"""
1000 系列喷码机网口通讯封装
协议: STX(0x02) + 指令 + 数据 + ETX(0x03)
反馈: $XX 成功 / !XX 失败 (XX 为两位校验)
"""
import socket
from rest_framework.exceptions import ParseError

STX = b"\x02"
ETX = b"\x03"
LF = b"\x0a"


class CoderError(ParseError):
    pass


class CoderClient:
    def __init__(self, ip: str, port: int = 3100, timeout: float = 2.0):
        if not ip:
            raise CoderError("打码器IP未配置")
        self.ip = ip
        self.port = port
        self.timeout = timeout

    def _send(self, frame: bytes) -> bytes:
        try:
            with socket.create_connection((self.ip, self.port), timeout=self.timeout) as s:
                s.sendall(frame)
                return s.recv(64)
        except (socket.timeout, OSError) as e:
            raise CoderError(f"打码器通讯失败 {self.ip}:{self.port} - {e}")

    @staticmethod
    def _check_ack(resp: bytes):
        if not resp:
            raise CoderError("打码器无响应")
        head = resp[:1]
        if head == b"$":
            return True
        if head == b"!":
            raise CoderError(f"打码器返回失败: {resp!r}")
        raise CoderError(f"打码器响应不识别: {resp!r}")

    @staticmethod
    def _encode_payload(value: str, label: str) -> bytes:
        if any(c in value for c in ("\x02", "\x03", "\x0a")):
            raise CoderError(f"{label}含控制字符(STX/ETX/LF), 会破坏帧结构")
        try:
            return value.encode("latin-1")
        except UnicodeEncodeError as e:
            raise CoderError(f"{label}含喷码机不支持的字符: {e}")

    def update_field(self, field_name: str, content: str) -> bool:
        """更新用户区: 02 55 <field> 0A <content> 03"""
        frame = STX + b"\x55" + self._encode_payload(field_name, "用户区名") + LF + self._encode_payload(content, "喷印内容") + ETX
        return self._check_ack(self._send(frame))

    def select_message(self, message_name: str) -> bool:
        """选择信息: 02 4D <name> 03"""
        frame = STX + b"\x4d" + self._encode_payload(message_name, "信息名") + ETX
        return self._check_ack(self._send(frame))

    def get_status(self) -> bytes:
        """获取喷码机状态: 02 45 03"""
        return self._send(STX + b"\x45" + ETX)

    def send_raw(self, frame_str: str) -> bytes:
        """发送任意已拼好的帧字符串(不含 STX/ETX), 自动补头尾"""
        return self._send(STX + frame_str.encode("ascii") + ETX)