return true;
}

}  // namespace

struct VimbaCameraSource::Impl {
    Impl(std::vector<CameraSpec> s, std::vector<CameraProfile> p)
        : specs(std::move(s)), profiles(std::move(p)), sys(VmbSystem::GetInstance()) {}

    struct Identity { std::string id, model, serial; };
    struct Telemetry {
        double exposure_us = 0, gain_db = 0, temperature_c = 0, actual_fps = 0;
    };

    // One spec and one profile per camera, index-aligned and in open order, so a
    // camera's settings are never those of the camera next to it.
    std::vector<CameraSpec>                specs;
    std::vector<CameraProfile>             profiles;
    VmbSystem&                             sys;
    std::vector<CameraPtr>                 cameras;
    std::vector<IFrameObserverPtr>         observers;
    std::vector<std::unique_ptr<CamStats>> stats;      // one per camera; survives restart
    std::vector<Identity>                  identity;    // read once at open()
    std::vector<Telemetry>                 telemetry;   // live values, cached ~1 Hz
    long long                              telemetry_ms = 0;  // last telemetry refresh
    ICameraSource::FrameCallback           callback;
    bool                                   started          = false;
    long long                              last_captured_ts = 0;  // freshness watermark
    long long                              last_no_frame_warn_ms = 0;

    // Begin/end a free-run acquisition session (fresh observers each time). Split out so
    // trigger() can restart the stream when it stalls. Stats persist across restarts.
    void startAcquisition() {
        // Stop first, unconditionally. Clearing `observers` drops the last
        // references to the FrameObserver objects, and until
        // StopContinuousImageAcquisition() has returned the SDK's acquisition
        // thread may still be calling FrameReceived on them - destroying them
        // under it is a use-after-free, not a leak.
        stopAcquisition();
        // A fresh session has delivered nothing, so a watermark from the previous
        // one would make every genuinely-new frame look stale to trigger().
        last_captured_ts = 0;
        int cam_id = 0;
        for (auto& cam : cameras) {
            IFrameObserverPtr observer(new FrameObserver(cam, cam_id, stats[cam_id].get()));
            if (cam->StartContinuousImageAcquisition(5, observer) != VmbErrorSuccess)
                throw std::runtime_error("Could not start acquisition");
            observers.push_back(observer);
            ++cam_id;
        }
    }
    void stopAcquisition() {
        for (auto& cam : cameras) cam->StopContinuousImageAcquisition();
        observers.clear();
    }
    // Newest frame timestamp across all cameras (0 if none delivered yet).
    long long newestTs() {
        long long t = 0;
        for (auto& obs : observers)
            t = std::max(t, SP_DYN_CAST<FrameObserver>(obs)->latestTimestamp());
        return t;
    }

};

VimbaCameraSource::VimbaCameraSource(std::vector<CameraSpec> specs,
                                     std::vector<CameraProfile> profiles)
    : impl_(std::make_unique<Impl>(std::move(specs), std::move(profiles))) {}

VimbaCameraSource::~VimbaCameraSource() {
    try {
        stop();
        close();
    } catch (const std::exception& e) {
        LOG_WARN << "VimbaCameraSource shutdown: " << e.what();
    }
}

void VimbaCameraSource::open() {
    if (impl_->sys.Startup() != VmbErrorSuccess)
        throw std::runtime_error("Could not start Vimba X API");
    for (const auto& spec : impl_->specs) {
        const std::string& id = spec.id;
        CameraPtr cam;
        if (impl_->sys.GetCameraByID(id.c_str(), cam) != VmbErrorSuccess)
            throw std::runtime_error("Camera '" + spec.name + "' not found: " + id);
        if (const VmbErrorType rc = cam->Open(VmbAccessModeFull); rc != VmbErrorSuccess) {
            std::string why;
            if (rc == VmbErrorInvalidAccess || rc == VmbErrorBusy)
                why = " - another process has it open (is the VimbaX Viewer still running?)";
            else if (rc == VmbErrorNotFound)
                why = " - it disappeared between discovery and open (USB reset?)";
            throw std::runtime_error("Could not open camera '" + spec.name + "': " + id +
                                     " (Vimba error " + std::to_string(rc) + ")" + why);
        }
        impl_->cameras.push_back(cam);
        // Per-camera stats (persist across restart) + identity (read once here).
        impl_->stats.push_back(std::make_unique<CamStats>());
        impl_->telemetry.emplace_back();
        impl_->identity.push_back({id, getString(cam, "DeviceModelName"),
                                   getString(cam, "DeviceSerialNumber")});
        LOG_INFO << "Opened camera '" << spec.name << "' " << id << " ("
                 << impl_->identity.back().model << ')';
    }
    // Configure each camera ONCE, here. Settings are GenICam features that live on
    // the device and survive a stop/start of acquisition, so re-applying them
    // whenever the stream starts is both wasted work (thousands of features) and
    // wrong in principle: it lets a request to *stream* alter the *configuration*.
    // A scan frame and a manual snapshot must come off an identically configured
    // camera, and the only way to guarantee that is to never touch the
    // configuration in between.
    for (size_t i = 0; i < impl_->cameras.size() && i < impl_->profiles.size(); ++i)
        applyProfile(impl_->cameras[i], impl_->profiles[i]);
}

void VimbaCameraSource::close() {
    for (auto& cam : impl_->cameras) cam->Close();
    impl_->cameras.clear();
    impl_->sys.Shutdown();
}

// Start/stop the free-running stream. Configuration is NOT touched here - that
// happened at open(), and changes only through setProfile().
void VimbaCameraSource::start() {
    // Idempotent. Several callers reach here without knowing whether another
    // already has - `start` (scan), `snapshot`, and --start on the command line -
    // and re-entering would restart acquisition under the SDK's feet.
    if (impl_->started) return;
    impl_->startAcquisition();
    impl_->started = true;
}

bool VimbaCameraSource::setProfile(int camera_index, const CameraProfile& profile) {
    const size_t idx = static_cast<size_t>(camera_index);
    if (camera_index < 0 || idx >= impl_->cameras.size() || idx >= impl_->profiles.size()) {
        LOG_WARN << "camera: setProfile for unknown camera index " << camera_index;
        return false;
    }

    impl_->profiles[idx] = profile;
    if (!impl_->started) {
        // Idle: every feature is writable, so apply directly. start() no longer
        // applies profiles, so skipping this would leave the camera on the old one.
        return applyProfile(impl_->cameras[idx], profile);
    }

    // Binning, ROI and pixel format cannot be written while the stream runs, and a
    // profile may change any of them, so always cycle the stream. Profile switches
    // are rare; a per-feature "is this writable live" allow-list would be fragile.
    try {
        impl_->stopAcquisition();
        const bool ok = applyProfile(impl_->cameras[idx], profile);
        impl_->startAcquisition();
        if (!ok) return false;
    } catch (const std::exception& e) {
        LOG_ERROR << "camera: applying profile '" << profile.name << "' failed: " << e.what();
        return false;
    }
    // The next trigger() must not hand back a frame exposed under the old profile.
    impl_->last_captured_ts = nowMs();
    return true;
}

void VimbaCameraSource::stop() {
    if (!impl_->started) return;
    impl_->stopAcquisition();
    impl_->started = false;
}

bool VimbaCameraSource::trigger() {
    // Deliver the freshest complete frame per waypoint. This host's USB3 stream
    // reliably delivers the first frames of a session but stalls after a burst; if
    // no frame newer than the last capture is available, the stream has stalled -
    // restart acquisition to unstick it and wait briefly for a fresh frame. Without
    // this, keep-latest would hand the same stale frame to every remaining waypoint
    // (all overwriting one file).
    const long long newest = impl_->newestTs();

    // A session that has delivered NOTHING is warming up, not stalled. These are
    // different states that both fail the "no newer frame" test, and conflating
    // them is expensive: restarting throws away the warm-up and blocks the control
    // thread for 3 s, so a cold stream would be repeatedly reset just as it was
    // about to produce its first frame. Return empty-handed instead; the caller
    // retries every tick.
    if (newest == 0) {
        long long now = nowMs();
        if (now - impl_->last_no_frame_warn_ms > 5000) {
            LOG_WARN << "camera: no frame yet (stream warming up)";
            impl_->last_no_frame_warn_ms = now;
        }
        return false;
    }

    if (newest <= impl_->last_captured_ts) {
        LOG_TRACE_CAT(LogCat::Camera) << "stream stale; restarting acquisition";
        for (auto& s : impl_->stats) s->restarts.fetch_add(1);
        try {
            impl_->stopAcquisition();
            impl_->startAcquisition();
        } catch (const std::exception& e) {
            LOG_WARN << "camera: acquisition restart failed: " << e.what();
        }
        const long long deadline = nowMs() + 3000;
        while (impl_->newestTs() <= impl_->last_captured_ts && nowMs() < deadline)
            std::this_thread::sleep_for(std::chrono::milliseconds(50));
    }

    bool any = false;
    for (auto& obs : impl_->observers) {
        Frame f;
        if (SP_DYN_CAST<FrameObserver>(obs)->takeLatest(f)) {
            LOG_TRACE_CAT(LogCat::Camera) << "capture cam" << f.cam_id << " ts=" << f.timestamp_ms;
            impl_->last_captured_ts = std::max(impl_->last_captured_ts, f.timestamp_ms);
            if (impl_->callback) impl_->callback(f);
            any = true;
        }
    }
    if (!any) {
        // Frames HAVE arrived this session (the newest == 0 case returned above), so
        // this is the restart-did-not-help path. The scheduler retries every tick,
        // so rate-limit.
        long long now = nowMs();
        if (now - impl_->last_no_frame_warn_ms > 5000) {
            LOG_WARN << "camera: stream stalled and did not recover after a restart";
            impl_->last_no_frame_warn_ms = now;
        }
    }
    return any;
}

void VimbaCameraSource::setFrameCallback(FrameCallback cb) { impl_->callback = std::move(cb); }

int VimbaCameraSource::cameraCount() const { return static_cast<int>(impl_->cameras.size()); }

std::vector<CameraDeviceInfo> VimbaCameraSource::deviceInfo() {
    // Refresh the live sensor telemetry at most ~1 Hz - deviceInfo() is called every UI
    // tick (~10 Hz) but runs on the control thread (serialized with trigger()), and reading
    // camera features is not free. Identity + stats come from cached/atomic state.
    const long long now = nowMs();
    if (now - impl_->telemetry_ms > 1000) {
        impl_->telemetry_ms = now;
        for (size_t i = 0; i < impl_->cameras.size(); ++i) {
            auto&      cam = impl_->cameras[i];
            auto&      t   = impl_->telemetry[i];
            t.exposure_us    = getFloat(cam, "ExposureTime");
            t.gain_db        = getFloat(cam, "Gain");
            t.temperature_c  = getFloat(cam, "DeviceTemperature");
            t.actual_fps     = getFloat(cam, "AcquisitionFrameRate");
        }
    }

    std::vector<CameraDeviceInfo> out;
    out.reserve(impl_->cameras.size());
    for (size_t i = 0; i < impl_->cameras.size(); ++i) {
        const CamStats&        s = *impl_->stats[i];
        const Impl::Telemetry& t = impl_->telemetry[i];
        CameraDeviceInfo       d;
        d.id            = impl_->identity[i].id;
        d.model         = impl_->identity[i].model;
        d.serial        = impl_->identity[i].serial;
        d.streaming     = impl_->started && !impl_->observers.empty();
        d.width         = s.last_w.load();
        d.height        = s.last_h.load();
        d.payload_bytes = s.last_bytes.load();
        d.exposure_us   = t.exposure_us;
        d.gain_db       = t.gain_db;
        d.temperature_c = t.temperature_c;
        d.actual_fps    = t.actual_fps;
        d.frames_delivered = s.delivered.load();
        d.frames_dropped   = s.dropped.load();
        d.restarts         = s.restarts.load();
        out.push_back(std::move(d));
    }
    return out;
}

}  // namespace fgc