##
## SL2-100 UDP Forwarder
## 监控 CSV 文件，将新行通过 UDP 发送到目标端口
##
## 用法: python udp_forwarder.py [csv文件路径] [目标IP] [目标端口]
## 示例: python udp_forwarder.py d:/sl2-100.csv 127.0.0.1 12345
## 默认: python udp_forwarder.py d:/sl2-100.csv 127.0.0.1 12345
##

import socket
import sys
import os
import time


def main():
    # 默认参数
    csv_file = "d:/sl2-100.csv"
    target_host = "192.168.1.155"
    target_port = 41234

    # 命令行参数解析
    if len(sys.argv) >= 2:
        csv_file = sys.argv[1]
    if len(sys.argv) >= 3:
        target_host = sys.argv[2]
    if len(sys.argv) >= 4:
        target_port = int(sys.argv[3])

    print(f"[UDP Forwarder] 启动")
    print(f"  CSV 文件: {csv_file}")
    print(f"  UDP 目标: {target_host}:{target_port}")
    print(f"  等待 CSV 文件生成...")

    # 创建 UDP socket
    sock = socket.socket(socket.AF_INET, socket.SOCK_DGRAM)

    # 等待 CSV 文件出现
    while not os.path.exists(csv_file):
        time.sleep(0.1)

    print(f"  CSV 文件已发现，开始监控...")

    # 读取文件初始大小（跳过表头）
    file_size = os.path.getsize(csv_file)
    with open(csv_file, 'r', encoding='gbk') as f:
        header = f.readline()  # 跳过 "x坐标,y坐标" 表头
        file_size = os.path.getsize(csv_file)
    print(f"  已跳过表头: {header.strip()}")

    # 轮询文件变化
    while True:
        try:
            current_size = os.path.getsize(csv_file)
            if current_size < file_size:
                # 文件被截断了（重新开始），重新定位
                print(f"  检测到文件被重置，重新开始跟踪")
                file_size = current_size
                with open(csv_file, 'r', encoding='gbk') as f:
                    f.readline()  # 跳过表头
                    file_size = os.path.getsize(csv_file)

            if current_size > file_size:
                # 有新数据写入
                with open(csv_file, 'r', encoding='gbk') as f:
                    f.seek(file_size)
                    new_lines = f.read()
                    file_size = current_size

                # 逐行发送
                for line in new_lines.strip().split('\n'):
                    line = line.strip()+',0'
                    if line:
                        data = (line + '\n').encode('utf-8')
                        sock.sendto(data, (target_host, target_port))
                        print(f"  UDP -> {target_host}:{target_port}: {line}")

            time.sleep(0.01)  # 10ms 轮询间隔

        except FileNotFoundError:
            print(f"  CSV 文件丢失，等待重新创建...")
            while not os.path.exists(csv_file):
                time.sleep(0.5)
            file_size = 0
            print(f"  CSV 文件重新出现，继续监控...")
        except KeyboardInterrupt:
            print(f"\n[UDP Forwarder] 已停止")
            break
        except Exception as e:
            print(f"  错误: {e}")
            time.sleep(0.5)

    sock.close()


if __name__ == '__main__':
    main()