// OLEI 2D lidars over UDP — Family A (0xFAF0), Family B (0xFEF0) and
// Family C / Protocol V3 (0xFEAC, GS1-5) packet parsing.
#include "olei_driver.hpp"
#include "plugin_helpers.hpp"

#include <cerrno>
#include <cstring>
#include <cmath>
#include <arpa/inet.h>
#include <sys/select.h>
#include <sys/socket.h>
#include <unistd.h>

namespace xlidar {

// Normalize into (-180, 180]: 0 = ahead, + = left, - = right.
static inline float to_signed_deg(float deg) {
    deg = std::fmod(deg, 360.f);
    if (deg < 0.f)    deg += 360.f;
    if (deg > 180.f)  deg -= 360.f;
    return deg;
}

static inline float maybe_invert(float signed_deg, bool inverted) {
    return inverted ? to_signed_deg(-signed_deg) : signed_deg;
}

// CRC32 poly 0x04C11DB7, MSB-first
static uint32_t crc32_olei(const uint8_t* data, size_t len) {
    uint32_t crc = 0xFFFFFFFF;
    for (size_t i = 0; i < len; ++i) {
        crc ^= static_cast<uint32_t>(data[i]) << 24;
        for (int b = 0; b < 8; ++b)
            crc = (crc & 0x80000000u) ? (crc << 1) ^ 0x04C11DB7u : (crc << 1);
    }
    return crc;
}

static constexpr uint16_t FRAME_ID_A = 0xFAF0;  // 2D Ethernet (VB, VF, LR-1F)
static constexpr uint16_t FRAME_ID_B = 0xFEF0;  // LR-1BS5 / LR-1BS2 Ethernet variant
static constexpr uint16_t FRAME_ID_C = 0xFEAC;  // Protocol V3 (GS1-5)

OleiDriver::OleiDriver(const ModelConfig& cfg, const std::string& ip, uint16_t port,
                       bool inverted)
    : cfg_(cfg), ip_(ip), port_(port), inverted_(inverted)
{
    auto_detect_ = (std::strcmp(cfg.name, "AUTO") == 0);
}

OleiDriver::~OleiDriver() { close(); }

ErrorCode OleiDriver::open() {
    if (is_open()) return set_error(ErrorCode::AlreadyOpen);

    sockaddr_in addr{};
    addr.sin_family = AF_INET;
    addr.sin_port   = htons(port_);
    if (::inet_pton(AF_INET, ip_.c_str(), &addr.sin_addr) != 1)
        return set_error(ErrorCode::InvalidAddress);

    sock_fd_ = ::socket(AF_INET, SOCK_DGRAM, 0);
    if (sock_fd_ < 0) return set_error(ErrorCode::SocketError);

    int reuse = 1;
    ::setsockopt(sock_fd_, SOL_SOCKET, SO_REUSEADDR, &reuse, sizeof(reuse));
#ifdef SO_REUSEPORT
    ::setsockopt(sock_fd_, SOL_SOCKET, SO_REUSEPORT, &reuse, sizeof(reuse));
#endif

    if (::bind(sock_fd_, reinterpret_cast<sockaddr*>(&addr), sizeof(addr)) < 0) {
        int err = errno;
        ::close(sock_fd_);
        sock_fd_ = -1;
        return set_error((err == EADDRINUSE || err == EACCES) ? ErrorCode::PortInUse
                                                              : ErrorCode::BindFailed);
    }

    // Reset per-revolution state so a close()/open() cycle starts clean.
    pending_angle_deg_.clear();
    pending_dist_m_.clear();
    pending_intensity_.clear();
    pending_info_ = ExtraInfo{};
    latest_diag_  = Diagnostics{};
    last_angle_   = -1.f;
    scan_ready_   = false;

    pending_angle_deg_.reserve(2048);
    pending_dist_m_.reserve(2048);
    pending_intensity_.reserve(2048);
    return set_error(ErrorCode::Ok);
}

void OleiDriver::close() {
    if (sock_fd_ >= 0) {
        ::close(sock_fd_);
        sock_fd_ = -1;
    }
}

bool OleiDriver::recv_scan(ScanResult& out, int timeout_ms) {
    if (!is_open()) { set_error(ErrorCode::NotOpen); return false; }
    scan_ready_ = false;

    while (!scan_ready_) {
        if (timeout_ms > 0) {
            fd_set fds; FD_ZERO(&fds); FD_SET(sock_fd_, &fds);
            timeval tv{ timeout_ms / 1000, (timeout_ms % 1000) * 1000 };
            int r = ::select(sock_fd_ + 1, &fds, nullptr, nullptr, &tv);
            if (r <= 0) {
                set_error(r == 0 ? ErrorCode::Timeout : ErrorCode::DeviceDisconnected);
                return false;
            }
        }
        if (!poll_packet()) return false;
    }
    out = std::move(ready_result_);
    set_error(ErrorCode::Ok);
    return true;
}

bool OleiDriver::spin_once() {
    if (!poll_packet()) return false;
    if (scan_ready_) {
        scan_ready_ = false;
        if (cb_) cb_(ready_result_);
    }
    return true;
}

bool OleiDriver::poll_packet() {
    if (!is_open()) { set_error(ErrorCode::NotOpen); return false; }
    uint8_t* buf = recv_buf_;
    sockaddr_in from{};
    socklen_t   fromlen = sizeof(from);

    ssize_t n = ::recvfrom(sock_fd_, buf, sizeof(recv_buf_), 0,
                            reinterpret_cast<sockaddr*>(&from), &fromlen);
    if (n < 0) { set_error(ErrorCode::DeviceDisconnected); return false; }

    // A/C carry the frame id at [0-1]; B has a 0x010F preamble, real id at [2-3].
    if (n < 4) return true;
    uint16_t id_at_0 = le16(buf);
    uint16_t frame_id_b = le16(buf + 2);

    if      (id_at_0 == FRAME_ID_A)    parse_family_a(buf, static_cast<int>(n));
    else if (id_at_0 == FRAME_ID_C)    parse_family_c(buf, static_cast<int>(n));
    else if (frame_id_b == FRAME_ID_B) parse_family_b(buf, static_cast<int>(n));

    return true;
}

// Append with angle-unwrapping so the ±180° seam stays a continuous ramp.
void OleiDriver::push_point(float signed_angle_deg, float dist_m, uint8_t intensity) {
    float angle = signed_angle_deg;
    if (!pending_angle_deg_.empty()) {
        float prev = pending_angle_deg_.back();
        while (angle - prev >  180.f) angle -= 360.f;
        while (angle - prev < -180.f) angle += 360.f;
    }
    pending_angle_deg_.push_back(angle);
    pending_dist_m_.push_back(dist_m);
    pending_intensity_.push_back(intensity);
}

void OleiDriver::flush_scan() {
    if (pending_angle_deg_.empty()) return;

    const size_t n = pending_angle_deg_.size();

    LaserScan& scan      = ready_result_.scan;
    scan.timestamp_ms     = pending_ts_;
    scan.angle_min        = pending_angle_deg_.front() * kDeg2Rad;
    scan.angle_max        = pending_angle_deg_.back()  * kDeg2Rad;
    scan.angle_increment  = (n > 1)
        ? (scan.angle_max - scan.angle_min) / static_cast<float>(n - 1) : 0.f;
    scan.time_increment   = 0.f;
    scan.scan_time        = 0.f;
    scan.range_min        = cfg_.range_min_m;
    scan.range_max        = cfg_.range_max_m;
    scan.ranges.assign(pending_dist_m_.begin(), pending_dist_m_.end());
    scan.intensities.assign(pending_intensity_.begin(), pending_intensity_.end());

    // Inversion already happened per point (maybe_invert), so inverted=false.
    finalize_scan(scan, cfg_, /*inverted=*/false);

    ExtraInfo& info  = ready_result_.info;
    info             = pending_info_;
    info.detected_model = detected_model_name_;
    info.error_status    = pending_err_;

    latest_diag_ = decode_diagnostics(info);
    latest_diag_.device_timestamp_ms = scan.timestamp_ms;
    mark_scan_decoded();

    pending_angle_deg_.clear();
    pending_dist_m_.clear();
    pending_intensity_.clear();
    pending_info_ = ExtraInfo{};
    scan_ready_   = true;
}

// Family A (0xFAF0): 20B header + 3B blocks (u16 dist, u8 intensity).
bool OleiDriver::parse_family_a(const uint8_t* buf, int len) {
    static constexpr int HEADER_LEN = 20;
    static constexpr int BLOCK_LEN  =  3;

    if (len < HEADER_LEN) return false;

    uint8_t  dist_scale = buf[4];           // mm per count
    uint8_t  err_status = buf[5];
    float    ang_start  = static_cast<float>(buf[6]);
    uint16_t num_pts    = le16(buf + 8);
    uint16_t rotation_raw = le16(buf + 10);
    uint32_t timestamp  = le32(buf + 12);
    uint32_t crc_packet = le32(buf + 16);

    int block_bytes = len - HEADER_LEN;
    if (block_bytes < num_pts * BLOCK_LEN) return false;

    uint32_t crc_calc = crc32_olei(buf + HEADER_LEN, static_cast<size_t>(num_pts * BLOCK_LEN));
    if (crc_calc != crc_packet) return false;

    if (last_angle_ >= 0.f && ang_start < last_angle_ - 90.f) {
        flush_scan();
    }

    pending_ts_  = timestamp;
    pending_err_ = err_status;
    pending_info_.distance_scale_mm = dist_scale;
    pending_info_.rotation_raw      = rotation_raw;

    const float scale_mm = (dist_scale ? static_cast<float>(dist_scale) : 1.f);
    const float ang_end  = static_cast<float>(buf[7]);

    const uint8_t* blk = buf + HEADER_LEN;
    for (uint16_t i = 0; i < num_pts; ++i, blk += BLOCK_LEN) {
        uint16_t dist_raw = le16(blk);
        uint8_t  intensity = blk[2];

        float frac  = (num_pts > 1) ? static_cast<float>(i) / (num_pts - 1) : 0.f;
        float angle = to_signed_deg(ang_start + frac * (ang_end - ang_start) + cfg_.angle_offset_deg);
        angle       = maybe_invert(angle, inverted_);

        if (angle < cfg_.scan_angle_min || angle > cfg_.scan_angle_max) continue;

        push_point(angle, dist_raw * scale_mm * 0.001f, intensity);
    }

    last_angle_ = ang_start;
    return true;
}

// Family B (0xFEF0): 40B header (model string at [7-16]) + 8B blocks
// (u16 angle ×0.01°, u16 dist, u16 signal). No timestamp/error on the wire.
bool OleiDriver::parse_family_b(const uint8_t* buf, int len) {
    static constexpr int HEADER_LEN = 40;
    static constexpr int BLOCK_LEN  =  8;

    if (len < HEADER_LEN) return false;

    uint8_t dist_scale = buf[6];
    const float scale_mm = (dist_scale ? static_cast<float>(dist_scale) : 1.f);
    pending_info_.distance_scale_mm = dist_scale;
    if (auto_detect_ && !model_locked_) {
        std::string raw(reinterpret_cast<const char*>(buf + 7), 10);
        size_t z = raw.find('\0');
        if (z != std::string::npos) raw.resize(z);

        if (!raw.empty()) {
            detected_model_name_ = raw;
            model_locked_        = true;

            static constexpr struct { const char* key; const ModelConfig* cfg; } kModelTable[] = {
                { "1BS5", &MODEL_LR1BS5 },
                { "16F",  &MODEL_LR16F  },
                { "1FMI", &MODEL_LR1FMI },  // must precede "1F": "OLELR-1FMI" also contains "1F"
                { "1F",   &MODEL_LR1F   },
                { "VF",   &MODEL_VF     },
                { "VB",   &MODEL_VB     },
            };
            for (const auto& entry : kModelTable) {
                if (raw.find(entry.key) != std::string::npos) {
                    cfg_.scan_angle_min   = entry.cfg->scan_angle_min;
                    cfg_.scan_angle_max   = entry.cfg->scan_angle_max;
                    cfg_.range_min_m      = entry.cfg->range_min_m;
                    cfg_.range_max_m      = entry.cfg->range_max_m;
                    cfg_.angle_offset_deg = entry.cfg->angle_offset_deg;
                    break;
                }
            }
        }
    }

    int num_pts = (len - HEADER_LEN) / BLOCK_LEN;
    if (num_pts <= 0) return false;

    const uint8_t* blk = buf + HEADER_LEN;
    // A packet is only a ~22° arc and may span >1 rev, so the revolution
    // boundary is detected per point: a >90° drop between consecutive angles.
    static constexpr uint16_t INVALID_ANGLE = 0xFF00;
    for (int i = 0; i < num_pts; ++i, blk += BLOCK_LEN) {
        uint16_t angle_raw = le16(blk);
        if (angle_raw >= INVALID_ANGLE) continue;

        float    dev_deg   = std::fmod(angle_raw * 0.01f, 360.f);
        if (last_angle_ >= 0.f && dev_deg < last_angle_ - 90.f) {
            flush_scan();
        }
        last_angle_ = dev_deg;

        float    angle     = maybe_invert(to_signed_deg(angle_raw * 0.01f + cfg_.angle_offset_deg), inverted_);
        float    dist_m    = le16(blk + 2) * scale_mm * 0.001f;
        uint8_t  intensity = static_cast<uint8_t>(le16(blk + 4) >> 2);   // 10-bit → 8-bit

        if (angle < cfg_.scan_angle_min || angle > cfg_.scan_angle_max) continue;

        push_point(angle, dist_m, intensity);
    }

    return true;
}

// Family C / Protocol V3 (0xFEAC, GS1-5): 48B header + 2 or 4B points depending
// on Types. Ported from the C# driver OleiGS15Driver.cs; NOT verified on real
// hardware. Angle = (FirstIndex + i) * (360 / NumPointsScan) - 180.
bool OleiDriver::parse_family_c(const uint8_t* buf, int len) {
    static constexpr int HEADER_LEN = 48;
    if (len < HEADER_LEN) return false;

    uint16_t header_size_field = le16(buf + 8);
    uint8_t  distance_ratio_raw = buf[10];
    uint8_t  types             = buf[11];
    uint16_t scan_frequency_raw = le16(buf + 24);
    uint16_t num_pts_scan      = le16(buf + 26);
    uint16_t input_status      = le16(buf + 28);
    uint16_t output_status     = le16(buf + 30);
    uint32_t field_status      = le32(buf + 32);
    uint16_t first_index       = le16(buf + 40);
    uint16_t num_pts_packet    = le16(buf + 42);
    uint32_t status_flags      = le32(buf + 44);

    if (num_pts_scan == 0) return false;

    int header_size = (header_size_field == 0) ? HEADER_LEN : header_size_field;
    if (header_size < HEADER_LEN || header_size > len) return false;

    // Types: 0x00 = 2B/point (range only), 0x01 = 4B (range+intensity),
    // 0x10 = 4B (range at [+2,+4)).
    int bytes_per_point = (types == 0x00) ? 2 : (types == 0x01 || types == 0x10) ? 4 : 0;
    if (bytes_per_point == 0) return false;

    int payload_bytes = len - header_size;
    int num_pts        = num_pts_packet;
    if (num_pts == 0 || num_pts * bytes_per_point > payload_bytes) {
        num_pts = payload_bytes / bytes_per_point;
    }
    if (num_pts <= 0) return false;

    pending_info_.distance_ratio_raw  = distance_ratio_raw;
    pending_info_.scan_frequency_raw  = scan_frequency_raw;
    pending_info_.input_status        = input_status;
    pending_info_.output_status       = output_status;
    pending_info_.field_status        = field_status;
    pending_info_.status_flags        = status_flags;

    // Magic 0xFEAC == exactly one model (GS1-5).
    if (auto_detect_ && !model_locked_) {
        cfg_.scan_angle_min   = MODEL_GS15.scan_angle_min;
        cfg_.scan_angle_max   = MODEL_GS15.scan_angle_max;
        cfg_.range_min_m      = MODEL_GS15.range_min_m;
        cfg_.range_max_m      = MODEL_GS15.range_max_m;
        cfg_.angle_offset_deg = MODEL_GS15.angle_offset_deg;
        detected_model_name_  = MODEL_GS15.name;
        model_locked_         = true;
    }

    const float angle_inc = 360.f / static_cast<float>(num_pts_scan);
    float raw_first_angle = static_cast<float>(first_index) * angle_inc;

    if (last_angle_ >= 0.f && raw_first_angle < last_angle_ - 90.f) {
        flush_scan();
    }

    const uint8_t* blk = buf + header_size;
    for (int i = 0; i < num_pts; ++i, blk += bytes_per_point) {
        uint16_t range_mm;
        uint16_t inten_raw = 0;
        bool     has_inten = false;

        if (types == 0x00) {
            range_mm = le16(blk);
        } else if (types == 0x01) {
            range_mm  = le16(blk);
            inten_raw = le16(blk + 2);
            has_inten = true;
        } else {  // 0x10
            range_mm = le16(blk + 2);
        }

        float angle = to_signed_deg(static_cast<float>(first_index + i) * angle_inc - 180.f + cfg_.angle_offset_deg);
        angle       = maybe_invert(angle, inverted_);
        if (angle < cfg_.scan_angle_min || angle > cfg_.scan_angle_max) continue;

        push_point(angle, range_mm * 0.001f,
                   has_inten ? static_cast<uint8_t>(inten_raw > 255 ? 255 : inten_raw) : uint8_t{0});
    }

    last_angle_ = raw_first_angle;
    return true;
}

// ── plugin registration ─────────────────────────────────────────────────────

namespace {

const DriverInfo kDriverInfo = [] {
    DriverInfo info;
    info.vendor      = "OLEI";
    info.model       = "2D series (VB/VF/LR-1x/GS1-5)";
    info.driver_id   = "olei_lidar_driver";
    info.description = "OLEI 2D lidars over UDP — auto-detects the Family A/B/C "
                       "protocol per packet; model AUTO self-detects from the "
                       "stream (Family B/C). Default port 2368.";
    info.transport   = Transport::Udp;
    info.supported_models = {"AUTO", "VB", "VF", "LR-1F", "LR-1FMI", "LR-1BS5",
                             "LR-16F", "GS1-5"};
    return info;
}();

const ModelConfig* model_by_name(const std::string& name) {
    static constexpr const ModelConfig* kModels[] = {
        &MODEL_AUTO, &MODEL_VB, &MODEL_VF, &MODEL_LR1F, &MODEL_LR1FMI,
        &MODEL_LR1BS5, &MODEL_LR16F, &MODEL_GS15,
    };
    for (const ModelConfig* m : kModels)
        if (name == m->name) return m;
    return nullptr;
}

} // namespace

DriverInfo OleiDriver::get_driver_info() const { return kDriverInfo; }

} // namespace xlidar

XLIDAR_PLUGIN_EXPORT void get_driver_info(xlidar::DriverInfo* out) {
    *out = xlidar::kDriverInfo;
}

XLIDAR_PLUGIN_EXPORT xlidar::LidarDriverInterface*
create_driver_instance(const xlidar::DeviceConfig* cfg) {
    using namespace xlidar;
    if (!transport_supported(kDriverInfo, *cfg))
        return new InvalidConfigDriver(kDriverInfo,
            std::string("unsupported transport '") + to_string(*cfg->transport) + "'");
    const ModelConfig* preset = model_by_name(cfg->model);
    if (!preset) preset = &MODEL_AUTO;  // unknown model → auto-detect
    const uint16_t port = cfg->port ? cfg->port : 2368;
    return new OleiDriver(apply_device_config(*preset, *cfg), cfg->ip, port, cfg->inverted);
}