import re

from fastapi import HTTPException

from .config import MCU_BAUD_RATE, MCU_SERIAL_PORT, MCU_WRITE_TIMEOUT
from .schemas import MCUWriteParams


MCU_CMD_PATTERN = re.compile(r"^bodeplot=-?\d+,-?\d+,-?\d+,-?\d+,-?\d+$")


def _serial_module():
    try:
        import serial
    except ImportError as exc:
        raise HTTPException(status_code=500, detail="MCU COM Port功能需要安裝 pyserial") from exc
    return serial


def write_mcu_command_response(params: MCUWriteParams):
    cmd = params.command.strip()
    if not MCU_CMD_PATTERN.fullmatch(cmd):
        raise HTTPException(status_code=400, detail="MCU 指令格式錯誤")

    target_port = (params.port or MCU_SERIAL_PORT).strip()
    if not target_port:
        raise HTTPException(status_code=400, detail="MCU COM Port不可為空")

    serial = _serial_module()
    payload = (cmd + "\r\n").encode("ascii", errors="strict")

    try:
        with serial.Serial(
            port=target_port,
            baudrate=MCU_BAUD_RATE,
            timeout=MCU_WRITE_TIMEOUT,
            write_timeout=MCU_WRITE_TIMEOUT,
        ) as ser:
            written = ser.write(payload)
            ser.flush()
    except serial.SerialException as exc:
        raise HTTPException(status_code=500, detail=f"MCU COM Port傳送失敗: {str(exc)}") from exc

    return {
        "status": "ok",
        "command": cmd,
        "port": target_port,
        "baudrate": MCU_BAUD_RATE,
        "bytes_written": int(written),
    }


def list_mcu_ports_response():
    _serial_module()
    try:
        from serial.tools import list_ports
    except ImportError as exc:
        raise HTTPException(status_code=500, detail="MCU COM Port清單功能需要安裝 pyserial") from exc

    ports = [
        {
            "device": port.device,
            "description": port.description or "",
            "hwid": port.hwid or "",
        }
        for port in list_ports.comports()
    ]

    return {
        "default_port": MCU_SERIAL_PORT,
        "baudrate": MCU_BAUD_RATE,
        "ports": ports,
    }