#include <fcntl.h>
#include <termios.h>
#include <unistd.h>
#include <sys/ioctl.h>
#include <sys/socket.h>
#include <netinet/in.h>
#include <arpa/inet.h>
#include <cstring>
#include <cerrno>
#include <vector>
#include <deque>
#include <thread>
#include <atomic>
#include <sstream>
#include <iomanip>
#include <signal.h>

#include "rclcpp/rclcpp.hpp"
#include "nmea_msgs/msg/sentence.hpp"
#include "geometry_msgs/msg/twist_stamped.hpp"
#include <cmath>

class SerialNtripNmea : public rclcpp::Node
{
public:
    SerialNtripNmea() : Node("serial_ntrip_nmea")
    {
        // 声明参数
        this->declare_parameter("serial_port", "/dev/ttyUSB0");
        this->declare_parameter("baud_rate", 115200);
        this->declare_parameter("ntrip_host", "103.143.19.54");
        this->declare_parameter("ntrip_port", 8002);
        this->declare_parameter("mountpoint", "RTCM32GRCpro");
        this->declare_parameter("username", "7ripg398");
        this->declare_parameter("password", "97344");
        this->declare_parameter("nmea_topic", "navsat/nmea_sentence");
        this->declare_parameter("frame_id", "sentence");
        
        // 获取参数
        serial_port_ = this->get_parameter("serial_port").as_string();
        baud_rate_ = this->get_parameter("baud_rate").as_int();
        ntrip_host_ = this->get_parameter("ntrip_host").as_string();
        ntrip_port_ = this->get_parameter("ntrip_port").as_int();
        mountpoint_ = this->get_parameter("mountpoint").as_string();
        username_ = this->get_parameter("username").as_string();
        password_ = this->get_parameter("password").as_string();
        nmea_topic_ = this->get_parameter("nmea_topic").as_string();
        frame_id_ = this->get_parameter("frame_id").as_string();
        
        // 创建NMEA消息发布器
        nmea_pub_ = this->create_publisher<nmea_msgs::msg::Sentence>(nmea_topic_, 10);
        // 额外创建一个带 RMC 航向修正的 NMEA 话题，保持原有话题行为不变
        nmea_fix_pub_ = this->create_publisher<nmea_msgs::msg::Sentence>("navsat/nmea_sentence_fix", 10);

        // 订阅 /cruise/wheel/twist 用于静止判定
        twist_sub_ = this->create_subscription<geometry_msgs::msg::TwistStamped>(
            "/cruise/wheel/twist", 10,
            std::bind(&SerialNtripNmea::twist_callback, this, std::placeholders::_1));
        
        RCLCPP_INFO(this->get_logger(), "SerialNtripNmea初始化:");
        RCLCPP_INFO(this->get_logger(), "  串口: %s @ %d baud", serial_port_.c_str(), baud_rate_);
        RCLCPP_INFO(this->get_logger(), "  NTRIP服务器: %s:%d", ntrip_host_.c_str(), ntrip_port_);
        RCLCPP_INFO(this->get_logger(), "  挂载点: %s", mountpoint_.c_str());
        RCLCPP_INFO(this->get_logger(), "  NMEA话题: %s", nmea_topic_.c_str());
        
        // 启动服务
        if (setup_serial() && connect_ntrip()) {
            running_ = true;
            start_server();
        }
    }
    
    ~SerialNtripNmea()
    {
        running_ = false;
        if (serial_fd_ >= 0) close(serial_fd_);
        if (ntrip_socket_ >= 0) close(ntrip_socket_);
    }

private:
    std::string serial_port_;
    int baud_rate_;
    std::string ntrip_host_;
    int ntrip_port_;
    std::string mountpoint_;
    std::string username_;
    std::string password_;
    std::string nmea_topic_;
    std::string frame_id_;
    
    int serial_fd_{-1};
    int ntrip_socket_{-1};
    rclcpp::Publisher<nmea_msgs::msg::Sentence>::SharedPtr nmea_pub_;
    rclcpp::Publisher<nmea_msgs::msg::Sentence>::SharedPtr nmea_fix_pub_;
    rclcpp::Subscription<geometry_msgs::msg::TwistStamped>::SharedPtr twist_sub_;
    rclcpp::TimerBase::SharedPtr status_timer_;
    std::atomic<bool> running_{false};
    std::atomic<bool> ntrip_connected_{false};

    // 静止判定：从 /cruise/wheel/twist 获取，linear.x==0 且 angular.z==0 为静止
    std::atomic<bool> is_stationary_{false};

    // RMC 静止航向修正相关状态（仅用于 navsat/nmea_sentence_fix）
    std::deque<double> rmc_heading_history_;
    bool in_stationary_mode_{false};
    bool stationary_heading_locked_{false};
    double stationary_locked_heading_{0.0};
    
    bool setup_serial()
    {
        serial_fd_ = open(serial_port_.c_str(), O_RDWR | O_NOCTTY | O_NONBLOCK);
        if (serial_fd_ < 0) {
            RCLCPP_ERROR(this->get_logger(), "串口打开失败: %s - %s", 
                         serial_port_.c_str(), strerror(errno));
            return false;
        }
        
        struct termios tty;
        if (tcgetattr(serial_fd_, &tty) != 0) {
            RCLCPP_ERROR(this->get_logger(), "获取串口属性失败: %s", strerror(errno));
            return false;
        }
        
        // 设置波特率
        speed_t speed;
        switch (baud_rate_) {
            case 9600: speed = B9600; break;
            case 19200: speed = B19200; break;
            case 38400: speed = B38400; break;
            case 57600: speed = B57600; break;
            case 115200: speed = B115200; break;
            case 230400: speed = B230400; break;
            default:
                RCLCPP_ERROR(this->get_logger(), "不支持的波特率: %d", baud_rate_);
                return false;
        }
        
        cfsetospeed(&tty, speed);
        cfsetispeed(&tty, speed);
        
        // 设置串口参数
        tty.c_cflag &= ~PARENB;
        tty.c_cflag &= ~CSTOPB;
        tty.c_cflag &= ~CSIZE;
        tty.c_cflag |= CS8;
        tty.c_cflag &= ~CRTSCTS;
        tty.c_cflag |= (CREAD | CLOCAL);
        
        tty.c_lflag = 0;
        tty.c_iflag = 0;
        tty.c_oflag = 0;
        
        tty.c_cc[VTIME] = 0;
        tty.c_cc[VMIN] = 0;
        
        if (tcsetattr(serial_fd_, TCSANOW, &tty) != 0) {
            RCLCPP_ERROR(this->get_logger(), "设置串口属性失败: %s", strerror(errno));
            return false;
        }
        
        tcflush(serial_fd_, TCIOFLUSH);
        RCLCPP_INFO(this->get_logger(), "串口连接成功: %s", serial_port_.c_str());
        return true;
    }
    
    bool connect_ntrip()
    {
        ntrip_socket_ = socket(AF_INET, SOCK_STREAM, 0);
        if (ntrip_socket_ < 0) {
            RCLCPP_ERROR(this->get_logger(), "创建NTRIP socket失败: %s", strerror(errno));
            return false;
        }
        
        struct sockaddr_in ntrip_addr;
        ntrip_addr.sin_family = AF_INET;
        ntrip_addr.sin_port = htons(ntrip_port_);
        ntrip_addr.sin_addr.s_addr = inet_addr(ntrip_host_.c_str());
        
        if (connect(ntrip_socket_, (struct sockaddr*)&ntrip_addr, sizeof(ntrip_addr)) < 0) {
            RCLCPP_ERROR(this->get_logger(), "连接NTRIP服务器失败: %s", strerror(errno));
            return false;
        }
        
        // 构建NTRIP请求
        std::string auth_string = username_ + ":" + password_;
        std::string auth_b64 = base64_encode(auth_string);
        
        std::stringstream request;
        request << "GET /" << mountpoint_ << " HTTP/1.1\r\n";
        request << "User-Agent: NTRIP SerialNtripNmea/1.0\r\n";
        request << "Authorization: Basic " << auth_b64 << "\r\n";
        request << "Accept: gnss/data\r\n";
        request << "Connection: close\r\n";
        request << "\r\n";
        
        std::string request_str = request.str();
        
        RCLCPP_INFO(this->get_logger(), "发送NTRIP请求到服务器: %s:%d", ntrip_host_.c_str(), ntrip_port_);
        
        ssize_t sent = send(ntrip_socket_, request_str.c_str(), request_str.length(), 0);
        if (sent < 0) {
            RCLCPP_ERROR(this->get_logger(), "发送NTRIP请求失败: %s", strerror(errno));
            return false;
        }
        
        // 读取响应
        char buffer[1024];
        ssize_t received = recv(ntrip_socket_, buffer, sizeof(buffer) - 1, 0);
        if (received > 0) {
            buffer[received] = '\0';
            std::string response(buffer);
            
            if (response.find("200") != std::string::npos) {
                ntrip_connected_ = true;
                RCLCPP_INFO(this->get_logger(), "NTRIP连接成功: %s", mountpoint_.c_str());
                return true;
            } else {
                RCLCPP_ERROR(this->get_logger(), "NTRIP连接失败: %s", response.c_str());
            }
        } else {
            RCLCPP_ERROR(this->get_logger(), "未收到NTRIP服务器响应");
        }
        
        return false;
    }
    
    void twist_callback(const geometry_msgs::msg::TwistStamped::ConstSharedPtr msg)
    {
        constexpr double eps = 1e-6;
        bool stationary = (std::fabs(msg->twist.linear.x) < eps) &&
                          (std::fabs(msg->twist.angular.z) < eps);
        is_stationary_.store(stationary);
    }

    void start_server()
    {
        // 启动串口数据读取和NTRIP发送线程
        std::thread serial_thread(&SerialNtripNmea::read_serial_and_process, this);
        serial_thread.detach();
        
        // 启动NTRIP数据接收和写入串口线程
        std::thread ntrip_thread(&SerialNtripNmea::read_ntrip_and_write_serial, this);
        ntrip_thread.detach();
        
        // 使用定时器显示状态，使 spin() 能处理 twist 订阅回调
        status_timer_ = this->create_wall_timer(
            std::chrono::seconds(1),
            [this]() {
                if (rclcpp::ok() && running_) {
                    RCLCPP_INFO(this->get_logger(), "运行状态 - NTRIP连接: %s", ntrip_connected_ ? "是" : "否");
                }
            });
    }
    
    void read_serial_and_process()
    {
        std::vector<char> buffer(1024);
        std::string nmea_buffer;
        
        RCLCPP_INFO(this->get_logger(), "开始读取串口数据并处理");
        
        while (rclcpp::ok() && running_) {
            ssize_t bytes_read = read(serial_fd_, buffer.data(), buffer.size());
            if (bytes_read > 0) {
                // 处理接收到的数据
                for (ssize_t i = 0; i < bytes_read; ++i) {
                    char c = buffer[i];
                    nmea_buffer += c;
                    
                    // 检测NMEA语句结束符（换行符）
                    if (c == '\n') {
                        // 移除换行符和回车符
                        if (!nmea_buffer.empty()) {
                            // 先移除可能的换行符 '\n'
                            if (nmea_buffer.back() == '\n') {
                                nmea_buffer.pop_back();
                                // 再移除可能的回车符 '\r'
                                if (!nmea_buffer.empty() && nmea_buffer.back() == '\r') {
                                    nmea_buffer.pop_back();
                                }
                            } else if (nmea_buffer.back() == '\r') {
                                // 如果只有回车符，直接移除
                                nmea_buffer.pop_back();
                            }
                        }
                        
                        // 检查是否为有效的NMEA语句（以$开头）
                        if (!nmea_buffer.empty() && nmea_buffer[0] == '$') {
                            // 发布NMEA消息到ROS话题
                            auto nmea_msg = nmea_msgs::msg::Sentence();
                            nmea_msg.header.frame_id = frame_id_;
                            nmea_msg.header.stamp = this->now();
                            nmea_msg.sentence = nmea_buffer;
                            
                            // 原始 NMEA 话题，行为保持不变
                            nmea_pub_->publish(nmea_msg);
                            
                            // 带 RMC 航向修正的 NMEA 话题
                            auto nmea_msg_fix = nmea_msg;
                            nmea_msg_fix.sentence = make_fixed_nmea_sentence(nmea_buffer);
                            nmea_fix_pub_->publish(nmea_msg_fix);
                            
                            RCLCPP_DEBUG(this->get_logger(), "发布NMEA消息: %s", nmea_buffer.c_str());
                            
                            // 检查是否为GGA语句，发送到NTRIP服务器
                            bool is_gga = false;
                            if (nmea_buffer.length() >= 6) {
                                std::string nmea_type = nmea_buffer.substr(1, 5);
                                if (nmea_type == "GPGGA" || nmea_type == "GNGGA") {
                                    is_gga = true;
                                }
                            }
                            
                            if (is_gga && ntrip_connected_) {
                                // 发送GGA数据到NTRIP服务器
                                ssize_t sent = send(ntrip_socket_, nmea_buffer.c_str(), nmea_buffer.length(), 
                                                   MSG_DONTWAIT | MSG_NOSIGNAL);
                                if (sent > 0) {
                                    RCLCPP_DEBUG(this->get_logger(), "发送GGA数据到NTRIP: %s", nmea_buffer.c_str());
                                } else if (sent < 0) {
                                    if (errno == EPIPE || errno == ECONNRESET) {
                                        RCLCPP_ERROR(this->get_logger(), "NTRIP连接断开");
                                        ntrip_connected_ = false;
                                    }
                                }
                            }
                        }
                        
                        nmea_buffer.clear();
                    }
                }
                
                RCLCPP_DEBUG(this->get_logger(), "从串口接收到 %zd bytes 数据", bytes_read);
                
            } else if (bytes_read < 0) {
                if (errno == EAGAIN || errno == EWOULDBLOCK) {
                    usleep(10000); // 10ms轮询间隔
                } else {
                    RCLCPP_ERROR(this->get_logger(), "串口读取错误: %s", strerror(errno));
                    break;
                }
            } else {
                usleep(10000); // 10ms轮询间隔
            }
        }
    }
    
    void read_ntrip_and_write_serial()
    {
        std::vector<char> buffer(4096);
        
        while (rclcpp::ok() && running_ && ntrip_connected_) {
            ssize_t bytes_read = recv(ntrip_socket_, buffer.data(), buffer.size(), MSG_DONTWAIT);
            if (bytes_read > 0) {
                // 将NTRIP返回的数据写入串口
                ssize_t bytes_written = write(serial_fd_, buffer.data(), bytes_read);
                if (bytes_written > 0) {
                    RCLCPP_DEBUG(this->get_logger(), "写入串口NTRIP数据: %zd bytes", bytes_written);
                } else if (bytes_written < 0) {
                    if (errno == EAGAIN || errno == EWOULDBLOCK) {
                        RCLCPP_WARN(this->get_logger(), "串口写入缓冲区满");
                    } else {
                        RCLCPP_ERROR(this->get_logger(), "串口写入错误: %s", strerror(errno));
                    }
                }
                
            } else if (bytes_read == 0) {
                RCLCPP_ERROR(this->get_logger(), "NTRIP服务器断开连接");
                ntrip_connected_ = false;
                break;
            } else {
                if (errno == EAGAIN || errno == EWOULDBLOCK) {
                    usleep(10000); // 10ms轮询间隔
                } else {
                    RCLCPP_ERROR(this->get_logger(), "NTRIP读取错误: %s", strerror(errno));
                    ntrip_connected_ = false;
                    break;
                }
            }
        }
        
        // 尝试重新连接
        if (running_ && !ntrip_connected_) {
            RCLCPP_INFO(this->get_logger(), "尝试重新连接NTRIP服务器...");
            usleep(5000000); // 5秒后重试
            if (connect_ntrip()) {
                std::thread ntrip_thread(&SerialNtripNmea::read_ntrip_and_write_serial, this);
                ntrip_thread.detach();
            }
        }
    }
    
    std::string base64_encode(const std::string& input)
    {
        static const std::string base64_chars = 
            "ABCDEFGHIJKLMNOPQRSTUVWXYZ"
            "abcdefghijklmnopqrstuvwxyz"
            "0123456789+/";
            
        std::string encoded;
        int i = 0;
        int j = 0;
        unsigned char char_array_3[3];
        unsigned char char_array_4[4];
        
        for (char c : input) {
            char_array_3[i++] = c;
            if (i == 3) {
                char_array_4[0] = (char_array_3[0] & 0xfc) >> 2;
                char_array_4[1] = ((char_array_3[0] & 0x03) << 4) + ((char_array_3[1] & 0xf0) >> 4);
                char_array_4[2] = ((char_array_3[1] & 0x0f) << 2) + ((char_array_3[2] & 0xc0) >> 6);
                char_array_4[3] = char_array_3[2] & 0x3f;
                
                for(i = 0; i < 4; i++)
                    encoded += base64_chars[char_array_4[i]];
                i = 0;
            }
        }
        
        if (i) {
            for(j = i; j < 3; j++)
                char_array_3[j] = '\0';
            
            char_array_4[0] = (char_array_3[0] & 0xfc) >> 2;
            char_array_4[1] = ((char_array_3[0] & 0x03) << 4) + ((char_array_3[1] & 0xf0) >> 4);
            char_array_4[2] = ((char_array_3[1] & 0x0f) << 2) + ((char_array_3[2] & 0xc0) >> 6);
            char_array_4[3] = char_array_3[2] & 0x3f;
            
            for (j = 0; j < i + 1; j++)
                encoded += base64_chars[char_array_4[j]];
            
            while(i++ < 3)
                encoded += '=';
        }
        
        return encoded;
    }
    
    // 生成带 RMC 航向修正的 NMEA 语句，仅影响 navsat/nmea_sentence_fix 话题
    std::string make_fixed_nmea_sentence(const std::string& sentence)
    {
        // 只处理以 $ 开头的 RMC 语句，其余直接原样返回
        if (sentence.size() < 6 || sentence[0] != '$') {
            return sentence;
        }
        
        std::string type = sentence.substr(1, 5);
        if (type != "GPRMC" && type != "GNRMC") {
            return sentence;
        }
        
        // 分离出不含校验和的部分（$ 与 * 之间）
        std::size_t asterisk_pos = sentence.find('*');
        std::string body_no_checksum;
        if (asterisk_pos == std::string::npos) {
            // 没有显式校验和时，直接去掉起始的 $
            body_no_checksum = sentence.substr(1);
        } else {
            body_no_checksum = sentence.substr(1, asterisk_pos - 1);
        }
        
        // 使用逗号分隔字段
        std::vector<std::string> fields;
        std::size_t start = 0;
        while (true) {
            std::size_t comma = body_no_checksum.find(',', start);
            if (comma == std::string::npos) {
                fields.emplace_back(body_no_checksum.substr(start));
                break;
            } else {
                fields.emplace_back(body_no_checksum.substr(start, comma - start));
                start = comma + 1;
            }
        }
        
        // RMC 标准字段中，索引 7 为地速（节），索引 8 为真航向
        if (fields.size() <= 8) {
            return sentence;
        }
        
        bool heading_ok = false;
        double heading_deg = 0.0;

        if (!fields[8].empty()) {
            try {
                heading_deg = std::stod(fields[8]);
                heading_ok = true;
            } catch (...) {
                heading_ok = false;
            }
        }
        
        if (!heading_ok) {
            // 航向字段无法解析时，不做任何改动
            return sentence;
        }

        // 静止判定：从 /cruise/wheel/twist 获取，linear.x==0 且 angular.z==0 为静止
        bool stationary = is_stationary_.load();

        // 进入/退出静止模式（在写入历史前判定，使用前10条那条数据的航向）
        if (stationary) {
            std::cout << "进入静止模式" << std::endl;
            bool just_entered = !in_stationary_mode_;
            in_stationary_mode_ = true;
            if (just_entered && rmc_heading_history_.size() >= 10) {
                stationary_locked_heading_ = rmc_heading_history_[rmc_heading_history_.size() - 10];
                stationary_heading_locked_ = true;
            }
        } else {
            std::cout << "退出静止模式" << std::endl;
            in_stationary_mode_ = false;
            stationary_heading_locked_ = false;
        }

        // 记录当前 RMC 航向到历史（用于下次静止时取前10条）
        rmc_heading_history_.push_back(heading_deg);
        if (rmc_heading_history_.size() > 50) {
            rmc_heading_history_.pop_front();
        }

        double output_heading = heading_deg;
        if (in_stationary_mode_ && stationary_heading_locked_) {
            output_heading = stationary_locked_heading_;
        }
        
        // 更新航向字段
        {
            std::ostringstream oss;
            oss << std::fixed << std::setprecision(2) << output_heading;
            fields[8] = oss.str();
        }
        
        // 重新拼接不含校验和的部分
        std::ostringstream body_oss;
        for (std::size_t i = 0; i < fields.size(); ++i) {
            if (i > 0) {
                body_oss << ',';
            }
            body_oss << fields[i];
        }
        std::string new_body_no_checksum = body_oss.str();
        
        // 重新计算校验和（对 $ 与 * 之间的字符做 XOR）
        unsigned char checksum = 0;
        for (char ch : new_body_no_checksum) {
            checksum ^= static_cast<unsigned char>(ch);
        }
        
        std::ostringstream result;
        result << '$' << new_body_no_checksum << '*'
               << std::uppercase << std::hex << std::setw(2) << std::setfill('0')
               << static_cast<int>(checksum);
        
        return result.str();
    }
};

int main(int argc, char** argv)
{
    // 忽略SIGPIPE信号
    signal(SIGPIPE, SIG_IGN);
    
    rclcpp::init(argc, argv);
    auto node = std::make_shared<SerialNtripNmea>();
    rclcpp::spin(node);
    rclcpp::shutdown();
    return 0;
}